FIELD OF THE INVENTION

[0001] Embodiments of the present invention relate to a pulley for and in a wire saw device, a wire saw device, use of a wire saw device and a method for operating a wire saw device. More particularly, they relate to a pulley configured for a wire saw device, and a wire saw device for cutting or sawing hard materials such as blocks of silicon or quartz, e.g., for cutting silicon wafers, for a squarer, for a cropper or the like.

BACKGROUND OF THE INVENTION

[0002] Wire saw devices exist for cutting blocks or bricks, thin slices, e.g. semiconductor wafers, from a piece of hard material such as silicon. In such devices a stretched wire is fed from a spool and is both guided and tensioned by pulleys for guiding the wire in the cutting area. The wire that is used for sawing is generally provided with an abrasive material. As one option, the abrasive material can be provided as a slurry. This may be applied shortly before the wire touches the material to be cut. Thereby, the abrasive is carried to the cutting position by the wire for cutting the material. As another option, the abrasive can be provided on the wire with a coating. For example, diamond particles can be provided on a metal wire, e.g. with a coating, wherein the diamond particles are imbedded in the coating of the wire. Thereby, the abrasive is firmly connected to the wire.

[0003] Wire saw devices are used in a plurality of industrial fields such as semiconductor business or solar business. Thereby, throughput and costs of the manufactured articles are of steadily increasing consideration. For wire saw devices cutting of the hard material such as silicon needs to be done at very high precision, that is, within a few tens of microns or even microns and at a very high speed. Thereby, the wire is transported through the wire saw device at a very high speed and movable parts for cutting the material are moved with micron precision. The very high precision can not be provided if the wear of the components in the wire saw device is too large. Since these components need to be replaced or furbished up in order to provide the desired throughput and position, they need to be replaced on a regular basis at the production side where the wire saw device is operated. This can significantly increase the cost of ownership (COO) because the respective components need to be either on stock for immediate replacements or the wire saw device will not be in operation, for example during re-furbishing of the components.

[0004] Accordingly there is a desire to reduce the cost of ownership of a wire saw device and provide for easier maintenance while still providing the desired precision and throughput.

SUMMARY

[0005] In view of the above, a wheel unit for a rotating wire guide according to independent claim 1, a tire for a wire guide according to independent claim 3, a wire guide according to claim 11, a wire saw device according to claim 15, and a method of maintaining a wire guide according to independent claim 18 are provided. Further advantages, features, aspects and details are apparent from the dependent claims, the description and drawings.

[0006] According to one embodiment, a wheel unit for a rotating wire guide having a rotation axis is provided. The wire guide is configured for a wire saw device having a wire forming a wire web. The wheel unit includes an radially outer surface for receiving a wire guiding structure in a predetermined position, wherein the wheel unit comprises a fixation element for detachably connecting the wire guiding structure to the wheel unit.

[0007] According to a further embodiment, a tire for a wire guide being adapted for a wire saw device having a wire forming a wire web is provided. The tire includes a tire portion having a radially inner surface adapted to be received at a radially outer surface of the wire guide, wherein the tire portion comprises an engaging element adapted for engaging with a fixation element of the wire guide, and a wire guiding structure provided at a radially outer surface of the tire portion for guiding the wire.

[0008] According to a yet further embodiment, a wire guide configured for a wire saw device having a wire forming a wire web is provided. The wire guide includes a wheel unit having an radially outer surface for receiving a wire guiding structure in a predetermined position, wherein the wheel unit comprises a fixation element for detachably connecting the wire guiding structure to the wheel unit, and tire having a tire portion having a radially inner surface adapted to be received at a radially outer surface of the wire guide, wherein the tire portion comprises an engaging element adapted for engaging with a fixation element of the wire guide, and a wire guiding structure provided at a radially outer surface of the tire portion for guiding the wire.

[0009] According to yet an even further embodiment, a wire saw device is provided. The wire saw device is adapted for a wire forming a wire web. The wire saw device includes a wire guide including a wheel unit having an radially outer surface for receiving a wire guiding structure in a predetermined position, wherein the wheel unit comprises a fixation element for detachably connecting the wire guiding structure to the wheel unit, and tire having a tire portion having a radially inner surface adapted to be received at a radially outer surface of the wire guide, wherein the tire portion comprises an engaging element adapted for engaging with a fixation element of the wire guide, and a wire guiding structure provided at a radially outer surface of the tire portion for guiding the wire.

[0010] According to yet an even further embodiment, a method of maintaining a wire guide of a wire saw device having a wire forming a wire web is provided. The method includes providing a wire guide having a wheel unit and a tire, disconnecting the tire from the wheel unit, and connecting a further tire to the wheel unit.

[0011] Embodiments are also directed at apparatuses for carrying out the disclosed methods and including apparatus parts for performing each described method step. These method steps may be performed by way of hardware components, a computer programmed by appropriate software, by any combination of the two or in any other manner. Furthermore, embodiments according to the invention are also directed at methods by which the described apparatus operates. It includes method steps for carrying out every function of the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments. The accompanying drawings relate to embodiments of the invention and are described in the following:

FIG. 1 shows a schematic view of a wire saw device according to embodiments described herein; FIGS. 2A and 2B show a wire guide as it is commonly used in wire saw devices and an enlarged view of a portion of the wire guide;

FIG. 3 shows a perspective view of a wire management unit including the portion shown in previous Figures; and

FIG. 4A shows a schematic view of a wire guide according to embodiments described herein having a wheel unit and a tire;

FIG. 4B shows a schematic view of an enlarged portion of figure 4A;

FIG. 5 shows a schematic view illustrating yet further embodiments of wire guides according to embodiments described herein;

FIG. 6 is a schematic view of a tire for a wire guide according to embodiments described herein; and

FIG. 7 shows a flow chart illustrating a method of maintenance of a wire guide according to embodiments described herein.

DETAILED DESCRIPTION OF THE INVENTION

[0013] Reference will now be made in detail to the various embodiments of the invention, one or more examples of which are illustrated in the figures. Within the following description of the drawings, the same reference numbers refer to same components. Generally, only the differences with respect to individual embodiments are described. Each example is provided by way of explanation of the invention and is not meant as a limitation of the invention. Further, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield yet a further embodiment. It is intended that the description includes such modifications and variations.

[0014] Furthermore, in the following description a wire management unit will be understood as a device handling the supply of wire to a cutting area or working area of a wire saw device, such as a cropper, a squarer, or a wafer cutting wire saw. Typically, the wire saw includes a wire guide for transporting and guiding the wire in a wire moving direction while the wire management unit provides control of the wire tension. Furthermore, the wire provided by the wire management unit forms a wire web in the cutting area. Often, a wire web will be considered as the web formed by a single wire management unit. It should be understood that a wire web may contain more than one working area which is defined as an area in which a sawing process is performed. Thus, according to some embodiments described herein, a wire web can have multiple areas that are formed by a wire from different wire management units.

[0015] For modern wire saw devices like croppers, squarers, or wire saws, there is the desire to cut hard materials such as semiconductor materials, for example silicon, quartz, or the like at high speed. The wire speed, that is the speed of the wire moving through the wire saw device, the wire management unit and the material to be sawed, respectively, can be, for example, 10 m/s or higher. Typically, the wire speed can be in a range of 15 to 20 m/s. However, higher wire speeds of 25 m/s or 30 m/s can also be desirable and could be realized under certain conditions.

[0016] For unwinding the wire at the desired wire speed, the spool rotates with a rotation speed of up to several thousand rotations per minute. For example, 1000 to 2000 rpm can be provided for unwinding the wire.

[0017] Figure 1 shows a wire saw device 100. As can be seen from the pattern of the wire 10 forming the wire web in the wire web compartment 110, the example shown in figure 1 illustrates a squarer. The housing of the wire saw device is separated into different areas as indicated by the dotted line. The wire web is formed in the wire web compartment 110. Further, a housing portion 111, which houses further components and equipment of the wire saw device 100 is provided. For example, a wire handling device compartment 112 and an electrical cabinet 114 can be provided. Within the further housing portion 111, tanks 120 and 124 as well as respective pumps 121 and 125 can also be provided.

[0018] According to some embodiments, which can be combined with other embodiments described herein, the first tank 120 can be used for unused cooling fluid, e.g. in the case where the wire saw device is operated with diamond wire, or can be used e.g. for unused (fresh) slurry, in the case where the wire saw device 100 is operated with a wire requiring additional abrasive. The pump 121 pumps the cooling fluid (or slurry, respectively) towards the desired position in the cutting area. This is indicated in figure 1 by conduit 122. The used cooling fluid (or slurry) may flow back through conduit 126 and is pumped by pump 125 into the second tank 124. In those cases where cooling fluid or slurry is used, a portion of the used consumable fluid can be re-used if it is reinserted into the tank 120. Thus, according to different embodiments only a portion of the consumable fluid, all of the consumable fluid or none of the consumable fluid may be reused and, thus, be reinserted in tank 120. As one example, an additional valve might be provided in conduit 126 for selectively choosing the tank into which the used fluid is pumped. According to yet another example, a fluid connection between the tanks 124 and 120 can be provided in order to reinsert a portion of the used fluid in tank 120. According to different embodiments, as already described above, the consumable fluid can be cooling fluid or slurry. Generally, if slurry is used, the slurry also takes over the function of cooling the position at which the wire cuts the material.

[0019] In the wire handling compartment 112 two handling sections for delivering the wire 10 to the cutting area and receiving the wire from the cutting area, respectively, are provided. According to some embodiments, which can be combined with other embodiments described herein, the wire is provided on a spool 132 rotating around the spool axes 132a. The wire is guided over a plurality of rollers 134 into the wire web compartment 110. Further pulleys 134 and 136 guide the wire 10 into the cutting area to form the wire web. Thereby, further pulleys (not shown) are required to guide the wire 10 from one pulley 136 to a further pulley 136. In order to avoid unnecessary complexity, these further pulleys are not shown in figure 1. After cutting, the wire is guided by a further pulley 134 towards the wire handling compartment 112 and is therein provided over pulleys 134 on the spool 130 rotating around the spool axes 130a.

[0020] According to yet further embodiments, which can be combined with other embodiments described herein, the wire handling system can be adapted for bi-directional use, such that in one direction the wire is fed from spool 132 to spool 130 and in a further direction, the wire is fed from spool 130 to spool 132. Thereby, according to typical implementations the two units corresponding to spools 130 and 132 include similar components such as pulleys or the like to have a corresponding wire handling in both sawing directions. The bi-directional use of the wire saw device may be of particular interest if diamond wire is used.

[0021] Typically, the wire is guided from the wire handling compartment to the wire cutting area and back with a wire speed of 10 m/s or higher, typically in a range of 15 to 20 m/s. or even up to 25 m/s or 30 m/s. The material to be cut is positioned on the support 140. The support 140 and the wire web defined by pulleys 136 can be moved relative to each other such that the cutting of the material can be conducted. According to one embodiment, the pulleys 136 maintain in a fixed position and the support 114 moves the material to be cut through the wire web while the wire is at a speed of about 10 m/s or higher. For easier understanding, this movement of the support 140 would in figure 1 be perpendicular to the plane of the drawing. According to another embodiment, the pulleys 136 and, thus, the web generated by wire 10 is moved relative to the support 140 to cut the wire through the material. According to yet further embodiment, both the support 140 and the wire web can be both moved with respect to each other.

[0022] As indicated by the dotted lines in figure 1 the electrical cabinet 114 may serve to control the operation of the different components. For example, movement of the support 140, operation of the pumps 121 and 125, rotation of the spools 130 and 132 can be controlled. Further, additionally or optionally, the filling level of the tanks 120 and 124 can be measured and respective signals can be fed into the control unit. According to yet further embodiments, other control signals and monitoring signals can be fed to and from the electrical cabinet 114. For example signals from the motors driving the spools, from a wire tensioner, to a wire tensioner, pressure signals for feeding the consumable fluids like slurry or cooling fluid, or a wire break detection signal can be fed to and from the electrical cabinet. Even though an electrical cabinet 114 integrated in a wire saw device 100 is shown in figure 1, it is apparent to a person skilled in the art that an electrical cabinet or a control unit in general can be provided at a different location in the wire saw device, e.g., also external of the wire device, and corresponding control signals from and to the control unit can be provided accordingly.

[0023] The pulleys 136, which are provided on one side of the support 140, are typically connected by a common axis 152 such as a tube, a pipe, a rod or the like. Thereby, synchronous rotation of the pulleys 136 during sawing of the material with the wire 10 can be provided. The pulleys 136 with the axis 152 thereby form a wire guide 150 for the wire web. In order to form the web with high precision the pulleys are typically provided with one or more grooves for guiding the wire in the groove. According to some embodiments, as for example shown in figure 1, four wire guides 150 are provided in the wire saw device 100.

[0024] Wire guides 150, which are commonly used for example with a squarer, are illustrated with respect to figures 2A and 2B. Figure 2A shows the axis 252 and the pulleys 136 which are provided with a wheel portion 256 and a wire guiding portion 254. As can be seen from the enlarged view in figure 2B the wheel portion 256 and the wire guiding portion 254 are a one-piece assembly wherein grooves 258 are machined in the wire guiding portion 254. [0025] The wire, which is guided under tension at high speed in the wire saw device, wears out the grooves 258 during use of the wire saw device. For this reason, a plurality of grooves can be provided such that the wire can be moved to a different, for example an adjacent groove when the first groove can not be used anymore. Typically the wire needs to be moved to another groove if the wear of the groove does not allow for the desired precision anymore. After all grooves 258 are worn out, the wire guide 150 is typically moved out of the wire saw device and the wire guiding structure is re-grooved or the wire guiding structure 254 is re- coated and re-grooved thereafter.

[0026] In order to reduce the downtime of a wire saw device typically three sets of wire guides are used for each wire saw device. One set, that is for wire guides for the example of squarer shown in FIG. 1, is in use for operation, one set of wire guides is presently refurbished by re-coating and/or re-grooving, and a third set of wire guides is on stock waiting for the next required exchange during maintenance.

[0027] The additional sets of wire guides, the costs for refurbishing and the transportation costs associated with the external refurbishing provide a contribution to the cost of ownership which can not be neglected during production.

[0028] In light of the above, according to embodiments described herein, improved wire guides are provided, which reduce the maintenance effort and the cost of ownership. According to embodiments described herein, a wheel unit and a separate tire having the wire guiding structure manufactured therein are provided such that the tire can be detachably connected with the wheel unit and, thus, the wire guide.

[0029] According to different embodiments, a wire saw device can be a cropper, a squarer, a wire saw or a multiple wire saw. Thereby, a cropper is to be understood as a device, which can be used to saw end pieces from bricks or blocks, which have been separated into bricks in a squarer. A squarer is a wire saw that generally saws the silicon ingot into squares of the desired size such that a wire saw or a multiple wire saw can saw wafers from the bricks in a wafering process. The wire management unit herein is particularly useful for the wire saw device being a squarer, but not limited to a squarer.

[0030] The above-described systems are particularly useful if thin wires or wires with a coating, e.g. a diamond coating, are used. Accordingly, in embodiments, which can be combined with other embodiments described herein, the wire handling sections and wire saw devices described herein are adapted for thin wires having a diameter below about 400 μιη, such as diameters between about 200 μιη and about 400 μιη, more particularly between about 200 μιη and about 300 μιη. However, in other cases embodiments may also have a wire diameter as low as for example 100 μιη or even 80 μιη. Further, the wire handling sections and wire saw devices described herein are adapted for coated wires, for example a wire having a nickel coating with diamond particles embedded therein. Such wires may typically have a diameter of about 300 μιη to about 400 μιη, e.g. 310 μιη to 340 μιη. For those wires a twisting of the wire might increase the risk of breaking of the wire or of damaging the coating, so that a twist- free operation is advantageous. By using diamond wire, the throughput may be increased by a factor of 2 or even more. In the case of a squarer, throughput rates of 100MW or even more can be achieved in this manner. When a diamond wire is used, further parts of the wire saw may be adapted to the diamond wire. For example, mechanical parts, electrical parts and / or software may be adapted to the use of diamond wire.

[0031] Typically, embodiments of wire guides described herein are adapted or configured for wire saw devices, they can be used in wire saw devices and/or can be a part of a wire saw device. Besides other aspects that can be used for making the pulley adapted or configured for a wire saw device, the pulley can have a groove structure which is made to guide a wire with a thickness of 400 μιη or below, or a thickness of any of the other diameters mentioned above. Thereby, it has to be noted that the groove structure is designed specially for the wire diameter and the cutting process in order to allow for a high precision cutting, e.g. with a precision of 250 μιη or below, or even of 50 μιη or below.

[0032] In the following, yet further embodiments are described, whose elements can be combined with any elements of other embodiments described herein. Within the following description, only those elements will be described, which deviate from those of previous or other embodiments described herein. It is to be understood that components, aspects and details described with respect to other embodiments can as well be applied to those embodiments which do not describe all components, aspects or details.

[0033] Fig. 3 shows a perspective view of a wire management unit according to some embodiments, which can be combined with other embodiments described herein. The embodiment of Fig. 3 includes a spool 312, mounted on spool shaft 310, and the pulleys 320,

330 and 340 are arranged to guide the wire, particularly with a wire tracking system.

Examples of a wire tracking system are described in European patent application No.

09153051.9, entitled "Wire saw device and method for operating same" filed February 17, 2009, which is incorporated herein by reference to the extent the applications are not inconsistent with this disclosure. Additionally, a recess 116 can be seen. The recess 116 is provided in the main frame portion. The recess is dimensioned and arranged for accommodating at least partially the first pulley 220. This recess allows the first pulley 220 and, hence, the spool 212 to be arranged closer to the main frame portion while still allowing the first pulley 220 motion track to cover most or all of the wire carrying area 213a. Further, the pulley carrying unit 224 is provided as a retractable or telescopic bar. The retractable or telescopic bar is longitudinally movable along a bar axis parallel to the spool axis. The bar is longitudinally movably mounted to a wall portion of the main frame portion, e.g. of a wall portion of the recess 116.

[0034] Further, in the embodiment of Fig. 3 the main frame portion includes a mounting member 114, to which the second and third pulley 230 and 240 are mounted. The mounting member 114, being part of the main frame portion, is rigidly connected to the chassis of the wire saw device. While other designs of the mounting member are possible in the specific embodiment of Fig. 3, the mounting member is a bar, more specifically an L-shaped bar with a first leg 114a extending to a side surface of the main frame portion (i.e. extending parallel to the x axis), and with a second leg 114b forming an essential right angle with the first leg and extending to a top surface of the main frame portion (i.e. extending parallel to the z axis). Independently from the shown embodiment, it is a general aspect that the first pulley 220 and the second pulley 230 (and, if present, optionally also other pulleys such as a third and / or fourth pulley) are mounted on a common mounting member, especially on a one-piece mounting member.

[0035] Further, a fourth pulley 350 is shown. The fourth pulley 250 receives the wire from the third pulley and redirects the wire by a fourth redirection angle. The fourth pulley 250 is rotatably mounted to the frame for rotation around a fourth pulley axis. Here, the fourth redirection angle is about 90°. In other embodiments, the fourth redirection angle may be between 60° and 120°. The fourth pulley axis is essentially parallel to the spool axis 212a. Further, the fourth pulley axis is essentially perpendicular to the first pulley axis, the second pulley axis, and the third pulley axis. In other embodiments, the fourth pulley axis may be essentially parallel to at least one of these axes.

[0036] The embodiment of Fig. 3 further includes a wire tensioner for controlling the tension of the wire. The wire tensioner includes a fifth pulley 360 rotatably mounted to the frame for rotation around a fifth pulley axis 362 and a sixth pulley 370 rotatably mounted to a movable element 374 for rotation around a sixth pulley axis 372. The movable element 374 is movably mounted on the main frame portion. The movement of the movable element 374 may be controlled by a motor, or the movable element3274 may be pre-biased e.g. by a spring, for controlling the wire tension. In Fig. 3, the movable element 374 is shown as a pre-biased swivel lever. The wire tensioner receives the wire 10 from the fourth pulley 350 and provides the wire 10 to the wire web (to the right of the wire management unit shown in Fig. 3). More precisely, the fifth pulley 360 receives the wire 10 from the fourth pulley 350 and deflects the wire by a fifth deflection angle, and then the sixth pulley 360 receives the wire 10 from the fourth pulley 350 and deflects the wire by a sixth deflection angle.

[0037] With the x-y-z reference frame defined above, it is a general aspect, illustrated in the embodiment of Fig. 3, that at least one condition (and in some embodiments, even all conditions) selected from the following list is satisfied:

the wire tensioner is on a side of the spool 312 essentially opposite to the first pulley 320; the wire between the fourth pulley and the wire tensioner, more specifically between the fourth and the fifth pulley, extends primarily along the z axis;

the wire between the fifth pulley and the sixth pulley extends primarily along the y axis; the wire leaves the sixth pulley essentially parallel to the y axis;

the fifth and sixth pulley having respective axes each extending essentially in the x direction;

the fifth redirection angle is in the range of about 60° to 90°, especially in the range of about 80° to 90°; and / or

the sixth redirection angle is about 180°.

[0038] Generally, in embodiments which may be combined with other embodiments herein, the pulleys have at least one and in embodiments all of the following radiuses: The spool shaft 310 has a diameter of about 150 mm. The first pulley 320 and the second pulley 330 have a diameter of between 100 mm and 150 mm, especially of 112 mm (here, the diameter means the diameter observed by the wire, i.e. diameter within the wire guiding groove). The third pulley 340 has a diameter of between 140 and 170 mm, especially of 158 mm. The fourth pulley 350 has a diameter similar to the first pulley 320. The fifth 360 pulley and the sixth 370 pulley have a diameter similar to the third pulley 340.

[0039] Continuing the description of Fig. 3, besides the wire handling section 300, which in the following will also be called primary wire handling section 300, the wire management unit of Fig. 3 also has a secondary wire handling section 300b. Here, the terms "primary" and "secondary" are introduced for ease of identification, and do not imply any hierarchical or functional order of the wire handling sections, spools etc. The secondary wire handling section 300b is constructed similarly to the primary wire handling section 300 and has corresponding elements to the elements of the primary wire handling section 300. The elements of the secondary wire handling section 300b are denoted as "secondary" elements and assigned reference signs 310b, 312b etc. corresponding to the corresponding "primary" elements 310, 312 etc. of the primary wire handling section 300. Thus, the secondary wire handling unit 300b has e.g. a secondary spool shaft 310b for a spool 312b, a secondary first pulley 320b, a secondary second pulley 330b etc. The secondary first pulley 320b is rotatably mounted to a secondary pulley carrying unit 324b for rotation around a secondary first pulley axis 322b, the secondary pulley carrying unit being longitudinally movable along a secondary pulley motion track. The primary and the secondary wire handling sections 300, 300b are placed in y direction adjacent to each other. As a general aspect illustrated by but independent of the shown embodiment, the primary and the secondary wire handling sections 300, 300b may be placed on a common wall portion of the main frame portion. Further, the primary and the secondary wire handling sections 300, 300b may be placed in a common compartment of the wire saw device. Further, it can be seen that in Fig. 3, the primary spool 312 is of a different type than the secondary spool 312b (as can be seen from the absence of slits in the front flange of the secondary spool 312b).

[0040] Generally, the secondary wire handling section 300b is formed in the same manner as the wire handling section 300 according to any embodiment described herein. The description of elements of the primary wire handling section 300 is therefore also applicable to the corresponding elements of the secondary wire handling section 300b.

[0041] In an example mode of operation, henceforth called primary-to-secondary-spool sawing, the primary wire handling section provides wire from the primary first spool 312 to the web 10, so that the wire can be used for sawing in the web. Then, the secondary wire handling section 300b receives the wire 10 from the web. Thereby, the wire 10 is transported from the web to the secondary wire tensioner, more precisely to the secondary sixth pulley 370b and then to the secondary fifth pulley 360b, from there to the secondary fourth pulley 350b, from there to the secondary third pulley 340b, from there to the secondary second pulley 330b, from there to the secondary first pulley 320b, and from there finally is wound onto the spool 312b. Further, a controller controls the motion of the secondary first pulley 320b along the secondary pulley motion track so that the wire is wound in a controlled manner onto the wire carrying area of the secondary spool 312b.

[0042] For receiving the wire, a secondary first pulley controller includes a wire winding pattern and is programmed to determine a desired wire winding position for winding the wire on the wire carrying area of the secondary spool, and transmits a moving command to the secondary first pulley moving device 324b for causing the secondary first pulley moving device 324b to move the secondary first pulley 320b to the desired wire winding position.

[0043] The secondary second pulley 330b redirects the wire by about 180°, and the secondary first pulley redirects the wire by about 90°. Due to the large secondary second pulley 330b redirection angle, sharp tensions and vibrations during winding of the wire are avoided, as explained above, so that the wire can be securely wound with reduced risk of wire damage. Therefore, the secondary second pulley 330b may redirect the wire by no less than 60°, and the secondary first pulley redirects the wire by no more than 120°.

[0044] Generally, the spools in which new wire is provided are of a different type (say, a first spool type) than the spools onto which the used wire is wound (say, a second spool type). For example, the spools in which new wire is provided may be disposable spools from a wire manufacturer. Such spools may, on the other hand, be unsuitable for receiving used wire because they sometimes do not withstand the high wire tension of the used wire. In order to support these different spool types during primary-to-secondary-spool sewing, the primary spool shaft (i.e. the spool shaft of the primary wire handling section) may be adapted for carrying a spool of first type, and the secondary spool shaft (i.e. the spool shaft of the secondary wire handling section) is adapted for carrying a spool of second type, i.e. the second type being different from the first type.

[0045] Also, in some embodiments, which can be combined with any other embodiment herein, the wire management section may support bidirectional sawing. Herein, bidirectional sawing is understood to be a sawing process during which first the wire is transported from the primary spool to the secondary spool, and thereafter is transported back from the secondary spool to the primary spool, and again from the primary spool to the secondary spool etc. Thus, for bidirectional sawing the (primary) spool 312 is adapted for providing wire to the wire web and is also adapted for receiving used wire from the wire web. Likewise, a secondary spool 312b may be adapted for providing wire to the wire web and is also adapted for receiving used wire from the wire web. [0046] For the bidirectional sawing, a controller is adapted for sending actuating commands to the primary spool shaft and to the secondary spool shaft, the actuating commands causing, in a first step, the first spool shaft to unwind wire to the second spool, and causing, in a second step, the second spool shaft to unwind wire to the first spool.

[0047] The above-described arrangements of the pulleys are particularly useful if thin wires or wires with a coating, e.g. a diamond coating, are used. Accordingly, in embodiments, which can be combined other embodiments described herein, the wire handling sections and wire saw devices described herein are adapted for thin wires having a diameter below about 400 μιη, such as diameters between about 200 μιη and about 400 μιη, more particularly between about 200 μιη and about 300 μιη. However, in other cases embodiments may also have a wire diameter as low as for example 100 μιη or even 80 μιη. Further, the wire handling sections and wire saw devices described herein are adapted for coated wires, for example a wire having a nickel coating with diamond particles embedded therein. Such wires may typically have a diameter of about 300 μιη to about 400 μιη, e.g. 310 μιη to 340 μιη. For those wires a twisting of the wire might increase the risk of wire breakage or of damaging the coating, so that a twist- free operation is advantageous. By using diamond wire, the throughput may be increased by a factor of 2 or even more. In the case of a squarer, throughput rates of 100MW or even more can be achieved in this manner.

[0048] When a diamond wire is used, further parts of the wire saw may be adapted for the diamond wire. For example, mechanical parts, electrical parts and / or software may be adapted for the use of diamond wire.

[0049] Embodiments relating to wire guides, wheel units and tires will now be described with respect to figures 4A and 4B. Figure 4A shows a wire guide 400. Figure 4B shows an enlarged view of a portion of figure 4A as indicated in the drawings. The wire guide 400 has an axis 252. The axis 252 can, for example be a rod, a tube, a pipe or the like. The pulleys 436 are mounted on the axis 252. According to some embodiments, which can be combined with other embodiments described herein, one or more pulleys 436 can be mounted to the axis 252. Typically, there can be four or more pulleys or there can be 2 to 12 pulleys, such as for example 4 to 8 pulleys. In the example shown in figure 4A six pulleys 436 are provided.

[0050] Each of the pulleys 436 includes a wheel unit 456 and a wire guiding unit such as a tire 460. As shown in figure 4B the wheel unit 456 has a radially outer surface 457. The radially outer surface 457 is adapted for receiving the tire 460. Thereby, the tire 460 has a radially inner surface 461 to be in contact with the surface 457.

[0051] Thereby, according to some embodiments, which can be combined with other embodiments described herein, the radially outer surface 457 of the wheel unit 456 is essentially flat in a direction parallel to the axis 252. This means, the wheel unit 456 does not have a wire guiding structure such as grooves or the like. To the contrary, the surface is adapted to receive the tire 460. According to yet further embodiment, which can be combined with other embodiments described herein, the radially outer surface 457 of the wheel unit 456 can have a bow, a step, a curvature, or the like along the direction parallel to the axis 252. However, this curve or step is not formed as a wire guiding groove or the like. For example it can be described such that the first derivation of the curvature does not change the sign, that structures like steps have the size of at least 4 mm in a direction parallel to the axis 252, and/or that these structures are not recesses with a fine tip such as a groove.

[0052] As shown in figure 4B, according to some embodiments, protrusions 457 such as a rim, an alignment element or the like can be provided. Thereby, the tire 460 can be detachably connected with the wheel unit 456 in a predetermined position, wherein small tolerances can be provided. The small tolerances allow for the desired precision in forming the wire web of the wire saw device. According to different embodiments, which can be combined with other embodiments described herein, a tolerance of ±150 μιη or less for positioning the wire can be provided both in axial and radial directions. Typically, a tolerance can be in the direction parallel to the rotation axis ± 10 μιη to ± ΙΟΟμιη, more typically ±30 μιη to ±70 μιη. According to yet further optional or alternative implementations, in a radial direction, typically a tolerance of ± 5 μιη to ± 60μιη, more typically of ± 10 μιη to ± 30μιη can be provided.

[0053] According to embodiments described herein, a tire 460 is provided radially outward of the wheel unit 456. Thereby, the tire 460 has a wire guiding structure 468, for example one or more grooves. According to different embodiments, for example 4 to 20, e.g. 7 to 15 grooves can be provided.

[0054] Accordingly, no wire guiding portion 254 shown in figure 2B which is provided by a grooved coating that can be refurbished by re-grooving or by re-coating and re-grooving is provided. According to embodiments of wheel units, tires and wire guides, which are described herein, a tire receiving wheel unit or a tire that can be replaced with high precision in its entirety is provided. Thereby, the used and potentially worn out tire can be replaced after use with a new tire. Thereby, according to some embodiments, which can be combined with other embodiments described herein an adjustment from the maintenance person is not required since the wire guide is designed such that an automatic adjustment of the tire on the wheel unit is provided. This can for example be done by adjustment elements like corresponding protrusions and recesses, by rims as shown in figure 4, or as shown in FIG. 5 which is described in more detail below.

[0055] In light of the above, the replacement tire can be configured as a disposable product, that is, a product manufactured for a single use only. The tire can thereby be already grooved before mounting the tire on the wire guide. Thus, the wire guide does not need to be shipped to a different factory for re-coating and/or re-grooving. This can reduce the need for a plurality of sets of wire guides, maintenance time and transportation effort and results thereby in a more attractive cost of ownership. Typically, if maintenance times should be minimized, the number of sets of wire guides might be reduced from three sets to two sets, wherein one set will be provided with new tires while the other set is in operation.

[0056] According to some embodiments, which can be combined with other embodiments described herein, the tire can be a plastic tire for example for single operation or disposable. Typically, the tire can have the shape of a ring as described in more detail below with respect to figure 6. Thus, a removable, detachably connectable and/or replaceable coating for the pulley can be provided.

[0057] The embodiments described herein allow an operator of a wire saw device further an improved control of replacement of the tire, wherein potential delays due to transportation or the like can be avoided or reduced. Further, the transportation costs are reduced because shipment of the tires themselves is sufficient. As a yet further option, a new configuration of the wire saw device, for example changing from a wire with first diameter to a wire with a second different diameter or changing from a first type of wire, e.g. using slurry, to a diamond wire or vice versa can be more easily implemented by the operator. The different types of wires generally require a different pitch of grooves, a different depth of grooves and/or a different shape of grooves. Thus, according to some embodiments, which can be combined with other embodiments described herein, the pitch, the depth, and/or the shape of the wire guiding structure grooves can be changed by exchanging the tires of the wire guide.

Accordingly, different sets of wire guides, which might be on stock for providing different grooving structures at an operation site, can also be avoided because the groove structure with different pitch, depth and/or shape of the grooves can more easily be provided by providing a different tire type with a different grooving.

[0058] Further embodiments, which can be combined with other embodiments described herein, are now described with respect to figure 5. In figure 5, one wheel unit 556 is mounted to an axis 252. The wheel unit has a radially outer surface 557 for receiving a wire guiding structure, a detachably connectable coating with a wire guiding structure, such as the tire 460 with the grooves 468 forming the wire guiding structure. The tire portion has a radially inner surface 461 configured to be received by the radially outer surface 557 of the wheel unit 556. Further, an engaging element 462 is provided. According to some embodiments, as shown in figure 5, the engaging element can be a protrusion. However, according to yet further embodiments, the engaging element can be a recess, an opening or another structure into which the fixation element can engage such that the tire 460 is detachably connected to the wheel unit 556. According to yet further embodiments, the fixation element 510 can be a clamping device as shown in figure 5, which gets in contact with the engaging element such as the protrusion 462. As already described above, according to some embodiments, which can be combined with other embodiments described herein, the wire guiding structure, illustrated by reference number 464 in figure 5, can be a plurality of grooves 468. Thereby, the tire 460 has a wire guiding structure. According to different embodiments, for example 4 to 20, e.g. 7 to 15 grooves can be provided.

[0059] Figure 6 illustrates embodiments of a tire as described herein. Thereby, it is to be understood, that a wheel unit and the tire are interrelated components, which are used to form a wire guide according to yet further embodiments described herein. The tire 460 has the wire guiding structure 464 the engaging element 462, for example provided as a protrusion on the respective sides in a direction parallel to the rotation axis, and a radially inner surface to be in contact with the wheel unit. Typically, according to some embodiments, the tire can be provided as a plastic tire wherein grooves are already provided when delivered for operation. Accordingly, the replacement tire can be configured as a disposable product, that is, manufactured for a single use only. The tire can thereby be already grooved before mounting the tire on the wire guide. Thus, the wire guide does not need to be shipped to a different factory for re-coating and/or re-grooving. This can reduce the need for a plurality of sets of wire guides, maintenance time and transportation effort and results thereby in a more attractive cost of ownership. Typically, if maintenance times should be minimized, the number of sets of wire guides might be reduced from three sets to two sets, wherein one set will be provided with new tires while the other set is in operation.

[0060] According to yet further embodiments, which can be combined with other embodiments described herein, the tire 460 can be provided as a ring with an opening 612, that is the tire is an opened ring. Thereby, the tire can be more easily positioned to be located radially outward of the outer surface of the wheel unit before detachably connected to the wheel unit. Thereby, the opening 612 is to be understood as an interrupted ring. For example the interruption can be as small as 1 mm or below such as for example 0.3 to 0.7.

[0061] In light of the above, an operator of a wire saw device can reduce the number of sets of wire guides which need to be on stock fur minimized downtime of the wire saw device and can conduct improved maintenance procedures. Embodiments of methods of maintaining a wire saw device or a wire guide according to embodiments described herein are illustrated in the flowchart shown in figure 7. Thereby, potentially required maintenance steps that are not related to the wire guide are not taking into consideration. Accordingly, maintenance of the wire guides is described. Generally, according to embodiments of maintaining a wire guide as described herein, the tire, which is provided detachably on the wire guide, can be disconnected from the wire guide or the wheel unit, respectively, and a further tire, such as a new tire with the sufficient grooving structure, that is a wire guiding structure, is connected to the wire guide. As shown in figure 7, maintenance starts in step 702. Generally, for dismounting the wire guides in step 706 the wire web can be removed in step 704. After the wire guide has been dismounted from the wire saw device, the used wire guiding structure, which is detachably connected, can be removed in step 708 and a new wire guiding structure is installed in step 710 by detachably connecting the new wire guiding structure with the wire guide. According to typical embodiments, a disposable tire such as plastic tire with the desired groove structure can be removed in step 708 and replaced by the new disposable tire in step 710. Accordingly, the wire guide is ready for new operation after step 710. The wire guide can be mounted in the wire saw device in step 712, a new web can be generated by feeding the wire through the desired pulleys and over the appropriate wire guiding structures in step 714, and production can be re-started in step 716.

[0062] According to yet further embodiments, which can be combined with other embodiments described herein, downtime of the system can be further reduced if a second set of wire guides is provided at the operation facility. As indicated in step 718 in figure 7, after dismounting the wire guide in step 706, the first set of wire guides can be replaced by the second set of wire guides in step 718 and the second wire guide can be mounted in the wire saw device in step 712. In parallel to production of step 716 or at another appropriate time, the tires can be replaced on the first set of wire guides as described above with respect to step 708 and 710.

[0063] In the following, some general aspects of the embodiments described herein will be summarized. Each of these general aspects can be combined with any other general aspect, within any embodiment described herein, to generate yet another embodiment.

[0064] According to one embodiment, a wheel unit for a rotating wire guide having a rotation axis is provided. The wire guide can be configured for a wire saw device having a wire forming a wire web. The wheel unit includes a radially outer surface for receiving a wire guiding structure in a predetermined position, wherein the wheel unit comprises a fixation element for detachably connecting the wire guiding structure to the wheel unit. Thereby, as an optional implementation, the radially outer surface can be essentially flat in a direction parallel to the rotation axis, can have a convex or concave curvature in the direction parallel to the rotation axis, can have a convex or concave step structure in the direction parallel to the rotation axis, or a mixture thereof. Thereby, the radially outer surface does not have a groove, grooves, a groove structure, all of which being adapted for the wire in the wire saw device.

[0065] According to another embodiment, a tire for a wire guide being adapted for a wire saw device having a wire forming a wire web is provided. The tire includes a tire portion having a radially inner surface adapted to be received at a radially outer surface of the wire guide, wherein the tire portion comprises an engaging element adapted for engaging with a fixation element of the wire guide, and a wire guiding structure provided at a radially outer surface of the tire portion for guiding the wire. According to typical alternative or additional implementations thereof, one or more of the following aspects can be provided: the wire guiding structure can be a plurality of grooves, for example 5 to 30 grooves, typically 7 to 20 grooves are provided; the grooves can have a groove pitch of 0.5 mm to 4 mm, typically, 1 to 3 mm; and the pitch can have a tolerance of ± 1 μιη to ± 10 μιη, typically ± 2 μιη to ± 5 μιη. According toy et further embodiments, which can be combined with the other embodiments described herein, the tire can consist essentially of plastic material; the tire portion is an opened ring; the engaging element can be two protrusions extending along the circumference of the rim unit on opposing sides of the rim unit; and/or the tire can be configured for diamond wire. [0066] For some embodiments, which can be combined with other embodiments described herein, a wire saw device and/or a wire guide for a wire saw device can be adapted for diamond wire, and methods of operating can be performed with diamond wire. This can, for example, be done by adapting the groove structure with an appropriate pitch of grooves, a different depth of grooves and/or a different shape of grooves. By using diamond wire, typically the cutting speed can be increased, e.g., by a factor of 2, the energy consumption of the wire saw device can be reduced and, further, as yet another example, the costs of squaring silicon ingots or wafering silicon can be significantly reduced.

[0067] According to a yet further embodiment, a wire guide configured for a wire saw device having a wire forming a wire web can be provided. The wire guide includes a wheel unit according to embodiments described herein and a tire according to embodiments described herein. According to typical alternative or additional implementations thereof, one or more of the following aspects can be provided: at least 4 wire guides, typically 6 to 10 wire guides and a corresponding number of tires can be provided; alignment elements can be provided at the wheel unit and the tire such that the predetermined position has a tolerance of ±150 μιη or less in the direction parallel to the rotation axis, typically of ± 10 μιη to ± ΙΟΟμιη, more typically of ±30 μιη to ±70 μιη, and has a tolerance of ±150 μιη or less in the radial direction, typically of ± 5 μιη to ± 60μιη, more typically of ± 10 μιη to ± 30μιη; and the fixation element and the engaging element can be provided such that the predetermined position has a tolerance of ±150 μιη or less in the direction parallel to the rotation axis, typically of ± 10 μιη to ± ΙΟΟμιη, more typically of ±30 μιη to ±70 μιη, and has a tolerance of ±150 μιη or less in the radial direction, typically of ± 5 μιη to ± 60μιη, more typically of ± 10 μιη to ± 30μιη in a radial direction.

[0068] According to a yet further embodiment, a wire saw device is provided. The wire saw device includes at least one wire guide or at least four wire guides according to embodiments described herein. For example, the wire saw device can be an element selected from the group consisting of a wire saw, a multiple wire saw, a squarer, and a cropper.

[0069] According to an even further embodiment, a method of maintaining a wire guide of a wire saw device having a wire forming a wire web is provided. The method includes providing a wire guide having a wheel unit and a tire, typically a wire guide according to embodiments described herein, disconnecting the tire from the wheel unit, and connecting a further tire to the wheel unit. Thereby, according to yet further additional or alternative implementations, the further tire can be essentially unused; the disconnecting and the connecting can be conducted at the site of the wire saw device; and/or during the connecting the tire is automatically aligned with a tolerance of ±150 μιη or less in the direction parallel to the rotation axis, typically of ± 10 μιη to ± ΙΟΟμιη, more typically of ±30 μιη to ±70 μιη, and with a tolerance of ±150 μιη or less in the radial direction, typically of ± 5 μιη to ± 60μιη, more typically of ± 10 μιη to ± 30μιη in a radial direction.

[0070] According to a further aspect, a wire management unit can include a first pulley wire tracking system allowing actuation of a first pulley moving device in response to a detected wire position. According to a further aspect, the first pulley wire tracking system includes: a first pulley moving device being at least one element selected from the group of a linear actuator, a linear motor, a pneumatic cylinder, and a motor with a worm drive; a wire position detection device adapted for detecting the wire position along the direction of the motion path; a first pulley position controller being operatively connected to the wire position detection device for receiving the detected wire position, and being adapted for determining a target position, and being operatively connected to the first pulley moving device for transmitting a moving command thereto for causing the first pulley moving device to move the first pulley to the target position.

[0071] According to a further aspect, the wire management unit is adapted for the wire being a diamond wire, i.e. including diamonds. According to a further aspect, a main frame portion is rigid, and rigidly connectable or connected or integral with the chassis of the wire saw device.

[0072] According to a further aspect, a spool is adapted for providing wire to the wire web and is also adapted for receiving used wire from the wire web. According to a further aspect, the spool has a wire carrying area, and the first pulley position controller includes a wire winding pattern and is programmed for determining a target position, and being operatively connected to the first pulley moving device for transmitting a moving command thereto for causing the first pulley moving device to move the first pulley to the target position. According to a further aspect, the wire handling section is a primary wire handling section, the wire management unit further including a secondary wire handling section. According to a further aspect, the primary wire handling section has a spool shaft that is adapted for carrying a spool of first type, and the secondary wire handling section has a spool shaft that is adapted for carrying a spool of a second type. [0073] According to a further aspect, a wire saw device is provided, the wire saw including a wire management unit according to any one of the embodiments described herein, wherein the main frame portion is rigidly connected to a chassis of the wire saw device. According to a further aspect, the wire saw device is an element selected from the group consisting of a wire saw, a multiple wire saw, a squarer, and a cropper. The present pulleys, wire management units and wire handling units can be particularly useful for a squarer.

[0074] While the foregoing is directed to embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.