Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
WIRE MANAGEMENT SYSTEM FOR A WIRE SAW AND METHOD OF OPERATING A WIRE SAW WITH SUCH A SYSTEM
Document Type and Number:
WIPO Patent Application WO/2020/026134
Kind Code:
A1
Abstract:
The invention relates to a wire management system (7) for a wire saw (8) comprising - a control device (30), - a wire supplying side (5), - a wire receiving side (6), wherein the wire supplying side (5) and/or the wire receiving side (6) comprise(s) a controllable tensioner (20, 31) for adjusting the tension of cutting wire (3) and a traveler pulley drive (32) for moving a traveler pulley (4) along the rotational axis of a storage spool (2), characterized in that a pulley sensor (33) is provided for measuring a force acting on the traveler pulley (4) in a direction which is transverse to the rotational axis of the traveler pulley (4) and that the control device (30) is configured to control the tensioner (20, 31) and the traveler pulley drive (32) each in dependence of the sensor data of the sensor (33) of that wire side (5, 6).

Inventors:
FRECH GREGOR (CH)
WENGER MARKUS (CH)
Application Number:
PCT/IB2019/056482
Publication Date:
February 06, 2020
Filing Date:
July 30, 2019
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
PREC SURFACING SOLUTIONS GMBH (CH)
International Classes:
B28D5/04; B23D57/00; B28D5/00
Domestic Patent References:
WO2013011854A12013-01-24
WO2014087340A22014-06-12
WO2014087340A22014-06-12
Foreign References:
JP6256870B22018-01-10
Attorney, Agent or Firm:
PATENTBÜRO PAUL ROSENICH AG (LI)
Download PDF:
Claims:
Claims

1. Wire management system (7) for a wire saw (8), which has a cutting area (13) and wire guiding means for carrying at least one section of cutting wire (3), preferably a wire web (17), in the cutting area (13),

5 the wire management system (7) comprising

a control device (30),

a wire supplying side (5) for supplying new cutting wire (3) to the cutting area (13),

a wire receiving side (6) for receiving used cutting wire (3) from0 the cutting area (13),

wherein at least one of the wire supplying side (5) and the wire receiving side (6), preferably the wire supplying side (5) and the wire receiving side (6) each, comprise(s) a controllable tensioner (20, 31) for adjusting the tension of cutting wire (3) and a traveler pulley drive5 (32) for moving a traveler pulley (4) along the rotational axis of at least one spool (1, 2) for receiving a portion of the cutting wire (3) in windings,

characterized in that at least one of the wire supplying side (5) and the wire receiving side (6), preferably the wire supplying side (5) and0 the wire receiving side (6) each, comprise(s) a pulley sensor (33) for measuring a force acting on the traveler pulley (4) in a direction which is transverse, preferably perpendicular, to the rotational axis of the traveler pulley (4),

and that the control device (30) is configured to control within a wire5 side (5, 6) the tensioner (20, 31) and the traveler pulley drive (32) each in dependence of the sensor data of the sensor (33) of that wire side (5, 6).

2. Wire management system (7) for a wire saw (8), which has a cutting area (13) and wire guiding means for carrying at least one section of0 cutting wire (3) in the cutting area (13), particularly according to claim

1 , the wire management system (7) comprising

a control device (30), a wire supplying side (5) for supplying cutting wire (3) to the cutting area ( 13) ,

a wire receiving side (6) for receiving cutting wire (3) from the cutting area ( 13) ,

5 wherein the wire supplying side (5) and the wire receiving side (6) each com prise a controllable tensioner (20, 31 ) for adj usting the tension of cutting wire (3) and a traveler pulley drive (32) for m oving a traveler pulley (4) along the rotational axis of at least one spool ( 1 , 2) for receiving a portion of the cutting wire (3) in windings,

0 characterized in that at least one of the wire supplying side (5) and the wire receiving side (6) , preferably the wire supplying side (5) and the wire receiving side (6) each, com prises a pulley sensor (33) for measuring a force acting on the traveler pulley (4) in a direction which is transverse, preferably perpendicular, to the rotational axis of the5 traveler pulley (4) ,

and that at least one of the wire supplying side (5) and the wire receiving side (6) , preferably the wire supplying side (5) and the wire receiving side (6) each, comprises at least one further pulley (20, 9) for guiding the cutting wire (3) , wherein none of the further pulley(s)0 (20, 9) has or interacts with a pulley sensor.

3. Wire managem ent system according to claim 1 or claim 2, wherein the control device (30) is configured to operate the wire managem ent system (7) in a cutting mode in which cutting wire (3) is m oved through the cutting area ( 13) , preferably in a num ber of cycles back5 and forth, wherein in the cutting m ode the tensioner (20, 31 ) is controlled by the control device (30) in dependence of sensor data of the sensor (33) .

4. Wire m anagement system according to one of the preceding claims, wherein the control device (30) is configured to control the tensioner0 (20, 31 ) , such that the tension of the cutting wire (3) rem ains essentially constant, wherein preferably the position or tensioning state of the tensioner (20, 31 ) is used to control the rotational speed of the spool ( 1 , 2) .

5. Wire m anagement system according to one of the preceding claims, wherein the control device (30) is configured to operate the wire

5 managem ent system (7) in a preparation mode, in which, preferably prior to the cutting procedure, cutting wire (3) is transferred from the wire supplying side (5) via the cutting area ( 13) to the spool ( 1 , 2) of the wire receiving side (6) , wherein in the preparation mode the traveler pulley drive (32) moving the traveler pulley (4) is controlled0 by the control device (30) in dependence of sensor data of the sensor

(33) , wherein preferably the controllable tensioner (20, 31 ) is controlled as to keep the tension in the cutting wire (3) in a desired range.

6. Wire m anagement system according to one of the preceding claims,5 wherein the control device (30) is configured to control, preferably in dependence of sensor data of the sensor (33) , the traveler pulley drive (32) , such that the angle between the rotational axis of the spool ( 1 , 2) and the section of cutting wire (3) extending between traveler pulley (4) and spool ( 1 , 2) remains essentially constant, preferably0 essentially 90° .

7. Wire managem ent system according to one of the preceding claim s, wherein the tensioner com prises a tensioning pulley (20) and a tensioning drive (31 ) for adj usting the tensioning pulley (20) .

8. Wire managem ent system according to one of the preceding claim s,5 wherein the tensioning pulley (20) is arranged in the cutting wire path extending between the cutting area ( 13) and the traveler pulley (4) , wherein preferably the tensioning pulley (20) is a dancer.

9. Wire m anagement system according to one of the preceding claims, wherein the traveler pulley (4) deflects the cutting wire (3) about an angle between 45° and 135° , preferably between 80° and 1 10° , m ore preferred about essentially 90° .

10. Wire m anagement system according to one of the preceding claims, wherein the sensor (33) is configured to measure the force under an

5 angle to the direction from which the cutting wire (3) when com ing from the cutting area ( 13) reaches the traveler pulley (4) , wherein preferably the angle preferably is essentially 45° .

1 1 . Wire m anagement system according to one of the preceding claims, wherein the cutting area ( 13) is arranged in a compartm ent, wherein0 the traveler pulley (4) and the sensor (33) are arranged outside the com partm ent, wherein preferably the com partment ( 10) is free from any pulley-related sensor.

12. Wire m anagement system according to one of the preceding claims, wherein at least one, preferably at least two pulley(s) (9) are arranged5 between the cutting area ( 13) and the spool ( 1 , 2) , wherein at least one, preferably at least two of these pulleys does/do not have or does/do not interact with a pulley sensor.

13. Wire m anagement system according to one of the preceding claims, wherein the traveler pulley (4) is moveable along the rotational axis of0 a storage spool (2) for tem porarily receiving a portion of the cutting wire (3) in windings, preferably along the whole length of the storage spool (2) , and along the rotational axis of a reservoir spool ( 1 ) for carrying at least a portion of the cutting wire (3) in overlapping windings, preferably along the whole length of the storage spool (2) ,5 wherein the rotational axis (2b) of the storage spool (2) essentially coincides with the rotational axis ( 1 b) of the reservoir spool ( 1 ) .

14. Wire saw for cutting a piece of material, preferably sem iconductor material, particularly a wafer cutting wire saw for cutting a plurality of wafers from a piece of m aterial or a wire saw for bricking and/or squaring a piece of material, the wire saw comprising, the wire saw (8) comprising

a cutting area (13),

guiding means for guiding the cutting wire (3) through the cutting area (13) and

driving means for selectively driving the cutting wire (3) in a first direction and in a second direction which is opposite to the first direction,

characterized in that the wire saw (8) comprises a wire management system (7) according to one of the preceding claims, and wherein preferably the guiding means are formed by wire guiding rollers (14) for carrying a cutting wire web (17).

15. Method of operating a wire saw (8) with a wire management system (7) according to one of the claims 1 to 13 and/or with a wire saw (8) according to claim 14.

Description:
W l RE MANAGEM ENT SYSTEM FOR A W I RE SAW AN D M ETHOD OF OPERATI NG A W l RE SAW W I TH SUCH A SYSTEM

The invention relates to a wire managem ent system for a wire saw according to the pream ble of claim 1 or claim 2, a wire saw and a m ethod of

5 operating a wire saw.

WO2014087340A2 discloses a wire m anagement system for a wire saw wire saw, which has a cutting area and wire guiding means for carrying a wire web in the cutting area. The wire managem ent system com prises a wire supplying side for supplying (new) cutting wire to the cutting area, and0 a wire receiving side for receiving (used) cutting wire from the cutting area. Clearly, the supplying side also receives cutting wire and the receiving side also supplies cutting wire as the wire is m oved back and forth through the cutting area ( Pilgrim m ode) , but on average the wire m oves from the supplying side, where the spool with new wire is located, to the receiving5 side, where the spool for used-up wire is located. Each wire side comprises pulleys for guiding or deflecting the cutting wire when m oving between the cutting area and the storage and/or reservoir spool(s) of a wire side. Particularly, there is provided a tensioning pulley for adj usting the tension within the wire and a traveler pulley for guiding/spooling the wire towards0 (or from ) the storage and/or reservoir spool.

From other prior art relating to wire saws it is known, to use a deflection pulley in the im m ediate vicinity of the cutting area - or even in the cutting com partment - in order to deflect the wire when com ing from (or m oving to) the wire guiding means (carrying the wire web) . A load cell is used for5 measuring a force on the pulley exerted by the deflected wire. That force is a m easure of the wire tension. The wire tension may then be adj usted by a tensioner, which usually com prises an adjustable tensioning pulley.

It is however, very disadvantageous to have a load cell in the im mediate vicinity of the cutting area or even within the cutting com partm ent. The0 load cell is exposed there to cutting liquid, dirt and dust, causing erroneous measurements, short life tim e and even dam ages of the load cell. I n addition costs should be reduced too.

It is therefore an object of the invention to provide a wire m anagem ent system by m eans of which the disadvantages arising in prior art may be

5 solved. Particularly, the system should be capable of reliably controlling the tension of the wire. The function should be independent of negative im pacts resulting from the conditions in the im m ediate vicinity of the cutting area (i.e. should not be impaired by cutting liquid, dirt, dust, etc.) . At the sam e tim e the wire m anagement system should have a simple construction and0 be realizable by customary com ponents.

The object is achieved by a wire m anagement system as mentioned at the beginning, wherein at least one of the wire supplying side and the wire receiving side, preferably the wire supplying side and the wire receiving side each, com prise(s) a pulley sensor for measuring a force acting on the5 traveler pulley in a direction which is transverse, preferably perpendicular, to the rotational axis of the traveler pulley,

and that the control device is configured to control within a wire side the tensioner and the traveler pulley drive each in dependence of the sensor data of the sensor of that wire side. 0 The sensor data of the sensor are used within a wire side to control both, the tensioner and the traveler pulley drive. This m ay be done concurrently (both , the tensioner and the traveler pulley drive, are controlled at the same tim e based on the sam e data) , at different times (at one point in time the tensioner is controlled based on that data and at another point in tim e5 the traveler pulley drive is controlled based on that data) or any com bination thereof.

The pulley sensor, which is preferably a load cell, measures a force exerted by the deflected wire on the traveler pulley. That force originates by the tension of the wire and is therefore a direct m easure of the wire tension. 0 According to the invention the control device is - not only configured to control the tensioner in dependence of the sensor data of the sensor,

- but also configured to control the traveler pulley drive in dependence of the sensor data of the (same) sensor of that wire side.

5 Thus, the sensor data of the same sensor are used for perform ing two different functions. I n contrast to prior art the number of sensors (e.g. load cells) m ay be reduced, thus reducing material, installation and m aintenance costs. Moreover, the sensor according to the invention is arranged at the traveler pulley, i.e. m easures the force exerted by the wire on the traveler0 pulley. The traveler pulley, however, is arranged in the vicinity of the storage spool and serves to spool the wire onto the storage spool or from the storage spool. Hence, the traveler pulley and the pulley sensor are arranged apart from the cutting area and the pulley sensor according to the invention is not adversely influenced by the conditions prevailing in the5 cutting area.

As already m entioned, the sensor data of the sam e sensor are used for two different ends: controlling the tensioner and controlling the traveler pulley (drive) . Both are done in dependence of the sensor data of the sam e sensor. It is, however, not necessary to perform the two control functions at0 the same tim e or within the sam e operational m ode of the wire managem ent system . Rather, it m ay be preferred to control the traveler pulley (drive) during a first operational m ode (e.g. a preparation mode) in dependence of the sensor data and to control the tensioner during a second operational mode (e.g. a cutting mode) in dependence of the sensor data.5 The invention includes following possibilities:

- controlling only the tensioner in dependence of the sensor data (i.e. not the traveler pulley drive) in a first mode; controlling only the traveler pulley drive in dependence of the sensor data (i.e. not the tensioner) in a second m ode or at a different tim e;0 and - controlling both, the tensioner and the traveler pulley drive, in dependence of the sensor data at the sam e time.

The traveler pulley drive may not be confused with a rotational drive keeping the pulley in rotation. The traveler pulley drive is a drive for m oving

5 or shifting the whole traveler pulley including its rotational axis along a path along the storage spool. The angle between the rotational axis of the storage spool and the section of cutting wire extending between traveler pulley and storage spool depends on the relative position between traveler pulley and storage spool. I n order to guarantee an optimal transfer without0 wire wear or wire damage, the angle should be held essentially constant and preferably 90° . By controlling the traveler pulley drive and thus the position of the traveler pulley, the transfer of cutting wire during preparation of the wire saw may be efficiently optim ized.

The“at least one spool” in claim 1 may be a spool for receiving cutting wire5 in low density windings (e.g. low num ber of overlapping winding layers) or non-overlapping windings (also called: temporary or interm ediate storage spool) or a spool for receiving cutting wire in high density windings, i.e. highly m ulti-layered windings (also called: reservoir spool, such as new wire spool or used-up wire spool) . 0 It should be m entioned that the supplying side also receives cutting wire and the receiving side also supplies cutting wire as the wire is m oved back and forth through the cutting area in the cutting mode (or Pilgrim m ode) , but on average the wire m oves from the supplying side, where the spool with new wire is located, to the supply side, where the spool for used-up5 wire is located. With the terms “wire supplying side for supplying new cutting wire” and “wire receiving side for receiving used cutting wire” is meant, that on average and/or in the course of a plurality of cutting cycles the (new) wire m oves from the supplying side, where the spool with new wire is located, to the receiving side, where the spool for used-up wire is0 located. The pulley sensor m ay be a force sensor or any other sensor capable of directly or indirectly m easuring the force exerted by the deflected wire on the traveler pulley. The pulley sensor may be form ed from or com prise a load cell and/or a strain gauge and/or a piezoelectric component and/or a

5 capacitive sensor (com ponent) and/or an optical sensor, preferably measuring a deform ation or shift of a m oveable component or the wire.

The object is also achieved by a wire m anagem ent system , wherein at least one of the wire supplying side and the wire receiving side, preferably the wire supplying side and the wire receiving side each, com prises a pulley0 sensor for m easuring a force acting on the traveler pulley in a direction which is transverse, preferably perpendicular, to the rotational axis of the traveler pulley, and that at least one of the wire supplying side and the wire receiving side, preferably the wire supplying side and the wire receiving side each, com prises at least one further pulley for guiding the cutting wire,5 wherein none of the further pulley(s) has or interacts with a pulley sensor.

By this m easure based on the same inventive idea of arranging the pulley sensor at the traveler pulley the problems of prior art (according to which load cell are arranged in the vicinity of the cutting area and therefor prone to failures and dam ages) are efficiently solved. The pulley sensor is not only0 arranged at a location apart of the conditions prevailing in the cutting area, but the overall num ber of sensors and therefore costs m ay be reduced.

I n a preferred embodiment the control device is configured to operate the wire m anagement system in a cutting mode in which cutting wire is moved through the cutting area, preferably in a number of cycles back and forth,5 wherein in the cutting mode the tensioner is controlled by the control device in dependence of sensor data of the sensor. I n the cutting mode is im portant to have constant wire tension in order to guarantee high and constant cutting quality and prevent wire breakage. Deviations of an optim al wire tension m ay be com pensated by controlling the tensioner in0 dependence of sensor data. I n a preferred embodiment the control device is configured to control the tensioner, such that the tension of the cutting wire rem ains essentially constant, wherein preferably the position or tensioning state of the tensioner is used to control the rotational speed of the (storage) spool(s) ,

5 the wire guiding m eans or both. The tensioner (e.g. a so-called“dancer”) preferably comprises a tensioning pulley and a tensioning drive for m oving the tensioning pulley (resulting in a lower or higher tension of the wire) . It is preferred that the position or tensioning state of the tensioner, particularly the position of the tensioning pulley, is used for controlling the0 rotational speed of the (storage) spools, which is/are driven by rotational drive(s) . The rotational drive(s) of the storage spool may be also controlled by the control device in dependence of the sensor data and/or the position and/or tensioning state of the tensioner.

I n a preferred embodiment the control device is configured to operate the5 wire managem ent system in a preparation m ode, in which, preferably prior to the cutting procedure, cutting wire is transferred from the wire supplying side via the cutting area to the (storage) spool of the wire receiving side, wherein in the preparation m ode the traveler pulley drive m oving the traveler pulley is controlled by the control device in dependence of sensor0 data of the sensor, wherein preferably the controllable tensioner is used as to keep the tension in the cutting wire in a desired range (e.g. maybe also independent of the senor data) . I n the preparation m ode it is im portant to guarantee a reliable transfer of the cutting wire. As already m entioned the angle between the rotational axis of the (storage) spool and the section of5 cutting wire extending between traveler pulley and storage spool is of great im portance. By controlling the traveler pulley drive and thus the position of the traveler pulley based on the data provided by the sensor, said angle may be held constant.

I n a preferred embodiment the control device is configured to control,0 preferably in dependence of sensor data of the sensor, the traveler pulley drive, such that the angle between the section of cutting wire extending between traveler pulley and storage spool rem ains essentially constant, preferably essentially 90° .

I n a preferred em bodim ent the tensioner com prises a tensioning pulley and a tensioning drive for adj usting the tensioning pulley. “Adj usting” means

5 that the tensioning pulley is m oved and/or that the force exerted by the tensioning drive on the tensioning pulley is increased or decreased.

I n a preferred embodiment the tensioning pulley is arranged in the cutting wire path extending between the cutting area and the traveler pulley, wherein preferably the tensioning pulley is a dancer. 0 I n a preferred embodim ent the sensor is a force transducer, preferably a load cell, and/or wherein the sensor is a one-dim ensional sensor.

I n a preferred em bodim ent the traveler pulley deflects the cutting wire about an angle between 45° and 135° , preferably between 80° and 1 1 0° , more preferred about essentially 90° . The direction, in which the force5 acting on the traveler pulley is m easured by the sensor, lies within said angle area.

I n a preferred em bodim ent the sensor is configured to measure the force under an angle to the direction from which the cutting wire when com ing from the cutting area reaches the traveler pulley, wherein preferably the0 angle preferably is essentially 45° .

I n a preferred em bodiment the cutting area is arranged in a compartm ent, wherein the traveler pulley and the sensor are arranged outside the com partm ent. The com partm ent may be chamber-like and/or m ay be partially closed or from all sides closed. The walls of the compartment cause5 that spray of cutting liquid as well as dirt and dust is lim ited to the cutting area. The traveler pulley and the sensor are arranged outside the com partm ent and are therefore efficiently protected.

I n a preferred em bodiment at least one, preferably at least two pulleys are arranged between the cutting area and the storage spool, wherein at least one, preferably at least two of these pulleys does/do not have or does/do not interact with a pulley sensor. As already mentioned the num ber of sensors m ay be reduced, since one sensor is used for at least two different functions/ends. I t is preferred that each wire side (supplying and receiving

5 side) com prises only one pulley sensor.

I n a preferred em bodim ent the com partment is free from any pulley and or pulley-related sensor. I n the case one or m ore wire deflection pulley(s) is/ are provided within the cutting com partm ent, this means, that said wire deflection pulley(s) do/does not have or interact with a sensor. 0 I n a preferred embodim ent the wire supplying side, the wire receiving side or both com prise(s) a rotatable reservoir spool for carrying at least a portion of the cutting wire in overlapping windings or loops, wherein within that side(s) the rotational axis of the storage spool essentially coincides with the rotational axis of a reservoir spool. The reservoir spool and the5 storage spool m ay each build the spool for tem porarily receiving a portion of the cutting wire in windings (loops) .

I n a preferred em bodim ent the traveler pulley is moveable along the rotational axis of a storage spool for tem porarily receiving a portion of the cutting wire in windings, preferably along the whole length of the storage0 spool, and along the rotational axis of a reservoir spool for carrying at least a portion of the cutting wire in overlapping windings, preferably along the whole length of the storage spool, wherein the rotational axis of the storage spool essentially coincides with the rotational axis of the reservoir spool. Such an arrangem ent of reservoir spool and storage spool is disclosed in5 detail WO2014087340A2, the disclosure of which is incorporated into the present application by reference.

The object is also achieved with a wire saw for cutting a piece of material, preferably sem iconductor material, particularly a wafer cutting wire saw for cutting a plurality of wafers from a piece of m aterial or a wire saw for0 bricking and/or squaring a piece of m aterial, the wire saw com prising, the wire saw com prising a cutting area,

guiding means for guiding the cutting wire through the cutting area and

driving means for selectively driving the cutting wire in a first direction and 5 in a second direction which is opposite to the first direction,

characterized in that the wire saw comprises a wire management system according to one of the preceding claims, and wherein preferably the guiding means are formed by wire guiding rollers for carrying a cutting wire web. 0 The object of the invention is also achieved by a method of operating a wire saw with a wire management system according to the invention.

Further embodiments of the invention are indicated in the figures and in the dependent claims. The list of reference marks forms part of the disclosure. The invention will now be explained in detail by the drawings. In the5 drawings:

Fig. 1 shows a wire saw comprising a wire management system according to the invention,

Figs.2 to 6 shows a unit of storage spool and reservoir spool,

Fig.7 shows a wire saw with a wire management system in more0 detail and with its cutting area being accommodated within a compartment,

Fig.8 shows the force F acting on the traveler pulley, and

Fig.9 shows an example of a sensor mounted to traveler pulley.

Figs. 1 and 7 show a wire management system 7 of a wire saw 8. The wire5 saw has a cutting area 13 and wire guiding means - here in form of wire guiding rollers 14 - carrying a section of cutting wire 3, thereby forming a wire web 17 in the cutting area 13. The wire m anagement system 7 comprises a control device 30, a wire supplying side 5 for supplying new cutting wire 3 to the cutting area 13 and a wire receiving side 6 for receiving used cutting wire 3 from the cutting area 13.

5 As can be seen from Fig. 1 the wire supplying side 5 comprises a controllable tensioner 20, 31 for adj usting the tension of cutting wire 3. I n the present em bodiment the tensioner com prises a tensioning pulley 20 and a (linear) tensioning drive 31 for adj usting the tensioning pulley 20, i.e. shifting it along the direction of the double arrow in Figs. 1 and 7. 0 The wire supplying side 5 further com prises a traveler pulley drive 32 for moving a traveler pulley 4 along the rotational axis of at least one spool 1 , 2 for receiving a portion of the cutting wire 3 in windings. The m oving direction of the traveler pulley 4 is indicated by a double arrow. The traveler pulley 4 of Figs. 1 , 7 and 8 deflects the cutting wire 3 about an angle of5 essentially 90° .

The angle between the rotational axis of the storage spool 2 and the section of cutting wire 3 extending between traveler pulley 4 and storage spool 2 depends on the relative position between traveler pulley 4 and storage spool 2. I n order to guarantee an optimal transfer without wire wear or wire0 damage the angle should be held essentially constant. By controlling the traveler pulley drive 32 and thus the position of the traveler pulley 4 the transfer of cutting wire 3 during preparation of the wire saw may be efficiently optim ized. Fig. 7 shows - indicated with dashed lines - suboptimal runs of the cutting wire between spool 2 and traveler pulley 4.5 The optim al run is indicated by the m iddle solid line corresponding to an angle of essentially 90° .

As can be seen from Figs. 1 and 7 the tensioning pulley 20 is arranged in the cutting wire path extending between the cutting area 13 and the traveler pulley 4, wherein preferably the tensioning pulley 20 is a so called0 dancer (not shown here) . I n the present em bodim ent a storage spool 2 for temporarily receiving cutting wire 3 and a reservoir spool 1 (new wire spool or used wire spool) for temporarily or finally receiving cutting wire 3. It would be, however, possible to use only one spool.

5 The traveler pulley 4 is moveable along the rotational axis 2b of the storage spool 2 for tem porarily receiving a portion of the cutting wire 3 in windings, preferably along the whole length of the storage spool 2, and along the rotational axis 1 b of the reservoir spool 1 for carrying at least a portion of the cutting wire 3 in overlapping windings, preferably along the whole0 length of the storage spool 2, wherein the rotational axis 2b of the storage spool 2 essentially coincides with the rotational axis 1 b of the reservoir spool 1 .

The advantages of using two spools 1 , 2 consists in the fact, that the storage spool 2 may be used for temporarily (i.e. during a Pilgrim cycle)5 receiving cutting wire in non-overlapping windings and/or windings having a lower density than the windings on the reservoir spool 1 (see WO2014087340A2) . Figs. 2 to 5 show the action of the traveler pulley during the cutting m ode within a Pilgrim cycle. Here, cutting wire 3 is spooled off from the storage spool 2 while traveler pulley 4 m oves to the0 left, in order to hold the angle of the wire between storage spool 2 and traveler pulley 4 constant. I n Fig. 5 the moving direction of the cutting wire 3 has changed and wire is spooled on the storage spool 2. Fig. 6 shows a preparation mode, in which (new) cutting wire 3 is spooled off from the reservoir spool 1 (of the supplying side 5) for transferring it directly to (the5 storage spool 2 of) the receiving side 6.

It should be mentioned that the wire receiving side 6 m ay be designed in analogous m anner as the wire supplying side 5.

A pulley sensor 33 is provided for m easuring a force F acting on the traveler pulley 4 in a direction which is transverse, preferably perpendicular, to the0 rotational axis of the traveler pulley 4 (see also Fig. 8) . The sensor 33 m ay be a force transducer, preferably a load cell, and/or a one-dim ensional sensor, i.e. delivering one value (e.g. voltage) . The sensor 33 m ay be configured to m easure the force F under an angle to the direction from which the cutting wire 3 when com ing from the cutting area 13 reaches the traveler pulley 4, wherein preferably the angle preferably is essentially 45°

5 (see Fig. 8) .

The control device 30 is configured to control the tensioner 20, 31 and the traveler pulley drive 32 each in dependence of the sensor data of the sam e sensor 33.

It can be seen from Figs. 1 and 7 that the wire supplying side 5 and the0 wire receiving side 6 each com prise further deflection pulley 9 for guiding the cutting wire 3. Flowever, note that pulley 9 does not have or interact with a pulley sensor. Also, the tensioning pulley 20 does not have or interact with a pulley sensor.

As can be seen from Fig. 7 the cutting area 13 is arranged in a5 com partment 10, wherein the traveler pulley 4 and the sensor 33 are arranged outside the com partment 10. The com partment 10 is free from any pulley-related sensor. Preferably, pulley 9 is also outside of the com partm ent 1 0 (not shown here)

According to a preferred em bodiment at least one, preferably at least two0 pulley(s) 9, 20, 4 are arranged between the cutting area 13 and the spool 1 , 2, wherein at least one, preferably at least two of these pulleys 9, 20 does/do not have or does/do not interact with a pulley sensor.

The control device 30 may be configured to operate the wire m anagem ent system 7 in a cutting mode in which cutting wire 3 is moved through the5 cutting area 13, preferably in a number of cycles back and forth ( Pilgrim mode) . I n the cutting m ode, the tensioner 20, 31 is controlled by the control device 30 in dependence of sensor data of the sensor 33. The control device 30 is configured to control the tensioner 20, 31 , such that the tension of the cutting wire 3 rem ains essentially constant. As indicated in0 Fig. 7, the control device also controls the spool drive 12. I t is preferred, if the position or tensioning state of the tensioner 20, 31 is used to control the rotational speed of the spools 1 , 2 (the spools 1 , 2 m ay be fixed with each other or each spool 1 , 2 m ay have its own drive) .

For the purpose of preparation of the wire saw the control device 30 m ay be

5 configured to operate the wire m anagement system 7 in a preparation mode, in which, preferably prior to the cutting procedure, (new) cutting wire 3 is transferred from the wire supplying side 5 via the cutting area 13 to the spool(s) 1 , 2 of the wire receiving side 6. I n the preparation mode the traveler pulley drive 32 moving the traveler pulley 4 (along the spool 2)0 is controlled by the control device 30 in dependence of sensor data of the (same) sensor 33. At the sam e time the tensioner 20, 31 may keep the tension in the cutting wire 3 in a desired range.

The control device 30 is preferably configured to control, preferably in dependence of sensor data of the sensor 33, the traveler pulley drive 32,5 such that the angle between the rotational axis of the spool(s) 1 , 2 and the section of cutting wire 3 extending between traveler pulley 4 and spool 1 , 2 rem ains essentially constant, preferably essentially 90° .

The invention is not restricted to these em bodim ents. Other variants will be obvious for the person skilled in the art and are considered to lie within the0 scope of the invention as form ulated in the following claim s. I ndividual features described in all parts of the above specification, particularly with respect to the figures m ay be com bined with each other to form other embodiments and/or applied m utatis m utandis to what is described in the claims and to the rest of the description, even if the features are described5 in respect to or in combination with other features. List of reference sig ns

1 reservoir spool

1 b rotational axis of reservoir spool 1

2 storage spool

2b rotat ion al ax is of storag e spool 2

3 cutting wire

4 traveler pulley

5 wire supplying side

6 wire receiving side

7 wire m anagement system

8 wire saw

9 deflection pulley

10 compartm ent

12 spool drive

13 cutting area

14 wire guide rollers

15 driving m eans

17 wire web

20 tensioning pulley

30 control device

31 tensioning drive

32 traveler pulley drive

33 sensor