| WO/1999/064212 | PORTABLE SAWMILL |
| JP08132316 | PORTABLE BAND SAW |
| JP10076423 | PORTABLE BAND SAW MACHINE |
Nadali, Cristiano (Via D. Alighieri 25, Cerea, I-37053, VR)
| 1. | A sawing machine, particularly a band sawing machine, comprising a blade (3) driven along a movement axis (A), a workpiececarriage (11) on which an article to be cut (14) is located, and translation means (12,13) for translating the workpiececarriage (11) in order to move the carriage relative to the blade (3) along a plane (X, Y) substantially perpendicular to the movement axis (A), characterized in that it comprises pivoting means (16), associated with the workpiececarriage (11), for pivoting the carriage about a pivot axis (B) which is stationary relative to the carriage and substantially parallel to the movement axis (A). |
| 2. | A sawing machine according to Claim 1 in which the pivoting means (16) are associated with the workpiececarriage (11) in a manner such that the pivot axis (B) is defined in a front edge region (11b) of the workpiececarriage, facing the blade (3). |
| 3. | A sawing machine according to one or more of the preceding claims in which the translation means (12,13) can translate the workpiececarriage (11) along two substantially perpendicular axes, one of the axes being parallel to a cutting axis (X) defined by the blade (3). |
| 4. | A sawing machine according to Claim 3 in which first sensor means (18) are provided for detecting the position of the workpiececarriage (11) along the axes (X, Y), and second sensor means (19) are provided for detecting the angular position of the workpiececarriage (11) about the pivot axis (B). |
| 5. | A sawing machine according to one or more of the preceding claims in which the translation means (12,13) and the pivoting means (16) are operatively subject to a numerical control unit (17). |
| 6. | A sawing machine according to Claim 5 in which the numerical control unit (17) is of the CNC type. |
| 7. | A sawing machine according to one or more of the preceding claims, comprising a routing unit (30) disposed beside a cutting unit (2) which comprises the blade (3). |
Technological background The invention is for use, particularly but not exclusively, in the field of the mass production of wooden products with shaped profiles.
In this field, it is known to produce these articles by cutting of a wooden board, which is typically performed by means of a band sawing machine. For this purpose, the board is arranged on a workpiece-carriage which is guided towards the saw blade along a predetermined cutting path, producing a product with the desired curved profile. The cutting path is defined by a sample profile (or "template") which is mounted on the workpiece-carriage and is abutted by corresponding guide elements which are stationary relative to the cutting plane of the blade.
However, the technology described above requires the provision of a sample for each type of product. This leads to many disadvantages, amongst which is the need for all of the templates required for the various types of production to be stored in suitable stores. A second limitation of this known technique is that the machining of the templates requires a particular manual skill which is ever more difficult to obtain on the market, as well as being expensive and unsuitable for the short processing times that are required for industrial production.
Moreover, since the templates are usually made of wood, they are liable to deform over time and have to be remade.
To overcome these problems, band sawing machines have recently been developed in which the cutting path is defined by translation means which are subject to numerical control and which can move the workpiece-carriage towards the blade in a direction resulting from a combination of perpendicular translational components (a process known as"cross movement").
However, the use of this solution is fimited by the fact that, when the movement of the workpiece carriage relative to the blade has an appreciable component perpendicular to the cutting axis, owing to the lateral pressure exerted
by the board, the blade tends to be displaced from the seats defined on the respective drive pulleys (an effect known as"slipping off") A subsequent improvement to sawing machines of this type attempted to overcome this limitation by associating twisting means, also subject to numerical control, with the saw blade. These twisting means act on the blade by twisting it about its own longitudinal axis so as to keep it always coplanar with the cutting axis.
However, some disadvantages have also been found in this case; the first disadvantage is that, in order not to meet with the"slipping-off"feared in connection with the previous solution, the blade has to be driven at reduced speed, giving rise to cutting of unsatisfactory quality.
Moreover, at slow speeds of movement problems of production continuity are encountered owing to difficulty in discharging the wood shavings from the blade.
A further limitation is that the twisting of the blade can be performed only within a small angular range.
Description of the invention The problem underlying the present invention is that of providing a sawing machine, particularly a band sawing machine, which is designed structurally and functionally to overcome the limitations set out above with reference to the prior art mentioned.
This problem is solved by the present invention by means of a sawing machine formed in accordance with the appended claims.
Brief description of the drawings The characteristics and the advantages of the invention will become clearer from the detailed description of a preferred embodiment thereof, described by way of non-limiting example with reference to the appended drawings, in which: - Figure 1 is a schematic side elevational view of a band sawing machine formed in accordance with the present invention, - Figure 2 is a schematic front elevational view of the sawing machine of Figure 1, and - Figure 3 is a schematic plan view of a variant of the sawing machine of the previous drawings.
Preferred embodiments of the invention In the drawings, a sawing machine formed in accordance with the present invention is generally indicated 1.
The sawing machine 1 comprises a cutting unit 2 including a band-type blade 3 for cutting wooden planks and boards, and a loading unit 4 on which planks and boards are supported, guided, and supplied to the unit 2 during cutting. The blade 3 extends around two pulleys 5 in an endless loop, defining a path along which it is moved by drive means 6. Also identified in the working path is a substantially vertical working portion 7, in which the blade 3 is used for cutting.
Identified with reference to the portion 7 are a cutting axis X, associated with the serrated edge of the blade 3, and an axis A of movement of the blade substantially perpendicular to the cutting axis X.
The loading unit 4 comprises a base 10 on which a workpiece-carriage 11 is mounted so as to be movable along a plane substantially perpendicular to the movement axis A. For this purpose, the loading unit 4 comprises first translation means 12 which can translate the workpiece-carriage 11 substantially parallel to the cutting axis X and second translation means 13 which can translate the workpiece-carriage 11 along an axis Y perpendicular thereto.
Preferably, the first translation means 12 comprise a rack device 12a and the second translation means 13 comprise a ball screw with an adjustable precision nut.
The first translation means 12 are arranged to move the workpiece-carriage 11 along the axis X with a total travel of about three metres, whereas the total movement which can potentially be performed along the axis Y by the second translation means 13 is about 0.8 metres.
Also identified on the workpiece-carriage 11 are a front edge 11 b facing the blade 3 and a support surface 11 a on which the material arranged for cutting, for example, a plank 14, is supported.
Loading means 15 are mounted on the workpiece-carriage 11 for moving the plank 14 towards the front edge 11b at the beginning of each cutting stage.
The loading means 15 also serve to restrain the plank 14 on the surface 11a during the above-mentioned cutting stage.
According to a principal characteristic of the invention, pivoting means 16 are associated with the workpiece-carriage 11 and can pivot the workpiece- carriage 11 about an axis B which is stationary relative to the carriage and substantially parallel to the axis of movement A of the blade 3. Advantageously, the pivoting means 16 are arranged in the vicinity of the front edge 11 b so that the pivot axis B is as close as possible to the axis of movement A of the blade 3.
Both the pivoting means 16 and the first and second translation means 12, 13 are subject to a numerical control unit 17 of the CNC type into which data relating to the profile to be cut in the plank 14 are loaded.
The sawing machine 1 also comprises first sensor means 18 for detecting the coordinates of the position of the workpiece-carriage 11 along the axes X and Y and second sensor means 19 for detecting its angular position about the pivoting axis B. All of the data detected by the sensor means 18 and 19 are transmitted to the control unit 17.
The cutting of the plank 14 takes place in the manner described below.
By interacting with the control unit 17, the operator sets the desired cutting profile, amongst other operative parameters, by entering the data relating to the profile, or by selecting it from curves which are present in the data bank of the control unit 17.
The plank 14 is then placed on the surface 11a, restrained by the loading means 15, and moved forwards thereby towards the front edge 11b of the workpiece-carriage 11.
The workpiece-carriage 11 is then moved towards the blade 3 by the translation means 12,13 and by the pivoting means 16. All of these movements are controlled by the control unit 17 which breaks down the cutting profile set by the operator into a combination of translational movements along the axes X and Y and/or pivoting movements about the pivot axis B.
The actual cutting profile is compared with the theoretical profile by the control unit 17, by means of the data relating to the positioning of the workpiece- carriage 11, transmitted by the sensor means 18 and 19. These data are also processed by the control unit 17 to define the subsequent movements of the translation means 12,13 and/or of the pivoting means 16.
The pivoting of the workpiece-carriage 11 about the axis B is performed in a manner such that, at every moment of the cutting stage, the blade 3 is in a position tangential to the profile of cutting of the plank 14.
This prevents any pressure component being exerted by the plank 14 along the axis Y, which would tend to slip the blade off the drive pulleys 5.
Upon completion of the cutting stage, the workpiece-carriage 11 is returned to the starting position and the plank 14 is moved a predefined distance towards the front edge 11 b by the loading means 15, ready for the next cutting stage.
Figure 3 shows a variant of the machine of the preceding drawings.
Identical details are marked by the same reference numerals. The machine of the variant of Figure 3 differs from the preceding embodiment solely in that, beside the cutting unit 2, it has a routing unit 30 with a vertical axis, with one or more motor-driven routing cutters 31 disposed at a known distance from the cutting path of the blade 3. Upon completion of the cutting of a workpiece, the plank 14 is thus brought in front of the routing unit 30 by the loading unit 4 for an optional routing operation (for example, to form patterns and/or mouldings on the visible face of the workpiece), in which the cutting movement is produced by the rotation of the routing cutters and the forward movement is generated by the translation means 12, 13, by the loading means 15, and by the pivoting means 16. All of the movements are subject to the numerical control unit 17. Upon completion of any routing, the plank 14 is then brought back to the cutting unit, where the pre- processed workpiece is cut and separated from the plank.
The present invention thus solves the problem discussed above with reference to the prior art mentioned, at the same time offering many further advantages, amongst which is the ability to drive the blade with a speed of movement fast enough to ensure good cutting quality. In fact, it will be noted that the direction of cutting of the blade is never changed, whatever profile is being cut.
A further advantage is that, at least in theory, there are no limits to the pivoting of the workpiece-carriage relative to the saw blade. This permits the production of a large range of wooden articles with curved profiles.
Next Patent: DRY-CAST HOLLOWCORE CONCRETE SANDWICH PANELS