Wire saw

Abstract: A wire saw 110 comprises a wire 114 extending between two reels 112, 126 and guided around a plurality of grooved rollers 122 to form wire rows 124, the wire rows 124 being treated with a solution 140 containing abrasive grains and adapted to contact a workpiece 154 in order to cut the workpiece 154 into a number of thin wafers. At least one of the reels 112, 126 and grooved rollers 122 is connected to a rotary shaft of a driving motor 128, 130, 132 for driving said at least one of the reels and grooved rollers coaxially with said rotary shaft. The motor may be formed integrally on a frame of a main body of the wire saw. A turntable 170 may be connected to said rotary shaft 162 of said motor coaxially with said rotary shaft, said turntable 170 being connected to said at least one of the reels 112, 126 and grooved rollers 122.

Description: This invention relates to a wire saw according to the preamble of claim 1 and as known e.g. from US-A-3.841.927. The invention relates, more particularly, to a wire saw for cutting a workpiece such as a columnar semiconductor ingot, ceramic or glass into a multitude of wafers by wire rows. A known device for cutting a workpiece such as a semiconductor ingot, ceramic or glass into thin sheet-shaped wafers is a wire saw. This wire saw is a device used in such a manner that a workpiece is abutted against a wire running between a pair of wire reels while working solution containing abrasive grains is supplied to the wire, whereby the workpiece is cut into wafers through the lapping action of the abrasive grains. In recent years, the diameters of the wafers have tended to increase in size, for example from 8 inches (203 mm) to 12 inches (304 mm). For this reason, longer wires are used for cutting. As a result, the weight of the wire reels, around which the wire is wound has tended to increase in weight, exceeding 100 kg. Heretofore, the wire reels of the wire saw have been driven in a manner to transmit the rotation of a drive motor by a belt transmission. Furthermore, there are two methods of using the wire saw, including one-way feeding cutting, in which the workpiece is cut while the wire is caused to run only in one way, and a double-way feeding cutting, in which the workpiece is cut while the wire is caused to run reciprocatingly. In the case of the double-way feeding cutting, the wire reel should necessarily repeat acceleration and deceleration in a short period of time (1 to 6 sec.), so that a high acceleration torque becomes necessary due to the inertia of the wire reel. However, if the wire reel having a large weight is driven by the driving method using conventional belt transmission, then a motor having a high inertia is necessary for driving the wire reel, so that a large-sized motor should be used for driving the wire reel, thus causing a problem in that a driving section becomes large-sized. Furthermore, when the acceleration or deceleration torque is high, damage to the belt and the like can be caused, thus raising such a problem that the period of time for the acceleration or deceleration cannot be shortened and so forth. US 3841297 (Mech) discloses a wire saw in which a wire extends between two reels and is guided around a plurality of grooved rollers to form a row of wires which contact a workpiece in order to cut the workpiece into thin wafers. The reels and one of the grooved rollers are connected to rotary shafts of drive motors for driving the reels and the grooved rollers coaxially with said rotary shaft. The invention is distinguished over the prior art by the characterizing features of claim 1. At least one of the wire reels and the grooved roller is directly connected to the drive motors and driven directly by the drive motors. With this arrangement, the period of time needed for acceleration or deceleration can be shortened, so that through-put can be improved. Furthermore, for the drive motors, motors being low in inertia, i.e., small-sized motors can be used, so that the driving sections can be made compact in size. Further, space for a belt transmission mechanism, which has heretofore been necessary, can be saved, so that the driving section can be made compact in size. The invention will now be described by way of example only and with reference to the accompanying drawings, in which:- Fig.1 is a general diagram of the wire saw, and Fig. 2 is a sectional view showing the driving portion of the wire reel. Fig. 1 is the general diagram showing a wire saw 110. A wire 114 wound around a wire reel 112 passes through a wire guiding device 116, a plurality of fixed guide rollers 118 and 118, and a dancer roller 120, and is successively guided around three grooved rollers 122, 122 and 122 to form wire rows 124. Then, the wire 114 passes through a further plurality of fixed guide rollers 118, 118, an another dancer roller 120 and another wire guiding device 116, and is wound up by a wire reel 126. Each of weights 144 having a predetermined weight is hung down from each of the dancer rollers 120, whereby tensile force of a predetermined value is constantly given to the running wire 114. Wire washing devices 146 are provided on the half-ways of the running wire, whereby working solution 140 adhering to the wire 114 is removed by these wire washing devices 146. The wire reels 112 and 126 are connected to drive motors 128 and 130 which are capable of being rotated in the forward and reverse directions, and one 122 of the three grooved rollers is connected to a drive motor 132 capable of being rotated in the forward and reverse directions. With this arrangement, the wire 114 runs reciprocatingly between wire reel 112 and wire reel 126. A working solution 140 containing abrasive grains (normally used in the order of GC#600 - #1000), which is stored in a working solution storage tank 138, is supplied to the wire rows 124 through working solution supplying nozzles 142. Beneath the wire rows 124, a workpiece, such as a semiconductor ingot 154, is supported by a work feeding table 148 through a work block 156 and a slice base 158. This work feeding table 148 is made vertically movable by a ball screw 152 being rotated by a motor 150. The work feeding table 148 is moved upwardly, whereby the semiconductor ingot 154 is abutted against the wire rows 124 running at high speed, and cut into a multitude of wafers through the lapping action of the working solution 140 supplied to the wire rows 124. Fig. 2 is a sectional view showing the construction of the driving portion of the wire reel 112. In a casing 160 fixed to a frame of a main body of the wire saw, not shown, a rotary shaft 162 is rotatably supported through bearings 164, 164 and 164. Permanent magnets 166 and 166 are secured to the circumferential surface of this rotary shaft 162. On the other hand, on the inner peripheral wall Of the casing 160, armature coils 168 and 168 are opposed to the permanent magnets 166 and 166 and secured to the casing 160. Electric current is passed through these armature coils 168 and 168 to rotate the rotary shaft 162. A turntable 170 formed as a disc is connected to the top end portion of the rotary shaft 162. This turntable 170 is connected to the rotary shaft 162 coaxially therewith, and a connected portion thereof is bolted through two joining bolts 172 and 172. The wire reel 112 is connected to the top surface of this turntable 170. A truncated cone-shaped recessed portion 113A is formed at the center of the undersurface of a flange 113 of the wire reel 112. On the other hand, a truncated cone-shaped projected portion 170A is opposed to the truncated cone-shaped recessed portion 113A and formed at the center of the top surface of the turntable 170. At the time of connection, this recessed portion 113A and the projected portion 170A are coupled to each other, whereby the wire reel 112 and the turntable 170 can be coaxially connected to each other. The wire reel 112 and the turntable 170, which are connected to each other, are fixed to each other by being bolted through bolts 174 and 174 at the circumferential end portions thereof. With this arrangement, the rotation of the turntable 170 can be imparted to the wire reel 112 without slipping. The rotatable driving section of the turntable 170 is turned into a built-in type as described above, whereby the wire reel 112 is directly connected to the drive motor 128 to be directly driven. With this arrangement, the period of time needed for acceleration or deceleration is shortened, so that the through-put can be improved. Furthermore, for the drive motor, a low-inertia motor, i.e., a small-sized motor can be used, so that the driving section can be made compact in size. Further, the space for the belt transmission mechanism, which has heretofore been necessary, can be saved, so that the driving section can be made compact in size. Furthermore, with this arrangement, the danger of belt damages during operation can be eliminated. The other wire reel 126 is driven by the drive motor 130 connected thereto similarly to the case-of the wire reel 112. Incidentally, the driving of the grooved roller 122 forming the wire rows 124 is performed by the drive motor connected thereto similarly to the case of the wire reels 112, 116 so that the advantages similar to the case of the wire reels 112, 116 can be achieved. As has been described hereinabove, the wire reels and the grooved roller are directly connected to the drive motors to be directly driven by the respective drive motors. With this arrangement, the period of time needed for the acceleration or deceleration can be shortened, so that the through-put can be improved. Furthermore, for the drive motors, low-inertia motors, i.e., small-sized motors can be used, so that the driving sections can be made compact in size. Further, the space for the belt transmission mechanism, which has heretofore been necessary, can be saved, so that the driving sections can be made compact in size. It should be understood, however, that there is no intention to limit the invention to the specific forms disclosed, but on the contrary, the invention is to cover all modifications, alternate constructions and equivalents falling within the scope of the invention as expressed in the appended claims.

Claims: A wire saw (110), comprising a wire (114) extending between two reels (112, 126) and guided around a plurality of grooved rollers (122) to form a row of wires (124), the wire row being treated with an abrasive solution (140) and adapted to contact a workpiece (154) in order to cut the workpiece (154) into thin wafers, at least one of the reels (112, 126) and grooved rollers (122) being connected to a rotary shaft (162) of a drive motor (128, 130, 132) for driving said at least one of the reels (112, 126) and grooved rollers (122) coaxially with said rotary shaft (162); characterised in that a turntable (170) with a positioning projection (170A) at a centre thereof is connected to said rotary shaft (162), and a flange (113) is provided on said at least one of the reels (112,126) and the grooved rollers (122), said flange (113) having a concave portion (113A) at a centre thereof and being connected to said turntable (170) with the concave portion (113A) of the flange (113) engaging the projection (170A) of said turntable. A wire saw as claimed in claim 1, wherein said drive motor (128, 130, 132) is formed integrally on a frame of the wire saw (110). A wire saw as claimed in any preceding claim, wherein said drive motor (128, 130, 132) is connected to one of the grooved rollers (122). A wire saw as claimed in any preceding claim, wherein said projection (170A) is a truncated cone. A wire saw as claimed in any preceding claim, wherein said wire reels (112,126) and said motor (128,130) are arranged vertically.

Inventors: KATAMACHI SHOZO, OKUBO SHIGERU, KATAMACHI, SHOZO, OKUBO, SHIGERU
Applicants: TOKYO SEIMITSU CO LTD, TOKYO SEIMITSU CO.,LTD.
Application year: 1996
Main classification: B23D57
IPC codes: B23D57, B28D5