JP3105431B2 - Wire tension control device for wire saw - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire tension control device for controlling the tension of a cutting wire in a wire saw to improve processing accuracy and prevent wire breakage.

[0002]

2. Description of the Related Art As a means for cutting a wafer from a semiconductor ingot, a wire saw is known. In this wire saw, a cutting wire pulled out from a wire feeding member is wound around a plurality of guide rollers and then collected by a wire winding member. The rotation of both bobbins and the guide rollers causes the cutting wire to extend in its longitudinal direction. In the state of being driven at a high speed in the direction, by cutting and feeding the work made of the semiconductor ingot or the like in a direction substantially orthogonal to the plurality of wires arranged between the guide rollers, a large number of thin pieces are formed from this work. Are cut out at the same time.

[0003] In such a wire saw, it is necessary to adjust the wire tension to an appropriate value in order to perform good cutting work and prevent disconnection of the cutting wire.
Conventionally, the following is known as a means for that.

A) A dancer roller is applied to a wire portion from a wire feeding member to a guide roller and a wire portion from a guide roller to a wire take-up member, and the dancer roller is urged by a spring or the like to apply a wire. Tension. Further, the position of the dancer roller is detected, and the rotational speed of the bobbin is adjusted so as to keep this position at a preset reference position (for example, see JP-A-1-11-1).
77958).

[0005] B) In a region from the wire feeding member to the guide roller and in a region from the guide roller to the wire winding member, tension detecting means for detecting the tension of the wire in each region is provided. The rotation speed of the bobbin is adjusted so that the tension detected by the means is maintained at an appropriate tension (for example, see Japanese Patent Application Laid-Open No. H4-152061).

[0006]

In the means of the above A), the dancer roller moves up and down in accordance with the tension of the wire. In particular, when the wire tension changes suddenly, the movement of the dancer roller is caused by the inertia force of the dancer roller itself. There is a disadvantage that the wire tension cannot be quickly followed and the wire tension cannot be accurately controlled.

Means B) controls the tension by adjusting the rotation speed of the bobbin. However, the moment of inertia of the bobbin is quite large and its rotation speed cannot be changed instantaneously. Can't follow quickly.

[0008] Therefore, it is difficult to control the wire tension with high responsiveness in both A) and B). In particular, when the wire tension suddenly fluctuates due to the cutting resistance, it cannot cope with this. In addition, the wire tension becomes unstable, the processing accuracy deteriorates, and the wire may be disconnected.

SUMMARY OF THE INVENTION In view of such circumstances, an object of the present invention is to provide an apparatus which can quickly follow an actual change in wire tension and perform good control.

[0010]

As a means for solving the above-mentioned problems, the present invention provides a wire winding member in which a cutting wire fed from a wire feeding member is wound around a plurality of guide rollers. In a wire saw in which a workpiece is cut and fed to a plurality of wires arranged between guide rollers in a state where the workpiece is wound and driven in an axial direction, the wire feeding member is provided. A pair of fixed pulleys on which the wire is hung in a region from the guide roller to the guide roller and a region from the guide roller to the wire winding member; a movable pulley disposed between the fixed pulleys; and driving the movable pulley. Pulley position operating means for changing the position thereof, tension detecting means for detecting the tension of the wire in each of the above areas, It is obtained by a wire length adjusting means for operating the pulley position operating means so as to approach the preset reference tension detected tension by means.

According to this configuration, even if the wire tension suddenly rises (or falls) due to the cutting resistance of the work or the like, the tension detecting means detects this and receives the detection signal to adjust the wire length. The means drives the movable pulley by the pulley position operating means to change its position, whereby the wire tension is quickly adjusted and kept within a predetermined allowable range.

In this device, when the movable pulley is far away from a preset reference position for controlling the wire tension, the moving allowance of the movable pulley is eliminated, and the wire tension further varies from this state. However, there is a possibility that the position of the movable pulley on the wire feeding side and the position of the movable pulley on the wire winding side are respectively detected, and the positions of the detected movable pulleys are respectively set in advance. By providing speed adjustment means for adjusting the wire feeding speed from the wire feeding member and the wire winding speed by the wire winding member so as to approach the position, the position of the movable pulley is substantially set to the reference position in a steady state. Therefore, it is possible to always favorably adjust the tension by moving the movable pulley.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the drawings.

The wire saw shown in FIG. 3 has a pair of wire feeding / winding devices 10A and 10B, a fixed pulley 12A,
12B, fixed pulleys 14A, 14B, fixed pulley 16
A, 16B, wire length operating devices 18A, 18B, fixed pulleys 22A, 22B, and four guide rollers 24A,
24B, 26A and 26B. Guide roller 2
4A and 24B are arranged at the same height position, and the guide rollers 26A and 26B are
4B.

[0015] Each wire feeding and winding device 10A, 10
B is a bobbin 9A, 9B around which a cutting wire W is wound.
And bobbin drive motors 11A and 11
B. One wire feeding and winding device 1
The wire W paid out from the 0A bobbin 9A is fixed to pulleys 12A, 14A, 16A and a wire length operating device 18A.
Of the movable pulley 20A and the fixed pulley 22A, and the guide rollers 24A, 24B, 26B, 2
After being wound many times outside 6A, the fixed pulley 22B,
The movable pulley 20B and the fixed pulleys 16B, 14B, 12B of the wire length operating device 18B are wound in this order, and are wound around the bobbin 9B of the other wire feeding / winding device 10B. An appropriate tension is applied to the wire W. Further, a roller drive motor 25 for rotating the rotation shaft is connected to a rotation shaft of a specific one of the guide rollers 24A, 24B, 26B, 26A (in the illustrated example, the guide roller 26A).

The bobbin drive motors 11A, 11A
B, the rotational drive direction of the bobbins 9A and 9B and the rotational drive direction of the guide roller 26A by the roller drive motor 25 are switched between forward and reverse, so that the wire W
A state in which it is fed out from A and wound on a bobbin 9B,
The state in which the wire W is unreeled from the bobbin 9B and wound around the bobbin 9A is switched.

That is, in this wire saw, a number of wires W are stretched in parallel with each other between the guide rollers 24A and 24B and are reciprocated in the longitudinal direction.

Above the wire W stretched between the guide rollers 24A and 24B, there is provided a work feeder 30 for moving a cylindrical work (for example, a semiconductor ingot) 28. The work feed device 30 includes a work holding unit 32 and a work feed motor 34. The work holding unit 32 holds the work 28 in a direction in which a target crystal orientation can be obtained based on the crystal axis. The work feed motor 34 is provided with a work holding unit in combination with a ball screw (not shown). 32 and the work 28 are integrally moved up and down (that is, cut and fed).

Above the wire W stretched between the guide rollers 24A and 24B, slurry supply devices 36A and 36B are provided at positions on both left and right sides of the work 28. These slurry supply devices 36A and 36B simultaneously supply a processing liquid (slurry) in which abrasive grains are mixed to each of the wires W driven at a high speed, and cause the wires W to adhere to the surface of the wires W.

Accordingly, in this wire saw, a large number of wires W stretched between the guide rollers 24A and 24B are simultaneously driven at a high speed in the longitudinal direction, and the working fluid is supplied to these wires W from the slurry supply devices 36A and 36B. While being supplied, the work W is cut and sent downward with respect to these wires W, whereby a large number of wafers are simultaneously cut out from the work W at one time.

Next, the structure of the wire length operating device 18A will be described with reference to FIGS. Note that the configuration of the wire length operation device 18B is completely the same as the structure of the wire length operation device 18A, and a description thereof will be omitted.

The movable pulley 20A includes a fixed pulley 16
A, 22A, and the wire length changes due to the vertical movement of the movable pulley 20A (specifically, the wire length increases when the movable pulley 20A descends, and the movable pulley 2
0A rises, the wire length decreases).
A, 20A and 22A are provided.

A tension detector 40 composed of a load cell or the like is attached to the support member 38 of the fixed pulley 22A. The tension detector 40 detects the load applied to the support member 38, and thus the tension of the wire W. Is detected.

The movable pulley 20A is attached to the tip of a lever 44 so as to be rotatable about a rotation shaft 42. A rotation center shaft 46 is fixed to the base end of the lever 44, and the rotation center shaft 46 is connected to a swing cylinder (pulley position operation means) 50 fixed to a fixed side plate 48. The operation of the moving cylinder 50 causes the lever 44 and the movable pulley 20A to rotate around the rotation center axis 46. Further, an encoder (pulley position detecting means) 52 is connected to the rotation center shaft 46, and the encoder 52 can detect the rotation angle position of the rotation center shaft 46, in other words, the position of the movable pulley 20A. ing.

The wire saw is provided with a controller 60 as shown in FIG. This controller 6
0 has a wire length adjusting means 62 and a speed adjusting means 64.

The wire length adjusting means 62 includes a tension detector 40 on each of the wire feeding side and the wire winding side.
An electric signal is output to the pneumatic servo circuit 54 for driving the swing cylinder 50 so as to maintain the wire tension detected in the step (c) at a preset reference tension, and the movable pulleys 20A and 20
The position of B is adjusted. Specifically, for example, when the detected tension on the wire feeding / winding device 10A side is higher than the reference tension, the lever 44 connected to the swing cylinder 50 is rotated clockwise in FIG. By moving the pulley 20A closer to the fixed pulleys 16A and 22A, the wire length is reduced. Conversely, when the detected tension is lower than the reference tension, the lever 44 connected to the swing cylinder 50 is turned counterclockwise in FIG. , The movable pulley 20A is moved away from the fixed pulleys 16A and 22A to increase the wire length.

The speed adjusting means 64 shifts the positions of the movable pulleys 20A and 20B detected by the encoder 52 to a preset reference position (here, a position where the lever 44 becomes horizontal as shown by a solid line in FIG. 1). The control signals are respectively output to the bobbin drive motors 11A and 11B so that the rotational speeds of the bobbins 9A and 9B are adjusted so as to approach each other.
For example, in a state where the wire W is paid out from the bobbin 9A and is wound around the bobbin 9B, the movable pulley 20A on the payout side is used.
Is detected at a position lower than the reference position, the rotational speed of the bobbin 9A on the side serving as the wire feeding member is reduced in order to raise the movable pulley 20A. If it is detected that 20A is located above the reference position, the movable pulley 20A
In order to lower A, the rotational speed of the bobbin 9A on the side serving as the wire feeding member is increased. On the other hand, when it is detected that the movable pulley 20B on the wire winding side is at a position lower than the reference position, the bobbin 9B on the side serving as the wire winding member is moved to raise the movable pulley 20B. When the rotational speed is increased and, conversely, it is detected that the movable pulley 20B is at a position above the reference position, the bobbin 9B on the side serving as a wire winding member is moved to lower the movable pulley 20B. It is configured to reduce the rotation speed of.

In the above example, the state in which the wire is fed from the bobbin 9A and wound on the bobbin 9B has been described.
Conversely, the wire is unreeled from the bobbin 9B and the bobbin 9A
The speed adjusting means 64 performs the same control even in the state of being wound.

Next, the operation of this device will be described.

For example, when the wire W is unreeled from the bobbin 9A and wound on the bobbin 9B, the detection value of the tension detector 40 attached to the fixed pulley 22A (ie, the upstream side of the work processing position) Is detected by the wire length adjusting means 62.
The wire length adjusting means 62 compares the detected tension value with a preset reference tension value, and when the former is higher than the latter, raises the movable pulley 20A by an amount corresponding to the difference. If the wire length is reduced to lower the wire tension, and if the latter is higher than the former, the movable pulley 20A is lowered by an amount corresponding to the difference to increase the wire length and increase the wire tension. Therefore, work 2
8, even if the wire tension rises momentarily due to the cutting resistance or the like, the movable pulley 20A is quickly driven up in response to this, so that an excessive rise in the wire tension is avoided, which results in Disconnection of the wire W is prevented.

On the other hand, the detection signal (ie, the movable pulley 20) of the encoder 52 provided in the wire length operating device 18A is provided.
The A position detection signal) is taken into the speed adjusting means 64. The speed adjusting means 64 compares the detection position of the movable pulley 20A with a preset reference position, and when the former is higher than the latter, the bobbin which is a wire feeding bobbin to lower the movable pulley 20A. Increase the rotation speed of 9A. Conversely, if the former is lower than the latter, the rotational speed of the bobbin 9A, which is a wire feeding bobbin, is reduced to raise the movable pulley 20A. By such control, in the steady state, the movable pulley 20A is held substantially at the reference position, and a margin for the movement is secured.

That is, in this apparatus, the movable pulley 20
The position of each movable pulley 20A, 20B is adjusted to the reference position by adjusting the rotational speed of the bobbin 9A, 9B, while the instantaneous increase and decrease of the wire tension can be dealt with by the vertical movement of A, 20B.

In addition, the present invention can adopt the following embodiments in addition to the above.

(1) In the above embodiment, the movable pulleys 20A and 20B are displaced by the rotation of the lever 44.
The movable pulleys 20A and 20B may be moved linearly by guidance by a rail or the like. In this case, as a means for changing the position, a feed screw mechanism, a rack and pinion mechanism, or the like may be used. Also, when the movable pulley is swung, the drive source thereof is not limited to the swing cylinder 50, and for example, a servo motor may be used.

(2) The specific configuration of the tension detector 40 is not particularly limited, and may be a combination of a differential transformer and a spring in addition to the load cell.

(3) If the movable range of the movable pulleys 20A and 20B can be sufficiently secured, the speed adjusting means 64 is not particularly required. However, if the positions of the movable pulleys 20A and 20B are stabilized by the speed adjusting means 64 and the range of movement thereof is reduced, the entire apparatus can be made compact as much.

(4) In the above-described embodiment, control is performed so that the actual wire tension or the movable pulley position approaches the reference tension or the reference position. However, the reference tension or the reference position is given a width (that is, the tension or the movable position). Set the allowable range of the pulley position.) If the detected tension or the detected position is within the allowable range, do not change the movable pulley position or the bobbin rotation speed. Only the position of the movable pulley and the rotational speed of the bobbin may be controlled so that the tension and the position of the movable pulley are within the allowable range.

[0038]

As described above, the present invention detects the wire tension in the region from the wire feeding member to the guide roller and the region from the guide roller to the wire winding member in the wire saw, and sets each detected tension in advance. Since the wire length is adjusted by driving the movable pulley between the fixed pulleys so as to approach the set reference tension, the wire tension can be adjusted in response to a rapid change in the wire tension, and the tension can be adjusted. There is an effect that it is possible to prevent inconveniences such as deterioration of processing accuracy and wire breakage due to the fluctuation beforehand.

Further, a pulley position detecting means for detecting the position of the movable pulley, and a speed for respectively adjusting the wire feeding speed and the wire winding speed such that the detected position of the movable pulley approaches a preset reference position. If the position of the movable pulley is kept substantially at the reference position in a steady state by providing an adjusting means, the movable range of the movable pulley can be reduced and the whole apparatus can be compacted by that much, and good movement due to the movement of the movable pulley can be achieved. Tension control can be secured.

[Brief description of the drawings]

FIG. 1 is a front view of a wire tension control device according to an embodiment of the present invention.

FIG. 2 is a plan view of the wire tension control device.

FIG. 3 is an overall configuration diagram of a wire saw provided with the wire tension control device.

FIG. 4 is a block diagram showing a functional configuration of a controller provided in the wire saw.

[Explanation of symbols]

9A, 9B bobbin (wire feeding member and wire winding member) 11A, 11B bobbin drive motor 16A, 16B, 22A, 22B fixed pulley 18A, 18B wire tension operating device 20A, 20B movable pulley 24A, 24B, 26A, 26B guide roller Reference Signs List 28 Workpiece 40 Tension detector 50 Swing cylinder (movable pulley position operating means) 52 Encoder (movable pulley position detecting means) 60 Controller 62 Wire length adjusting means 64 Speed adjusting means W Wire

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-63-62655 (JP, A) JP-A-1-177958 (JP, A) JP-A-4-152061 (JP, A) JP-A-4- 75862 (JP, A) JP-A-1-295758 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B24B 27/06 B28D 5/04

Claims (4)

(57) [Claims] 1. A cutting wire fed from a wire feeding member is wound around a plurality of guide rollers and wound on a wire winding member, and the guide wire is driven in an axial direction. In a wire saw in which a workpiece is cut by being sent to a plurality of wires arranged between rollers, the workpiece is cut, and a region from the wire feeding member to the guide roller and a region from the guide roller to the wire winding member. With the above wire hung
And a pair of fixed pulleys
And the movable pulley
A pulley position operating means for changing the Risono position, a tension detecting means for detecting the tension of the wire in the respective regions, the pulley as close to a preset reference tension detected tension by the tension detecting means A wire tension control device for a wire saw, comprising: wire length adjusting means for operating a position operating means . 2. The wire tension control device according to claim 1, wherein the pulley position operating means includes:
To the lever on which the movable pulley is rotatably mounted
A wire tension control device for a wire saw, wherein the wire tension control device is connected and driven to rotate . 3. The wire tension control device for a wire saw according to claim 1 , wherein said tension detecting means is provided.
Is a tension detector that detects the load applied to the fixed pulley.
A wire tension control device for a wire saw , which is an output device. 4. The wire according to claim 1, wherein:
Wire feed control in wire tension control device in saw
Position of the movable pulley on the pulling side and the movable pulley on the wire winding side
Pulley position detecting means for detecting the
The position of each movable pulley to a preset position.
Wire feeding from the wire feeding member so as to approach
Wire speed with the wire take-up member
Characterized by having speed adjusting means for adjusting each.
Wire tension control device in a wire saw.