JP2024053358A - Wire saw - Google Patents

Abstract

[Problem] To provide a wire saw capable of uniformly supplying machining fluid to a wire array. [Solution] The wire saw includes a plurality of rotatably driven wire guides (2), a wire (3) wound around the wire guide to form a wire array, a tank (5) for storing machining fluid to be supplied to the wire array, a guide (6) extending from the tank above the wire array at a downward incline, a weir (7) erected to separate the tank from the guide, and an inner nozzle (8) provided within the tank, extending in the wire array direction of the wire array and having a plurality of discharge ports (82) in the longitudinal direction, the discharge ports being located lower than the upper end of the weir, and the inner nozzle being located at a position such that a distance X from a rear wall (53) of the tank facing the weir to the inner nozzle is wider than a distance Y from the weir to the inner nozzle in the axial direction of the wire, forming a flow path within the tank through which machining fluid discharged from the discharge ports flows in a direction away from the guide. [Selected Figure] Figure 4

Description

The present invention relates to a wire saw.

A wire saw is known as a device that cuts a workpiece, such as a silicon ingot, into slices. In a wire saw, a wire is unwound from a bobbin on one side, wound around multiple wire guides to form a wire row, and then wound onto a bobbin on the other side. The wire is driven at high speed, and the workpiece is pressed against the wire row to cut it into multiple pieces.

In such wire saws, machining is performed while supplying a machining fluid that cools, lubricates, and supplies abrasive grains to the wires, to a wire array in which multiple wires are arranged in parallel. There are two types of machining methods for wire saws: the loose abrasive method and the fixed abrasive method. In the loose abrasive method, a machining fluid called a slurry in which abrasive grains are suspended is supplied to the wire array. In the fixed abrasive method, a machining fluid that does not contain abrasive grains is supplied to a wire array of diamond wires, which have abrasive grains such as diamonds fixed to the wire surface.

Conventionally, wire saw machining fluid supply devices have adopted different structures depending on the machining method as described above. In wire saws using a loose abrasive grain method, the viscosity of the machining fluid is relatively high, so it is common to drop the machining fluid in a curtain-like manner onto the wire from a slit-shaped machining fluid supply port, as disclosed in Patent Document 1, for example. In wire saws using a fixed abrasive grain method, the viscosity of the machining fluid is relatively low, so it is common to supply the coolant via a coolant supply path with an inclined portion that slopes toward the vicinity of the workpiece, as disclosed in Patent Document 2, for example.

Japanese Patent Application Laid-Open No. 9-76231 Patent No. 6795899

In any machining method, the challenge has always been to supply the machining fluid to the wire array uniformly, but as described above, it is inefficient to change the machining fluid supply device to suit the machining method. In addition, in any machining method, the viscosity of the machining fluid changes as time passes from the start of machining due to the machining fluid containing cutting chips, etc., but when the viscosity of the machining fluid changes, the pressure distribution in the tank that stores the machining fluid also changes, causing the flow rate balance in the longitudinal direction of the tank to be disrupted and the machining fluid cannot be supplied uniformly. Furthermore, when a thin wire, especially a wire of φ0.10 or less, is used for machining, if the flow rate of the machining fluid is too high, the wire is likely to vibrate, so measures are taken to suppress the flow rate, but suppressing the flow rate causes the flow rate balance in the longitudinal direction of the tank to be disrupted and the machining fluid cannot be supplied uniformly, which is another problem.

The present invention was made in consideration of these points, and its purpose is to provide a wire saw that can supply machining fluid uniformly to the wire array even if the viscosity or flow rate of the machining fluid changes.

To achieve the above objective, this invention creates a flow path in the tank where the machining fluid first flows in a direction away from the guide, thereby reducing the force of the flow and reducing rippling.

Specifically, in the first invention,
A plurality of wire guides that are rotationally driven;
a wire wound around the wire guide to form a wire row;
a tank for storing a machining liquid to be supplied to the wire array;
a guide extending from the tank and inclined downwardly above the wire array;
a weir erected so as to separate the tank and the guide;
an inner nozzle provided in the tank, extending in a wire arrangement direction of the wire array and having a plurality of discharge ports in a longitudinal direction;
The discharge port is provided at a position lower than an upper end of the weir,
the inner nozzle is provided at a position where a distance from a back wall of the tank facing the dam to the inner nozzle is wider than a distance from the dam to the inner nozzle in an axial direction of the wire,
A flow path is formed in the tank, through which the machining fluid discharged from the discharge port flows in a direction away from the guide.

According to the above configuration, the inner nozzle extending in the wire arrangement direction of the wire array has multiple discharge ports in its longitudinal direction, so that machining fluid is uniformly supplied from the inner nozzle into the tank in the longitudinal direction, and variation in flow rate can be suppressed. In addition, by arranging the inner nozzle in the tank so that the distance from the inner nozzle to the rear wall of the tank facing the weir in the axial direction of the wire is wider than the distance from the weir to the inner nozzle, machining fluid discharged from the discharge port can form a flow path that flows away from the guide once, passes between the rear wall of the tank and the inner nozzle, passes above the inner nozzle, and flows into the guide, rather than flowing directly toward the guide. Therefore, the momentum of the flow of machining fluid is suppressed in the tank, rippling is reduced, and machining fluid with a stable flow rate balance can be uniformly supplied from the guide to the wire array.

The second invention is characterized in that in the first invention, the surface of the tank facing the outlet is not perpendicular to the direction in which the machining fluid is discharged from the outlet.

According to the above configuration, when the facing surface facing the discharge port is perpendicular to the discharge direction of the machining fluid discharged from the discharge port, the machining fluid discharged from the discharge port flows while maintaining its flow momentum, but when the facing surface facing the discharge port is not perpendicular to the discharge direction, the facing surface can reduce the flow momentum of the machining fluid, making it possible to further enhance the above-mentioned effect.

The third invention is characterized in that in the second invention, the surface of the tank facing the discharge port is an inclined surface that descends in a direction away from the guide.

With the above configuration, when the machining fluid discharged from the discharge port flows toward the opposing surface, the opposing surface can guide the machining fluid away from the guide, reducing the force of the flow, thereby further enhancing the above-mentioned effects.

The fourth invention is characterized in that in any one of the first to third inventions, the sum of the cross-sectional areas of the multiple outlets is smaller than the cross-sectional area of the inner nozzle when cut in a direction approximately perpendicular to the longitudinal direction.

According to the above configuration, if the total cross-sectional area of the discharge ports is smaller than the cross-sectional area of the inner nozzle, the machining fluid filling the inner nozzle will apply internal pressure to the inner nozzle, and even if the flow rate of the machining fluid is reduced or the machining fluid is introduced into the inner nozzle from one end of the inner nozzle (even if it is not introduced from both ends), the amount of machining fluid discharged from each discharge port will tend to be uniform. Furthermore, if the machining fluid is introduced from one end of the inner nozzle configured in this way, it will also be possible to make the tank smaller.

The fifth invention is characterized in that in any one of the first to third inventions, the inner nozzle is installed on both longitudinal ends of the tank.

With the above configuration, the inner nozzle is attached to the tank by being erected on both ends of the tank, making it easy to remove the inner nozzle during maintenance and improving workability.

The sixth invention is characterized in that in any one of the first to third inventions, the upper end of the weir is a smooth or curved surface.

According to the above configuration, by making the upper end of the weir a smooth or curved surface, it is possible to further reduce rippling of the machining fluid that flows from the tank over the weir to the guide, thereby improving the effect of uniformly supplying machining fluid with a stable flow rate balance from the guide to the wire row.

As described above, the technology disclosed herein makes it possible to supply machining fluid uniformly to the wire array even if the viscosity or flow rate of the machining fluid changes.

FIG. 2 is a schematic front view showing a main part of the wire saw. FIG. 2 is a perspective view of one side of the machining liquid supply device. 4 is a perspective view of the machining fluid supplying device on the other side. FIG. 1 is a cross-sectional view of a machining fluid supplying device according to an embodiment of the present invention. FIG. FIG. 5 is a partially enlarged view of FIG. 4 . FIG. 11 is a cross-sectional view of a machining fluid supplying device according to another embodiment.

The following describes an embodiment of the present invention with reference to the drawings.

(Wire saw)
1 is a schematic front view showing a main part of a wire saw 1 according to an embodiment of the present invention. The wire saw 1 is used to simultaneously cut a workpiece W, such as a silicon ingot used in the manufacture of semiconductor devices, solar cells, etc., at multiple locations to obtain a workpiece such as a thin plate-like wafer. The wire saw 1 includes a pair of cylindrical wire guides 2, 2 each having a rotation axis parallel to each other and rotated about the rotation axis, a wire 3 wound between the pair of wire guides 2, 2, and a processing liquid supply device 4 that supplies processing liquid to the wire 3. In this embodiment, the wire guides 2, 2 are arranged on the left and right, and the rotation axes of the wire guides 2, 2 extend in the front-rear direction of the wire saw.

The wire 3 is wound around the left and right wire guides 2, 2, forming a wire row in which multiple wires 3 are arranged approximately parallel to each other. The wire row is arranged in a direction parallel to the extension direction of the rotation axis of the wire guide, which is the front-to-back direction in this embodiment. The wire 3 is driven to reciprocate in the axial direction at high speed, so that the wire row has a cutting region. The workpiece W is driven so as to be pressed from above downward against the wire row, and multiple thin slice-shaped workpieces are cut out from the workpiece W.

On both the left and right sides of the wire row cutting area, machining fluid supply devices 4, 4 are arranged to supply machining fluid above the wire row. The two machining fluid supply devices 4, 4 are arranged facing each other across the wire row cutting area, and are formed approximately symmetrically.

(Machining fluid supply device)
Fig. 2 is a perspective view of one side of the machining liquid supplying device, Fig. 3 is a perspective view of the other side of the machining liquid supplying device, and Fig. 4 is a cross-sectional view of the machining liquid supplying device cut in the axial direction of the wire. As shown in Figs. 2 to 4, the machining liquid supplying device 4 includes a tank 5 for storing machining liquid, a guide 6 extending from the tank 5 at an angle downward, a dam 7 erected to separate the tank 5 from the guide 6, and an inner nozzle 8 provided in the tank. The machining liquid supplying device 4 extends in the wire arrangement direction of the wire row.

The tank 5 stores the machining fluid to be supplied to the wire row. The tank 5 is positioned farther from the cutting area of the wire row than the guide 6. The bottom surface of the tank 5 has an inclined surface 51 that descends in a direction away from the guide 6, and a horizontal bottom 52 that is connected to the lower end of the inclined surface 51. The bottom 52 is located at the deepest part of the tank 5.

In this embodiment, the machining method of the wire saw 1 is a free abrasive method, and abrasive grains are suspended in the machining fluid. The machining fluid supply device of this embodiment can uniformly supply machining fluid regardless of the machining method, but in the case of the free abrasive method, through holes 52a are provided in the bottom 52. As shown in FIG. 2, the through holes 52a are provided at both ends of the wire row in the wire arrangement direction in the bottom 52. The through holes 52a allow a predetermined amount of machining fluid to constantly flow out, preventing the accumulation of abrasive grains in the machining fluid on the bottom 52 of the tank 5.

A tank-side partition wall 56 that forms part of the weir 7 stands on the upper end of the inclined surface 51. A rear wall 53 that stands from the bottom 52 faces the weir 7 in the axial direction of the wire 3. The axial direction of the wire 3 is the direction in which the wire 3 extends substantially perpendicular to the direction in which the wire rows are arranged, which is the left-right direction in this embodiment.

The side walls 54, 54 erected from both ends of the tank 5 in the direction of the wire row arrangement are provided with mounting holes 54a for mounting the inner nozzle 8 on the top of the inclined surface 51. The tank 5 is covered at the top by a lid 55 that can be opened and closed. The lid 55 is located above the tank side partition wall 56 with a gap between them. The machining fluid in the tank 5 overflows and flows over the weir 7 toward the guide 6. The lid 55 extends toward the guide 6 so as to cover the top of the tank side end of the guide 6. The lid 55 prevents the mixing of machining fluid and cutting chips scattered during machining.

The guide 6 slopes downward from the top of the tank 5 and extends above the cutting area of the wire row. The guide 6 has a guide-side partition wall 61 that forms a weir 7 together with the tank-side partition wall 56. The lower end of the guide-side partition wall 61 is located at the upper part of the inclined surface 51. The guide 6 has a guide surface 62 that slopes downward from the lower end of the guide-side partition wall 61 toward the cutting area of the wire row. Side walls 63, 63 are erected at both ends of the guide surface 62 in the arrangement direction of the wire row, and the upper part of the guide 6 is covered by a cover part 64. The cover part 64 partially overlaps with the lid part 55 of the tank 5. A guard wall 65 is erected at the end of the cover part 64 on the side away from the tank 5. The guard wall 65 prevents machining fluid and cutting chips scattered on the cover part 64 from falling onto the wire row.

At the end of the guide 6 near the cutting area, a supply port 66 is formed, which is an opening surrounded by the guide surface 62, side walls 63, 63, and cover portion 64. The machining fluid that overflows from inside the tank 5 over the weir 7 flows along the guide surface 62 and is supplied to the cutting area from the supply port 66.

The weir 7, which is erected to separate the tank 5 and the guide 6, is formed by overlapping the tank side partition wall 56 and the guide side partition wall 61 in the axial direction of the wire. The weir 7 has an auxiliary member 9 to reduce rippling of the machining fluid.

The auxiliary member 9 is formed from a single plate material extending in the direction in which the wire rows are arranged. The auxiliary member 9 has an inclined portion 91 that is provided so as to lean obliquely from the guide surface 62 to the guide side partition wall 61, and a curved portion 92 that curves from the inclined portion 91 to the tank 5 side so as to straddle the tank side partition wall 56 and the guide side partition wall 61. The curved portion 92 has an upwardly convex curved surface formed at the upper end of the weir 7. The end of the curved portion 92 is located on the tank 5 side at a distance from the tank side partition wall 56. Although it is not necessary to provide the auxiliary member 9 as in this embodiment, it is preferable that the upper end of the weir 7 is a smooth or curved surface in order to reduce rippling of the machining fluid that flows from the tank 5 over the weir 7 to the guide 6. By making the upper end of the weir 7 a smooth or curved surface, it is possible to reduce rippling of the machining fluid that flows from the tank 5 over the weir 7 to the guide 6, and to enhance the effect of uniformly supplying the machining fluid with a stable flow rate balance from the guide to the wire row.

Figure 5 is a perspective view of the inner nozzle. The inner nozzle 8 is a cylindrical member that extends in the direction in which the wires are arranged in the wire row. The inner nozzle 8 has an inlet 81 at one end in the longitudinal direction for introducing the machining fluid, and the other end is closed. As shown in Figures 2 and 3, in the left and right machining fluid supply devices 4, 4, the inner nozzles 8 have inlets 81 in the same direction.

The inner nozzle 8 has multiple outlets 82 in the longitudinal direction. In this embodiment, the outlets 82 are holes with a circular cross section. The sum of the cross-sectional areas of the multiple outlets 82 (the cross-sectional area of the holes when cut perpendicularly to the holes) is smaller than the cross-sectional area of the inside of the inner nozzle 8 when cut in a direction approximately perpendicular to the longitudinal direction of the inner nozzle 8.

The inner nozzle 8 is inserted through a mounting hole 54a on one side of the tank 5, and then through mounting holes 54a on both sides. The inner nozzle 8 is fixed to the tank 5 from the outside with a fixing member 83, and is thus installed on both ends of the tank 5 in the longitudinal direction. The inner nozzle 8 is disposed above the inclined surface 51 in the tank 5 with a gap therebetween. The inner nozzle 8 is disposed with the discharge port 82 facing directly downward. The inner nozzle 8 is disposed so that the discharge port 82 is located at a position lower than the upper end of the weir 7. The surface of the tank 5 facing the discharge port 82 is not perpendicular to the discharge direction of the machining fluid discharged from the discharge port 82. When the discharge port 82 is a hole-shaped port as in this embodiment, the discharge direction is the central axis direction of the hole. The surface of the tank 5 facing the discharge port 82 is the inclined surface 51.

The inner nozzle 8 is provided in a position in the axial direction of the wire 3 where the distance from the rear wall 53 of the tank 5 facing the weir 7 to the inner nozzle 8 is wider than the distance from the weir 7 to the inner nozzle 8. In this embodiment, the inner nozzle 8 is provided in a position where the distance X from the rear wall 53 to the inner nozzle 8 is wider than the distance Y from the tank side end of the auxiliary member 9 to the inner nozzle 8.

By arranging the inner nozzle 8 in the above-mentioned position, a flow path is formed in the tank 5 through which the machining fluid discharged from the discharge port 82 flows in a direction away from the guide 6. FIG. 6 is a partially enlarged view of FIG. 4, and is a diagram for explaining the flow path of the machining fluid in the tank 5. More specifically, as shown by the arrow in FIG. 6, the machining fluid is discharged downward from the discharge port 82, and when it hits the inclined surface 51 facing the discharge port 82, the flow momentum is suppressed and it flows in a direction away from the guide 6 along the inclination of the inclined surface 51. After that, the machining fluid hits the back wall 53 and rises, goes over the top of the inner nozzle 8, and overflows from the weir 7. The machining fluid overflowing from the weir 7 flows along the auxiliary member 9 to the guide 6 and is supplied to the wire row from the supply port 66.

The wire saw 1 configured as above is positioned in such a way that the distance from the rear wall 53 of the tank 5 facing the weir 7 to the inner nozzle 8 is wider in the axial direction of the wire 3 than the distance from the weir 7 to the inner nozzle 8. This allows the machining fluid discharged from the discharge port 82 to form a flow path that flows away from the guide 6, passes between the rear wall 53 of the tank 5 and the inner nozzle 8, passes above the inner nozzle 8, and flows to the guide 6, rather than flowing directly toward the guide 6. This suppresses the flow momentum of the machining fluid within the tank, reducing rippling, and makes it possible to uniformly supply machining fluid with a stable flow rate balance from the guide to the wire row.

By making the total cross-sectional area of the multiple discharge ports 82 smaller than the cross-sectional area inside the inner nozzle 8 when cut in a direction approximately perpendicular to the longitudinal direction of the inner nozzle 8, the inner nozzle 8 is subjected to internal pressure by the machining fluid filled in the inner nozzle 8. Therefore, even if machining fluid is introduced into the inner nozzle 8 from one end in the longitudinal direction of the inner nozzle 8 rather than from both longitudinal sides of the inner nozzle 8, the amount of machining fluid discharged from each discharge port tends to be uniform. By configuring the inner nozzle 8 to introduce machining fluid from one end, the machining fluid supply device 4 can be made smaller.

When performing maintenance such as cleaning the inside of the tank 5, the inner nozzle 8 can be easily removed by releasing the fixing members 83 attached to both ends of the tank 5 and pulling out the inner nozzle 8 from one side in the direction of the wire row arrangement. In addition, by opening the lid portion 55, the top of the tank 5 opens, making it possible to easily clean the inside of the tank 5. Since the inner nozzle 8 is attached by bridging between both ends of the tank 5, there are no members inside the tank 5 for attaching the inner nozzle 8 to the tank 5, making cleaning easy.

(Machining Fluid Supply Apparatus According to Another Embodiment)
Fig. 7 is a cross-sectional view showing a machining liquid supplying apparatus according to another embodiment, cut in the axial direction of the wire. The same members as those in the above embodiment are given the same reference numerals, and detailed description thereof will be omitted. The machining liquid supplying apparatus in Fig. 7 differs from the above embodiment in that a buffer material 10 is attached inside the tank 5.

In this embodiment, the cushioning material 10 is attached inside the tank 5 opposite the discharge port 82. The cushioning material 10 is capable of passing the machining fluid discharged from the inner nozzle 8. The cushioning material 10 is capable of suppressing the force of the flow of the machining fluid by passing it through. The shape and material of the cushioning material 10 are not important, but it is, for example, a mesh. The cushioning material 10 is attached below the inner nozzle 8 inside the tank 5 opposite the discharge port 82.

In the wire saw 1 configured as described above, the momentum of the machining fluid flow is suppressed inside the tank by the buffer material 10, reducing rippling, and machining fluid with a stable flow rate balance can be uniformly supplied from the guide to the wire row.

Note that the above embodiments are essentially preferred examples and are not intended to limit the scope of the present invention, its applications, or uses.

REFERENCE SIGNS LIST 1 Wire saw 2 Wire guide 3 Wire 4 Machining fluid supply device 5 Tank 6 Guide 7 Weir 8 Inner nozzle 9 Auxiliary member 10 Cushioning material 51 Inclined surface 53 Back wall 82 Discharge port W Workpiece

Claims (6)

A plurality of wire guides that are rotationally driven;
a wire wound around the wire guide to form a wire row;
a tank for storing a machining liquid to be supplied to the wire array;
a guide extending from the tank and inclined downwardly above the wire array;
a weir erected so as to separate the tank and the guide;
an inner nozzle provided in the tank, extending in a wire arrangement direction of the wire array and having a plurality of discharge ports in a longitudinal direction;
The discharge port is provided at a position lower than an upper end of the weir,
the inner nozzle is provided at a position where a distance from a back wall of the tank facing the dam to the inner nozzle is wider than a distance from the dam to the inner nozzle in an axial direction of the wire,
The wire saw is characterized in that a flow path is formed within the tank, through which the machining fluid discharged from the discharge port flows in a direction away from the guide. The wire saw according to claim 1, characterized in that the surface of the tank facing the outlet is not perpendicular to the direction in which the machining fluid is discharged from the outlet. The wire saw according to claim 2, characterized in that the surface of the tank facing the discharge port is an inclined surface that descends in a direction away from the guide. The wire saw according to any one of claims 1 to 3, characterized in that the sum of the cross-sectional areas of the multiple discharge ports is smaller than the cross-sectional area of the inner nozzle when cut in a direction approximately perpendicular to the longitudinal direction. The wire saw according to any one of claims 1 to 3, characterized in that the inner nozzle is installed at both longitudinal ends of the tank. The wire saw according to any one of claims 1 to 3, characterized in that the upper end of the dam is a smooth or curved surface.