JPH04152060A - Grooved roller for multi-wire saw - Google Patents

Abstract

PURPOSE:To reduce the wire cost and to stabilize the cutting accuracy and cutting efficiency, by enlarging the diameter at both end sides of a resin made sleeve on which the grooves in the same depth are engraved more than the diameter of a center part, and forming the shape that the wire winding radius of curvature becomes almost uniform in the roll axial direction with a thermal expansion. CONSTITUTION:A grooved roller 20 is made in a hourglass shape larger than the outer diameter Db of a center part 21b at the outer diameter Da of both ends 21a a resin made sleeve, and is engraved with groove 11-1 in the same width (g) on the resin made sleeve 21, both ands 21a and center 21b of the sleeve are manufactured so that wire winding radius of the groove 11-1 becomes uniform in the roll axial direction, in the state of the grooved roller 20 under cutting being subjected to temperature rising. Because of its becoming in the structure that the wire winding radius after the thermal expansion of the sleeve becomes uniform, the disconnection generation rate of the wire caused by the thermal expansion of sleeve under cutting becomes extremely low, and not only the operation rate of wire saw can drastically be improved but also the loss of a work due to disconnection can drastically by reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a groove roller for a multi-wire saw that cuts brittle materials such as semiconductor materials, magnetic materials, and ceramics into a large number of thin wafers using a wire. The present invention relates to a grooved roller that prevents wire breakage due to thermal expansion of the roller, improves cutting accuracy, and reduces wire costs.

Conventional technology A multi-wire saw used to cut ingots of brittle materials such as semiconductor materials into wafer shapes presses an object to be cut (hereinafter referred to as a workpiece) against a wire that is hung in multiple strands at a predetermined pitch, and then applies abrasive grains. This is a device that moves the wire and workpiece relative to each other while pouring a grinding liquid (hereinafter referred to as abrasive liquid) containing the grinding liquid, and cuts the workpiece by grinding action. Methods of giving relative motion between the wire and the work include a method of reciprocating the wire (e.g., Japanese Patent Publication No. 56-199), a method of reciprocating the work with respect to a wire running in one direction (e.g., Japanese Patent Publication No. 524).
2954), a method of running a wire in one direction with respect to a fixed workpiece (for example, JP-A-6L-100361)
etc., but all of them use grooved rollers as a means for hanging multiple wires.

For example, as shown in Fig. 3, one wire (4) is wound around a large number of grooves carved on the outer circumferential surface of three grooved rollers (1), (2), and (3) that are rotatably held. A method of maintaining the wire pitch has been adopted. The pitch of the wire is determined by taking into account the thickness of the wafer to be cut, the diameter of the wire, and grinding loss due to abrasive grains.

The abrasive liquid (6) can be supplied by pouring it onto the wire array from a nozzle (7) placed above the workpiece (5), or by immersing the workpiece (5) in the abrasive liquid. During cutting, the workpiece (5) is not attached and the push-up table (8) is gradually raised to complete the cutting.

By the way, in a multi-wire saw, it is extremely important to prevent wire breakage. That is, once a wire breakage occurs, not only is there a loss of expensive wires and a huge amount of man-hours for restoration, but in the worst case, the workpiece has to be discarded, and the losses are extremely large. In particular, if a disconnection occurs between the grooved rollers (1), (2), and (3) shown in Figure 3,
The wire may become entangled with the grooved roller and damage the groove of the grooved roller, further increasing the damage.

Needless to say, wire breakage occurs when excessive tensile force is applied to the wire, but wires between grooved rollers in particular lose their strength due to frictional heat caused by sliding with the workpiece. Wire breakage is likely to occur because damage to the wire surface due to sliding is unavoidable.

Therefore, there are two ways to prevent wire breakage: 1. Slow down the running speed of the wire to suppress heat generation, and 2. Renew the wire before the wire breaks.

Problems to be Solved by the Invention However, the conventional wire breakage prevention measures described above have the following problems.

■The method to suppress heat generation by slowing down the running speed of the wire is as follows.
Since the amount of grinding per unit time decreases, cutting efficiency decreases. To compensate for this, for example, there is a method of reciprocating the workpiece in the wire running direction and the opposite direction (Japanese Patent Publication No. 52-12
954), but the "play" of the mechanism necessary for reciprocating motion
There is a concern that cutting accuracy may decrease and marks (flaws that occur on the cut surface) may occur.

■Pre-renewal of wires has the problem of high wire costs. That is, in a wire saw that reciprocates a wire and a workpiece, the wire is usually discarded after one cut. Of course, even if the wire is cut only once, if the sliding distance of the same part of the wire is long, the wire will break, so the length of the new wire being paid out and the reversal of the new wire is increased, and the sliding distance of the same part of the wire is reduced. Measures will be taken to reduce it. However, in this case, the total length of the wire required for cutting becomes thicker, increasing the cost of the wire.

In addition, with a wire saw that fixes the workpiece and runs the wire in one direction, the sliding distance between the wire and the workpiece can be minimized, so it is possible to use the used wire repeatedly, but even in this case, the wire may break. To avoid this, we have no choice but to discard it after using it several times.

In any case, in a multi-wire saw, it is necessary to renew the wires one after another to avoid wire breakage, which is uneconomical.

In view of these circumstances, the present invention aims to reduce the wire cost and stabilize the cutting accuracy and cutting efficiency of multi-wire saws, and provides a groove roller that can significantly reduce the risk of wire breakage in multi-wire saws. This is what I am trying to do.

Means for Solving the Problems As a result of detailed investigation into the causes of wire breakage between grooved rollers in a wire saw, the inventor found that in addition to the aforementioned reduction in wire strength due to frictional heat and sliding damage on the wire surface, It was found that the shape of the shape has a large influence.

That is, a typical example of the cross-sectional structure of a conventional grooved roller is shown in Figure 4 (A is the overall cross-sectional structure, B is the dotted circle in Figure A (groove)
As shown in the enlarged view of the resin sleeve (11
) is press-fitted into a metal core (12), positioned by placing one end against the core flange (12-1), and tightening the opposite end with a nut (13). A groove (11-1) having the same depth (g) is carved on the outer peripheral surface of the sleeve (11) over the entire length. The reason why the sleeve is made of resin is that the wire needs to be easily gripped by the groove in order to suppress slippage between the wire and the groove.

In the case of a grooved roller having such a structure, as described above, the wire being cut generates heat as it slides against the workpiece, and the heat is transmitted to the sleeve (11), causing the sleeve to expand.

FIG. 5 illustrates the shape of a thermally expanded sleeve.

The reason for this bulge in the middle is that both end surfaces of the sleeve (11) are restrained by the flange (12-1) and the nut (13), and heat is removed by the flange and nut. This is due to the small increase in the outer diameter of the sleeve, and because the expansion of the sleeve (11) in the longitudinal direction is restricted at both ends.
) is subjected to compressive force in the longitudinal direction, causing bulging in the center.

Naturally, the tension of the wire array wound around the sleeve expanded into a medium bulge shape is affected by this. FIG. 6 shows the thermally expanded three grooved rollers at both ends and the center of the sleeve.

Groove contour (lla) (llb) and wire (4a)
The relationship (4b) is shown.

In other words, the three groove rollers (1) (2) (3) are -
The length of the surrounding wire is longer at the center of the sleeve than at both ends of the sleeve. Therefore, as the wire goes around from the sleeve end toward the center, the tension in the wire increases, and then decreases as it moves toward the opposite sleeve end. Needless to say, this process of increasing tension increases the risk of wire breakage.

By the way, in order to maintain cutting accuracy with a multi-wire saw, strong tension is applied to the wire before cutting begins, and as soon as cutting begins, the resistance caused by sliding with the workpiece is added as tension, and this is also due to thermal expansion of the sleeve. If an increase in tension is applied, the risk of wire breakage increases.

This invention focuses on the fact that wire breakage accidents are largely caused by the increase in tension caused by the thermal expansion of the sleeve, and has invented a grooved roller that prevents the increase in tension caused by the thermal expansion of the sleeve by the shape of the sleeve. It's arrived.

That is, the grooved roller for a multi-wire saw according to the present invention has a shape such that the radius of the wire winding in the groove becomes uniform in the roll axis direction when the temperature of the grooved roller during cutting increases due to frictional heat. The gist of this is that the diameter at both ends of a resin sleeve with grooves of the same depth is larger than the diameter at the center of the sleeve, and due to the thermal expansion of the sleeve during the cutting process, the wire winding has a radius of curvature. It is characterized by having a shape that is almost uniform in the axial direction of the roll, and the depth of the groove of the resin sleeve of the same diameter is changed by thermal expansion of the sleeve during the cutting process, so that the radius of curvature of the wire winding becomes uniform in the roll axis direction. It is characterized by being carved shallowly at both ends and deeply at the center so that it is substantially uniform in the axial direction.

Function: The diameter of a resin sleeve with grooves of the same depth is cut at both ends of the sleeve so that the radius of curvature is almost uniform in the roll axis direction due to thermal expansion of the sleeve during cutting. In the case of a grooved roller that is larger than the center part, even if the temperature of the sleeve rises due to frictional heat between the wire and the workpiece during cutting, the center part swells due to the compressive force in the longitudinal direction that acts on the sleeve, and is approximately equal to both ends. Since they have the same diameter, the tension of the wire does not increase at the center of the sleeve and remains approximately constant over the entire length.

In addition, the depth of the groove of the sleeve, which has the same diameter over the entire length, is carved shallow at both ends of the sleeve and deep at the center so that the radius of curvature of the wire winding is almost uniform in the roll axis direction due to thermal expansion of the sleeve. In the case of grooved rollers, even if the temperature of the sleeve rises during the cutting process and compressive force in the longitudinal direction is applied to the sleeve, causing the central part of the sleeve to bulge, the groove is deep and the radius of curvature of the wire winding is large. Therefore, the tension in the wire does not increase at the center of the sleeve and remains approximately constant over the entire length.

As mentioned above, in the case of the grooved roller for a multi-wire saw of the present invention, by changing the shape of the resin sleeve itself or the depth of the groove, it is possible to prevent the increase in tension on the wire due to thermal expansion of the sleeve during cutting. Therefore, even if the strength of the wire decreases due to frictional heat with the work, the risk of wire breakage is greatly reduced, and damage to the wire surface is also reduced.

Examples Example 1 jlIIIXl is an example of a grooved roller corresponding to claim 1 of the present invention. Figure (A) is a longitudinal cross-sectional side view showing the entire roller, and Figure (B) is a dotted circle ( b) is an enlarged view of part.

In other words, the grooved roller (20) of the present invention has a hook shape in which the outer diameter Da of both ends (21a) of the resin sleeve is larger than the outer diameter Db of the center part (21b), and this resin sleeve (21) Grooves (11-1) of the same depth (g) are carved in the sleeve, and both ends (21a) and the center (21b) of the sleeve are grooved (11-1) when the temperature of the grooved roller increases during cutting. 11-1) The wire winding is manufactured so that the radius is uniform in the roll axis direction.

An example in which the above-mentioned chain-shaped grooved rollers are applied to a unidirectional running wire saw having a three-roll configuration (distance between axes of 400 mm) shown in FIG. 3 will be shown below.

The grooved roller used was a sleeve made of ultra-high molecular weight polyethylene with a length of 300 m and a shape shown in Fig. 1.
a 150+u+, D b -149,50111, with a groove of depth 1.7+++o carved into the sleeve, and a piano wire with a diameter of 0.16 mm is attached to this groove roller at a tension of 2 kg and a pitch of 21jI11. The sleeve was wound over its entire length and run at a speed of 400 mm per minute, and a quartz block with a 100 mm square cross section was cut at a pushing speed (constant) of 0.5 mm per minute while pouring an abrasive liquid. As a result, no wire breakage occurred even after repeated cutting 10 times, and cutting could be performed stably.

On the other hand, for comparison, D = 150s+a shown in Figure 4
When a similar cutting process was carried out using a grooved roller with a constant + - constant and a groove depth of 1.7+a+a, wire breakage occurred in the 6th and 7th cuts.

Embodiment 2 FIG. 2 shows an example of a grooved roller corresponding to claim 2 of the present invention, and FIG.
B) and cause (C) are point circles (b) and (c) in figure (A), respectively.
) is an enlarged view of the part.

That is, in the grooved roller (30) shown in FIG. 2, the outer diameter of the resin sleeve (31) is uniform in the axial direction;
The depth (g,) of the groove (11-2) at both ends (31a) of the sleeve is made shallower than the depth (gk) of the groove (11-3) at the center (31b), so that the groove depth is It is formed so that it gradually becomes deeper from both ends to the center, and in this case, when the temperature of the roller increases during cutting, the groove (g, > (gk) is The groove pitch p and the groove opening angle θ are the same for all grooves.

An example in which the grooved roller described above is applied to the same unidirectional running wire saw as in Example 1 will be shown below.

The grooved roller used was the same as in Example 1, with a length of 30011 mm.
IIn, an ultra-high molecular weight polyethylene snub with an outer diameter of D 15011101, and as shown in Fig. 2, the depth was continuously adjusted so that ga = 1.2 mm at the end and gbxl at the center, 7 mai. Similar to Example 1, the grooved roller was wound with a tension of 2 kg and a pitch of 2 mm over its entire length, and was run at 400 ma+ per minute. While pouring abrasive liquid, a quartz block with a square cross section of 100 a+m was formed. As a result of cutting at a (constant) push-up speed of 0.5 mm per minute, no wire breakage occurred even after repeated cutting 10 times, and stable cutting could be performed.

In Examples 1 and 2 above, only the outer diameter of the resin sleeve is changed and the groove depth is changed, but it goes without saying that a combination of these is also possible. Furthermore, the above two examples show cases in which the wire is wound around almost the entire length of the resin sleeve;
When winding a wire only in a certain range in the axial direction of a resin sleeve, it is sufficient to use a resin sleeve with a shape that allows the wire to be wrapped with a uniform radius within that range after thermal expansion. Needless to say.

As described in the detailed description of the invention, the grooved roller according to claim 1.2 of the present invention has a structure in which the radius of the wire wrapping after thermal expansion of the sleeve is uniform, so that the grooved roller has a uniform radius during cutting. The incidence of wire breakage due to thermal expansion of the sleeve is extremely low, and not only can the operating rate of the wire saw be greatly improved, but also the loss of workpieces due to wire breakage can be greatly reduced, which has great economic effects. Furthermore, since the cross-sectional shape of the wire is maintained as a perfect circle by reducing damage to the wire surface, there is no concern about saw marks, and wafers that can be cut with high precision and have high surface quality can be obtained.

[Brief explanation of the drawing]

FIG. 1 illustrates a grooved roller corresponding to claim 1 of the present invention, and FIG. 1A is a vertical side view showing the entire roller;
Figure (B) is an enlarged view of the point (a) in Figure (A), Figure 2 illustrates a grooved roller corresponding to claim 2 of the present invention, and Figure (A) shows the entire roller. Longitudinal side view, diagram (B
) An enlarged view of the point (b) in Figure (A), Figure (C) is an enlarged view of the point (b) in Figure (A).
FIG. 3 is a schematic perspective view showing the main parts of a general multi-wire saw, and FIG. 4 shows a typical example of the cross-sectional structure of a groove roller for a conventional multi-wire saw. Figure (A) is a vertical cross-sectional side view showing the entire roller, Figure (B) is an enlarged view of the part (b) in Figure (A), and Figure 5 shows the thermal expansion of the grooved roller. FIG. 6 is a side view showing an example of the shape of the sleeve. FIG. 6 is a schematic view showing the relationship between the contours of the grooves and the wires at both ends and the center of the sleeve of three grooved rollers that have been thermally expanded. 11-1.11-2.11-3...Groove 12.
...Core metal 12-1...Flange 13.
...Nut 20.30...Groove roller 21.31...Resin sleeve 21a, 31a...Sleeve both ends 21b, 31
b...Central part of sleeve Applicant: Sumitomo Metal Industries, Ltd.

Claims (1)

[Claims] 1. While running a wire row formed by winding a wire many times between a plurality of grooved rollers, and pressing a member to be cut against the wire row, machining fluid is supplied to the part. In the groove roller of a multi-wire saw that cuts the workpiece into a number of wafers of the required thickness, the diameter of both ends of a resin sleeve with grooves of the same depth is larger than the diameter of the center part of the sleeve. A grooved roller for a multi-wire saw, characterized in that the wire-wound radius of curvature becomes substantially uniform in the roll axis direction due to thermal expansion of the sleeve during processing. 2. While running a wire row formed by winding a wire many times between a plurality of grooved rollers, while pressing a member to be cut against the wire row, machining fluid is supplied to the part to cut a large number of objects to be cut. In the groove roller of a multi-wire saw that cuts into wafers, the depth of the groove in a resin sleeve of equal diameter is such that the radius of wire winding curvature becomes almost uniform in the roll axis direction due to thermal expansion of the sleeve during the cutting process. The groove roller of a multi-wire saw is characterized by having shallow grooves at both ends and deep grooves at the center.