JP3700342B2 - Wire saw and workpiece cutting method using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a wire saw that cuts a hard material such as a semiconductor material, a magnetic material, or quartz while acting abrasive grains on a wire (wire array) such as a drawn steel wire, and a work cutting method using the wire saw. Specifically, a sufficient amount of abrasive fluid is always supplied between the wire that cuts the workpiece and the workpiece cutting section during traveling to prevent abrasive grain breakage during workpiece cutting, and this abrasive grain breakage is the cause. The present invention relates to a wire saw that solves various problems and a method for cutting the workpiece.
[0002]
[Prior art]
  A wire saw is a device that cuts a workpiece such as a silicon single crystal ingot into a plurality of parts by a traveling wire. That is, a wire that travels in one direction or reciprocates while continuously supplying an abrasive liquid containing free abrasive grains such as alumina and SiC (hereinafter sometimes simply referred to as abrasive grains) in a dispersant such as pure water and cutting oil. The workpiece is relatively pressed against the (wire array), and the workpiece is cut into a plurality of workpieces by the grinding action between the workpiece and abrasive grains generated there.
  Hereinafter, the workpiece cutting state by the wire saw will be specifically described with reference to FIGS.
  FIG. 6 is a cross-sectional view along a plane including a workpiece axis in a workpiece cutting operation state using a wire saw according to a conventional means. FIG. 7 is a cross-sectional view along a plane orthogonal to the workpiece axis in the cutting work state of the workpiece. FIG. 8A is an enlarged cross-sectional view of a plane perpendicular to the wire axis in the vicinity of point a in FIG. FIG. 8B is an enlarged cross-sectional view of a plane perpendicular to the wire axis in the vicinity of the point b in FIG.
[0003]
  As shown in FIG. 6, at the time of cutting the workpiece I which is a cylindrical ingot by a conventional wire saw, while supplying abrasive liquid containing abrasive grains from above, on the cutting portion on the back side of the cutting groove of the workpiece I, The workpiece I is cut by relatively pressing each wire of the wire row 100 that reciprocates.
  This is because the abrasive grains in the supplied abrasive liquid are rubbed violently against this cutting part while partly rolling by the running motion and pressing force of the wire row 100, so that the workpiece I is continuously crushed little by little. Or by cutting by cutting.
[0004]
  By the way, when the workpiece I is cut in this way, since the workpiece I has a cylindrical shape, as shown in FIG. 7, the cutting portion distance d from the cutting point a to the cutting point b of the wire row 100 to the workpiece I is shown. Changes according to the cutting progress of the workpiece I. The location of the maximum value is the diameter portion of the workpiece I.
  In the case of a silicon single crystal ingot whose diameter has recently been increased, the maximum value of the cut distance d reaches 150 to 300 mm. However, as the cutting distance d increases, the cutting efficiency of the workpiece I decreases greatly.
[0005]
  There are two reasons for this. That is, (1) In the latter half portion of the cutting portion of the workpiece I, the abrasive grains that are between the cutting portion on the far side of the cutting groove of the workpiece I and the running wire are gradually increased by the strong pressing force of the wire. (See FIGS. 8A and 8B). (2) Abrasive grains are pushed out from the cutting portion as much as chips, which are cutting waste discharged from the cutting portion of the workpiece I into the abrasive liquid during cutting, are gradually accumulated in the abrasive liquid. This is because the phenomena (1) and (2) reduce the total number of abrasive grains between the cutting portion and the wire that effectively work for cutting (hereinafter referred to as abrasive grain breakage).
[0006]
  This abrasive grain breakage phenomenon is a factor that causes various harmful effects to the conventional wire saw process.
  That is, as a direct influence on the cutting efficiency of cutting of abrasive grains, suppression of cutting speed can be mentioned.
  For example, in the one-way traveling mode in which the entire length of the wire is moved only once in one direction and cuts the workpiece I, the vicinity of the cutting point b at the cutting portion distance d has insufficient abrasive grains compared to the vicinity of the cutting point a. ing. As a result, the cutting speed of this portion is reduced and wire breakage is likely to occur. Therefore, in order to avoid this, in the case of a large-diameter workpiece, the traveling speed of the wire during actual operation is usually lowered by 30 to 50% or more compared to that of the small-diameter workpiece.
  In the reciprocating mode in which the wire I is reciprocated and the workpiece I is cut as shown in FIG. 7, idling is performed each time the traveling direction of the wire is switched. That is, the cutting speed fluctuation repetition in the corresponding period occurs at both ends of the cutting distance d in place of the insertion of the cutting point a and the cutting point b. Realized. As a result, when other cutting conditions are the same, the cutting speed as a whole is usually set to a value that is 15 to 25% or more lower than the cutting speed near the cutting point a.
[0007]
  In addition, for example, the dimensional accuracy of the workpiece after cutting is also affected by abrasive grains. That is, the cutting efficiency is good on the cut point a side in the one-way traveling mode, so that the cutting allowance is large and small on the cut point b side. Thereby, in the case of cutting with a wire array running in parallel, the thickness distribution of the obtained workpiece, for example, a wafer or a thin plate, is tapered so that the a point side is thin and the b point side is thick. Moreover, the thickness unevenness increases as it exceeds 10 to 20 μm. In areas such as semiconductors where high-precision dimensions are required, this uneven thickness must be removed by machining such as lapping and grinding in the subsequent process, which reduces the raw material crystal and processing yield and increases processing costs. Invited.
[0008]
  In an industrial field such as a semiconductor in which the workpiece I tends to have a large diameter, several proposals have been made to cover such weak points of the conventional wire saw.
  For example, in order to cover a significant decrease in the cutting speed, the wire traveling speed is increased from about 100 to 300 m / min with a small-diameter workpiece to about 400 to 1000 m / min, and the cutting speed is brought close to that of a small-diameter product, At the same time, measures are taken to reduce the amount of wear per unit length of the wire (per same cutting load) and to prevent a reduction in work efficiency due to wire replacement work.
  However, this method increases the amount of wire wound around the supply reel. For example, it is necessary to use a steel wire having a diameter of 180 μm and a length of 300 to 500 m. In this case, the weight is 60 to 100 kg. As a result, a wire saw using the same has become enormous and equipment costs have increased.
[0009]
  By the way, conventionally, as a wire saw for rotating each wire of a wire row around an axis, for example, one disclosed in Japanese Utility Model Laid-Open No. 59-14136 or one disclosed in Japanese Patent Laid-Open No. 9-70747 is known.
  The former conventional means uses a rotational force generated by the relative reciprocation of these rollers while sandwiching the running wire row with two rollers at a position away from the cutting portion. It is a device that reciprocally rotates around the axis.
  In the latter conventional means, the wire is wound in a state in which the wire is shifted by one pitch between the groove rollers by installing a moving table that presses the workpiece against the wire row on the side where the rotary shaft of the groove roller is located. Under the structure of the wire saw, the wire is naturally twisted little by little every time the wire changes over the wire groove of each groove roller. Thereby, the partial wear of a wire and the waviness of a workpiece cutting surface can be reduced.
[0010]
[Problems to be solved by the invention]
  However, in the former conventional means, when the wire row is run at a high speed, the rotation of the wire while being sandwiched between the rollers slips on the circumferential surface of the roller. As a result, undulation in the direction opposite to the cutting direction of the workpiece cut surface caused by uneven wear of the wire is caused again.
  On the other hand, in the latter conventional means, for example, when the wire used is a new wire, there is a problem that the intended effect cannot be obtained sufficiently unless the wire is used 2 to 4 times. This is supported by the example data in the accompanying specification. That is, according to the data, not only the effects and effects are not sufficient, but also the above-mentioned problems due to abrasive grain breakage of large-diameter workpieces (decrease in cutting efficiency, insufficient cutting accuracy, decrease in yield) and high-speed wire running The associated problems (wire reel and equipment weight) are not solved.
[0011]
OBJECT OF THE INVENTION
  According to the present invention, a sufficient amount of abrasive liquid can be always supplied between the wire (wire array) for cutting the workpiece and the cutting portion of the workpiece cutting groove during traveling, Prevents abrasive grain breakage, stabilizes the cutting efficiency at a high level, secures a high cutting speed and high-accuracy cutting surface, reduces uneven thickness of the workpiece after cutting, improves workpiece yield from raw materials, The purpose is to realize a long life of the wire by simplifying the post-process, reducing the amount of wear and uneven wear of the wire, and reducing the wire breakage. Another object of the present invention is to provide a wire saw capable of stably displacing a wire in a pulse shape with a relatively simple and inexpensive structure.
[0012]
[Means for Solving the Problems]
  In the first aspect of the present invention, the wire fed from the feeding reel is bridged between a plurality of groove rollers spaced apart from each other to form a wire row, and while supplying abrasive liquid containing free abrasive grains, In a wire saw in which a workpiece, which is a workpiece, is cut into a plurality of parts by running a wire row, and the wire after the cutting is wound up on a take-up reel, the contact portion of the wire row with the workpiece is cut when the workpiece is cut. Pulse displacement means for displacing in a pulse shape in the direction opposite to the cutting direction is provided, and this pulse displacement meansIn one place on the outer peripheral surface,It is a wire saw having a pulse displacement roller provided with a pulse displacement protrusion that makes a pulse-like displacement of the wire row by contacting the traveling wire row.
  The wire saw to which the present invention is applied may be of any type. For example, the structure may be such that the workpiece is pressed against the wire and cut or the wire is pressed against the workpiece and cut. Further, the wire may be of a type that travels in the horizontal direction, or may be a type that travels in the other direction. Furthermore, the thing of the type which the pressing direction of a workpiece | work presses against the wire running surface from which side may be sufficient. The traveling direction of the wire may be traveling in one direction or reciprocating.
  Furthermore, the portion of the wire that is displaced in a pulse shape by the pulse displacing means (hereinafter sometimes referred to as pulse displacement) may be at least a portion that contacts the workpiece when cutting the workpiece. Therefore, for example, the total length of the wire may be used. The pulse-like displacement here means a displacement such as a pulse in which the amplitude instantaneously changes from a steady state to a predetermined displacement state, and this continues for a finite time and returns to the original state.
[0013]
  And the abrasive liquid for cutting | disconnection may be the water which does not contain a free abrasive grain in the fixed abrasive system with which the abrasive grain was fixed to the wire. Even when loose abrasive grains are used, there are various applicable abrasive grains and abrasive liquids as described above. For example, as the abrasive, 20 kg of SiC abrasive grains having an average particle diameter of about 25 μm and 20 liters of lap oil to have a viscosity of 230 to 250 cp can be used. The abrasive liquid supply device may have any structure and function.
  Any mechanism may be installed in the wire travel path as long as it does not prevent the pulse displacement of the wire by the pulse displacement means.
[0014]
  Next, examples of the pulse displacing means include a means for pulsing the wire with mechanical means such as a cam. In this case, the pulse-like displacement of the wire means that the stretched wire is perpendicular to its axis and has a predetermined amplitude in the opposite direction to the cutting direction and in the opposite direction. It means being allowed to.
[0015]
  The amplitude of the wire needs to be about the same as or larger than the average particle size of the abrasive grains contained in the used abrasive liquid. In particular, 0.5 to 3.0 times the abrasive grain size is preferable. If the abrasive grain size is less than 0.5 times, the replacement of the abrasive fluid becomes insufficient. If the abrasive grain size exceeds 3.0 times, the time during which the workpiece is not cut (pulse displacement time) becomes longer, and the wire is cut. There is a possibility that the time for contributing to the process will be shortened and the cutting speed will be lowered.
  In any case, what is important is that the wire during workpiece cutting is displaced in a pulsed manner (displaced in a plane perpendicular to the axis), and a forcible gap is formed between the wire and the workpiece cutting portion, and negative pressure is applied. It is to replenish the abrasive grains together with the abrasive liquid in this gap.
[0016]
[0017]
  Note that the multi-wire saw to which the present invention is applied may be of any type. For example, the workpiece may be cut by bringing the workpiece into contact with the wire row, or conversely, the workpiece may be cut by pushing the wire row against the workpiece. Further, the wire row may travel in the horizontal direction, vertical or other directions, and the workpiece may be pressed from either side of the wire traveling surface. The number of groove rollers may be two or more that are spaced apart from each other at a predetermined interval. The wire train may be unidirectional or reciprocating.
[0018]
  As used herein, the pulse displacement roller includes, for example, a cam roller having a pulse displacement protrusion protruding from the outer peripheral surface. This roller has a trajectory that stably maintains the wire level at a fixed position, and applies a pulse-like displacement instantaneously to the wire in the direction opposite to the cutting direction only when contacting the pulse displacement protrusion. Must.
  As the drive unit of the cam roller, various types such as an electric motor, an air cylinder, an electric cylinder, a hydraulic cylinder, and a feed screw mechanism can be adopted.
[0019]
  Formation position of the roller displacement protrusion on the roller peripheral surface,The shape of this protrusion is(1) When the wire is displaced, it is possible to replenish fresh abrasive grains by flowing loose abrasive grains in the gap between the wire and the workpiece cutting section, and (2) when cutting the workpiece, the wire is cut. There is no limitation as long as it is a change that satisfies the two conditions of not reducing the work cutting speed so much without shortening the time that contributes to the action.
[0020]
[0021]
  In a wire saw made of a semiconductor material such as a silicon single crystal currently used, it is general to cut a cylindrical workpiece having a diameter of 150 to 200 mm at a wire traveling speed of 5 to 15 m / min. Therefore, the time until each point of the wire comes into pressure contact with the workpiece during cutting is about 10 to 40 milliseconds.
  Therefore, a pulse-like displacement of the total deration time of 1/10 or less of this numerical value, preferably 1 to 4 milliseconds, is given 1 to 10 times, preferably about 2 to 5 times in the meantime. In this case, the effects of the present invention can be obtained with a commonly used abrasive liquid.
[0022]
  The invention described in claim 2In a workpiece cutting method using a wire saw that cuts a workpiece by pressing the workpiece against a traveling wire while supplying abrasive fluid containing loose abrasive grains to the workpiece, the workpiece of the wire The contact portion is displaced in a pulse shape, and the free abrasive grains in the abrasive fluid are replenished into the gap formed between the wire and the workpiece cutting portion at the time of displacement. Loose abrasiveWhile the average particle diameter is 0.5 to 3.0 times, the pulse-like displacement is given at an interval of 1/10 or less of the time from when the wire is pressed against the workpiece until it is released.This is a workpiece cutting method using a wire saw.
[0023]
[Action]
  According to the wire saw according to claim 1 and the work cutting method with the wire saw according to claim 2,While supplying the abrasive liquid containing loose abrasive grains, the workpiece is relatively pressed against the traveling wire row, and the workpiece is cut by the grinding action.
  At this time, the contact portion of the traveling wire with the workpiece is forcibly displaced in the direction opposite to the cutting direction of the workpiece by the pulse displacement means. Thereby, the contact portion of the wire with the workpiece can be pulse-displaced regardless of the wire feed speed. Moreover, each time this displacement is performed, a gap is formed between the wire and the workpiece cutting portion, and the abrasive liquid flows into the gap due to the negative pressure generated at this time, and the abrasive grains are replenished. As a result, the amount of wear of the wire becomes relatively uniform around the axis, disconnection due to uneven wear is greatly reduced, the life of the wire is extended, and the running cost of the wire saw is reduced.
[0024]
  For example, when the wire is run at a high speed of 300 to 1000 m / min, during the workpiece cutting, the time during which the wire travels within the distance of the cutting portion from the time the wire is cut into the workpiece, the large diameter workpiece (for example, 150 to 300 mm in diameter) Ingot) is as short as 9 to 60 milliseconds. During this time, the abrasive concentration is reduced due to the extrusion of the abrasive liquid from the cutting portion by the pressing force of the wire to the cutting portion and the accumulation in the cutting portion of the work chip discharged during cutting.
[0025]
  By the way, in the direction around the axis of the wire, the wire portion on the opposite side to the side facing the workpiece cutting portion is in contact with the fresh abrasive fluid supplied to the workpiece cutting groove. Therefore, the wire is pulse-displaced, and the abrasive pressure is replenished by forcing fresh abrasive fluid into the gap between the wire and workpiece by the negative pressure generated at the time of displacement. Always ensure a sufficient amount of abrasive grains on the surface for cutting.
  As a result, it was confirmed that the abrasive grain breakage phenomenon that occurred in the conventional method did not occur, and the workpiece cutting speed increased to 0.8 to 1.0 mm / min, which is equivalent to a small-diameter workpiece, and at the same time a one-way traveling type Then, it was found that a workpiece surface taper of 3 to 5 μm, and a reciprocating traveling type with a flatness greater than 3 μm can be realized with a large diameter workpiece and a high speed traveling condition.
[0026]
  In particular, since the pulse displacement roller is moved by the driving unit and the wire is pulse-displaced by the pulse displacement roller, the contact portion of the wire with the workpiece can be pulse-displaced with a relatively simple mechanism and at a stable timing. . Thereby, the wire saw which has the effect mentioned above can be reduced in size, and installation cost can also be reduced.
[0027]
[0028]
DETAILED DESCRIPTION OF THE INVENTION
  Embodiments of the present invention will be described below with reference to the drawings. First, a wire saw and its work cutting method according to a first embodiment of the present invention will be described.
  FIG. 1 is a perspective view of a wire saw according to a first embodiment of the present invention, FIG. 2 is an explanatory view showing a pulse displacement state of a wire by the pulse displacement means, and FIG. 3 is an explanatory view during cutting of the ingot. 4 (a) is an enlarged cross-sectional view of a portion a in FIG. 3, and FIG. 4 (b) is an enlarged cross-sectional view of a portion b in FIG.
[0029]
  In FIG. 1, reference numeral 10 denotes a wire saw. This wire saw 10 is made of single crystal silicon pulled up by the CZ method and has an ingot I (workpiece) having a diameter of 200 mm on a plurality of wafers having a maximum thickness of, for example, 900 μm. This is a device for cutting a wire, and has a wire row 11 in which a large number of wires 11a are bundled in a horizontal row. The wire row 11 travels back and forth or in one direction between three groove rollers 12 arranged in a triangular shape. Specifically, a wire fed from a feeding reel (not shown) is bridged between three groove rollers 12 spaced apart from each other to form a wire row 11, and this wire row 11 is formed at a maximum speed of 1000 m / min. The ingot I is cut by running, and the wire after cutting is taken up on a take-up reel (not shown).
  Above the both sides of the groove roller 12, a pair of abrasive liquid supply portions 13 that continuously supply the abrasive liquid onto the wire row 11 are disposed. The abrasive liquid is, for example, one having a viscosity of about 230 to 250 cp in which 20 kg of lap oil is blended with 20 kg of SiC abrasive grains having an average particle diameter of 25 μm. The ingot I is mounted on the lifting platform 15 via the carbon bed 14.
[0030]
  Further, as shown in FIGS. 1 and 2, a long pulse displacement that causes pulse displacement of each wire 11a of the wire array 11 at regular intervals in the vicinity of the lower part of the abrasive liquid discharge port of both abrasive liquid supply units 13 is shown. A pair of pulse displacement rollers 16, which are an example of cam members provided with protrusions 16 a, are arranged in parallel to the groove rollers 12. An electric motor 17, which is an example of a drive unit that rotates the pulse displacement roller 16 at 0 to 6000 rpm, is connected to one end of each pulse displacement roller 16 via a power transmission system (not shown). The pulse displacement protrusion 16 a is provided along the axis of the pulse displacement roller 16 so as to extend over the entire length of the roller outer peripheral surface. When each pulse displacement roller 16 is rotated by the electric motor 17, the pulse displacement roller 16 rotates under the wire row 11, whereby each wire 11 a is repelled by the pulse displacement protrusion 16 a at a constant timing. The pulse displacement roller 16 and the electric motor 17 constitute pulse displacement means 18 for pulsing the contact portion of the wire row 11 with the ingot I when the ingot is cut.
  2 to 4, Ia is a cutting groove formed by the wire 11a of the ingot I, and x is abrasive grains contained in the abrasive liquid.
[0031]
  Next, a wire saw work cutting method according to the first embodiment using the wire saw 10 will be described.
  As shown in FIG. 1, the wire saw 10 reciprocates the wire row 11 between the three groove rollers 12 at 600 m / min while supplying the abrasive liquid from the abrasive liquid supply unit 13. When the wire row 11 reciprocates, the ingot I is pressed against the wire row 11 from below, so that the ingot I sequentially cuts the contact start end portion with the short contact length and the contact length with the long contact length as shown in FIG. It is gradually cut into a central portion, a cutting end portion having a short contact length. That is, during the reciprocating travel of the wire row 11, the abrasive grains x in the abrasive liquid move while rolling or cutting while being pressed against the bottom of the cutting groove Ia by the wires 11 a of the wire row 11, that is, the cutting portion. The surface of the ingot I is gradually scraped, and finally the ingot I is cut into a number of wafers.
[0032]
  At this time, as shown in FIG. 1, the contact portion of the traveling wire 11 a with the ingot I is forcibly displaced in a pulse shape in a direction opposite to the cutting direction of the ingot I using the pulse displacing means 18. That is, if the pulse displacement roller 16 is always rotated at 6000 rpm by the electric motor 17 during ingot cutting, it protrudes from the outer peripheral surface of the roller every 1/100 seconds (in terms of wire travel distance, every 0.1 m). The pulse displacement protrusion 16a repels each wire 11a of the wire row 11. The pulse displacement width of each wire 11a at this time is determined by the height of the pulse displacement roller 16 from the reference circumferential surface, and is about 30 μm at the cut portion of the ingot I. When the wire 11a is pulse-displaced in this way, a gap is formed between the wire 11a and the cut portion of the ingot I simultaneously with this displacement, and the fresh abrasive fluid flows into this gap due to the negative pressure generated at this time. The abrasive grain x is replenished.
  FIG. 5 is a graph reference showing the pulse displacement of the wire during the ingot cutting according to the first embodiment. As shown in FIG. 5, the wire 11a always cuts the ingot I while maintaining the height of at least one abrasive grain. Further, during this cutting, if the wire 11a is pulse-displaced with a pulse displacement roller 16 at a constant pulse period and a pulse width, a pulse-like displacement amplitude having the waveform shown in the figure is generated.
[0033]
  For this reason, even if the wire feed speed is high, the amount of wear of the wire 11a is uniform around the axis, breakage due to uneven wear is less likely to occur, the life of the wire is extended, and the running cost of the wire saw 10 is increased. Is reduced.
  Moreover, since the pulse displacement roller 16 is rotated and the wire 11a is repelled by the pulse displacement protrusion 16a at regular intervals, the contact portion of the wire 11a with the ingot I can be stably formed by a relatively simple mechanism. Pulse displacement is possible. As a result, the wire saw 10 can be reduced in size and the equipment cost can be reduced.
[0034]
  Further, the front half of the cutting groove Ia of the ingot 11 can be cut well in the conventional manner regardless of whether the wire 11a is traveling in the forward or reverse direction (see also FIGS. 4A and 8A). Then, even in the latter half of the cutting groove Ia where the abrasive liquid has been cut, a sufficient amount of abrasive liquid containing the normal concentration of abrasive grains x can be fed, and the entire cutting including this part can be cut well. (See also FIG. 4 (b) and FIG. 8 (b)). As a result, the wire 11a is relatively free from abnormal wear (uneven wear) or wire breakage, and because of the uniform wear, the wire life is increased by 50 to 70%, and the running cost is reduced while the ingot I is reduced. Can be cut while maintaining a high cutting speed (0.8 to 1.0 mm / min).
  Further, the thickness unevenness of the wafer immediately after cutting is reduced, the yield of the wafer per one ingot I is increased, and the warpage of the wafer immediately after cutting is reduced. Reduced cracking. Note that the pulse displacement of the reciprocating wire 11a by the two pulse displacement rollers 16 is only applied to the pulse displacement roller 16 on the cutout side of the ingot I, even if only the pulse displacement roller 16 on the cutout side of the ingot I is operated. Alternatively, both pulse displacement rollers 16 may be operated simultaneously.
[0035]
  An experimental example using the wire saw 10 of the first embodiment will be described. For example, the cutting speed of the ingot I even under the condition that the effective cutting time loss of the ingot I due to the pulse-like wire displacement is set to about 10%. Improved by about 30% compared with the conventional method (for example, 0.5 mm / min).
  In addition, the shape accuracy of the cut wafer was greatly improved. That is, a silicon wafer having a diameter of 200 mm and a flatness of 3 μm or less and a parallelism of 5 μm or less could be easily obtained.
[0036]
[0037]
[0038]
【The invention's effect】
  According to the wire saw and the workpiece cutting method of the present invention, the contact portion of the wire with the workpiece is displaced in a pulse shape at the time of cutting the workpiece, and the abrasive fluid is caused to flow into the gap between the wire and the workpiece cutting portion. Therefore, it is possible to always supply a sufficient amount of the free abrasive grains in the abrasive liquid to the workpiece cutting portion. This eliminates the abrasive grain breakage phenomenon at the workpiece cutting part, can stabilize the cutting efficiency at a high level, secures a high cutting speed and a highly accurate cutting surface, and reduces the thickness unevenness of the workpiece after cutting. Thus, the work yield can be improved, the post-process can be simplified, the amount of wire wear and uneven wear can be reduced, and the life can be extended by reducing the number of disconnections.
[0039]
  In particular, since each wire of the wire array is collectively pulse-displaced by the pulse displacing means, the present invention can be applied well to a multi-wire saw that can cut a workpiece into a plurality of pieces at once.
[0040]
  In addition, the pulse displacement roller is moved by the drive unit, and the pulse displacement protrusion is applied to the wire so that the pulse is displaced. The contact portion can be pulse-displaced. As a result, the wire saw can be reduced in size, and an increase in equipment cost can be prevented.
[0041]
[Brief description of the drawings]
FIG. 1 is a perspective view of a wire saw according to a first embodiment of the present invention.
FIG. 2 is an explanatory view showing a pulse displacement state of a wire by the pulse displacement means.
FIG. 3 is an explanatory view during cutting of the ingot.
4 (a) is an enlarged cross-sectional view of a portion a of FIG.
  (B) is an expanded sectional view of the b part of FIG.
FIG. 5 is a graph showing the pulse displacement of the wire during ingot cutting according to the first embodiment.
FIG. 6 is a cross-sectional view taken along a plane in the workpiece axial direction in a workpiece cutting operation state using a wire saw according to a conventional means.
FIG. 7 is a cross-sectional view taken along a plane orthogonal to the workpiece axis direction in the cutting work state of the workpiece.
8A is an enlarged cross-sectional view of a plane perpendicular to the wire traveling direction in the vicinity of point a in FIG. 7;
  (B) is the cross-sectional enlarged view in the surface perpendicular | vertical to the wire running direction in the b point vicinity of FIG.
[Explanation of symbols]
  10 Wire saw,
  11 Wire row,
  11a wire,
  12 groove roller,
  16 pulse displacement roller,
  16a pulse displacement protrusion,
  17 drive unit,
  18, 30 pulse displacement means,
  31 electromagnetic coil,
  33 Pulse signal generator,
  I ingot (work),
  x Abrasive grains (free abrasive grains).

Claims (2)

The wire fed from the feeding reel is stretched between a plurality of groove rollers spaced apart from each other to form a wire row, and this wire row is run while supplying the abrasive liquid containing the loose abrasive grains to be processed. In a wire saw in which a workpiece that is an object is cut into a plurality of parts, and the wire after cutting is wound up on a take-up reel,
When the workpiece is cut, pulse displacement means is provided for pulsing the contact portion of the wire row with the workpiece in a direction opposite to the workpiece cutting direction, and this pulse displacement means travels at one place on the outer peripheral surface. A wire saw having a pulse displacement roller provided with a pulse displacement projection for projecting the wire row in a pulse shape by contacting the wire. In a workpiece cutting method using a wire saw that cuts a workpiece by pressing the workpiece against a traveling wire while supplying abrasive fluid containing free abrasive grains to the workpiece as a workpiece,
When the workpiece is cut, the contact portion of the wire with the workpiece is displaced in a pulse shape, and free abrasive grains in the abrasive fluid are replenished into the gap formed between the wire and the workpiece cutting portion at the time of displacement. The amplitude of the wire is 0.5 to 3.0 times the average particle size of the free abrasive grains ,
The pulse-like displacement is a workpiece cutting method using a wire saw given at an interval of 1/10 or less of the time from when the wire is pressed against the workpiece until it is released .

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