JP2006035515A - Cutting method and apparatus for the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting method which can reduce residual cutting powder in relation to a cutting surface without causing the increase of the number of processes when a molding is cut and an apparatus for the method. <P>SOLUTION: A step (a) in which a prescribed amount of an object to be processed is cut while a cutting means traveling in a prescribed direction is pressed against the object and a step (b) in which the cutting means is moved back relatively to a prescribed position in the direction to release the pressing are repeated. For example, a wire saw 1 for cutting the object which is pressed against the object while traveling in the prescribed direction and a driving part including a parallel link mechanism driving the wire saw 1 are provided, and the wire saw 1 is arranged at a position corresponding to the connection rod in the parallel link mechanism, so that the cutting method can be materialized. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and apparatus for cutting a workpiece using a wire saw, and more particularly to a wire saw cutting method and apparatus suitable for cutting a molded body.

  There are several methods for processing a sintered body produced by powder metallurgy, such as a ferrite sintered magnet and a rare earth sintered magnet, into a predetermined shape and size. One of them is a method of producing a sintered body that approximates a predetermined shape and size, and finishing the surface by processing such as grinding. In addition, there is a method in which a block-shaped sintered body is prepared, and the block-shaped sintered body is cut using a diamond grindstone and a cutter to obtain a plurality of sintered bodies having a predetermined shape. Even in this case, processing such as grinding may be performed on the cut surface or the non-cut surface after the cutting processing.

Since the sintered body has a high hardness, attempts have been made to cut it at the stage of a green body that is easy to process. For example, in Patent Document 1 (Japanese Patent Laid-Open No. 53-899), a molded body in the process of manufacturing an Sm—Co based sintered magnet is made of a cemented carbide in a nitrogen gas atmosphere to prevent oxidation. Proposals for cutting with a blade saw have been made. Patent Document 2 (Japanese Patent Laid-Open No. 8-181028) discloses that a molded body and a rotating processing blade are made of mineral oil or the like for the purpose of preventing oxidation, preventing clogging with grinding stone cutting powder, and continuously discharging cutting powder. There has been proposed a method of cutting while immersed in a processing liquid.
However, according to the processing method using a blade saw, there is a problem that the cutting cost of the molded body is large and the product yield is poor. In addition, a degreasing process that removes mineral oil and the like from the molded body after cutting and before sintering is indispensable. When degreasing is insufficient, carbon contained in the oil functions as an impurity during the sintering process, resulting in magnet characteristics. It will deteriorate.

  Patent Document 3 (Japanese Patent Application Laid-Open No. 2003-303728) discloses a method for solving the above problems, a step of producing a molded body of magnet powder, a step of processing a molded body using a wire saw, and a molded body. A method of manufacturing a sintered magnet including a step of sintering is disclosed. According to Patent Document 3, since the molded body in a relatively soft state before sintering is processed with a thin wire saw, the processing load is reduced, and heat generation of the molded body can be suppressed. For this reason, even when a magnet is manufactured using magnet powder that is easily oxidized, the time for processing can be greatly shortened and the manufacturing cost can be greatly reduced without degrading the final magnet characteristics. Moreover, since the cutting allowance can be reduced compared with the case of using a conventional rotary blade, the yield of the material is improved.

JP-A-53-899 JP-A-8-181028 JP 2003-303728 A

  Although the cutting with the wire saw disclosed in Patent Document 3 has the excellent effects as described above, it has been pointed out that the cutting powder remains and adheres to the cut surface. The cutting powder remaining on the cut surface causes the compacts (sintered bodies) to fuse together when sintering is performed in a state where the compacts are in contact with each other. Therefore, Patent Document 3 proposes that the wire saw is moved relative to the cut surface once formed. Patent Document 3 proposes supplying cutting fluid to a wire saw. However, when the wire saw is thin, for example, when the wire saw is as low as 0.2 to 0.5 mm, it has been found that the above-mentioned proposal has a small effect of removing the cutting powder. Further, the relative movement of the wire saw is added as a new process after the cutting is completed, resulting in an increase in the process. Then, an object of this invention is to provide the cutting method and cutting device which can reduce the residue of the cutting powder with respect to a cut surface, without causing the process increase.

  As described in Patent Document 3, the wire saw presses a wire saw traveling in one direction or in both directions against a molded body to be processed, and the molded body is formed by abrasive grains between the wire saw and the molded body. It is a processing technology. However, when the formed body is cut as described above, residual cutting powder is remarkable. Therefore, the present inventors studied to give a cutting powder removing function to the wire saw that travels for cutting. Then, it was made to retreat from the position which cuts, making a wire saw run. As a result, it was found that the cutting powder was scraped by the retraction of the wire saw, and as a result, the residual amount of the cutting powder was reduced. The cutting method (first cutting method) of the present invention based on the above knowledge includes a step (a) of cutting a workpiece by a predetermined amount while pressing a cutting means traveling in a predetermined direction against the workpiece, and pressing. The step (b) of retreating the cutting means relatively to a predetermined position in the opening direction is repeated. This cutting means includes not only a wire saw but also a band saw described later. Hereinafter, the cutting means will be collectively referred to as a wire saw.

  According to this first cutting method, the cutting with the wire saw and the scraping of the cutting powder by the retraction of the wire saw are repeated until the cutting is completed and the workpiece is cut. Therefore, the generated cutting powder is sequentially discharged, and the amount of cutting powder remaining on the cut surface can be reduced. Moreover, according to the 1st cutting method, since the removal operation | work of cutting powder is not performed again after completion | finish of a cutting | disconnection, it also has the advantage that it does not accompany an increase in a process. Note that the retraction of the wire saw means a relative positional relationship with the workpiece, and even when the workpiece is moved away from the wire saw, it is included in the concept that the wire saw in the present invention retracts.

  In the first cutting method, the wire saw can be continuously reciprocated between a position where the wire saw is pressed against the workpiece and a predetermined position. By doing so, since cutting and cutting powder removal can be performed alternately and continuously, cutting can proceed while suppressing the residue of cutting powder on the cut surface as much as possible.

  The first cutting method is not limited to the above, and the pressing of the wire saw can be maintained for a predetermined time. By doing so, the cutting amount can be adjusted appropriately. For example, when emphasizing the amount of cutting, the cutting operation is performed by setting a longer time to press the wire saw, and then moving the wire saw to a predetermined position and then continuously moving the wire saw to the pressed position. can do.

  In order for the wire saw to continuously reciprocate between a pressed position and a predetermined position, a reciprocating linear motion can be used. However, the wire saw can be continuously reciprocated between a pressed position and a predetermined position by operating the wire saw so that the locus of the fixed point on the wire saw draws a circle. In this case, since the speed component of the wire saw due to the motion has two components orthogonal to each other, the wire saw can be run and retracted by a single motion.

  In the first cutting method described above, the wire saw itself to be cut has a cutting powder removing function. However, in addition to a wire saw having a cutting function, a wire saw having a cutting powder removing function may be provided. Therefore, the present invention includes a step (c) of performing cutting by pressing the first wire saw traveling in a predetermined direction against the workpiece, and a first step disposed behind the first wire saw with respect to the workpiece. A wire saw cutting method (second cutting method) characterized by comprising the step (d) of scraping cutting powder generated by cutting by moving the wire saw of 2 in a cutting completion region.

  According to the second cutting method described above, since cutting with the first wire saw and scraping of the cutting powder with the second wire saw can be performed in parallel, the residual amount of cutting powder without substantially reducing the cutting efficiency. Can be reduced.

In the second cutting method, it is desirable that the second wire saw is disposed at a predetermined angle with respect to the first wire saw. This is to increase the scraping efficiency of the cutting powder.
Further, the second wire saw can move in synchronization with the traveling of the first wire saw. The generated cutting powder can be quickly scraped and eliminated.

The present invention provides a wire saw cutting device that executes the first cutting method described above. The wire saw cutting device (first cutting device) includes a wire saw that cuts a workpiece while being pressed by the workpiece while traveling in a predetermined direction, and a drive unit that includes a parallel link mechanism that drives the wire saw. The wire saw is arranged at a position corresponding to the connecting rod in the parallel link mechanism.
As is well known, the movement locus of the fixed point on the connecting rod in the parallel link mechanism draws a circle. Therefore, the wire saw arranged at the position corresponding to the connecting rod in the parallel link mechanism is between the position where the wire saw is pressed against the workpiece and the predetermined position as described in the first cutting method. It can be continuously reciprocated. Moreover, the locus of the fixed point on the wire saw draws a circle.

  The present invention also provides a wire saw cutting device that performs the second cutting method described above. This wire saw cutting device (second cutting device) includes a first wire saw that presses a workpiece to perform cutting, and a second wire saw that scrapes off cutting powder generated by the cutting. .

  In this second cutting apparatus, it is desirable for scraping of the cutting powder that the second wire saw is disposed at a predetermined angle with respect to the first wire saw and is translated along the traveling direction of the first wire saw. . Furthermore, it is desirable for efficient scraping of the cutting powder that the first wire saw travels in both directions and the second wire saw moves in parallel with the first wire saw.

  As described above, according to the present invention, it is possible to provide a wire saw cutting method and a wire saw cutting device that can reduce the residual of cutting powder on a cross section. Moreover, according to the wire saw cutting method and the wire saw cutting device of the present invention, the cutting powder can be removed in parallel with the cutting, so that the cutting efficiency is hardly lowered.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
<First form>
First, an example of a first cutting method and a first cutting device (sometimes collectively referred to as a first form) in which a traveling wire saw itself has a cutting powder removing function will be described.
As shown in FIG. 1, the cutting apparatus 10 includes a wire saw 1 that cuts an object to be cut. The wire saw 1 is stretched around a frame 2 having a U-shaped cross section. The frame 2 is fixed to a pair of pulleys 3 and 4 that are rotatably supported by a column, for example. The pulleys 3 and 4 can be rotated synchronously by the wound timing belt 5. The timing belt 5 can also be a chain belt. A pulley 6 having a diameter larger than that of the pulley 4 is arranged coaxially with the pulley 4. A timing belt 7 is wound around the pulley 6, and the timing belt 7 is rotationally driven by a motor 8. However, the pulley 4 does not need to have a larger diameter than the pulley 6. Further, the timing belt 7 may be a chain belt or a normal belt.

  Now, in the cutting device 10 having the above configuration, when the motor 8 is driven, the pulley 6 rotates in the arrow direction, and the pulleys 3 and 4 also rotate in the arrow direction along with this rotation. As the pulleys 3 and 4 rotate, the frame 2 also moves. This motion is equivalent to the motion by the parallel link mechanism having the rotation centers c1 and c2 of the pulleys 3 and 4 and the pulleys 3 and 4 and the fixing points c3 and c4 of the frame 2 as nodes. The wire saw 1 is disposed at the position of the connecting rod of this parallel link mechanism. 1 to 4 sequentially show the process of this movement. FIG. 2 shows a state where the pulleys 3 and 4 are rotated by 90 ° from the state of FIG. 1, and FIG. 2 shows that the pulleys 3 and 4 are rotated by 90 ° from the state of FIG. 3 shows a state where the pulleys 3 and 4 are rotated by 90 ° from the state shown in FIG.

  As can be understood from FIGS. 1 to 4, the wire saw 1 travels in the arrow direction (vertical direction) and reciprocates in the horizontal direction. More specifically, assuming that the state of FIG. 1 is an initial state, the wire saw 1 moves from the initial state (movement start end) by a predetermined distance L in the left direction in the figure (movement end), and then in the right direction in the figure. It moves by a predetermined distance L and returns to the movement start end. The predetermined distance L is L = 2r, where r is the distance from the rotation center c1 (c2) of the pulley 3 (pulley 4) to the pulley 3 (pulley 4) and the fixed portion c3 (c4) of the frame 2.

  FIG. 5 shows a movement locus of a predetermined fixed point (indicated by a black circle) on the wire saw 1 when the cutting device 10 performs the operations of FIGS. In FIG. 5, the fixed point on the wire saw 1 moves on a virtual circle with a radius r. At this time, the wire saw 1 reciprocates in the vertical direction. This vertical reciprocation corresponds to the bidirectional traveling of the wire saw 1. The wire saw 1 reciprocates between the movement start end on the right side in the figure and the movement end point on the left side in the figure.

  Furthermore, the wire saw 1 exhibits a function of cutting the molded body GB mainly by moving from the position (4) to the position (1). Thereafter, the wire saw 1 moves from the position (1) to the position (2), and further moves to the position (3). The movement of the wire saw 1 scrapes off the cutting powder from the cut surface. Thus, the wire saw 1 has both the function of cutting the molded body GB and the function of discharging cutting powder. By the way, the wire saw 1 has two velocity components in the vertical direction and the horizontal direction in the process of movement. By having two velocity components in this way, cutting and movement can be continuously performed by a single movement called a circular movement.

<Second form>
Although the 1st form gave the cutting function and the cutting powder discharge function to the wire saw 1 using the parallel link mechanism, the example which gives the cutting function and the cutting powder discharge function by a mechanism different from the 1st form in the 2nd form. Show.
FIG. 6 is a diagram for explaining a wire saw cutting method according to the second embodiment.
As shown in FIG. 6, a plurality of wire saws 11 are stretched on a frame 12 having a U-shaped cross section. The frame 12 can reciprocate in the vertical direction by an actuator (not shown). The frame 12 can be reciprocated in the horizontal direction by an actuator (not shown). The formed body GB that is a workpiece can be moved forward and backward with respect to the wire saw 11 while being held by a chuck (not shown). The shaped body GB is cut by pressing the wire saw 11 against the shaped body GB while reciprocating the frame 12 in the vertical direction.

In the second embodiment, when the wire saw 11 is cut into the formed body GB by a predetermined amount, the wire saw 11 is moved backward by a predetermined distance from the cutting position of the formed body GB. After retreating, cut a predetermined amount again. In the second embodiment, the molded body GB is cut by repeating the above operation, and FIG. 7 shows the relationship between the elapsed time from the start of cutting and the cutting amount of the wire saw 11 into the molded body GB. As is clear from FIG. 7, the second embodiment repeats the predetermined amount of cutting, the wire saw 11 retracting, the predetermined amount of cutting, the wire saw 11 retracting, the predetermined amount of cutting, etc., but when the wire saw 11 is retracted, scraping of cutting powder Is done effectively. In the second embodiment, when performing the cutting, the wire saw 11 is pressed against the compact GB for a predetermined time, and when the predetermined time has elapsed, the wire saw 11 is moved backward. After retreating by a predetermined amount, the wire saw 11 is advanced for cutting and pressed against the cut portion of the molded body GB. In the second form, the wire saw 11 is reciprocating in the vertical direction even when it is retracted, that is, is traveling, so that the cutting powder removal effect is high.
In the first embodiment, the time for pressing the wire saw 1 against the molded body cannot be ensured for a long time because the rotary motion is used, whereas the second embodiment presses the wire saw 11 against the molded body GB. In other words, there is an advantage that the cutting time can be set arbitrarily.

<Third form>
In the first embodiment and the second embodiment, the wire saw 1 (11) that performs the cutting function is also provided with a cutting powder removing function. However, the third embodiment has a cutting powder removing function in addition to the wire saw that performs the cutting function. An example of separately preparing a wire saw will be described.
FIG. 8 is a diagram for explaining a wire saw cutting method according to the third embodiment.
As shown in FIG. 8, a plurality of wire saws 21 are stretched on a frame 22 having a U-shaped cross section. This wire saw 21 is a wire saw that performs a cutting function. In the cutting device according to the third embodiment, a plurality of wire saws 23 are further stretched on the frame 22. The wire saw 23 is disposed behind the wire saw 21 with reference to the molded body GB that is a workpiece. Further, the wire saw 23 may be disposed in parallel with the wire saw 21, but it is desirable that the wire saw 23 be disposed at a predetermined angle with the wire saw 21, as shown in FIG. As the wire saw 21 and the wire saw 23, it is possible to use ones having different wire diameters or abrasive grain sizes described later.

  The frame 22 can reciprocate in the vertical direction by an actuator (not shown). The frame 22 can be reciprocated in the horizontal direction by an actuator (not shown). The molded body GB that is a workpiece can be moved forward and backward with respect to the wire saw 21 while being held by a chuck (not shown). The shaped body GB is cut by pressing the wire saw 21 against the shaped body GB while reciprocating the frame 22 in the vertical direction.

  A 3rd form removes cutting powder with the wire saw 23, cutting the molded object GB with the wire saw 21. FIG. This will be described with reference to FIG. As shown in FIG. 9, the wire saw 21 reciprocates in the vertical direction to cut the formed body GB. The wire saw 23 reciprocates in synchronization with the reciprocating motion of the wire saw 21. Since the wire saw 23 forms a predetermined angle with the wire saw 21, the cutting powder remaining in the cutting completion region can be scraped out from the cutting completion region by reciprocating. In order to cut the molded body GB, the number of cuts by the wire saw 21 is increased. In the process, the wire saw 23 scrapes off the cutting powder.

  Although the 3rd form provided the wire saw 23 as a wire saw which exhibits a cutting powder removal function, providing the wire saw 24 which exhibits a cutting powder removal function further as shown in FIG. 10 improves the cutting powder removal effect. Can do.

Although three forms of the cutting method according to the present invention have been described above, items common to the three forms will be described below.
The wire saw used in the present invention is obtained by fixing abrasive grains such as diamond on the surface of a wire saw core wire.
The wire saw core wire is made of a material having high tensile strength, such as a hard steel wire (piano wire), a Ni—Cr-based or Fe—Ni-based alloy, a refractory metal such as W or Mo. Not only metal but also a resinous wire saw core can be used.
On the other hand, if the diameter of the wire saw core wire is too large, the cutting amount of the workpiece is increased and the material yield is lowered. On the other hand, if the wire saw wire is too thin, the wire saw core wire may be cut by a load during cutting. For this reason, the outer diameter of the wire saw core wire used in the present invention is preferably 0.1 to 0.6 mm, and more preferably 0.15 to 0.5 mm.
As the abrasive grains fixed to the wire saw core wire, it is preferable to use a high hardness material such as diamond, SiC or Al ₂ O ₃ , and the particle diameter is typically 10 to 500 μm, desirably 20 to 300 μm. .
The abrasive grains are preferably fixed to the surface of the wire saw core with a metal bond such as Cu or Ni, or a resin such as phenol resin, epoxy resin or polyimide resin.

The traveling speed of the wire saw greatly affects the machining load. In order to keep the processing load within a practically appropriate range, this speed is preferably set to, for example, 10 to 100 m / min, and more preferably set to 20 to 50 m / min. Further, the cutting speed by the wire saw is preferably set to 10 to 400 mm / min, and more preferably set to 50 to 200 mm / min.
Although the wire saw has been described above as an example, the present invention can also be applied to a band saw having a plate thickness of about 1 mm or less.

Hereinafter, the present invention will be described based on specific examples.
An alloy was prepared using a strip cast method so as to have a composition of 29.5 wt% Nd-2.5 wt% Dy-1 wt% B-0.5 wt% Co-remainder Fe, coarsely pulverized by hydrogen treatment, and jet mill Finely pulverized to obtain a fine powder having an average particle size of 4 μm. This fine powder was molded in a magnetic field at a pressure of 150 MPa in a magnetic field of 1.5 T to obtain a molded body of 45 mm × 35 mm × 60 mm (magnetic field orientation direction).

<Comparative example>
The molded body was cut using the cutting device shown in FIG. The wire saw used has an outer diameter of 0.25 mm to which diamond abrasive grains having an average particle diameter of 60 μm are fixed. The wire saw was reciprocated at 16 Hz, and the molded body was cut at a rate of 100 mm / min. After cutting, the molded body was moved once again in the direction opposite to the cutting direction along the cut surface. At this time, the movement of the wire saw is the same as that during cutting.

  The obtained 45 mm × 35 mm × 4 mm compacts were sintered in vacuum at 1190 ° C. for 1 hour. At this time, anti-fusing powder was laid on the 45 mm × 35 mm surface of the molded body, and 14 sheets were stacked in the horizontal direction and sintered. After sintering, 3 of the 14 sintered bodies were peeled off, but 11 were fused and could not be separated. The cutting powder generated when the molded body is cut adheres firmly to the cut surface of the molded body, and the adhered powder takes in the anti-fusion powder during sintering and sinters. It is understood that this was caused by inhibition.

<Example>
Using the same molding apparatus and wire saw as in the comparative example, the molded body similar to the above was cut into a pattern as shown in FIG. In addition, the molded body cut | disconnected on these conditions is sample No.2. Set to 1.
A molded body similar to the above was cut using the apparatus shown in FIG. 8 under the same conditions as in the comparative example. The molded body cut under these conditions was designated as Sample No. 2.
Furthermore, the molded object was cut | disconnected on the same conditions as the comparative example after using the apparatus which shows the similar molded object in FIG. The molded body cut under these conditions was designated as Sample No. 3.
The molded bodies of Sample Nos. 1 to 3 were each spread with anti-fusing powder in the same manner as in the comparative example, stacked in the same manner as in the comparative example, and sintered under the same conditions as in the comparative example. When the obtained sintered body was separated, the results shown in Table 1 were obtained. It can be seen that since the residual amount of the cutting powder is small in the molded body by the cutting method of the example, fusion after sintering is suppressed.

It is a figure explaining the wire saw cutting method by a 1st form. It is another figure explaining the wire saw cutting method by a 1st form. It is another figure explaining the wire saw cutting method by a 1st form. It is another figure explaining the wire saw cutting method by a 1st form. It is a figure explaining operation | movement of the wire saw by a 1st form. It is a figure explaining the wire saw cutting method by a 2nd form. In a 2nd form, it is a graph which shows the relationship between the elapsed time from the start of cutting, and the cutting amount to the molding of a wire saw. It is a figure explaining the wire saw cutting method by a 3rd form. It is a figure explaining operation | movement of the wire saw in the wire saw cutting method by a 3rd form. It is a figure explaining the other wire saw cutting method by a 3rd form.

Explanation of symbols

  1, 11, 21, 23, 24 ... wire saw, 2, 12, 22 ... frame, 3, 4, 6 ... pulley, 5, 7 ... timing belt, 8 ... motor, 10 ... cutting device, GB ... molded product

Claims (12)

A step (a) of cutting the workpiece by a predetermined amount while pressing a cutting means traveling in a predetermined direction against the workpiece;
Retreating the cutting means relatively to a predetermined position in the direction of releasing the pressing (b);
A cutting method characterized by repeating.   The cutting method according to claim 1, wherein the cutting means continuously reciprocates between the pressed position and the predetermined position.   The cutting method according to claim 1, wherein the pressing means maintains the pressure for a predetermined time.   The cutting method according to claim 3, wherein after the predetermined time is maintained, the cutting means is continuously moved to the pressed position after the cutting means is moved to the predetermined position.   The cutting method according to claim 2, wherein the locus of the fixed point on the cutting means draws a circle. A step (c) of performing cutting by pressing a first cutting means that travels in a predetermined direction against the workpiece;
(D) scraping off cutting powder generated by the cutting by moving the second cutting means disposed behind the first cutting means with respect to the workpiece in a cutting completion region; ,
A cutting method comprising:   The cutting method according to claim 6, wherein the second cutting means is disposed at a predetermined angle with respect to the first cutting means.   The cutting method according to claim 7, wherein the second cutting unit moves in synchronization with traveling of the first cutting unit. Cutting means for cutting the workpiece while being pressed against the workpiece while traveling in a predetermined direction;
A drive unit including a parallel link mechanism for driving the cutting means,
The cutting device, wherein the cutting means is disposed at a position corresponding to a connecting rod in the parallel link mechanism. A first cutting means for performing cutting by pressing against a workpiece;
A second cutting means for scraping off the cutting powder generated by the cutting;
A cutting device comprising:   The said 2nd cutting means is arrange | positioned at a predetermined angle with respect to the said 1st cutting means, and translates along the running direction of the said 1st cutting means. Cutting device.   The cutting apparatus according to claim 11, wherein the first cutting means travels in both directions, and the second cutting means moves in parallel with the first cutting means.

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