JP2013018096A - Outer peripheral surface grinding method of insert - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce variations in a cutting edge position when an insert is attached to a holder by applying outer peripheral surface grinding machining to the insert while assuming the mounting of the insert to the holder.SOLUTION: In a method of the outer peripheral surface grinding of an insert, the grinding of the outer peripheral surface is carried out in a state that a positional relationship between the insert and the grinding processing tool is decided while an inner surface of the through hole of the insert of flat plate shape has a convex shaped surface formed thereon on which the reference plane of a first processing tool comes in contact with, and the insert is sandwiched for fixation by the first processing tool and a second processing tool that has a rotation shaft connected with a driving device.

Description

  The present invention relates to an outer peripheral surface grinding method for an insert for a cutting tool.

  An element required for an insert for cutting edge-exchangeable cutting tools is that the position of the cutting edge does not change when the insert is detached or re-fixed after rotation. Therefore, when grinding is performed on the insert, it is desirable to perform the grinding while reproducing the mounting state on the holder. Among them, in grinding of the outer peripheral portion corresponding to the flank and restraint surface of the insert, a configuration in which the insert is fixed by being sandwiched from the upper surface and the bottom surface in the thickness direction is common. Especially when the insert has a through hole for the clamp screw in the center, the center can be caught by passing the pin therethrough, but it is necessary to secure a gap for fitting by penetrating the pin. It cannot be said to be the center. In addition, there is a method of catching the center of the insert by forming a concave shape on the top and bottom of the insert and attaching a jig there, but even if the center of the insert and the center of the processing machine shaft can be aligned, It is not enough to reproduce the mounting.

  In Patent Document 1, an insertion hole for passing a clamp screw for attaching an insert body to a tool body is formed, and a tapered surface on which the reference surface of a processing jig abuts is formed on the periphery of the opening on the insert body upper surface side of the insertion hole. This discloses a method of performing machining by aligning the center of the insert and the center of the rotation axis of the processing machine by matching the tapered surface and the tapered surface of the reference jig. According to Patent Document 1, it is essential to provide a tapered surface for contacting the processing jig on the periphery of the upper surface opening of the insertion holes of all the inserts.

  In Patent Document 1, when the insert body is actually attached to the tool body, the inner surface of the insertion hole of the insert body is pressed by the head of the clamp screw, and the insert body is pressed to the seating surface side. If the insert body is polished in a state where the tapered surface of the upper portion of the insertion hole is pressed by the tapered surface of the pressing portion of the upper surface jig, the state in which the dimensional accuracy is ensured is reproduced at the time of mounting. Patent Document 1 shows that grinding is performed in a form close to the time when the insert is mounted on the holder, but even if the inner surface of the same insertion hole is pressed, the portion of the insert that is pressed during processing is clamped when mounted on the holder. It is different from the part where the screw contacts.

  Patent Document 2 is directed to an insert in which a plurality of depressions obtained by combining a cylindrical shape or a semispherical body or a combination of both are provided on the upper surface or the bottom surface. This shows a method of performing processing by determining the positional relationship between the insert and the processing machine shaft by performing positioning and posture adjustment using the recess when clamping by the chucking device. Patent Document 2 shows that the insert must be specially provided with a shape for positioning with the processing jig.

  Patent Document 2 also discloses a method in which a center pin is inserted into a recess of an insert first and centering is performed, and then a pin is inserted into a surrounding recess to perform posture adjustment. In Patent Document 2, the insertion of a pin into a recess means that there is a clearance in the fitting portion of the pin, and the concentricity is insufficient when the purpose is to completely capture the center. It can be said.

  In Patent Document 3, a dent whose shape of the edge is similar to the outline in plan view of the insert and whose depth gradually increases from the edge toward the center is provided at the center of the top surface or bottom surface of the insert, and at the tip thereof A method is shown in which a processing machine shaft centering pin having a convex conical shape with the same contour is pressed to determine the positional relationship between the insert and the processing machine shaft and perform processing. Patent Document 3 is a type that does not have a hole through the center of the insert, so the insert is not fixed using a clamp screw, but mounted on the holder based on the contour of the insert. The method is different.

  Patent Document 3 describes that a concave portion whose depth gradually increases from the edge portion of the insert toward the center portion is described. However, Patent Document 3 is in a shape such as a dent or a taper that is a contact point between the positioning jig and the insert side, and does not define a contact portion shape or a taper angle.

  Patent Document 4 forms a flat surface in contact with a clamp jig for holding the insert during grinding of the outer peripheral surface on the outer periphery of the upper surface opening opening periphery of the insert hole so as to be continuous with the opening peripheral edge. Information on the position of the surface for holding during processing is disclosed. Although the purpose of optimizing the shape of the peripheral grinding is the same, it does not mention that the through hole of the clamp screw for fixing the insert is aligned with the rotational axis center of the processing machine.

  Patent Document 5 defines the head taper angle of the clamp screw of the insert as 40 to 60 °, and the position where the taper of the clamp screw contacts the insert is defined as 80% or less of the screw diameter from the insert reference bottom surface. Thus, an optimal shape and size capable of preventing breakage of the screw while ensuring attachment strength to the holder is disclosed.

Japanese Patent No. 4134996 Japanese Utility Model Publication No. 62-039902 Japanese Utility Model Publication No. 61-178602 JP 2005-328771 A Japanese Utility Model Publication No. 5-49203

  The subject of this invention is providing the outer peripheral surface grinding | polishing method of insert which can reduce the dispersion | variation in the blade-tip position at the time of mounting to the holder of insert.

In the present invention, the flat insert includes a seating surface on the lower surface, a rake surface on the upper surface, a clearance surface on the outer peripheral surface between the lower surface and the upper surface, and a through hole for a clamp screw that penetrates from the upper surface to the lower surface. In the outer peripheral surface grinding method of the insert in which a cutting edge is formed at a crossing ridge line portion between the rake face and the flank face, the insert is disposed on a pedestal jig having a placement groove, A convex surface is formed on the inner surface of the through hole of the insert so that the reference surface of the first processing jig abuts, and the insert is a second processing having the first processing jig and a rotating shaft. The insert outer peripheral surface grinding method is characterized in that the outer peripheral surface of the insert is ground in a state in which it is fixed by being sandwiched by a jig for use and the positional relationship with the grinding tool is determined.
By employing the present invention, the problems of the invention can be solved. In other words, by subjecting the insert to peripheral grinding in a form that is assumed to be mounted on the holder of the insert, it is possible to reduce variations in the position of the blade edge when the insert is mounted on the holder.

  In the outer peripheral surface grinding method of the insert of the present invention, the convex surface on the inner surface of the through hole has an arc shape in cross section when viewed from the cross section in the thickness direction of the insert, and the radius R (mm) of the arc Is preferably from 1.5 mm to 3.5 mm.

  In the insert outer peripheral surface grinding method of the present invention, the first processing jig is columnar and has the reference surface at the tip, the reference surface has a tapered surface shape, and the tapered surface angle θ Is preferably in the range of 50 to 70 degrees.

  In the outer peripheral surface grinding method of the insert of the present invention, it is preferable that the second processing jig is columnar, and the second processing jig is also a rotating shaft and is connected to a driving device.

  In the insert outer peripheral surface grinding method of the present invention, it is preferable that a V groove block is provided on the main body of the pedestal jig via a cushioning material, and the disposition groove is a V groove having a shape along the insert contour.

  According to the present invention, it has been possible to provide a method for grinding an outer peripheral surface of an insert that can reduce variations in the position of the blade edge when the insert is mounted on a holder.

The perspective view of an insert is shown. The front view of the 1st jig | tool for a process is shown. , The side view of the 1st jig | tool for a process is shown. The cross section when the convex-shaped surface in a through-hole inner surface is seen from the thickness direction of insert is shown. The V groove block on the base jig is shown. FIG. 6 shows a state where an insert is placed on the V-groove block shown in FIG. 5. The state which pinched | interposed and fixed by the 1st processing jig and the 2nd processing jig is shown. The state which fixed the insert to the tool main body with the clamp screw is shown.

  In the present invention, the insert is first placed on a pedestal jig having a placement groove. The reason is that it is possible to roughly define the angle and position of the insert before grinding by placing it on a jig having an arrangement groove along the contour shape of the insert. Thereafter, more accurate positioning is performed by contact with the first processing jig. By performing the centering step by step in this way, it is possible to finally make the fixing center of the insert and the rotation axis center of the processing machine coincide with each other more accurately. Matching the fixed center of the insert with the rotation axis is effective in improving the dimensional accuracy of the insert.

  In the present invention, it is necessary that the inner surface of the through hole of the insert has a convex surface shape that contacts the reference surface of the first processing jig. The reason is that the shape of the inner surface of the insert through hole, which is a contact partner with the polished tapered surface of the first processing jig for centering, is a convex surface than the tapered surface similar to the first processing jig. This is because the insert can be fixed in a stable state with a single posture when it is sandwiched and fixed.

  In the present invention, the insert is fixed so as to be sandwiched between the first processing jig having the reference tapered surface and the second processing jig having the rotation drive shaft. In addition, the variation in the position of the blade edge when the holder is mounted can be evaluated by measuring the distance from the center hole in the insert to the outer peripheral grinding surface. In the present invention, since the insert being processed only has a rotational movement centered on the clamp screw hole that coincides with the rotation axis of the processing machine, fixing the insert so as to sandwich the insert has a high accuracy of the blade edge position when the holder is mounted. Necessary for improvement.

  The present invention grinds the outer peripheral surface of the insert in a state based on the positional relationship between the abrasive layer surface of the grindstone, which is a grinding tool, and the fixed shaft of the insert. The reason is that when the present invention is applied, the center of the hole for the clamp screw that is the fixing center of the insert coincides with the rotation axis of the processing machine, and the axis in the direction approaching at right angles to the processing axis is This is because it becomes the cutting axis of the whetstone. As a result, a simple relationship can be obtained in which controlling only the movement of the grindstone in the cutting axis direction directly leads to increasing the dimensional accuracy of the distance from the center of the insert to the outer peripheral grinding surface. Therefore, disposing the work material insert and the grindstone as the processing tool as described above is effective in improving the edge position accuracy when the holder is mounted on the insert.

In the insert outer peripheral surface grinding method of the present invention, as shown in FIG. 4, the convex surface on the inner surface of the through hole has a convex arc-shaped portion (11 on the inner surface of the insert through hole when viewed from the cross section in the thickness direction of the insert. The arc shape is preferable. The reason is,
When the shape of the contact portion on the insert side is a convex arc surface, the contact form with the first processing jig or the clamp screw is a line contact. When fixing the insert to the jig on the processing machine, This is because the reproducibility of the position of the blade edge when mounted on the holder can be improved.
The portion from the convex arcuate portion (11) on the inner surface of the insert through hole to the linear portion (12) on the inner surface of the insert through hole is a sintered skin, and is deformed into an unintended shape. On the other hand, the contact partner is the clamp screw or the tapered surface of the polished first processing jig. Stable surface contact between the tapered surfaces cannot actually occur, and fixing becomes unstable at the time of contact.

  In the insert outer peripheral surface grinding method of the present invention, the radius R (mm) of the arc shape of the convex arc-shaped portion (11) on the inner surface of the insert through hole is preferably 1.5 mm to 3.5 mm. The reason is that when the R value is less than 1.5 mm, the diameter of the first processing jig is also thin, so that the strength is insufficient. On the other hand, when the R value exceeds 3.5 mm, the insert is too large for the size of the pedestal jig to be used at the same time.

  In the insert outer periphery grinding method of the present invention, it is preferable that the first processing jig is columnar, has a reference surface at the tip, and the reference surface has a tapered surface. The reason is to make the center of the insert smoothly coincide with the center of the machine tool spindle when in contact with the insert. Further, in the present invention, which aims to perform processing with the same shape as possible when processing and holder mounting, the tip reference surface of the first processing jig is not a tapered surface but a hemispherical shape. It is inconvenient because it leads to a decrease in the reproducibility of the cutting edge position.

  In the outer peripheral surface grinding method of the insert of the present invention, it is preferable that the taper angle θ of the tapered surface of the first processing jig is formed in the range of 50 degrees to 70 degrees. The reason for this is that the same shape as the taper of the insert clamp screw is convenient for processing in the state of mounting on the holder. In addition, by defining the angle, when centering and fixing by contact between the convex shape of the inner surface of the insert through hole and the tapered surface of the processing jig, centering by radial component force and axial component force The balance of fixing by can be taken. If the taper angle is as small as less than 50 degrees, a large force is exerted in the radial direction. For example, when the second processing jig moves forward and the force pressing the insert is too strong, it is assumed that the insert is expanded from the inner diameter and destroyed. On the other hand, when the taper angle is larger than 70 degrees, the force acting in the radial direction is weakened and smooth centering cannot be performed when the core is aligned while rubbing against the inner surface of the insert through hole. Therefore, in order to keep the force acting in the radial direction moderate, the taper angle θ is preferably in the range of 50 degrees to 70 degrees.

  In the insert outer peripheral surface grinding method of the present invention, it is preferable that the second processing jig has a columnar shape with a flat end surface, and the rotating shaft is connected to a driving device. The reason is that when grinding the entire circumference of the outer peripheral surface of the insert, the insert is rotated so that the surface to be ground is directed in the direction in which the grindstone as a processing tool exists. Further, by connecting the second processing jig having a flat end surface to the driving device, it is possible to avoid slipping of the processing jig and the insert when sandwiched and fixed.

  In the outer peripheral surface grinding method of the insert of the present invention, it is preferable that a V groove block is provided on the main body of the pedestal jig via a cushioning material, and the arrangement groove is a V groove along the contour of the insert. The reason for this is that when the insert jig is fixed, the taper surface of the first processing jig and the circular arc surface existing on the inner surface of the insert contact each other when the processing jig axis is aligned with the insert center line. This is because it is convenient to be able to center smoothly if it is movable.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited by the following Example.

(1) Tool shape The outer peripheral surface grinding method of the insert for cutting tools of this invention is described below. The cutting edge-exchangeable cutting tool for mounting the insert (8) is a shank type end mill with a blade diameter of 50 mm, and four inserts are arranged at equal intervals on the outer periphery of the tool body.

(2) Insert shape In FIG. 1, the insert shape used for the Example is shown. The insert used was a JDET150530R model insert manufactured by Hitachi Tool Co., Ltd. The cutting edge of the insert continues from the outer peripheral edge (7) through the corner edge (5) to the bottom edge (6). Two corners located diagonally can be used. In order to suppress cutting resistance, this insert has a structure in which the outer peripheral edge portion is inclined in a direction in which the rake angle is increased with respect to the tool rotation axis. When the thickness of the insert is defined as the distance from the seating surface (2) to the boss surface (1) at the peripheral edge of the upper surface, the insert shape is a twisted shape in which the corner blade is positioned higher than the thickness.

(3) Insert material In the embodiment of the present invention, a cemented carbide insert having a cobalt content of 9.5% by mass was used. In the production method, the granulated cemented carbide powder was press-molded by press-pressure molding using a press die, and an insert material having a rectangular top view profile was press-molded. At this point, major shapes such as the rake face were made, and the compact was sintered in a vacuum or inert gas atmosphere.

(4) Lower surface grinding process Before performing the outer peripheral surface grinding process, in order to accurately fix the insert during outer peripheral surface grinding, the seating surface (2) in contact with the second processing jig was ground. Grinding is performed by bringing the insert into contact with the grindstone using a servo motor, and processing that satisfies the design tolerance that the height difference between both corner blades (5) defined as parallelism is within 0.02 mm. went.

(5) Apparatus and processing conditions used for outer peripheral surface grinding For outer peripheral surface grinding, an AP460E insert outer peripheral grinding machine manufactured by Waida Seisakusho was used. For the grinding process, a resin bond grindstone containing diamond abrasive grains having a particle size of # 325 was used. The shape of the grindstone is a cup grindstone having a diameter of 350 mm, and the width of the abrasive grain layer is 8 mm. The spindle rotation speed was set to 1500 revolutions per minute, and the cutting feed rate was changed in a stepwise manner between 3.0 mm / min and 0.5 mm / min.

(6) Position adjustment and setup of pedestal jig performed before outer peripheral surface grinding The most important jig used for setup and outer peripheral surface grinding is loading to the processing position with an orthogonal robot for insert loading (not shown). 4 when the insert is placed first, and the first processing jig (9) which sandwiches and fixes the insert during processing and also serves as an indexing rotation shaft And a second processing jig (20).
In the embodiment, as shown in FIG. 2, the first processing jig (9) for holding the insert, which is the work material, during the grinding process has a reference surface at the tip of the first processing jig. It was set as the shape which has the taper surface which is (10). ,
Next, the pedestal jig shown in FIG. 4 was attached to a grinding machine (not shown) to adjust the position. The insert is actually sandwiched in a processing jig in a grinder (not shown) and fixed, and then the V groove (19) of the placement groove block of the base jig is applied to the insert, and the center of the through hole of the insert and the grinder Pedestal jig (13) so that the insert exists at a high position in the range of 0.05 mm or more and 0.5 mm or less in the vertical direction with a concentricity of 0.01 mm or less in the horizontal direction compared with the side rotation center The position of was adjusted.

(7) Peripheral surface grinding The peripheral surface grinding is performed on the outer peripheral surface located between the flank (4) or restraint surface of the insert and the rake surface (3) and the reference seating surface (2). It is all. When the insert placed on the pedestal jig (13) by the orthogonal robot (not shown) is inserted and fixed from the upper surface and the seating surface of the insert by the first and second processing jigs, Clamp the insert by contacting the reference surface (10) at the tip of the processing jig and the contact position (21) between the insert on the inner surface of the through hole through which the clamp screw (22) of the insert passes and the first processing jig. The center of the through hole through which the screw passes was made to coincide with the center of rotation on the grinding machine side. At the same time, a force for pushing the insert downward was applied, so that the angle when the insert was fixed was matched with the angle of the V groove (19) of the V groove block (18) of the base jig (13).
The insert is mounted on the holder body (23) by fixing the center of the through hole for the insert clamp screw and the center of rotation of the processing jig so as to coincide with each other by the centering operation before processing as described above. We were able to process in the state.

(8) Evaluation of shape after outer peripheral surface grinding After the outer peripheral surface grinding, the symmetry of the positions of the outer peripheral blade (7) and the bottom blade (6) was confirmed around the insert through hole. For the measurement, a projector was used in the transmitted illumination mode, and all 30 inserts were processed. FIG. 4 shows the measured location of the insert. The insert outer peripheral surface grinding method is defined by measuring the distance between the center of the insert through hole and the bottom blade as L1 and L3 (mm) and the distance between the center of the insert through hole and the outer peripheral blade as L2 and L4 (mm). Table 1 shows the measured values of the dimensions of the applied example of the present invention and the case of the conventional example that was processed without being applied. The conventional processing method in which the insert outer peripheral surface grinding method defined in the present invention is not applied here is that a taper surface is provided on the reference surface (10) at the tip of the first processing jig (9). This shows the case where the center of the through hole for the clamp screw and the center of rotation of the processing jig were not matched without using any object.

  As shown in Table 1, the outer peripheral surface grinding was performed on an insert in which two cutting edges exist in a point-symmetrical position, and the design values shown in Table 1 are target values for the dimensions of the part by grinding. . The standard deviation is calculated from a total of 60 data including the values L1 and L3 and L2 and L4 on both sides centered on the through hole of the 30 processed inserts, and indicates a variation in dimensions after processing. did. The difference between the maximum and minimum values is obtained by confirming the difference between the maximum value and the minimum value included in the 60 obtained dimension data. A decrease in variation in the dimensions of L2 and L4 leads to a reduction in blade diameter fluctuation when the holder is mounted, and a decrease in variations in the dimensions of L1 and L3 is a variation in the amount of protrusion of the bottom blade when the holder is mounted. Leads to a decrease. Therefore, when the comparison is made with variations in the dimensions of L2 and L4, the standard deviation of the conventional example is 0.007 mm and the difference between the maximum and minimum values is 0.024 mm, but the example of the present invention has a standard deviation of 0.002 mm and the maximum and minimum. The value difference was 0.006 mm. As described above, in the processing method to which the present invention is applied, the dimensional variation of the insert can be suppressed.

(9) Verification of runout accuracy as a tool Four out of 30 processed inserts were arbitrarily selected, and the directions of the blade edges were aligned and mounted on the holder. After this tool was mounted on a tool presetter, the runout of the outer peripheral blade was measured with a pick tester, and the protruding amount of the bottom blade was measured with a dial gauge. Table 2 shows an average value obtained by performing this operation five times for each of the inventive example and the comparative example.

  As shown in Table 2, in the conventional example, there was a difference of 0.06 mm between the maximum value and the minimum value of the deflection of the outer peripheral blade, but the present invention example was reduced to 0.04 mm.

  This method of grinding the outer peripheral surface of the insert using the positioning method according to the present invention is a shape having a through hole in the upper surface and the seating surface direction in the center when viewed from above, and a convex surface on the inner surface of the through hole. The same processing can be applied to a wide range of inserts.

DESCRIPTION OF SYMBOLS 1 Boss surface 2 Seating surface 3 Rake surface 4 Relief surface 5 Corner blade 6 Bottom blade 7 Outer peripheral blade 8 Insert body 9 First processing jig 10 Reference surface 11 of first processing jig tip 11 Inside insert through hole inner surface Convex arc shape part
12 Straight portion of inner surface of insert through hole 13 Base jig 14 Reference sliding surface 15 Second sliding surface 16 Buffer material 17 Gap 18 V groove block 19 V groove 20 of arrangement groove block Second processing jig 21 Insert and Contact position with the first processing jig
22 Clamp screw 23 Holder body

Claims (5)

  The flat insert has a seating surface on the lower surface, a rake surface on the upper surface, a clearance surface on the outer peripheral surface between the lower surface and the upper surface, and a through hole for a clamp screw that penetrates from the upper surface to the lower surface, In the outer peripheral surface grinding method of the insert, in which a cutting edge is formed at an intersecting ridge line portion between the rake face and the flank face, the insert is arranged on a base jig having an arrangement groove, and the through hole of the insert A convex surface is formed on the inner surface of the first processing jig so as to contact a reference surface of the first processing jig, and the insert includes the first processing jig and a second processing jig having a rotation axis. A method for grinding an outer peripheral surface of an insert, characterized in that the outer peripheral surface of the insert is ground in a state in which the positional relationship with a grinding tool is fixed.   The outer peripheral surface grinding method of the insert according to claim 1, wherein the convex surface on the inner surface of the through hole has a circular arc shape when viewed from a cross section in the thickness direction of the insert, and the radius of the arc. R (mm) is 1.5 mm to 3.5 mm, The outer peripheral surface grinding method characterized by the above-mentioned.   3. The insert outer peripheral surface grinding method according to claim 1, wherein the first processing jig has a columnar shape, the tip thereof has the reference surface having a tapered surface shape, and the tapered surface. The angle θ of the insert is in the range of 50 to 70 degrees.   The insert outer peripheral surface grinding method according to any one of claims 1 to 3, wherein the second processing jig has a columnar shape, and the rotating shaft is connected to a driving device. Insert outer peripheral surface grinding method.   5. The outer peripheral surface grinding method for an insert according to claim 1, wherein a V-groove block is provided on a body of the pedestal jig via a cushioning material, and the arrangement groove follows an insert contour. A method of grinding an outer peripheral surface of an insert, which is a V-shaped groove.

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