JP2005186233A - Face milling cutter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a milling cutter, keeping high-level finished surface roughness, reducing the replacement frequency of cutting insert, simplifying and quickening the replacement work of the cutting insert, and reducing the machining cost. <P>SOLUTION: All of cutting inserts 11 are provided with a flat drag 13, and the height of knife edge of every flat drag is within the height range of 50 μm. Therefore, in fitting all inserts 11, the knife edges are all uniform in height, and the main cutting blades 15 are all on the same circumference and generally fitted. Special consideration is not required for fitting unlike the case of using the conventional insert with a flat drag, but the machined surface is finished with any flat drag so that a good finished surface is obtained. One insert will not wear away earlier so that the relacement timing can be remarkably extended. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a face milling cutter.

In machining with a face mill formed by mounting a plurality of cutting inserts (also called cutting edge tips), the finished surface roughness (machined surface roughness: Rz) is the shape of the cutting edge of the cutting insert, cutting conditions (tool rotation speed, Cutting speed, feed rate, etc.). Specifically, Rz = (Fz ² ) / (8R). Here, Fz is a feed amount per blade, and R is a nose R (radius). In such face milling, in order to improve the surface finish roughness of the flat surface by the edge of the secondary cutting edge, the edge of the secondary cutting edge, that is, the corner of the primary cutting edge (peripheral cutting edge) and the secondary cutting edge In which a Saray blade (also referred to as a wiper cutting edge or a second auxiliary cutting edge) is provided on the secondary cutting edge side.

  On the other hand, assuming that such a Saray blade is a straight line (flat) and parallel to the finished surface, theoretically, the finished surface roughness can be best. However, it is usually a Saray blade formed in an arc shape with a large radius. This is because, in a straight line, the finished surface is deteriorated due to an attachment error such as an inclination in mounting of the cutting insert, whereas in the arc shape, such a problem can be easily avoided. However, it takes a lot of processing time to form such a Saray blade having an arc shape with a large radius by polishing or the like. For this reason, a cutting insert with an arc-shaped saray blade (hereinafter also referred to as an insert with a saray blade) has been expensive.

  By the way, in a milling cutter equipped with a plurality of cutting inserts, it is extremely difficult to completely match the heights of the cutting edges of all cutting inserts with zero error. On the other hand, it can be said that the finished surface by milling in milling is determined by the edge of the secondary cutting edge of the cutting insert that protrudes first on the front side (the spindle shaft tip side) among the plurality of cutting inserts. . This is because in the face milling, the main cutting edge on the outer peripheral side performs the main cutting, and the cutting surface is cut so that the cutting edge of the sub cutting edge rubs.

  Therefore, conventionally, in order to obtain a good finished surface, a cutting insert having a Saray blade formed in an arc shape with a large radius is used. However, due to its high cost, it has been common knowledge in the field of machining to use only one cutting insert with such a Saray blade. That is, other cutting inserts are ordinary ones without such a Saray blade, and for a cutting insert with one Saray blade, the Saray blade (second cutting edge) in the secondary cutting edge is used as another cutting insert. For example, the protrusion of the secondary cutting edge of the insert is positively (consciously) protruded by about 0.03 to 0.05 mm (Patent Document 1). By doing so, the Saray blade is surely responsible for improving the accuracy of the finished surface in the processing. For example, in the face milling cutter 1 shown in FIG. 3, six cutting inserts are mounted on the cutter body 2, but only one of these is the cutting insert 11 with a salai blade, and the remaining five Is equipped with ordinary cutting inserts 21a to 21e without a Saray blade. However, as shown in FIG. 4, for the one insert with salai blade 11, the saray blade (second cutting edge) 13 of the secondary cutting edge 12 is replaced with the secondary cutting edge of the other cutting inserts 21a to 21e. A predetermined amount T1 is projected from the 22 cutting edges.

On the other hand, in such an insert mounting method, the cutting insert 11 with the Sarai blade receives a larger cutting resistance than the other cutting inserts 21a to 21e due to the protrusion T1. For this reason, in such a milling cutter (hereinafter also simply referred to as a cutter) 1, in order to reduce the cutting resistance of the cutting insert 11 with the salai blade, the main cutting edge 15 in the cutting insert 11 with the salai blade is: The main cutting edge 25 of the other cutting inserts 21a to 21e is positioned on the inner peripheral side (spindle shaft side) by a predetermined amount T2. By doing so, in the insert with salai blade 11, cutting with the main cutting edge (outer peripheral cutting edge) 15 is prevented, and cutting resistance is reduced.
JP 2000-94211

  However, as described above, only one cutting insert 11 with a Sarai blade is used, and the secondary cutting edge is projected by a predetermined amount T1 from the secondary cutting edge of the other cutting inserts 21a to 21e, while the secondary cutting edge 11 In the case of the cutting insert 11, when the main cutting edge 15 is positioned a predetermined amount T2 on the inner peripheral side from the main cutting edge 25 of the other cutting inserts 21a to 21e, there are the following problems. That is, for example, when cutting with the above-described 6-blade milling cutter 1, intermittent cutting is performed every 60 degrees during one rotation. However, when the cutting insert 11 with the salai blade as described above is attached, the cutting with the main cutting edge 15 of the cutting insert with the saray blade is not performed during the rotary cutting. For this reason, in the cutting insert (hereinafter referred to as a specific insert in the present specification) 21c attached at the position next to the cutting insert 15 with the Sarai blade (after 60 degrees), as shown in FIG. Intermittent cutting is performed after a rotation of 120 degrees after cutting by the cutting insert 21b in front of the cutting insert 11 with a blade (second insert from the left side in FIG. 4). That is, the feed amount L1 per blade is constant, but the feed amount for the two blades is up to the specific insert 21c. For this reason, cutting resistance or a burden will be doubled in the specific insert 21c. As a result, in the cutter in which such a cutting insert is attached, only the specific insert 21c is quickly worn out and damaged, and its life is halved.

  On the other hand, in order to solve such a problem, it is necessary to reduce the feeding speed, but if so, the processing efficiency is lowered. Further, in replacement of cutting inserts in such processing, all cutting inserts (above-mentioned), which is a throw-away method at the time when a preset number of processings have been performed, particularly in an unmanned factory, for stable and efficient quality control. In a cutter, it is common to replace 6 inserts) at once for each machine.

  However, in the conventional cutter described above, the replacement time of all cutting inserts is set based on the life of one cutting insert (specific insert 21c) that is quickly worn. For this reason, there has been a problem that the replacement frequency (the number of replacements) of the cutting insert is doubled from the life of the cutting insert according to the original usage. In addition, at the time of the replacement, it is necessary for the cutting insert 11 with one Saray blade to project the secondary cutting edge and to have the main cutting edge on the inner peripheral side. For this reason, since it is necessary for the operator to perform the installation work with special consideration, the work is extremely complicated, laborious and time consuming. For these reasons, the above-described milling cutter has a problem that the machining cost is increased as a result.

  The present invention has been made in view of solving the problems caused by the above-described milling cutter, and its purpose is to reduce the frequency of replacing the cutting insert while maintaining a high degree of finished surface roughness, and to replace the cutting insert. An object of the present invention is to provide a milling cutter capable of simplifying and speeding up the process and reducing the processing cost.

The invention according to claim 1 for solving the above problem is a front milling cutter having a plurality of cutting inserts attached thereto.
It is a face milling cutter characterized in that all of the cutting inserts have Saray blades.

  The invention according to claim 2 is the face milling cutter according to claim 1, wherein the Saray blade is arcuate. The invention according to claim 3 is characterized in that the height of the cutting edge of the saray blade of all the cutting inserts is within a height range of 50 μm. It is a cutter.

  In this invention concerning Claim 1, the thing with a Saray blade is used for all the cutting inserts. For this reason, in attaching all the cutting inserts, it is only necessary that the cutting edge heights are all the same and the main cutting edges on the outer periphery are all attached on the same circumference (same outer diameter). In other words, it is not necessary to pay special consideration only to a cutting insert with one Saray blade in the mounting of a cutting insert as in the past, and all cutting inserts have the same tolerance, the same height and the same outer diameter. By attaching in the same manner, there is an effect that a desired finished surface roughness can be obtained. This is because when a cutting insert with a Sarai blade is attached in this way, even if it is the same height, it is within an allowable error range (for example, -0.025 to 0.025 mm), and any one of them. The Sarai blades of the two cutting inserts always protrude to the front side, though they are very small. Accordingly, when cutting with such a cutter, a desired high degree of finished surface roughness is always maintained by the Saray blade of one cutting insert.

  Further, in such cutting with a cutter, the wear rate is not nearly doubled by the fact that one main cutting edge receives double feed as in the prior art. For this reason, the time until the replacement of the cutting insert is simply twice as long as the time until the replacement according to the conventional mounting method described above. That is, since the replacement frequency of the cutting insert can be reduced to half, the labor cost (cost) required for the replacement can be halved. At the time of the replacement, it is not necessary to pay special consideration, and the replacement work can be performed within a given allowable range, so that the work can be simplified and speeded up. Is also reduced. As a result, the processing cost as a whole can be greatly reduced.

  Some Saray blades are straight, but with this one, if there is an inclination in the height direction even at a minute angle, it will hit the corner and cause a reduction in the finished surface, making it difficult to set. On the other hand, by adopting an arc shape according to claim 2, it is possible to prevent the finished surface roughness from being lowered even if there is a slight attachment error. However, if the radius of the circular arc of the Saray blade is too small, the roughness of the finished surface is lowered, and it is preferable to increase the radius as much as possible, and it is preferable to set it in the range of R70 mm to R400 mm.

  In addition, as described in claim 3, it is preferable that the heights of the blades of the saray blades of all the cutting inserts to be mounted are within a height range of 50 μm. That is, it is preferable that this range be an allowable range of the height when the insert is mounted. If it is within such an allowable range, the insert can be set without any problem with normal attention. In addition, by setting within this range, even the secondary cutting edge that protrudes most is not excessive even when the amount of protrusion is maximum, and therefore the cutting resistance by the secondary cutting edge is extremely high. It can also be prevented from becoming large.

  The best mode for carrying out the present invention will be described in detail with reference to FIGS. In the drawing, reference numeral 1 denotes a front milling cutter, and in this example, six cutting inserts 11 are fixed to a cartridge 7 by a clamp screw 31 on a cylindrical milling cutter main body 2, and the cartridge 7 is attached to the main body 2. Each pocket 5 is fixed by screwing with a hexagon socket head bolt 32. In this example, in order to make the cartridge 7 minutely adjustable in the direction of the rotation axis G, a screw member with a head (hexagon socket head bolt) 33 for adjusting the blade edge height is screwed sideways into the milling cutter body 2. Then, by screwing the head-attached screw member 33, the head 33b is brought into contact with the inclined surface 8 at the rear end of the cartridge 7 so that the cartridge 7 is pushed out to the front end side (front side) which is the processing surface side. Is arranged. Such a basic configuration of the face milling cutter 1 itself is not different from the conventional one.

  However, in the front milling cutter 1 of this embodiment as described above, the cutting insert 11 fixed to the cartridge 7 is entirely formed of the secondary cutting edge 12 and the salai blade (first auxiliary cutting edge) 13 formed thereon. A cutting insert (hereinafter also referred to as an insert with a Sarai blade) 11 is used. However, in this embodiment, the Saray blade 13 is formed by an arc having a large radius R (for example, R is 70 to 400 mm). And this insert 11 with a salai blade is set and mounted so that the height of the edge of the salai blade 13 in the sub-cutting blade 12 falls within a predetermined allowable range H. In this example, the allowable range is 50 μm (± 25 μm). This allowable range is also an allowable range of the entire length of the cutter. The main cutting edge 15 is set within an allowable range (for example, ± 0.025 mm) so as to be located at a predetermined distance from the spindle axis G.

  That is, in this embodiment, six identical inserts 11 with salai blades are used and attached to the same cartridge 7, and the blade edge height of the salai blade 13 is set in each pocket 5 of the milling cutter body 2 in a normal attachment. It is installed so that it is within the allowable tolerance range.

  Thus, the front milling cutter 1 of the present embodiment is different from the conventional milling cutter in the structure in which the cutter body 2 and the cartridge 7 are attached to the cutter body 2 and the attachment structure of the screw member 33 with a head for adjusting the blade edge height. Although there is no point, the point that the insert with salai blade 11 is used for all the cutting inserts, and the height of the tip of the saray blade 13 is within the allowable range H (± 25 μm). This is completely different from the conventional cutter. Thereby, in the front milling cutter 1 of this form, there exist the following specific effects.

  That is, in such a face milling cutter 1, since the inserts with salai blades 11 are used for all six cutting inserts, the heights of all the saray blades 13 are set at the time of mounting all the cutting inserts. Assuming that the same outer peripheral position (outer diameter) of the main cutting edge 15 is the same, it is only necessary to pay attention so that it is within a predetermined allowable range by a normal mounting method. That is, as in the prior art, it is not necessary to pay special attention to only the cutting insert with one Saray blade in attaching the cutting insert. For all cutting inserts, just as with ordinary cutting inserts, the secondary cutting edge may be mounted at the same height and the main cutting edge at the same outer diameter position. By such attachment, there is an effect that a desired finished surface roughness can be obtained.

  That is, in this embodiment, the case where six inserts 11 with salai blades are mounted has been described, but in this case, as shown in FIG. Each subtle error in time varies, but is within the allowable range H. On the other hand, the cutting edge (secondary cutting edge) of the Saray blade 13 of any one of the inserts (second insert from the left in FIG. 2) protrudes first on the front side due to the variation. Therefore, when cutting with such a cutter 1, the cutting plane (processed surface) is cut (or burnished) by the salai blade 13 of one protruding cutting insert 11. For this reason, the desired flat finished surface by the Saray blade 13 is obtained as the cutting plane. In addition, even if the difference between the cutting edge height of the Saray blade of the cutting insert that protrudes first and the cutting edge height of the other cutting insert that protrudes next is small, it affects the finished surface roughness. This is the Saray blade 13 of the cutting insert that protrudes most (the second insert from the left in FIG. 2) regardless of the magnitude of the difference.

  Since the cutter 1 is equipped with six inserts 11 with salai blades, the main cutting edge 15 in each cutting insert 11 is equiangularly spaced at 60 degrees when viewed from the front side. They are on substantially the same circumference around the axis G. For this reason, even with the insert with the salai blade protruding most, which determines the finished surface roughness of the cutting plane, the cutting with the main cutting edge 15 is the same as other inserts at the feed amount per one rotation of the cutter. It bears the feed amount L1 per blade. Here, even if the insert with the salai blade is the one with the auxiliary cutting edge 13 protruding out, the protruding amount of the auxiliary cutting edge 13 is not intentionally protruded but inevitably occurs within the allowable range H. Since it is a very small amount, there is no great difference in the cutting resistance that all cutting inserts receive. Therefore, as in the conventional case described above (see FIG. 4), only one cutting insert with salai blade 11 is used, and the secondary cutting edge 13 is positively projected, while the main cutting edge 15 is disposed on the inner periphery. Unlike the case of the specific insert 21c that is positioned next to the specific insert 21c, the cutting force that is doubled is not received.

  Therefore, in the present embodiment, the six inserts with all the blades 11 have basically the same life and can manage the tool. In other words, the life of a specific insert is twice as long as that of other inserts in the past, so that its life is halved, while cutting insert replacement is performed simultaneously for all inserts based on the life of the halved specific insert. There was a need. On the other hand, in the present invention, since there is no cutting insert whose life is halved, the time until the replacement can be basically doubled compared to the conventional case. According to the inventor's investigation, the actual life is about 10 km in the case of the conventional specific insert, but it has been found that it was about 15 km in the present invention. . That is, it has been found that the replacement frequency of the insert can actually be reduced to about 2/3, and therefore, the processing efficiency can be greatly improved.

  Moreover, according to another investigation by the inventors of the present application, the standard time required for exchanging six inserts, as in the past, is to place the secondary cutting edge by paying special attention to one insert. In the case of this embodiment, it was 10 minutes compared with 60 minutes in the case of quantitative protrusion. For this reason, if this replacement operation is performed at the above-described replacement frequency, the replacement operation conventionally requires 2 hours, whereas this replacement requires only 20 minutes. Therefore, if the number of machines in operation is 10, the difference is 20 hours per year. Such a difference is calculated by the present inventor, for example, the total cost of the insert when all six inserts are used as inserts with a salai blade, and only one insert with a salai blade is used, and the other has no saray blade. The total cost of the insert when using the insert is expected to be approximately twice the difference during the same period. Such a cost ratio is a matter of demonstrating the reduction in processing cost that is the effect of the present invention.

  As described above, according to the present invention, the time until the cutting insert replacement time in the face milling cutter, that is, the life thereof can be extended. For this reason, the replacement frequency of the cutting insert can be reduced, and therefore the replacement work can be reduced and the replacement cost can be reduced. Moreover, even when the cutting insert is replaced, it is not necessary to pay special consideration to the cutting insert with one salai blade as in the conventional case, and if all the cutting inserts are installed within the normal allowable range. Since it is good, the work can be simplified and speeded up. As a result, the cost can be reduced when viewed comprehensively. This is particularly effective when applied to a machining mode in which an operator is required to regularly, simply, quickly and efficiently replace the cutting insert as in an unmanned factory.

  The present invention is not limited to the above-described embodiment, and can be embodied with appropriate design changes. For example, in the above description, the cutter having a cutting insert fixed to the cartridge is fixed to the cutter body, but the cutter of the present invention fixes the cutting insert directly to the cutting insert pocket of the cutter body with a clamp screw or the like. It can also be embodied in what is fixed by means. As a matter of course, the present invention can be realized regardless of the number of cutting inserts attached to one cutter and the diameter (diameter) of the cutter. And the height range of the cutting edge of the saray blade of all cutting inserts should just set the height range according to the number of inserts etc. attached. In the above description, the case where the Saray blade has an arc shape has been described.

A is a partially omitted half cross-sectional front view of the front milling cutter of the present invention, and B is a view of A viewed from the front side (sub cutting edge side). The schematic diagram explaining the positional relationship of the feed amount per blade of 1 rotation of the face milling cutter of FIG. 1, and the height of the blade edge | tip of the sub cutting blade in each cutting insert. A is a partially omitted half sectional front view of a conventional front milling cutter, and B is a view of A from the front side. The schematic diagram explaining the positional relationship of the feed amount per blade in the conventional face milling cutter, the height of the cutting edge of the sub cutting edge of each cutting insert, and the main cutting edge.

Explanation of symbols

1 Front milling cutter 2 Cutter body 11 Cutting insert 13 Saray blade

Claims (3)

In a face milling cutter that is equipped with multiple cutting inserts,
A face milling cutter characterized in that all of the cutting inserts have Saray blades.   2. The face milling cutter according to claim 1, wherein the Saray blade has an arc shape.   The front milling cutter according to claim 1 or 2, wherein the height of the cutting edge of the Saray blade of all the cutting inserts is within a height range of 50 µm.

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