JP2008000856A - Burr-less broach for inner surface machining - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a burr-less broach for inner surface machining restraining growth of a burr on the outlet side of broach machining of a thin work such as a press worked article. <P>SOLUTION: This burr-less broach for inner surface machining constitutes its characteristic feature that a tooth profile region and a cushioning region are provided in a side surface crest lie region made by a rake face and a side surface of each of teeth of a finishing tooth group of the broach for inner surface machining, the tooth profile region is provided within 0.1 to 0.5 mm from a cutting blade and the cushioning region is provided on a remaining part of the side surface crest line region and on the inside of a virtual extension crest line of the tooth profile region. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an inner surface processing broach for processing a thin molded part obtained by pressing a low carbon steel or a rolled steel plate excellent in spreadability.

Helical broaches and other internal machining broaches are precision tools that mainly machine the inner surface and surface of workpieces with high precision and efficiency. In automobiles, transmissions, engines, constant velocity joints, power steering, etc. The use of broaching is expanding in the processing of important parts such as. Patent Document 1 describes a surface broach provided with an interval for recovering deformation of a work material due to cutting resistance between cutting edges in order to suppress generation of burrs.
JP 2001-113411 A

However, Patent Document 1 does not consider any burrs in thin-walled inner surface broaching such as a pressed product. For example, if the workpiece is an automobile mission part, if the burr falls off while the part is in use, the performance will be greatly reduced, and the safety will be seriously affected. For this reason, burrs remaining on the parts are unacceptable in terms of quality.
In the present invention, the cause of the occurrence of burrs occurs when broaching a pressed product with a thin and rich material using an inner surface processing broach. 1) The material generated by a change in the cutting load during cutting The influence of the springback, 2) The springback causes friction on the side surfaces of the teeth, so that the welded material adheres, and the quality of the finished surface is remarkably deteriorated. 3) The burr is processed by broaching. Provided is a burr-less broach for inner surface processing that suppresses the occurrence of burrs on the outlet side of broaching of a thin workpiece such as a press-worked product by knowing that it occurs frequently on the inner peripheral side of the hole.

  The present invention has been made in order to solve the above-mentioned problems, and a tooth profile region and a buffer region are provided in a side ridge line region formed by a rake face and a side surface of each tooth of the finishing blade group of the inner surface processing broach, The tooth profile region is 0.1 mm to 0.5 mm from the cutting edge, and the buffer region is the remainder of the side ridge line region and is provided inside the virtual extension ridge line of the tooth profile region. This is a burr-less broach. With the above configuration, it is possible to reduce the burrs to the extent that no deburring work is required. Further, the buffer region is in a range of 0.1 mm to 0.6 mm at a substantially half height position of the tooth, and in a range of 0.3 to 0.8 mm on the bottom side of the longitudinal groove, and the tooth profile region is virtually extended. It is preferable to provide the inner side of the ridge line and coat the side surface with a lubricating film containing Cr or Si.

  According to the present invention, it is possible to provide a burrless broach for inner surface processing that suppresses generation of burrs on the outlet side of broaching of a thin workpiece such as a pressed product.

  As shown in FIGS. 1 and 2, the broach body 1 is provided with a rough blade group 3, a medium finishing blade group 4, and a finishing blade group 5 sequentially from the front guide portion 2 side to the broach rear portion side. The blade diameter of the rough blade group 3 is configured to gradually increase toward the rear part of the broach, and the intermediate finishing blade group 4 is configured so that the cutting amount gradually decreases by an amount smaller than the rough blade group, and the finishing blade group 5 Are constructed so that the blades have substantially the same height. In particular, it is preferable from the viewpoint of suppressing burrs that the cutting amount of the intermediate finishing blade group 4 is made a slight increment in the range of 0.01 to 0.05 mm in terms of the diameter of the broach to reduce the cutting resistance per blade. In the tooth profile shown in FIG. 2, a side area ridge line area 7 following the cutting edge 6 is provided with a buffer area 9 following the tooth profile area 8. The tooth profile region 8 is provided in a range of 0.1 mm to 0.5 mm according to the height of the tooth, and the tooth profile region 8 and the buffer region 9 are smoothly connected. The virtual tooth profile extension ridge line 10 indicates a virtual tooth profile extension ridge line of the tooth profile region 8. The tooth profile region 8 has substantially the same form as the processed shape of the workpiece, and the virtual tooth profile extended ridge line 10 is also the same. When the tooth profile region 8 is in a range of less than 0.1 mm, the cutting edge 6 is shaken with respect to the drawing direction of the broach at the time of broaching, the tooth trace accuracy cannot be obtained, and the machining accuracy is deteriorated. On the other hand, if the tooth profile area 8 exceeds 0.5 mm, the tooth profile area 8 becomes longer, and the resistance is increased by rubbing against the processed surface, and burrs are easily generated, and the quality of the processed product cannot be kept good.

The buffer region 9 is provided so as to be located inside the broach with respect to the virtual tooth profile extended ridge line 10, so that even if the work piece causes spring back and contracts, the side surface of the broach tooth and the work surface of the work piece Rub can be reduced. Thereby, it can suppress that a process surface is pressed by the side ridgeline area | region 7 and side of a tooth | gear of a broach, and can carry out plastic deformation, and can suppress that a burr | flash generate | occur | produces at the broach exit side of the process hole of a workpiece. Since the friction between the side ridge line area 7 and the processed surface of the workpiece can be suppressed, the soft workpiece can be prevented from adhering to the side surfaces of the broach teeth, and the processing surface can be prevented from being crumpled or frayed, thereby improving the processing accuracy. .
The depth 11 of the buffer region, which is the amount located inside the virtual tooth profile extension ridge line 10 of the buffer region 9, may be provided in the range of 0.1 mm to 0.6 mm at approximately half the height of the tooth. preferable. Here, the substantially half height of the tooth is a position approximately half the distance in the broach radial direction from the cutting edge 6 of the side ridge line region 7 to the bottom 12 of the longitudinal groove. If the buffer region is not provided, it is not possible to relieve the force of rubbing the processed surface due to the spring back, and the processed surface is pressed by the buffer region 9 to be plastically deformed and a burr is likely to occur. When the depth 11 of the buffer region exceeds 0.6 mm, the cutting edge 6 is shaken with respect to the drawing direction of the broach at the time of broaching, the tooth trace accuracy cannot be obtained, and the machining accuracy cannot be obtained. Further, there is a high possibility that the load concentrates on the tooth profile region 8 and is rubbed with the processed surface to generate burrs. In particular, since burrs are likely to come out on the bottom 12 side of the vertical groove on the side surface, as shown in FIG. 2, it is preferable to provide the buffer region 9 on the inner side as it goes from the cutting edge side to the bottom side of the vertical groove. The buffer region 9 is preferably located on the inner side in the range of 0.3 to 0.8 mm with respect to the virtual tooth profile extended ridge line 10 on the bottom side of the longitudinal groove of the region 9.

  It is preferable to coat a lubricating film containing Cr on the tooth side and flank face of the broach of the present invention, the friction coefficient can be reduced, the resistance caused by abrasion between the machined surface and the broach can be reduced, and burrs can be suppressed. In addition, when a hard coating containing Si is coated, the wear resistance of the cutting edge is improved, and the life of the cutting edge is greatly improved, thereby suppressing burrs and preventing welding. A film containing both Cr and Si may be used. For example, an AlCrSiN-based film or a CrSiN-based film is preferable.

  In the above description, the buffer region 9 is provided in the side ridge line region 7 of the tooth of the finishing blade 5. However, in the present invention, the buffer region 9 is preferably provided from the intermediate finishing blade 4 to the finishing blade 5. The broach of the present invention is a soft material and has a remarkable burr suppressing effect when processing a thin-shaped material having a thickness of 1 mm to 5 mm, particularly 3 mm or less. It is effective for the side ridge line region 7 of the tooth that is easily rubbed, particularly a spline broach and a serration broach. Depending on the processed shape and thickness of the workpiece, burrs may occur due to rubbing between the cutting edge and the processed surface. In this case, by removing a part of the cutting blades of the finishing blade group other than the final finishing blade as a non-cutting part, the spring back of the work piece is relaxed at the non-cutting part, and the burr is removed with the finishing blade at the rear part of the non-cutting part. You can wipe it off. For the broach base material of the present invention, melting high speed, powder high speed, and cemented carbide can be used. In particular, the powder high speed can provide a sharp cutting edge and reduce burrs. Hereinafter, based on an Example, it demonstrates concretely.

(Example 1)
As Example 1 of the present invention, 53 coarse blades 3 with a cutting amount of 0.06 mm are provided in the broach axis direction, and the cutting amounts of one blade are gradually reduced to 0.04 mm, 0.02 mm, and 0.01 mm. A cutting-type spline broach, in which only three cutting blade outer diameters were increased, was prepared with powder high speed, with three finishing blades 4 provided and five finishing blades 5 provided with one cutting edge being zero. Here, the cutting amount is an increase in broach diameter for each cutting edge.
The rake angles of the rough blade 3, the intermediate finishing blade 4 and the finishing blade 5 of Example 1 of the present invention are set to 12 °, and the pitch between the cutting edges is 4 mm. The outer diameter of the cutting edge of the finishing blade of Invention Example 1 was 23 mm, and the overall length of the broach was 650 mm. From FIG. 2, a tooth profile region 8 of 0.1 mm from the cutting edge 6 in the radial direction of the broach is provided in the side ridge line area 7 formed by the rake face and the side face of the cutting edge 6 of the finishing blade 5, and the tooth height is ½. A buffer region 9 having a depth of 0.05 mm was provided.
As Comparative Example 2, the side ridge line area 7 was entirely made of a tooth profile area, and a side face with a clearance angle of 0.02 ° was prepared.

Inventive example 1 and comparative example 2 are used as cutting tests, as shown in FIG. 3, a broaching portion 14 of work piece 13 is provided with a pilot hole, and broach body 1 inserted in the pilot hole is pulled downward. The inner gear can be processed by one broaching process by finishing the workpiece 13 into a predetermined processing shape while cutting the workpiece 13 from the rough blade 3 below the broach to the upper finishing blade 5 with the cutting amount of each cutting blade. Finished.
When the cutting resistance per processing time is measured at this time, as shown in FIG. 4, the cutting resistance is the largest when cutting with the coarse blade group 3, and at this time, the thin workpiece 13 is in the broach radial direction, Workpiece that spreads in the circumferential direction, and then the cutting resistance drastically decreases as the cutting amount of the intermediate finishing blade group 4, the finishing blade group 5 and one blade decreases, and accordingly, the workpiece that has spread in the broach radial direction and circumferential direction 13 is considered to have caused a springback. As a result, the side surfaces of the teeth, particularly the side of the longitudinal grooves on the side surfaces, are easily rubbed with the processed surface. The hot rolled steel material SAPH440 for automobile structure pressed into the workpiece 13 is used, the thickness of the broaching portion 14 of the workpiece 13 is 3 mm in the radial direction of the broach, and the cutting length is 11 mm.

As the cutting specifications, a cutting speed of 4 m / min and an oil-based cutting fluid were used.
As an evaluation, the burr height was measured with a non-contact type laser measuring device on the broach exit side of the broaching portion 14. The burr is measured by measuring the maximum burr height in the side ridge line area. If the burr height exceeds 0.1 mm, it is necessary to remove the burr by performing a deburring operation. For the tooth trace accuracy (distortion in the broach pulling direction of the tooth profile of the processed shape) and the tooth profile accuracy (distortion of the tooth profile itself), the broached portion 14 has a total form plug gauge having a tooth profile of the processed shape of the broached portion 14. Pass / fail was judged and the surface finish was visually observed.
As a result, as shown in FIG. 5, in Example 1 of the present invention, when the broached portion 14 is observed from the broach exit side, almost no burrs are generated, and the height of the burrs is 0.07 mm, which is not a problem. there were. The gauge could be passed through the broaching portion 14 and the tooth trace accuracy and tooth profile accuracy were good. In Comparative Example 2, as shown in FIG. 6, burrs are generated on the broach exit side of the workpiece, the burr height is as large as 1.8 mm, the quality of the workpiece is reduced, and the processing surface is crumpled or frayed. Was slightly recognized, and the surface finish was deteriorated. The gauge did not pass and the desired tooth profile accuracy and tooth profile accuracy were not achieved. It is considered that this is because the entire side ridge line area of the tooth has a tooth profile, the side surface rubbed against the processed surface, and the tooth was not stable with respect to the drawing direction of the broach.

(Example 2)
As Invention Examples 3-6 and Comparative Examples 7 and 8, the same specifications as in Invention Example 1 were prepared, and the range in which the tooth profile area was provided was changed from 0.05 mm to 0.6 mm. A cutting test and evaluation were performed. Table 1 shows the specifications and results of Invention Examples 3 to 6 and Comparative Examples 7 and 8.

  From Table 1, Invention Examples 3 to 6 have a burr height as small as 0.1 mm or less, can improve the quality of the work piece, can pass the gauge through the broached part, and have good tooth trace accuracy and tooth profile accuracy. The surface properties and processing accuracy were good. In Comparative Example 7, although the burr was small, the gauge could not pass and the tooth trace accuracy and the tooth profile accuracy deteriorated. This is probably because the cutting edge meanders because the tooth profile area is small and the fluctuation of the cutting edge in the direction of pulling out the broach cannot be suppressed. In Comparative Example 8, a large burr with a burr height of 0.12 mm was generated on the broach exit side of the workpiece, and burr suppression was not possible. This is probably because a large number of tooth profile regions were provided, so that the axial center side of the tooth profile region and the work surface contracted by the springback were rubbed, and the surface of the work surface was plastically deformed to generate burrs. Thereby, it was found that good results were obtained when the length of the tooth profile region was in the range of 0.1 mm to 0.5 mm.

(Example 3)
As Inventive Examples 9-13, the same specifications as in Inventive Example 4 were prepared, and the depth of the buffer region was provided in the range of 0.1 mm to 0.5 mm. The same cutting test and evaluation as in Example 1 Went. The results of Invention Examples 9 to 13 are shown in Table 2.

  From Table 2, Examples 9 to 13 of the present invention were in a good state because the height of the burr was as small as 0.05 mm or less, and it was not necessary to remove the burr. In addition, the gauge could be passed through the broaching part, the tooth profile and tooth trace accuracy were good, and the machined surface properties and machining precision could be improved. Thus, it was found that good results can be obtained when the depth of the buffer region is in the range of 0.1 mm to 0.5 mm.

Example 4
As Invention Example 14, the same specifications as in Invention Example 1, for serration drilling, 60 blades with a cutting amount of 0.055 mm, and 1 blade with a cutting amount of 0.02 mm 4 The blade has a medium finishing blade and 5 finishing blades with a cutting amount of one blade of zero. The rake angle of the rough blade is 18 °, the cutting edge diameter of the finishing blade is 28 mm, and the pitch of each cutting blade is 11 mm. The thing which is 1250 mm in total length was created. Here, the cutting amount is an increase in broach diameter for each cutting edge. As a cutting test, carbon steel S20C was used as a workpiece, a hollow member having steps on both sides, and a broaching portion having a cutting length of 49 mm and a wall thickness of 4 mm was prepared and broached. The cutting speed was 4 m / min, and an oil-based cutting fluid was used. As an evaluation, the size of the burrs was measured on the broach exit side of the workpiece, and the tooth profile accuracy was examined by passing a total form plug gauge through the broach processed portion as a first grade having a tooth profile as a processed shape.
In Example 14 of the present invention, it was not necessary to remove 0.05 mm and burrs on the broach exit side of the workpiece, and a gauge could be passed. The surface finish was also good.

FIG. 1 shows a schematic view of an inner surface processing broach. FIG. 2 is a cross-sectional view taken along line WW in FIG. FIG. 3 is a schematic diagram for explaining the machining state. FIG. 4 is a chart obtained by measuring the cutting resistance of Example 1 of the present invention. FIG. 5 shows the state of burrs after processing in Example 1 of the present invention. FIG. 6 shows the state of burrs after processing in Comparative Example 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Brooch body 2 Front guide part 3 Coarse blade group 4 Medium finishing blade group 5 Finishing blade group 6 Cutting blade 7 Side ridge line area 8 Tooth profile area 9 Virtual tooth profile extension line 10 Buffer area 11 Depth of buffer area 12 Bottom of vertical groove 13 Workpiece 14 Broaching part

Claims (3)

A tooth profile region and a buffer region are provided in a side ridge line region formed by a rake face and a side surface of each tooth of the finishing blade group of the inner surface processing broach, and the tooth profile region is 0.1 mm to 0.5 mm from the cutting edge, A burless broach for inner surface processing, characterized in that the buffer region is provided in the remainder of the side ridge line region and inside the virtual extended ridge line of the tooth profile region. The burless broach for inner surface processing according to claim 1, wherein the buffer region is in a range of 0.1 mm to 0.6 mm at a position of approximately 1/2 height of a tooth, and 0.3 to 0. A burless broach for inner surface processing, which is provided inside the virtual extended ridge line of the tooth profile region in a range of 8 mm. The burless broach for inner surface processing according to claim 1 or 2, wherein the side surface is coated with a lubricating film containing Cr.