Flat die for rolling and manufacturing method for the same

Abstract

To solve the problem that when surface roughness of the whole of a processing tooth of a biting part of a flat die for rolling is increased, only a tooth surface at a rear side of the processing tooth is intensively damaged with respect to a material to be processed, so that crack occurs on the tooth surface, which eventually damages the whole of the processing tooth.SOLUTION: A flat die 1 for rolling comprises a first processing part 10 provided with a plurality of processing teeth 11, 12 and 13 which first perform rolling processing to a work-piece and a second processing part, formed continuously to the first processing part 10, which is provided with a plurality of processing teeth that continuously perform rolling processing to the work-piece. Front-side tooth surfaces 12A and 13A, upper-side tooth surfaces 11B, 12B and 13B, rear-side tooth surfaces 11C and 12C and tooth bottom surfaces 11D and 12D, of the processing teeth 11, 12 and 13 of the first processing part 10 are formed along a moving direction A of the flat die 1 for rolling, in this order, where surface roughnesses of the front-side tooth surfaces 12A and 13A are made larger than surface roughnesses of the rear-side tooth surfaces 11C and 12C.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a rolling die for rolling a gear such as a spline tooth profile into a workpiece, and a method for manufacturing the same. [Background technology]

[0002] In recent years, flat dies for rolling are increasingly used in the manufacture of gears by rolling. Gear manufacturing by rolling differs from gear manufacturing by cutting, in that if slippage occurs between the flat die and the gear, which is the workpiece, the efficiency of the rolling process decreases. Therefore, in order to suppress this slippage, a rough surface is provided on the surface of the teeth at the engagement part of the flat die for rolling, aiming to prevent slippage between the workpiece and the teeth (see Patent Documents 1 to 4). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4266631 [Patent Document 2] Patent No. 4371191 [Patent Document 3] Patent No. 4830246 [Patent Document 4] Japanese Patent Application Publication No. 62-289339 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if the surface roughness of the entire processing tooth of the cutting portion of the flat die for rolling processing is increased, there is a problem that damage is concentrated only on the tooth surface on the rear side of the processing tooth relative to the workpiece, causing cracks to occur from that tooth surface, and ultimately causing damage to the entire processing tooth.

[0005] Therefore, the objective of the present invention is to provide a flat die for rolling that reduces damage to the processing teeth at the part (the chamfer) where rolling is first performed on the workpiece, thereby improving the tool life, and a method for manufacturing the same. [Means for solving the problem]

[0006] Therefore, the present invention provides a flat die for rolling having at least a first processing section having a plurality of processing teeth that first performs rolling on the workpiece, and a second processing section formed continuously from the first processing section and having a plurality of processing teeth that subsequently performs rolling on the workpiece, in which the processing teeth of the first processing section are formed from at least a front side tooth surface, an upper side tooth surface, a rear side tooth surface, and a bottom surface along the direction of movement of the flat die for rolling.

[0007] In addition, the surface roughness of the front tooth flank of the processing tooth of the first processing part is made larger than that of the rear tooth flank, and the surface roughness of the upper tooth flank is made larger than that of the bottom surface. For example, the surface roughness of the front tooth flank of the processing tooth of the first processing part can be in the range of 20 μm to 35 μm, and the surface roughness of the rear tooth flank can be in the range of 0.1 μm to 10 μm.

[0008] The invention of the manufacturing method of the flat die for rolling includes a first manufacturing step of manufacturing the first and second processed teeth by grinding the flat die material for rolling, and a second manufacturing step of performing shot blasting only on the front tooth surface and upper tooth surface of the first processed tooth after the first manufacturing step. When performing the shot blasting, ceramic shot materials can be used.

[0009] Alternatively, the method may be configured to include a first manufacturing step of grinding the first and second processed teeth from a rolling die material, a second manufacturing step of shot blasting the first and second processed teeth after the first manufacturing step, and a third manufacturing step of grinding or polishing only the rear tooth surface and bottom surface of the first processed tooth after the second manufacturing step. Note that the "surface roughness" in the present invention is synonymous with the "center line average roughness Ra" specified in JIS B0601. Effect of the Invention

[0010] The flat die for rolling of the present invention has a larger surface roughness on the front tooth surface of the processing teeth of the first processing portion (engaging portion) relative to the surface roughness on the rear tooth surface, thereby suppressing damage to the processing teeth in the portion (engaging portion) where rolling is first performed on the workpiece.As a result, the cutting ability into the workpiece is maintained while the life of the tool (flat die for rolling) is improved. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic perspective view of a flat die for rolling 1 according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] A flat die for rolling according to one embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic perspective view of a first processing portion 10 of a flat die for rolling 1 according to the present invention. As shown in FIG. 1, the first processing portion of the flat die for rolling according to the present invention has a plurality of processing teeth provided along the moving direction A of the flat die for rolling 1. The first processing portion 10 (11, 12, 13) of the flat die for rolling 1 shown in FIG. 1 is a portion where rolling is first performed on a workpiece (not shown), and is also called a so-called cutting portion.

[0013] The teeth 11 to 13 of the first processing section 10 are arranged in the order of front tooth surfaces 12A, 13A, upper tooth surfaces 11B, 12B, 13B, rear tooth surfaces 11C, 12C, and tooth bottom surfaces 11D, 12D along at least the moving direction A of the rolling flat die 1 during rolling. Specifically, the teeth are formed of three tooth surfaces: the front tooth surfaces 12A, 13A located at the most forward side in the moving direction A of the rolling flat die 1, the upper tooth surfaces 11B, 12B, 13B located rearward of the front tooth surfaces in the moving direction A and facing the upper side of the rolling flat die 1, and the rear tooth surfaces 11C, 12C located further rearward of the upper tooth surfaces in the moving direction A and facing the front tooth surfaces, and the tooth bottom surfaces 11D, 12D located further rearward of the rear tooth surfaces in the moving direction A.

[0014] The surface roughness of the front tooth flanks 12A, 13A of the processing teeth 11-13 of the first processing portion 10 is made larger than that of the rear tooth flanks 11C, 12C, and the surface roughness of the upper tooth flanks 11B, 12B, 13B is made larger than that of the tooth bottom surfaces 11D, 12D. By making the surface roughness of the front tooth flanks larger than that of the rear tooth flanks, slippage that occurs between the workpiece and the rolling die during rolling is suppressed, and at the same time, stress concentration and fracture origin caused by the surface roughness of the processing teeth, as in the processing teeth of conventional rolling flat dies, are prevented, thereby maintaining the durability of the rolling flat dies.

[0015] The surface roughness of the front tooth flank of the processing tooth of the first processing portion is preferably in the range of 20 μm or more and 35 μm or less, and the surface roughness of the rear tooth flank is preferably in the range of 0.1 μm or more and 10 μm or less.

[0016] Next, the manufacturing method of the flat die for rolling according to the present invention will be described. First, the method is composed of a first manufacturing step in which the first and second processed teeth are manufactured by grinding the flat die material for rolling, and a second manufacturing step in which only the front tooth surface and the upper tooth surface of the first processed tooth are shot blasted after the first manufacturing step. When the material for the flat die for rolling is shot blasted, it is preferable to inject (project) the blasting material from an oblique direction on the front side (the front side in the moving direction during rolling) of the flat die material for rolling. This makes it possible to efficiently roughen (increase the surface roughness) only the front tooth surface and the upper tooth surface of the first processed tooth of the flat die for rolling. Note that the blasting material may be made of ceramics. [Explanation of symbols]

[0017] 1. Flat die for rolling 10 1st processing section 11, 12, 13 Machining teeth of the first machining part 12A, 13A Front tooth surface of the machining teeth of the first machining part 11B, 12B, 13B Upper side tooth surface of the machining tooth of the first machining portion 11C, 12C Rear tooth surface of the machining tooth of the first machining part 11D, 12D Bottom surface of the machining teeth of the first machining part A: Direction of movement of the rolling die

Claims

1. A flat die for rolling having a first processing section having a plurality of processing teeth that first performs rolling on a workpiece, and a second processing section having a plurality of processing teeth formed continuously from the first processing section and subsequently performing rolling on the workpiece, wherein the processing teeth of the first processing section are formed from at least a front side tooth surface, an upper side tooth surface, a rear side tooth surface, and a bottom surface along the movement direction of the flat die for rolling, and the surface roughness of the front side tooth surface of the processing teeth of the first processing section is greater than the surface roughness of the rear side tooth surface.

2. 2. The flat die for rolling according to claim 1, wherein the surface roughness of the upper tooth flank of the processing tooth of the first processing portion is greater than the surface roughness of the bottom surface of the tooth.

3. A flat die for rolling processing as described in claim 2, characterized in that the surface roughness of the front tooth surface of the processing tooth of the first processing portion is in the range of 20 μm or more and 35 μm or less, and the surface roughness of the rear tooth surface is in the range of 0.1 μm or more and 10 μm or less.

4. A method for manufacturing a flat die for rolling processing as described in any one of claims 1 to 3, characterized in that it comprises a first manufacturing process in which the first and second processing teeth are manufactured by grinding a material of the flat die for rolling processing, and a second manufacturing process in which, after the first manufacturing process, a shot blasting process is performed only on the front tooth surface and upper tooth surface of the first processing tooth.

5. 5. The method for manufacturing a flat die for rolling according to claim 4, wherein a ceramic shot material is used for the shot blasting treatment.

6. A method for manufacturing a flat die for rolling processing as described in any one of claims 1 to 3, characterized in that it comprises a first manufacturing process in which the first and second processing teeth are manufactured by grinding a material of the flat die for rolling processing, a second manufacturing process in which the first and second processing teeth are subjected to shot blasting treatment after the first manufacturing process, and a third manufacturing process in which grinding or polishing is performed only on the rear tooth surface and bottom surface of the first processing tooth after the second manufacturing process.

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