JP3877956B2 - Method for manufacturing broach for inner surface processing - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an improvement in a method for manufacturing a broach for inner surface processing such as a round broach and a spline broach that performs processing of a round hole, a spline hole, and the like.
[0002]
[Prior art]
As for the manufacturing method of broach, since the final product hardness is HRC65 or more, the rough shape is performed by turning or cutting before the heat treatment step, and the final finish is processed by grinding after the heat treatment step and completed. Is common. In addition, since the tool life and machining accuracy are not sufficient for performing cutting after heat treatment, the broach tool is difficult to perform turning, that is, cutting, and has to be ground.
[0003]
[Problems to be solved by the invention]
However, there are the following three problems in grinding.
1) A thin and long broach such as a broach is usually susceptible to heat treatment distortion, but further, the cutting residual stress due to turning before heat treatment is released by heating, and the distortion is further increased. It takes time to take.
2) The surface accuracy of the grinding process is better than that of the turning process. However, since the number of cuts per time cannot be increased, it takes a long time to process the cutting edge. In some cases, setup change is necessary, and extra processing man-hours due to setup change are also required.
3) Grinding requires different grindstone shapes for each machining area. In roughing and finishing, in order to shorten the machining time as much as possible, the grindstone grain size is changed. In addition, there are many man-hours in the entire manufacturing process, and manufacturing costs are increased.
[0004]
[Object of the present invention]
The present invention has been made based on the background as described above, and provides a method for manufacturing a broach for inner surface processing that can reduce distortion, shorten the time required for manufacturing, reduce costs, etc. by improving the manufacturing process. The purpose is to do. It is another object of the present invention to provide a broach for inner surface processing that improves the surface roughness and tool life.
[0005]
[Means for Solving the Problems]
Therefore, in the present invention, a first step of preparing the material such as to cut the high-speed tool steel material into a predetermined length, followed the first step, a second step of performing quenching and tempering of the material, the Subsequent to the third step, following the third step and the third step in which the outer shape of the material after quenching and tempering, the shape processing of the blade groove and the finishing processing of the cutting edge rake face are performed by turning, the material after the turning And a fourth step of performing a finishing process of the cylindrical surface and the cutting edge flank by grinding.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
A description will be given based on the flowcharts of the present invention example and the conventional example in FIGS.
First, in the present invention, the turning process before the heat treatment is performed after the heat treatment in order to reduce the distortion removing process in the heat treatment process. By improving this process, it is no longer necessary to consider heat treatment distortion, such as the fact that the cutting residual stress due to prior lathe turning is released by heating and the distortion further increases. Most of the distortion removing process can be reduced.
[0007]
Second, turning is performed after heat treatment. By optimizing the turning conditions with a tool using a hard material such as CBN, it is possible to perform turning without any problem in tool tool life even with materials of HRC65 or higher. It becomes. The machining accuracy can be dealt with by optimizing the turning conditions including the shape of the cutting edge and the feed pitch. Even if the normal turning conditions are inferior to normal, the machining time can be shortened sufficiently faster than grinding.
[0008]
Third, in the entire manufacturing process flow, turning is collected by turning, and most of the machining is covered by turning, which improves the flow of the manufacturing process and minimizes the number of machine setup steps. The time required for production can be greatly reduced, the number of types of grindstones can be reduced, and the production cost and time required for production can be greatly reduced.
[0009]
Here, materials that have been heat-treated in the third process and the previous process of the turning process 3 are purchased and / or used, and / or the finishing process for maintaining the high accuracy of the vertical groove grinding process of the spline during the grinding process. It goes without saying that it is also within the scope of the present invention to perform a surface treatment such as a coating process or a nitriding process for improving the tool life of a broach after completion of a mechanical finishing process by a grinding process and / or a grinding process. In particular, there is almost no recurrence of tool runout due to a temperature rise accompanying surface treatment, and the tool accuracy is improved as compared with the conventional manufacturing method.
[0010]
In the present invention, technical means for performing processing after heat treatment, which could only be performed by grinding until now, is performed by turning, and the present invention will be specifically described below based on examples.
[0011]
【Example】
FIG. 1 shows an example of the present invention, and a flowchart of a manufacturing process applied to a spline broach in which the edge line shape of the outermost periphery of the cutting edge is an arc shape centered on the tool axis, and FIG. 2 is a flowchart of a conventional manufacturing process of the spline broach. Indicates. Compared to the example of the present invention shown in FIG. 1, the number of processes is large and the number of setup changes is also large.
[0012]
From the present invention example, FIG. 1, as a first step, following a material preparation step 1 for cutting a round bar material of high-speed tool steel into a predetermined length of a spline broach to be manufactured, a second step, a heat treatment step The HRC 66 to 68 is quenched and tempered in step 2 . Further, the strain removal in the heat treatment step 2 was not necessary as a result of the strain investigation. In the third process and turning process 3 , CBN cutting tools are used, and the entire shape of the broach including the shank and roughing and finishing, blade groove roughing and finishing, and cutting edge rake face finishing are performed in the same setup. went. Although the CBN bite was slightly worn, it was normal wear and was still cutable. Further, the surface roughness of the cutting edge rake face at this time was as good as Ry 1 μm or less. Fourth step, the grinding step 4, finishing of the cylindrical surface, the finishing cutting edge flank performs TatemizoAra processing and finishing the spline groove to complete the spline broach.
[0013]
Next, in the conventional example and FIG. 2, after the material preparation step 1 , the turning step 3 , and the heat treatment step 2 , the manufacturing method moves to the grinding step 4 .
The first step and the material preparation step 1 are the same as those of the present invention example, and the second step and the turning step 3 are steps of roughing the raw material before tempering, but can be omitted in the present invention example. . Further, in the third step , heat treatment step 2 , it is necessary to remove the strain every time the heat treatment is performed. This is because distortion is likely to occur because the blade groove is processed by roughing the material. Finally, in the fourth step and the grinding step 4 , roughing is performed before the heat treatment, but finishing is performed after roughing including a machining allowance, etc., and a cylindrical surface, a cutting edge flank as a tool, Finish and complete spline grooving.
[0014]
There is a big difference between the present invention example and the conventional example in the preparation stage, and heat treatment is performed after cutting, so distortion in the heat treatment may be determined by inspection after tempering, and it is possible to omit strain inspection in the middle. it can. Further, the strain removal in the heat treatment step 2 this time was not necessary as a result of the strain investigation. Further, in the comparison of the man-hours required for manufacturing, in the conventional example, time is required for the distortion removal after the heat treatment step 2 and the setup change by the processing machine change 5 in the grinding step 4. In the present invention example, these times are required. We were able to greatly reduce and delete.
[0015]
In the next turning process 3 , using CBN tools, the entire shape of the broach including the shank and roughing and finishing, blade groove roughing and finishing, and cutting edge rake face finishing can be performed in the same setup. did it. Further, since roughing is performed by turning, the machining allowance for grinding can be made constant. Moreover, although the CBN bite was slightly worn, it was normal wear and was still capable of being cut. Further, the surface roughness of the cutting edge rake face at this time was as good as Ry 1 μm or less.
In addition, as shown in FIG. 3, the turning surface of the example of the present invention is concentric with the outermost cutting edge ridge line and the machining mark on the rake face, and the grinding line appears on the outermost cutting edge ridge line. In contrast, a uniform and smooth ridge line can be obtained, whereas the grinding surface of the conventional example has a disk-like grinding wheel, so that the state of the rake face is inclined with respect to the grinding wheel feeding direction as shown in FIG. It becomes a grinding streak, and this grinding streak appears in the outermost peripheral edge ridgeline, and this edge ridgeline becomes a sawtooth ridgeline. From this, the broaching tool machined in the conventional example not only has a rough surface, but also the cutting load concentrates on the convex part of the saw-toothed ridgeline, which causes chipping. The strength of the edge part formed by the outermost peripheral edge ridgeline and the side tooth surface is weakened, chipping and chipping are caused, and the tool life is deteriorated. The machined surface roughness was improved, chipping and chipping were suppressed, and the tool life was extended while maintaining the machined surface roughness.
[0016]
The tool groove machined in the example of the present invention has only a turning surface, and the tool machined by the conventional manufacturing method has a level difference between the turning surface before heat treatment and the ground surface after heat treatment. The waste discharging performance was improved, and the machined surface roughness and tool life were further improved.
[0017]
Further, FIG. 5 shows a comparison of required manufacturing time between the example of the present invention and the conventional example. Since the manufacturing of the present invention is completed in about 2/3 of the time of the conventional example, and the time required for manufacturing is linked to the manufacturing cost, the reduction of the manufacturing time leads to the reduction of the manufacturing cost. Along with the consumption of the grindstone, the manufacturing cost was significantly reduced.
[0018]
【The invention's effect】
From the above results, by applying the present invention, the manufacturing cost and the time required for manufacturing can be greatly shortened in the manufacturing method of the broach for inner surface processing that processes round holes, spline holes, and the like. Moreover, in the inner surface processing broach, the processing surface roughness and the tool life could be improved.
[Brief description of the drawings]
FIG. 1 is a flowchart of an embodiment of the present invention.
FIG. 2 is a flowchart of a conventional example.
FIG. 3 is a view showing a state of a rake face of a broach processed in an example of the present invention.
FIG. 4 is a view showing a state of a rake face of a broach processed in a conventional example.
FIG. 5 is a diagram showing a comparison of required manufacturing time between an example of the present invention and a conventional example.
[Explanation of symbols]
1 Material preparation process
2 Heat treatment process
3 turning process
4 grinding process
5 Processing machine change

Claims (1)

Following the first step of preparing a material such as cutting the high-speed tool steel material into a predetermined length, the second step of quenching and tempering the material, following the first step , Following the third and third steps of turning the outer shape of the material after quenching and tempering , shape processing of the blade groove and finishing of the cutting edge rake face, the cylindrical surface and cutting edge of the material after turning And a fourth step of grinding the flank face by grinding.

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