JPS62114813A - Broaching method - Google Patents

Abstract

PURPOSE:To simplify the extent of chucking operation as well as to make various formed workpieces machinable with one broach, by using a smaller broach in diameter than that of a work lower hole, and broaching the workpiece in a state of its being deflected to the work lower hole. CONSTITUTION:A maximum diametral cutting edge 11a of an internal broach 11 is formed into an oval consisting of length A and breadth B, and this A size is set to be the smaller value than that of a diameter C of a lower hole 12a of a work 12. When each groove 12b in an internal of 120 deg. is machined on an inner circumferential surface of the lower hole 12a of the work 12 with this broach 11, first the broach 11 is inserted into the center of the lower hole 12a of the work 12, making it into relative deflection in the length direction to the center as far as a deflection variable D=E+(C-A)/2 to be cut to the extent of depth E, thus broaching takes place. When one groove 12a is allover, the broach 11 is put back to a central part of the lower hole 12a, while the work 12 and the broach 11 are relatively rotated as far as 120 deg., and broaching is carried out as deflecting the broach as far as the deflection variable D likewise. This operation is repeated and thus machining is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a processing method using an internal broach.

<Conventional technology> Conventional internal broaching uses a broach with a multi-stage cutting edge whose outer diameter gradually increases toward the rear in the axial direction. Alternatively, it is a machining method in which relative movement is performed in a spiral manner, and everything from rough cutting to finishing cutting is performed continuously in one step. With this broaching process, holes with complex cross-sectional shapes can be drilled with high accuracy and efficiency. (Problem to be solved by the invention) In conventional internal broaching process, the broach is pulled out once from the workpiece. Since machining is completed in 1 step, the shape of the finishing blade of the broach is the same as the finished cross-sectional shape of the workpiece. Therefore, if the finished cross-sectional shape of the workpiece differs, a different broach corresponding to the finished cross-sectional shape is required, and there is a problem that only one type of processing can be performed with one broach.

In addition, conventionally, once a broach has been pulled out, it cannot be moved back and passed through the workpiece again. Therefore, when attaching or removing a workpiece, first the char and king of the front grip part of the broach are released by the broaching machine. There was a problem in that the workpiece had to be attached to the broach, and after machining, the chucking of the rear grip part had to be released and the workpiece removed from there, making the chucking operation of the broach complicated.

<Helps to Solve the Problems> The present invention solves these problems in conventional broach processing, and allows machining of different shapes with one broach, and simplifies the broach chucking operation. The purpose is to provide a broaching method that can achieve the following.

The configuration of the broaching method according to the present invention for achieving this purpose uses a broach having a cutting edge dimension smaller than the diameter of the workpiece's prepared hole, and performs machining with the broach being biased with respect to the workpiece's prepared hole. It is characterized by this.

<Function> Since a broach having a cutting edge dimension smaller than the diameter of the workpiece's prepared hole is used, the broach can be freely reciprocated or rotated within the workpiece's prepared hole without interfering with the workpiece's prepared hole.

With this broach biased against the workpiece hole,
Machining is performed by interlocking cutting one or more times, and it is possible to create different shapes by changing the offset value and offset position.

<Example> Hereinafter, an uninvented example will be specifically described with reference to the drawings.

FIG. 1 is an explanatory diagram of a processing method according to an embodiment of the present invention;
FIG. 2 is a schematic front view of the broach used therein, FIG. 3 is a cross-sectional view taken along line 1--m in FIG. 2, and FIG. 4 is a cross-sectional view of the broach shown together with the workpiece.

As shown in FIGS. 2 to 4, the internal broach 11 according to this embodiment has a multi-stage cutting blade 11 whose outer diameter gradually increases toward the rear of the shaft, similar to the conventional broach.
a, llb, -1llc, and lid, and the final cutting edge lid, which has the largest cutting edge size, has an elliptical shape with a major axis of A and a minor axis of B. This brooch 1
1, the largest cutting edge dimension A is the pilot hole 12a of the workpiece 12.
This value is smaller than the diameter C of .

Next, as shown in FIG. 1, grooves are formed in the inner peripheral surface of the pilot hole 12a of the workpiece 12 at three locations at 120 degree intervals using this broach 11.
An example of processing 2b will be described. First, the broach 11 is inserted into the center of the prepared hole 12a of the workpiece 12 using an NC broaching machine or a broaching machine that can move and rotate the work table in a direction perpendicular to the broach axis. Then, in order to process the groove 12b to the depth E, the amount of deviation D=
Pro 9-chi machining is performed in a state where the broach 1 is biased relative to the center of the pilot hole L2a of the workpiece 12 in the long diameter direction by E+ (C-A), /2. one groove 12b
After completing the machining, the broach 11 is inserted into the lower hole L of the workpiece 12 again.
Return to the center of 2a and remove work 12 and broach 11.
After relative rotation of 120 degrees, broaching is performed by similarly biasing the broach 11 with respect to the prepared hole 12a of the workpiece 12 by the amount of bias. Similarly, rotate another 120 degrees and do the final ditch! 2b is processed and this processing is completed.

<Effects of the Invention> As described above in detail with reference to one embodiment, according to the present invention, various shapes can be processed with one broach by changing the deviation ψ and the deviation position of the broach with respect to the workpiece pilot hole. can do. In addition, since the broach can be moved freely without interfering with the workpiece's prepared hole, the workpiece can be attached or removed by releasing the chucking on either the front gripping part or the rear gripping part of the broach, simplifying the chucking operation. It is possible to convert

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a processing method according to an embodiment of the present invention;
FIG. 2 is a schematic front view of the broach used therein, FIG. 3 is a cross-sectional view taken along the line -■ in FIG. 2, and FIG. 4 is a cross-sectional view of the broach shown together with the workpiece. In the drawings, 11 is a broach, 12 is a workpiece, and 12a is a workpiece pilot hole.

Claims (1)

[Claims] A broach machining method characterized by using a broach having a cutting edge dimension smaller than the diameter of a workpiece's prepared hole and performing machining in a state where the broach is biased with respect to the workpiece's prepared hole.