JPS58177212A - Machining method of center hole - Google Patents

Abstract

PURPOSE:To machine a distance between both center holes to be constant even there are variations in the length of a workpiece as well as to machine the depth of at least one side of the center hole in a constant manner as well. CONSTITUTION:A work W is set between a movable punch P1 and a fixed punch P2 via a couple of supporting rests 5. An end face S1 of the work is fitly applied to the movable punch P1. When this movable punch P1 moves forward, another end face S2 of the work hits the fixed punch P2, and with the work further pressed, the punch protruded out of a punch holder 4a as far as by l1 comes to a stop after being punched by l to the end face S2. The forward limit position of the movable punch P1 is determined by a mechanical stopper so that the distance between both center holes is machined in a constant manner.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a center hole machining method for machining a center hole necessary for machining or measuring a workpiece.

The conventional method of machining a center hole is, for example, by installing a center drill facing the end face of a workpiece (workpiece), and drilling a center hole on the end face of the workpiece by drilling with this center drill. It is usually processed. After drilling center holes at both ends of a rod-shaped workpiece, when turning or measuring the workpiece using those center holes, the depth of the center hole or the distance between the two centers must be determined during processing or measurement. In many cases, these dimensions are used as standards, and in such cases, machining these dimensions with high precision will greatly affect the accuracy of machining or measurement.

Therefore, when machining the center hole with a drill as in the past, the depth of both center holes, which are machined separately, must be machined with a constant precision, and the distance between the two center holes must also be constant. That's what I was doing. However, in this case, unless the length of the rod-shaped workpiece before center hole machining has a certain precision, the distance between both center holes cannot be maintained with a certain precision.

For this reason, in the past, it was necessary to ensure the accuracy of the end face of the workpiece and the distance between both end faces with high precision, so forging dies, etc. for processing the workpiece had to be made with high precision. . In addition, with the conventional method described above, it is necessary to perform end face milling or counterbore processing on both end faces of the workpiece using a cutting tool or cutter before machining the center hole, which has the problem of requiring a large number of man-hours for machining the center hole. Ta.

The present invention has been made in view of the problems of the prior art described above, and it is possible to machine the distance between both center holes to be constant even if there are variations in the length of the workpiece, and to control the depth of at least one of the center holes. For the purpose of applying constant force, two punches each having a reference angle part having the same angle as the center hole to be used and a biting part continuous to the tip of the reference angle part and having an angle smaller than this angle, are used relative to each other. a step of movably arranging them facing each other, setting the biting part of one punch at a smaller angle than the biting part of the other punch, and placing the workpiece on the punch on the side having the biting part of the smaller angle; The above object can be achieved by using a method that includes a step of moving the two punches relatively close to each other at a constant interval while pressing both ends of the workpiece with two punches.

Next, an illustrated embodiment of the present invention will be described. FIGS. 1(A) and 1(B) are diagrams showing a punch P used in the center hole machining method of the present invention, respectively.
The punch P shown in (b) is provided with a reference angle part B defined by JIS etc. and having the same angle θ1) (for example, usually 60 degrees) as the center hole used, and at the tip of this reference angle part B. It also has a biting portion A having a small angle θa (for example, 50 degrees). It is known that there is a certain relationship between the angle of the punch and the pressure load required to punch a center hole in a workpiece, and it is known that the smaller the punch angle, the smaller the pressure load. .

Therefore, when punching a center hole in a workpiece with the punch P shown in FIG. By penetrating inside, the center hole having the desired angle can be pressurized with a smaller pressurizing load.

The punch P shown in FIG. 1(B) is aligned with the reference angle portion B at the biting part of the punch P shown in FIG. 1(A),
There is an angle θ larger than the reference angle part B behind the reference angle 13.
It has a chamfered portion C having an angle C (for example, 120 degrees). Therefore, when the center hole is machined using the punch P shown in Fig. 1 (O), a kind of chamfered part with an angle θC is formed on the raised part of the end face due to plastic deformation of the end of the workpiece during machining. This chamfer prevents the center hole from being damaged.

An example of a processing device used in the center hole processing method of the present invention is shown in FIG. 3, and includes two punches P1 and P2.
are arranged facing each other so as to be relatively movable. That is, in this example, one punch P1 is attached to a movable punch holder 2 provided on the headstock 1, and
The movable punch holder 2 is moved forward and backward by a hydraulic cylinder (not shown) provided in the punch P1.
is a movable punch that moves forward and backward toward the other punch P2. In this example, the other punch P2 is attached to the fixed punch holder 4 provided on the tail stock 3 and serves as a fixed punch, and these punches PI
+ The centers of P2 are located on the same axis.

The two punches P, P2, which are arranged opposite to each other as described above, each have a biting part A, a reference angle part B, and a chamfered part C, as shown in FIG. In the example, the angle θ of the biting part A of the fixed punch P2
a is formed at an angle (θa<θ2) smaller than the angle θA of the biting portion A of the movable punch 1'1. Incidentally, the angles θb and θC of the reference angle portion B and the chamfered portion C are the same, respectively.

The length B in which the fixed punch P2 protrudes from the front surface 4a of the fixed punch holder 4 is set to correspond to the length of the center hole to be machined on the end surface S2 of the work W, and the front surface 4a of the fixed punch holder 4 is It becomes a work stopper that restricts the movement of W. The forward limit position of the movable punch P1 is determined by a mechanical stopper (not shown), and the distance between the center holes can be maintained with high precision by the workpiece stopper and the mechanical stopper.

There is a workpiece W between the movable punch P1 and the fixed punch P2.
In order to support the workpiece so as to be movable in the axial direction, a pair of support stands 5 are disposed on the slider 6, and the slider 6 is movable in a direction parallel to the axial direction of the workpiece relative to a support member such as a table 7. installed on. This support stand 5 has a gripping means (not shown) for tightening the workpiece W.

As the movable punch P1 moves forward, the workpiece W is pressed.

In addition, by using a V block as the support base 5 and placing it on a fixed table in several cases, when the workpiece W is moved due to the advancement of the moving punch P, only the workpiece W moves to the corresponding block. Depending on the shape of the workpiece W, machining accuracy, etc., it is possible to use a support base that can slide on the top of the workpiece W, or restrict the movement of the workpiece W in the radial direction and allow the workpiece W to move only in the axial direction. It is possible depending on the situation.

Next, the center hole machining process of the present invention will be explained.

The workpiece is conveyed between the movable punch P and the fixed punch P2 by hand or by a conveyance device not shown, and is installed on the support stand 5 as shown in FIG. Fix it.

Next, actuate the hydraulic cylinder (not shown) and punch P1.
is advanced, and the movable punch 2 is brought into contact with the end surface S1 of the workpiece W as shown in FIG. 4(a). Furthermore, movable punch P
, moves forward, the work W moves together with the punch P1, and the other end surface S2 of the work W comes into contact with the fixed punch P2. When the hydraulic pressure cylinder 7 is further operated, both punches P1
．． Due to the pressure applied by P2, press forming begins on both end surfaces S, S2 of the work W as shown in FIG. 4(B).

At this time, as shown in FIG.
is set to be smaller than the angle θ5 of As shown in FIG. That is, work stopper 4
It often comes into contact with a. As a result, a center hole H2 having a depth of 11 is formed on the end surface S2 side of the workpiece W.

Subsequently, as the movable punch P moves forward at the forward limit position 1 set by a mechanical stopper (not shown),
A center hole 11° is also formed on the end surface S of the workpiece W,
The distance between both center holes H1 and H2 is 12. The movable punch P1 is stopped for several seconds at the forward limit position of the movable punch P, and the variation in the dimension of the distance 12 is reduced.

As a result, each center hole H,, II2 is formed by an acute angle part 11a formed by the biting part A of the punch p,, p, , and a reference angle part B, as shown in FIG. The center hole base Hb having an angle is formed, and the raised part of the end surface of the workpiece W is pushed out by the chamfered portion C to prevent other workpieces from colliding with the end surface of the workpiece W. A light portion 11c is formed to prevent damage to the center hole base Hb, which is the center hole to be used. Incidentally, as shown in FIG.
It is also possible to machine the center hole by .

Still, Bocchi 13. Although only one of the punches is movable, both punches may be movable and each may be provided with a stopper for regulating the forward limit position. In this case as well, it is a good idea to set the angle of the biting portion A of the punch having the work stopper 4a smaller than that of the other punches.

As described above, according to the present invention, two punches each having a reference angle part having the same angle as the center hole to be used and a biting part continuous to the tip of the reference angle part and having an angle smaller than this angle, are used relative to each other. Two punches that are movably arranged opposite each other, the biting part of one punch is set at a smaller angle than the biting part of the other punch, and a work stopper is provided on the punch on the side having the biting part of the smaller angle. In between, the processing method includes a step of installing the workpiece, and a step of moving the two punches relatively close to each other until a certain distance is reached while pressing both ends of the workpiece with the two punches, so that the length of the workpiece Even if there are variations in the length, it is possible to always keep the distance between both center holes constant, and it is possible to determine the distance between both center holes with high accuracy without being affected by variations in workpiece length. . Furthermore, among the facing punches, the depth of the center hole of the punch whose biting part is formed smaller than the biting part of the other punches and which has a work stopper also varies depending on the length of the workpiece. remains constant without being affected by Therefore, when machining or measuring work is performed based on the depth of the center hole, it is possible to perform the machining or measuring work with high accuracy. Further, since the pressurizing force of the punch is applied to the center hole, the strain exerted on the work by pressurization can be reduced.

[Brief explanation of drawings]

Figures 1 (a) and (b) are side views showing an example of the punch used for machining the center hole of the present invention, and Figure 2 is a partially omitted cross-section showing a state in which a workpiece is machined with the punch of the present invention. Figures 3 and 3 are cross-sectional views showing the state in which the workpiece is installed in the center hole machining device, and Figs. A...biting part, Pl...movable punch, W...
Worm 2 - driven punch holder, 4... fixed punch holder, 4a - work stopper. Patent applicant Nissan Motor Co., Ltd. II

Claims (1)

[Claims] Two punches each having a reference angle part having the same angle as the center hole to be used and a biting part connected to the tip of the reference angle part and having an angle smaller than this angle are arranged facing each other so as to be relatively movable, and one punch setting a biting part of the punch at a smaller angle than the biting part of the other punch, and installing a workpiece between two punches, the punch having the smaller biting part being provided with a work stopper; A method for machining a center hole, comprising the step of pressing both ends of the workpiece with two punches and moving the two punches relatively close to each other in a trench at a constant interval.