JPS58177211A - Machining method of center hole - Google Patents

Abstract

PURPOSE:To set a distance between both center holes in a highly accurate manner, by making the distance between the two center holes constant at all times even if there are variations in the length of a workpiece. CONSTITUTION:A work W is supported by a couple of supporting rests 7 in an interspace between two punches 1 and 2 which are oppositely disposed by the way of relatively movable and one side of them is provided with a work stopper 10. An end face having an easily machinable surface S1 of the work W is installed on the punch 2 which has the said work stopper 10. Both punches are relatively moved close to each other till they come to a fixed distance while pressing tight both ends of the work by the two punches, and punch holes are drilled in both end faces S1 and S2. A distance between both center holes can be determined without any influence from variations in the length of the work.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for machining a center hole necessary for machining or measuring a workpiece, which is subjected to such operations.

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. is usually processed.And,
After drilling center holes at both ends of a rod-shaped workpiece, when performing turning or measuring work on the workpiece using those center holes, the depth of the center hole and the distance between both centers are the standards for applying pressure or measuring. In many cases, adding these dimensions with high precision will greatly affect the accuracy of processing or measurement.

Therefore, when machining the center hole with a drill as in the past, the depth of both center holes that are machined separately must be machined with a constant accuracy, and the distance between both 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.

Conventionally, the precision of the end face of the workpiece and the distance between both end faces must be ensured with high precision, so forging dies and the like for machining the workpiece have to be finished 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 the length of the workpiece varies, and the depth of at least one of the center holes can be kept constant. The purpose of this is to machine a workpiece at a constant rate between two punches, which are placed opposite each other so as to be relatively movable, and one of which is provided with a work stopper. a step of installing a workpiece formed on an easy-to-work surface on which it is easy to form a center hole so that the easy-to-work surface is on the side of the punch having the workpiece stopper of the two punches; The above object can be achieved by providing a method for machining a center hole, which includes the step of pressing both ends of the workpiece and simultaneously moving the two notches toward each other until they are spaced apart from each other by a certain distance.

Next, an embodiment of the present invention shown in FIGS. 1 to 3 will be described. Two punches 1.2 are arranged opposite each other 1~, in this example one punch 1 is attached to a movable punch holder 4 provided on the headstock 3,
The movable punch holder 4 is moved forward and backward by a hydraulic cylinder (not shown) provided on the head stock 3, so that the punch 1 becomes a movable punch that moves forward and backward toward the other punch 2. Still, in this example, the other punch 2 is attached to a fixed punch holder 6 provided on the tail stock 5 and serves as a fixed punch, and the centers of these punches 1 and 2 are located on the same axis. .

Between the movable punch 1 and the fixed punch 2, a pair of support stands 7 are disposed on a slider 8 to support the workpiece W so as to be movable in the axial direction.

This slider 8 is attached to a table 9 so as to be movable in a direction parallel to the axial direction of the workpiece W. This support stand 7 has a gripping means (not shown) for clamping the workpiece W, and when the workpiece W is pressed and moved by the advance of the movable punch 1, the workpiece W moves together with the support stand 7 and the slide 8. In addition, by using a block as the support stand 7 instead of using the member having a special circular hole as shown in the figure, and by fixing this V block to the table, when the workpiece W moves due to the advance of the movable punch 1, It is also possible to allow only the workpiece W to slide on the V block, or it is possible to restrict the movement of the workpiece W in the radial direction and provide a support stand so that the workpiece W can only move in the axial direction. It is also possible to form a shape depending on conditions such as the shape of the workpiece and processing accuracy.

The length l of the fixed punch 2 protruding from the front surface 10 of the fixed punch holder 6 is set to correspond to the depth of the center hole to be machined in the end surface S1 of the work W, and the front surface 10 of the fixed punch holder 6 is The workpiece becomes a horn that restricts the movement of the workpiece W. The forward limit position of the movable punch 1 is determined by a mechanical stopper (not shown), and is determined by the distance between the center hole formed on the end surface S2 by the movable punch 1 and the center hole formed on the end surface S1 by the fixed punch 2. can be ensured with high precision.

Among both end surfaces of the workpiece W, one surface S1 is connected to the other surface S2.
It is formed on an easy-to-process surface that is more likely to undergo plastic deformation when punching the center hole with the punches 1 and 2. To make this surface easy to machine, this surface S1 should have a smaller diameter than the other surface S2, or if the workpiece W is a forged product, the end surface S1 should be removed by cutting and the surface portion hardened by forging should be removed. By removing , it is possible to make the surface easier to process than other surfaces that have not been removed. The illustrated workpiece W has one surface S1 cut, so that the two surfaces S1 are easily machined surfaces.

Next, the machining steps in the center hole machining method of the present invention will be explained.

A workpiece W is placed on a support stand 7 attached to a slider 8. In this case, the easy-to-process surface S of the workpiece W is positioned on the front surface 10 of the fixed chuck holder 6 for machining the workpiece, and the opposite surface S2 is placed on the side of the movable punch 1. do. The state in which the workpiece W is thus installed between the movable punch 1 and the fixed punch 2 is shown in FIG. 1.

Next, a hydraulic cylinder (not shown) is operated to bring the movable punch l into contact with the end surface S2 of the workpiece W. When the hydraulic cylinder is further actuated, the workpiece W slides together with the slide 8 toward the fixed punch 2, and the end surface S1 of the workpiece W comes into contact with the tip of the fixed punch 2.

After that, when the hydraulic cylinder is further operated, the end surface S1 of the workpiece W becomes an easier surface for machining the center hole than the end surface S2, so the end surface S becomes easier to machine as shown in FIG. The center hole H begins to be formed before the end surface S2.

Then, as shown in FIG. 3, the end surface S1 of the workpiece W hits the front surface 10 of the fixed punch holder 6 which forms a workpiece stopper, and
A center hole I-1 with a required dimension of 11 is provided on the end surface S1.

is formed. The forward limit position of the movable punch 1 is mechanical.]
・Since it is determined by the buckwheat flour, the forward movement of the movable punch 1 is based on the distance between the center holes of 12 for the dimension 7 of the workpiece W.
It can be continued until As a result, a center hole II2 of the required size is also formed on the end surface S2 of the workpiece W. Incidentally, by stopping the movable punch 1 for several seconds at the forward limit position, the variation in the distance e2 between the centers is reduced.

Each of the punches 1 and 2 shown in Figures 1 to 3 has a conical shape having the same angle (for example, 60 degrees) as the center hole used, but as shown in Figures 4 (A) and (B), A punch consisting of multiple parts with different angles may also be used. The punch 12 shown in FIG. 4(A) has a reference angle part 13 which is defined in JIS etc. and has the same angle θ1 as the center hole used (for example, usually 60 degrees), and a reference angle part B with a tip end. Angle θ
The cut-in portion A has an angle θa (for example, 50 degrees) smaller than b.

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 the smaller the angle of the punch, the smaller the pressure load. There is. Therefore, when punching a center hole in the workpiece W using the punch 12 shown in FIG. Sometimes, the hole sharply enters the workpiece W, and a center hole having a predetermined angle can be machined with a smaller pressurizing load.

The punch 12 shown in No. 4N-) is attached at an angle θC larger than the reference angle portion B at the rear of the reference angle portion (for example, 120 degrees). Therefore, when a center hole is punched using the punch 12 shown in FIG. 4(0), the plastic deformation of the end of the workpiece during machining creates a chamfered part at an angle θC on the raised part of the end face of the workpiece. is formed, and damage to the center hole used is prevented. In addition, punch 1
Although only the punch is movable, both punches may be movable forward and backward. In that case, it is not necessary to provide a stopper for regulating the advance limit position for each punch, and also to provide a workpiece stopper for the punch on the side of the workpiece that is easier to work with.

As described above, according to the present invention, one end surface forms a center hole in comparison with the other end surface between two punches that are arranged oppositely for relative movement and one of which is provided with a work stopper. installing a workpiece formed on an easy-to-work surface so that the easy-to-work surface is on the side of the punch having the work stopper of the two punches; and pressing both ends of the workpiece with the two punches. and moving the two punches relatively close to each other at a constant interval 1.
Even if there are variations in the length of the work, the distance between the two center holes can be kept constant at all times, making it possible to determine the distance between the two center holes with high precision without being affected by variations in the length of the work. is possible. Moreover, the depth of the center hole formed in the end face, which is the easy-to-process surface, is also constant without being affected by variations in the length of the workpiece. Therefore, when performing machining or measuring work based on the depth of the center hole, if the depth of one center hole is used as the reference,
It becomes possible to perform processing or measurement with high precision. ! Since the pressurizing force of the punch only needs to press the workpiece by the thrust force required to form the center hole, the effect of reducing the distortion imparted to the workpiece by pressurization can be obtained.

[Brief explanation of drawings]

Fig. 1 shows an embodiment of the present invention; Fig. 2 is a side view of a workpiece installed in a processing device; Fig. 2 is a side view of the workpiece in the middle of processing; and Fig. 3 is a side view of the workpiece after processing. 4 are side views showing the shape of a punch according to another embodiment of the present invention. 1... Movable punch, 2... Fixed punch, 4... Movable punch holder, 6... Fixed punch holder, 10... Work stopper, W... Work, Sl, S2... End surface. Patent applicant Nissan Motor Co., Ltd. 11-

Claims (1)

[Claims] A workpiece is placed between two punches that are arranged facing each other so as to be relatively movable, and a workpiece stopper is installed on one side.One end surface of the workpiece is formed into an easy-to-process surface that makes it easier to form a center hole than the other end surfaces. installing the workpiece so that the easy-to-process surface is on the side of the punch having the workpiece stopper of the two punches, and pressing the two punches at both ends of the workpiece while spacing the two punches at a constant interval. A method for machining a center hole, comprising the step of moving the center hole relatively close to each other in step 1.