JP4197982B2 - Bar material shearing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for shearing a bar and a mold (apparatus) suitable for the method.
[0002]
[Prior art]
Rolling elements such as cylindrical rollers used for bearings and the like are produced by cutting bar materials such as bearing steel (SUJ2).
Such bearing steel is very hard and difficult to cut to withstand high loads.
In particular, rollers used in thrust bearings are also required to have high finishing accuracy of the end faces.
Therefore, the bar is cut, and the end face is ground and finished one by one by liquid honing or the like.
This results in poor productivity and is one of the causes of high costs.
[0003]
Under the above background, the inventors of the present application examined whether a shearing process could be performed from a bar material such as a round bar, for example, with a punch press.
A conventional shearing method using a punch press will be described with reference to FIG.
A die hole is provided in the die 104, and a die cushion (knockout pin) 106 is provided so as to be fitted into the die hole.
A workpiece such as a bar is placed on the die 104, and the punch 103 is pressed downward from above by a striker (not shown).
At this time, the workpiece is pressed and sheared by the punch 103 while the workpiece is pressed by the spring-loaded workpiece presser (stripper) 102.
In this case, the die cushion is often spring-biased from below so that the workpiece is not deformed.
[0004]
When the bar material for the cylindrical roller of the bearing is sheared by such a method, it is sheared so that a crack enters in the direction 1b shown in FIG. In this case, the cracked fracture surface 1b was produced, the cutting quality of the end face was poor, and it could not be used for cylindrical rollers.
Therefore, I set the work support force of the die cushion large.
For example, when a SUJ2 round bar having a diameter of about 3 mm is sheared to a length of about 3.8 mm, the punch is biased with a force of 5 to 8 Ton from the bottom, and the punch is sheared by applying a pressing force of about 10 Ton. The sharpness of the shear end face could not be improved.
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described technical problems of the prior art, and an object of the present invention is to provide a shearing method excellent in end face quality that suppresses the occurrence of cracks on the end face of a bar.
[0006]
[Means for Solving the Problems]
As a result of earnest examination of a method for shearing a bar, the present inventors have found a completely new method that has never existed.
When the bar material is received by a die from below, the material supply side is supported by a work presser (stripper), and the stopper is brought into contact with the end surface of the bar material, so that when the bar is sheared with a punch, This is a point where compressive stress is generated in the longitudinal direction of the material.
More specifically, in the method of shearing a bar according to the present invention, the product side and the material supply side of the bar are received by a die from below, and the material supply side is connected to the workpiece support groove from the die hole provided in the die. The die and the stripper are pressed and supported with a predetermined clearance between them, and the end surface of the bar is brought into contact with the stopper to restrict the product side from extending, and a predetermined thickness is provided from the bar side. It is characterized by pressurizing with a punch having a punch, causing a product portion between the punch and the stopper to generate a compressive stress, and generating a sharp shear surface on the end material side to cause the end material to shear and fall into the die hole.
[0007]
In the shearing method as shown in FIG. 5, as shown in an enlarged view in FIG. 6, a clearance 1b is generated prior to the progress of the shear 1a on the punch or die side, and the clearance between the punch and the die. Due to the presence of d2, the cutting progresses so that the cracks are preliminarily developed outward with respect to the punch, so that it is estimated that the cracks appear largely on the end face.
Accordingly, in the present invention, for example, as shown in FIG. 1, pressure is applied by the punch 3 while the end surface of the work 1 is applied to the stopper 5.
In this state, when the punch 3 is pressed from the side of the bar (work), the bar sandwiched between the die 4 and the punch 3 tends to extend toward the tip by ductility, but the tip is a stopper. Since it is suppressed, a compressive stress f is generated in the longitudinal direction.
When shearing by the punch progresses in such a state, it is presumed that progress of the crack breaking is first suppressed, and that even if cracking occurs, it proceeds toward the inside of the punch due to compressive stress.
As a result, a shear surface having a metallic luster similar to smooth cutting was formed on the end face of the product 10 without generating a cracked cross section.
On the other hand, a cracked fracture surface was observed on the end face of the end material 11.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a schematic diagram of a mold or apparatus used in the shearing method according to the present invention.
A die hole 41 may be formed in the die 4 and the die hole may not include a die cushion.
The end surface of the bar (work) 1 is brought into contact with the stopper 5, the work is pressed and supported by the stripper 2 from the upper side on the supply side of the work 1, the punch 3 is lowered, and the product 10 is sheared.
The stripper 2 is biased from above by a stripper spring (not shown).
At this time, the end material 11 is dropped and discharged below the die hole.
[0010]
The action acting on the workpiece at this time will be described with reference to FIG.
The material supply side of the work 1 is pressed and supported by the die 4 and the stripper 2.
FIG. 2 shows a state where the pressure is supported.
A clearance d1 between the die 4 and the stripper 2 is set to a predetermined size.
For example, in the case of a round bar made of bearing steel having a diameter of about 3 mm, d1 = 0.04 mm was set.
[0011]
As shown in FIG. 1, the product 10 side is not supported by the stripper and the end face is regulated by the stopper 5 as shown in FIG. Trying to extend toward the tip.
However, since the tip is regulated by the stopper 5, a compressive stress f is generated by the reaction.
Accordingly, the shear 1a proceeds toward the punch tip and the die side, and the chip fracture 1b tends to precede, but a compressive stress acts on this portion.
This compressive stress suppresses the preceding of the shear shear 1b, and at least the oblique preceding to the product 10 side does not occur.
In addition, a crack fracture surface is recognized on both end faces on the end material side.
Here, in the case of the round bar having a diameter of about 3 mm, when the product length was about 3.8 mm, the end material width (punch thickness) was set to 1 to 1.2 mm.
[0012]
An example of the punch shape used in the present invention is shown in FIG. 3, and an example of the die hole shape is shown in FIG.
Note that the display magnifications do not match due to the size constraints of the drawings.
As shown in FIG. 3 (b), the thickness of the shearing blade portion 31 of the punch is reduced to about 1 to 1.2 mm to suppress the generation amount of the end material, and the side portion 32 of the punch is thickened. In this example, punch guide portions 42 are formed on both sides of the die hole 41 of the die 4 as shown in FIG.
A work support groove 43 is formed on the upper surface of the die 4.
[0013]
【The invention's effect】
In the present invention, the end of the bar is regulated by a stopper, the material supply side is clamped by a die and a work presser (stripper), and punch shearing is adopted. The generation of cross-sections can be suppressed, and products with clean end surfaces can be produced continuously while supplying materials continuously.
[Brief description of the drawings]
FIG. 1 shows an example of a shearing method according to the present invention.
FIG. 2 shows a relationship between a die and a stripper.
FIG. 3 shows an example of a punch shape.
FIG. 4 shows an example of a die hole.
FIG. 5 shows an example of conventional punch shearing.
FIG. 6 is an explanatory diagram showing the progress of a crack fracture in conventional punch shearing.
FIG. 7 shows a state example of a conventional cut end face.
[Explanation of symbols]
1 Bar 2 Workpiece presser (stripper)
3 Punch 4 Die 5 Stopper 10 Product

Claims (1)

The product side and the material supply side of the bar are received by a die from below, and the material supply side is pressed and supported by a die having a workpiece support groove and a stripper, leaving a predetermined clearance between the die hole provided in the die. At the same time, the end of the bar is brought into contact with the stopper to restrict the product side from being extended, and a pressure having a predetermined thickness is applied from the side of the bar to pressurize the product between the punch and the stopper. A shearing method for a bar material, characterized in that a millet shear surface is generated on the end material side and the end material is sheared and dropped into the die hole.

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