JP2004322258A - Shearing method of bar material and its die - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shearing method, and its die (a device) superior in an end surface quality by restraining generation of a crack on an end surface of a bar material. <P>SOLUTION: The bar material is received from below by the die, and the material supply side is supported by a work presser (a stripper). When shearing by a punch from a bar material side part by allowing a stopper to abut on this bar material end surface, compressive stress is generated in the longitudinal direction of the bar material. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD 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 rods such as bearing steel (SUJ2).
Such bearing steel is very hard and hard to cut to withstand high loads.
In particular, rollers used for thrust bearings are required to have high end surface finishing accuracy.
Therefore, the bar is cut, and the end face is subjected to grinding and finishing one by one by liquid honing or the like.
In this case, productivity is low, and this is one of the factors of high cost.
[0003]
Against this background, the inventors of the present application have examined whether a bar material such as a round bar can be sheared by, for example, a punch press or the like.
A shearing method using a punch press, which has been widely used in the past, will be described with reference to FIG.
The die 104 has a die hole, and a die cushion (knockout pin) 106 is provided so as to fit 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 work is pressed and sheared by the punch 103 while the work is held by the work holder (stripper) 102 which is biased by a spring.
In this case, the die cushion is often biased from below so that the work is not deformed.
[0004]
When the bar for the cylindrical roller of the bearing is sheared by such a method, the bar is sheared so as to have a crack in the direction of 1b shown in FIG. As a result, a cut surface 1b was generated, and the cutting quality of the end face was poor.
Therefore, the work supporting force of the die cushion was set to be 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 sheared by applying a pressure of about 10 Ton to the punch while applying a spring force with a force of 5 to 8 Ton from below. However, the sharpness of the sheared 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-mentioned technical problems of the related art, and has as its object to provide a shearing method excellent in end face quality in which generation of a crack on an end face of a bar is suppressed and a mold (apparatus) for the method.
[0006]
[Means for Solving the Problems]
As a result of intensive studies on a method of shearing a bar, the present inventors have found a completely new method that has never been seen before.
When a bar is received by a die from below, the material supply side is supported by a work retainer (stripper), and a stopper is brought into contact with the end surface of the bar, when the bar is sheared by a punch from the side of the bar, The point is that a compressive stress is generated in the longitudinal direction of the material.
[0007]
In the shearing method as shown in FIG. 5, as shown in an enlarged view in FIG. 6, a sharp 1b is generated before the shear 1a proceeds on the punch or die side, and the clearance between the punch and the die is increased. Due to the presence of d2, the cutting proceeds such that the sharpness precedes and expands outward with respect to the punch, and it is presumed that the sharpness largely appears on the end face.
Therefore, in the present invention, the work 1 is pressed by the punch 3 while the end face of the work 1 is brought into contact with the stopper 5 as shown in FIG.
In this state, when pressure is applied by the punch 3 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. Since it is pressed, a compressive stress f is generated in the longitudinal direction.
It was presumed that when the shearing by the punch progressed in such a state, the progress of the crack breakage was first suppressed, and that even if the cracks occurred, they proceeded toward the inside of the punch due to the compressive stress.
As a result, a sheared surface having a metallic luster similar to a smooth cut was formed on the end face of the product 10 without generating a sharp fracture surface.
On the other hand, a cracked cross section was recognized on the end face of the end material 11.
[0008]
An object of the present invention is to provide a die or a device suitable for the above-described shearing processing, and a die for receiving a bar from below and a work presser (stripping tool) for pressing and supporting a material supply side from above. ), A stopper for suppressing the escape of the tip of the work in the longitudinal direction, and a shearing die having a punch for shearing the bar from the side.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a schematic view of a mold or an apparatus used for the shearing method according to the present invention.
The die 4 may be an open type in which a die hole 41 is formed and the die hole is not provided with a die cushion.
The end face of the bar (work) 1 is brought into contact with the stopper 5, the work is pressed and supported by the stripper 2 from above on the supply side of the work 1, the punch 3 descends, and the product 10 is sheared.
The stripper 2 is biased from above by a stripper spring (not shown) or the like.
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 in which this pressing and supporting is performed.
The 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 was set to 0.04 mm.
[0011]
As described above, the workpiece supply side is sandwiched, and as shown in FIG. 1, the end face is regulated by the stopper 5 without supporting the stripper on the product 10 side. Attempts to extend towards the tip.
However, since the tip is regulated by the stopper 5, a compressive stress f is generated by the reaction.
Therefore, the shear 1a progresses toward the tip of the punch and the die, and the crack 1b tends to precede it, but a compressive stress acts on this portion.
This compressive stress suppresses the advance of the Kirez shear 1b, and at least oblique advance to the product 10 side does not occur.
In addition, a crack fracture surface is recognized on both end surfaces on the side of the scrap material.
Here, in the case of the above-mentioned round bar having a diameter of about 3 mm, when the product length is about 3.8 mm, the end material width (punch thickness) was set to 1 to 1.2 mm.
[0012]
FIG. 3 shows an example of the shape of the punch used in the present invention, and FIG. 4 shows an example of the shape of the die hole.
Note that the display magnifications do not match due to restrictions on the size of the drawing.
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 of scraps, and the side portion 32 of the punch is made thicker. This is an example in which punch guide portions 42 are formed on both sides of a die hole 41 of a 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 sandwiched between a die and a work holder (stripper), and a punch shearing method is employed. The generation of a cross section can be suppressed, and a product with a clean cut surface at the end face can be continuously produced while continuously supplying the material.
[Brief description of the drawings]
FIG. 1 shows an example of a shearing method according to the present invention.
FIG. 2 shows the 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 break in conventional punch shearing.
FIG. 7 shows a state example of a conventional cut end surface.
[Explanation of symbols]
1 bar 2 work holder (stripper)
3 Punch 4 Die 5 Stopper 10 Product

Claims (2)

The bar is received by a die from below, the material supply side is supported by a work holder (stripper), and a stopper is brought into contact with the end surface of this bar. A method for shearing a rod, wherein a compressive stress is generated in a longitudinal direction of the rod. A punch that has a die that receives the bar from below, a work holder (stripper) that presses and supports the material supply side from above, a stopper that suppresses longitudinal escape at the tip of the work, and a punch that shears the bar from the side. A shearing die comprising:

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