JP2000288654A - Die-less punching method of pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a hole small in deformation in a die-less manner in a thick- walled pipe by applying the shear force in the cutting line direction of the pipe with the pipe in a restricted condition to form a notch-like hole. SOLUTION: A punch having a flat section in which the thickness is smaller than the width and a blade portion at its forward end having a tip angle of >=35 deg. is attached and fixed to a punch holder 9 fixed to an inner slide 7. A major portion of a pipe P is restricted by fitting grooves 100, 200 to lower the inner slide 7. The punch 3 is lowered orthogonal to the axial direction of the pipe P, and moves in the cutting line direction of the pipe P through a notch 21 of an upper pipe holder 2. A blade tip projecting from the blade portion is bitten into a side of the pipe P to shear-cut the pipe step by step with the width equivalent to the thickness of the blade portion into a clear-cut section. Since the punch 3 has the tip angle of >=35 deg., generated chips flow along an inclined bottom surface of the blade portion, and are not deposited on a bottom surface of the punch 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for dieless drilling of pipe material.

[0002]

2. Description of the Related Art Parts for automobiles, such as undercarriage parts such as rear cross members and front members, are mainly made of pipe material from conventional sheet metal press-formed products in order to reduce weight, improve safety and reduce costs. It has been replaced by molded products. Such a hype-processed product is provided with a hole for introducing and discharging the coating liquid, a hole h for draining water, and the like as illustrated in FIG.
These holes are required to be as small as possible in order to reliably prevent air pockets and coating liquid from remaining during painting, and to completely remove water that has entered during running and cleaning. You. In addition, since these holes are used as reference holes in a pipe material processing step after drilling, high hole position accuracy is required.

At present, such holes are formed by forming a thick pipe material by bending or swaging, and thereafter, are formed by machining with a drill or laser processing. Therefore, the production efficiency is low and the cost is high. There was a big problem. As a countermeasure, a punching process using a press can be considered. However, at the stage of such drilling, the pipe material is often bent into a flat U-shape or partially changed in cross-sectional shape by molding. For this reason, it is difficult to insert the die into the inside of the hype material, and it has to be dieless punching. For this reason, large deformation is likely to occur in the pipe material, and a hole having a small deformation as described above is formed in a thick pipe material (generally, the thickness is 2.5 mm or more) even by a processing method such as punching by high-speed punching. It was difficult to get.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a simple method for forming a thick pipe material in a dieless manner. It is an object of the present invention to provide a method capable of drilling a hole with less number of holes.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method for punching a hole without inserting a die into the pipe material. It is characterized in that a notched hole is formed by applying a force. The punch has a tip angle of 3
It is preferable to use a material having an angle of 5 ° or more and set the depth of cut so as to exceed the elastic deformation of the material and to minimize the amount of deformation in the shear start region.

[0006]

[Action] When punching is performed by inserting a punch in the pipe material in the radial direction, a shear force acts in the radial direction, so the periphery of the hole is deformed inside the pipe, and this deformed portion acts like a dike. Therefore, the liquid in the pipe cannot be eliminated. In the present invention, a notch-shaped hole is formed by applying a shearing force in the cutting line direction of the pipe material, so that deformation due to the shearing force in the radial direction of the material does not occur, and dripping is formed on the inner surface of the pipe. Exhaust guide action can also be expected. In particular, when a punch having a tip angle of 35 ° or more is used, the discharge of shear chips becomes smooth, so that a good cut surface without unevenness can be obtained.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an example of an apparatus for carrying out the present invention.
Is a lower pipe holder fixed with
The main body 10 having the fitting groove 100 conforming to the half cross-sectional shape of the above is replaceably mounted. Reference numeral 2 denotes an upper pipe holder, which is disposed to face the lower pipe holder 1 and is urged by an elastic body 8 so as to be separated from the lower pipe holder 1 in a normal state. A main body 20 having a fitting groove 200 conforming to the half cross-sectional shape of the material P is exchangeably mounted. Reference numeral 3 denotes a punch, and as shown in FIGS. 3A and 3B, the punch 3 has a flat cross section in which the thickness t is smaller than the width w, and has a blade portion 3a at the tip.
Has a tip angle θ inclined backward with respect to the punch axis. Curvature portions 30, 30 are formed at the lowermost corners.

This tip angle θ is preferably 35 ° or more. In the punch having the tip angle θ of 0 °, the chips s generated in the first half of the stroke (from the start of shearing to reach the center line of the pipe material) tend to bend and remain on the punch end face as shown in FIG. In the first half of the stroke, a relatively good cut surface can be obtained, while the chips serve as a tool and the material is easily separated.
In the latter half of the stroke, the sheared cut surface becomes a cut surface with large irregularities as if torn. If the tip angle θ is set, the outflow of the chips s can be improved. According to the experiment by the present inventors, when the tip angle θ is 35 ° or more, the chips can flow out stably and smoothly. Can be done. However, if the tip angle θ is too large, tool wear tends to increase, so the upper limit is considered to be 40 °.

The punch 3 is fitted and fixed to a punch holder 9 fixed to an inner slide 7 so as to face a tangential position of the pipe material P. The tangent position is the pipe material P
Is a position where a predetermined notch amount (cut amount) L is obtained. A notch 21 is formed in the upper pipe holder 2 so as to allow the punch 3 to be inserted and removed.
The lower pipe holder 1 is also formed with a notch 11 at the same position toward the side.

The notch amount L is set to a value larger than the thickness of the pipe material P and exceeds the elastic deformation of the pipe material. However, if the notch amount L is increased too much, the deformation amount in the first half region of the stroke increases, so that it must be avoided.
The optimum notch amount L varies depending on the mechanical properties of the pipe material, the outer diameter, the wall thickness, the shape of the punch, and the like. The larger the tensile strength, the smaller the outer diameter, the thicker the wall, and the tip of the punch. The smaller the curvature portion is, the smaller the optimum notch amount L becomes. Normally, the notch amount L is equal to 1.1 of the wall thickness of the pipe material P.
About 5 to 2.2 times is preferable.

Reference numeral 4 denotes a receiving block integrated with the upper pipe holder 2 and has a cavity 40 so as to allow the punch holder 9 to move freely. Reference numeral 5 denotes a pressing block fixed to the outer slide 13 for pressing the upper pipe holder 2 through the receiving block to fix the pipe material P, and has a gap so as to allow the punch holder 9 to move freely. 50. The upper pipe holder 2 is used for loading the pipe material P and taking out a perforated product.
The hinge can be tilted at an appropriate position by a hinge. In addition, in order to easily set an optimum notch amount L for the pipe material P, the lower pipe holder 1 is movable in the left-right direction. In this embodiment, notched grooves 12, 12 ′ with seats are provided on both sides of the lower pipe holder 1, and fixing bolts 1 arranged in these notched grooves 12, 12 ′ are provided.
3, 13 'can be fixed to the base part 1a by tightening. A convex wall 14 is provided on the side of the base portion 1a, and an adjusting bolt 15 threaded through the convex wall 14 is in contact with the side surface of the lower pipe holder 1, and fixed bolts 13, 13 'are provided. The lower pipe holder 1 is moved by a desired distance by rotating the adjusting bolt 15, and the lower pipe holder 1 is fixed by tightening the fixing bolts 13 and 13 'at that position, whereby the notch amount L is reduced. It can change.

Next, a drilling process using the above-described apparatus will be described. A required range including a portion where a hole is to be formed in a pipe material P formed by bending or swaging in the preceding process is set to a lower pipe holder 1 fitting. The groove 100 is loaded. If the outer slide 13 is lowered in this state, the pressing block 5 comes into contact with the receiving block 4, whereby the upper pipe holder 2 is lowered against the urging force of the elastic body 8 and comes into contact with the lower pipe holder 1. . Thereby, the main part of the pipe material P is restrained by the fitting grooves 100 and 200 so as not to rotate firmly.

When the material is fixed, the punch 3 is at the upper limit position. If the inner slide 7 is lowered in this state, the punch 3 together with the punch holder 9 is lowered in the direction perpendicular to the axis of the pipe material P, and 2 notches 21
To the cutting line direction of the pipe material P. Thereby, the most protruding cutting edge of the blade portion 3a bites into the side surface of the pipe material P, and starts shearing at a width corresponding to the thickness t of the blade portion 2a. Since it is sequentially sheared and separated by the punch having the tip angle θ, a clean cut surface can be obtained. And
When the punch 3 descends, the blade portion 3a enters the notch 100 of the lower pipe holder 1 and cutting in the cutting line direction is continued. However, since the punch has a tip angle θ of 35 ° or more, the first half The chips s generated in the stroke of flow out along the inclined bottom surface 31 of the blade portion 3a as shown in FIG.
The chips do not bend and accumulate on the bottom surface of the punch. Therefore, even in the latter half of the stroke, smooth shearing by the most protruding cutting edge of the blade portion 3a proceeds.

By the above process, a clean hole 15 without unevenness as shown in FIGS. 5A and 5B is formed. This hole does not receive any shearing force in the radial direction of the material.
Is formed in the inner surface of the hole 15 so that the discharge of the liquid in the pipe material P can be smoothly guided.

[0015]

Next, examples of the present invention will be described. STKM13 material having an outer diameter of 57 mm and a thickness of 3.2 mm was used as a pipe material. The punch has a length of 100 mm, a blade width of 30 mm, a thickness of 14 mm, a curvature R7 at the tip, a tip angle θ of 0 ° (perpendicular to the axis), and a tip angle of 10 °, 15 °.
°, 20 °, 25 °, 30 °, 35 °, 40 °, 45 °
Was used. The notch amount (L) of the punch into the pipe material was changed at intervals of 2 mm between 2 and 10 mm by the method described above.

First, when θ = 0 °, when the notch amount L = 4 mm, which is larger than the plate thickness, a scraping mark is generated on the surface of the material, but a hole cannot be obtained. This was presumed to be due to the elastic deformation of the pipe material during cutting. L
However, as shown in FIG. 8, the amount of deformation Y at the notch start end increased as L increased, and L = 6 mm was optimal for this material, outer diameter, and wall thickness. However, when θ = 0 °, the cut surface sheared in the latter half of the stroke became a surface with large irregularities as if torn, and the shape was poor. In addition, since a burr-like projection is formed on the inner surface, there is a problem in discharging the liquid from the pipe. Next, L
= 10 °, 15 °, 20 °, 25 under the condition of = 6 mm
Drilling was performed in eight types, °, 30 °, 35 °, 40 °, and 45 °, and the cut surface properties of the obtained holes were visually observed.
As a result, unevenness decreases with an increase in θ, and a good cut surface can be obtained. Particularly, when θ is 35 ° or more, a hole with good accuracy in which there is almost no deformation and there is a droop on the inner surface of the hole is obtained. Was. However, when θ was 45 °, there was a problem that abrasion at the tip of the punch blade portion was increased. Therefore, it was confirmed that θ is at least 35 °, preferably 35 to 40 °.

[0017]

According to the present invention described above, a hole having an inner surface dripping which is less deformed under dieless conditions and which is convenient for discharging the liquid inside is easily and efficiently formed on the formed pipe material. An excellent effect is obtained. According to the second aspect, an excellent effect that a hole having a very good cut surface without unevenness can be machined can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view taken along the line XX of FIG. 2 showing an example of an apparatus for performing a dieless drilling method for a pipe material according to the present invention.

FIG. 2 is a sectional view taken along line YY of FIG.

FIG. 3 (a) is a side view of a punch used in the method of the present invention,
(B) is a bottom view of the same.

FIG. 4 is an explanatory view showing a state during drilling in the method of the present invention.

FIG. 5A is a partially enlarged perspective view of a pipe with a hole obtained by the present invention, and FIG. 5B is a cross-sectional view taken along the line ZZ in FIG.

FIG. 6 is an explanatory diagram showing a state during drilling when a punch having a tip angle of O degrees is used.

FIG. 7 is a diagram showing a relationship between a cutting amount and a hole deformation amount.

FIG. 8 is a perspective view showing an inverted product example.

[Explanation of symbols]

 1 Lower Pipe Holder 2 Upper Pipe Holder 3 Punch 3a Blade θ Angle

Claims (2)

[Claims] 1. A method for punching a hole without inserting a die into a pipe material, wherein a notch-shaped hole is formed by applying a shearing force in a cutting line direction of the pipe material with a strip that restrains the pipe material. Dieless drilling method of pipe material characterized by the following. 2. A dieless hole in a pipe material according to claim 1, wherein a punch having a tip angle of 35 ° or more is used, and the cutting amount is set to a value exceeding the elastic deformation of the material and the amount of deformation in a shear start region being the smallest. Dawn law.