JPH057921A - Method and device for extruding pipe shape part - Google Patents

Abstract

PURPOSE:To reduce the tensile force which a mandrel receives at the time of manufacturing a pipe shape part by extrusion. CONSTITUTION:At the time of manufacturing a pipe shape part l.2b from a perforated stock 12 by extrusion, working is executed, while allowing a mandrel 5 to descend at the same speed as a flow speed of a stock of the lower part of a bearing part 10 of a die 11. A punch 4 is provided in the lower end of a cylindrical body 13 provided on the lower part of a slide 5. and in the lower end of a cylinder rod of an auxiliary cylinder 14, the mandred 5 is inserted through the inside diameter part of the punch 4, and hung. In such a way, tensile force loaded to the mandrel can be reduced remarkably, and the pipe shape part whose inside diameter is smaller than that by a conventional method is produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for extruding pipe-shaped products.

[0002]

2. Description of the Related Art As shown in FIG. 5, a pipe-shaped extrusion apparatus has a slide 3 fixed to a head of a ram 2 of a main cylinder 1 provided above, and a hollow having a lower end fixed to a lower portion of the slide 3. Punch 4 and slide 3 on top
Upper structure consisting of a mandrel 5 fixed to the lower part of the punch 4 and inserted through the inner diameter of the punch 4, and a bolster 6 provided below, a hollow die receiver 7 and a die receiver 7 standing on the upper surface of the bolster 6. The bearing part is provided on the upper part of the table, and has a material insertion hole 8 into which the punch 4 fits and the material is inserted, a forming hole 9 in the lower part, and a gradient hole provided between the material inserting hole 8 and the forming hole 9. Dice with 10 11
The substructure consists of

In order to manufacture a pipe-shaped product, first, as shown in the left half of FIG. 5, the punching material 12 shown in FIG. 4 (A) is inserted into the material insertion hole 8 and the punch 4 is lowered. And press the material lightly. At this time, the mandrel 5 also descends together with the punch and inserts the inner diameter of the material 12. The punch 4 is further lowered, and as shown in the right half of FIG. 5, the material 12a is extruded through the bearing portion 10 and the forming hole 9 to manufacture the pipe-shaped product 12b.

[0004]

As described above, the material 1
When the 2a is extruded, the flow rate of the raw material is the same as the descending speed of the punch 8 (the descending speed of the ram of the main cylinder) above the bearing 10, but the bearing 10
On the lower side, when the surface reduction rate is ε, the flow velocity of the material is {1 / (1-ε)} × (punch descending velocity).
Since the area reduction ratio ε is 0.75 or less and extrusion processing is performed,
The flow velocity of the material below the bearing is greater than the flow velocity of the material above the bearing.

Since the processing speed of the mandrel 5 is the same as that of the punch 8, a relative speed is generated between the material and the mandrel in the lower part of the bearing portion.
Further, since the mandrel receives the processing pressure of the material, a frictional force is generated between the mandrel and the material. Therefore, the material flowing at a high speed pulls the mandrel downward, and receives a large tensile force.

Therefore, the mandrel often breaks due to the tensile force. In particular, in the case of a small-diameter mandrel for manufacturing a pipe-shaped product having a small internal diameter, the tensile stress increases in inverse proportion to the square of the diameter, so that selection of a high-strength material and strict machining accuracy are required.

It is an object of the present invention to provide a method for reducing the tensile force applied to a mandrel and a device therefor.

[0008]

DISCLOSURE OF THE INVENTION The present invention is intended to achieve the above-mentioned object, and one of them is to manufacture a pipe-shaped product from a perforated material by an extrusion process so that a mandrel is diced. The method for extruding a pipe-shaped product is characterized in that processing is performed while lowering the material at the same speed as the material flow speed in the lower part of the bearing part.

The other is an apparatus for carrying out the above method, wherein a punch is provided at a lower end of a tubular body provided at a lower portion of the slide, and a punch is provided at an inner diameter portion of the tubular body at a lower portion of the slide. An extrusion processing apparatus for a pipe-shaped product, characterized in that an auxiliary cylinder is provided by fixing its end, and a mandrel is vertically provided at a lower end of a cylinder rod of the auxiliary cylinder by inserting an inner diameter portion of the punch.

[0010]

FIG. 2 is a diagram showing the pressure distribution received by the mandrel at the upper and lower portions of the bearing portion of the die. The site where the mandrel receives pressure from the material can be broadly classified as follows. Maximum pressure rise part for extrusion (bearing part, forming hole) Internal pressure rise part that transmits punching force to bearing part through material Material spring-back part after processing

If there is a relative speed between the material and the mandrel 5 at these portions, a frictional force is generated. ,,
The frictional forces when there is a relative velocity between the material and the mandrel 5 at the area of are denoted by F ₁ , F ₂ , and F ₃ , respectively. From the magnitude of the pressure, F ₁ > F ₂ ≈F ₃ . In the case of the conventional device, the descent speed of the mandrel at the site is v ₀ , whereas the flow velocity of the material is v = {1 / (1-ε)} ×
Since v ₀ and a relative velocity are generated, (F ₁
+ F ₃ ) tensile force is applied. Here, ε is the area reduction rate.

As in the method of the present invention, the material flow velocity at the mandrel site is v = {1 / (1-ε)} × v ₀
When it is lowered by, the relative velocity between the parts disappears and the relative velocity is generated in the parts, so that the tensile force of F ₂ is applied to the mandrel.

Therefore, the tensile force of the mandrel of the method of the present invention is (F ₁ +
F ₃₎ by -F ₂ = F ₁ is reduced.

For example, when the intermediate product shown in FIG. 3 is extruded, the tensile stress σ ₀ generated on the mandrel is 1 when the descending speeds of the mandrel and the punch are the same as in the conventional method.
It becomes 13 kg / mm ² , and when the descending speed of the mandrel is the same as the material speed under the bearing as in the method of the present invention,
The tensile stress σ generated on the mandrel is 70 kg / mm ² .

In the apparatus of the present invention, the cylinder rod of the auxiliary cylinder provided under the slide is extended at a speed of (flow rate of material under bearing part-falling speed of punch) to lower the descending speed of the mandrel. Since the flow velocity of the lower material can be made the same, the frictional force (= mandrel tensile force) at the lower part of the bearing portion, which has a large frictional force, disappears.

[0016]

EXAMPLES Examples of the present invention will be described below. FIG. 1 is an explanatory view of the device of the present invention. The device includes a slide 3 fixed to a head of a ram 2 of a main cylinder 1 provided above, a punch 4 attached to a lower end of a tubular body 13 attached to a lower portion of the slide 3, an inner diameter portion of the tubular body 13. And an upper structure consisting of an auxiliary cylinder 14 having a rear end fixed to the lower part of the slide, a mandrel 5 that is connected to the tip of a cylinder rod 15 of the auxiliary cylinder via a joint 16 and is inserted through the inner diameter of the punch 4. And a bolster 6 provided below, a hollow die receiver 7 provided upright on the upper surface of the bolster 6, and a material insertion hole 8 provided on the upper part of the die receiver 7 into which the punch 4 fits and the material is inserted. , A lower structure composed of a die 11 having a bearing portion 10 formed in a sloped hole provided between the forming hole 9 and the material insertion hole 8 in the lower portion.

With the above construction, in this apparatus, the descending speed of the mandrel 5 is equal to the descending speed of the slide (= the descending speed of the punch 4) plus the descending speed of the cylinder rod 15 of the auxiliary cylinder. Become. Therefore, by changing the lowering speed of the rod 15 of the auxiliary cylinder, the lowering speed of the mandrel 5 can be lowered at a speed different from that of the punch 4.

Next, the method of the present invention will be described. First, Fig. 1
4A, as shown in the left half of FIG.
Is inserted into the material insertion hole 8, the punch 4 is lowered, and the material is lightly pressed. At this time, the cylinder rod 15 of the auxiliary cylinder descends at the same speed as the slide 3 at the top dead center to insert the inner diameter of the material 12a.

Next, as shown in the right half of FIG. 1, the cylinder rod 15 of the auxiliary cylinder is extended, and the punching speed is lowered while the descending speed of the mandrel 5 is made equal to the material speed under the bearing 10. 4 is further lowered and the material 12a is extruded through the bearing portion 10 and the molding hole 9 to manufacture the pipe-shaped product 12b shown in FIG. 4 (B).

Table 1 shows size: outer diameter 37.2 mmφ × inner diameter 10.2 mmφ × length 74.1 ± 0.5, material: SCM415H
FIG. 3 shows the mandrel tensile stress and the presence or absence of mandrel rupture of the method of the present invention and the conventional method (auxiliary cylinder extension speed = 0) when manufacturing and testing a product from the material
Table 2 shows the size: outer diameter 28.9 mmφ x inner diameter 8.2 mmφ x
Mandrel tensile stress and mandrel rupture presence / absence of the method of the present invention and the conventional method (auxiliary cylinder extension speed = 0) when manufacturing and testing a product from a material of length 59.7 ± 2.5 and SCR420H Is. This test was conducted using the device of the present invention. The punch descending speed is 15 mm / sec in both cases.

It can be seen from Tables 1 and 2 that the tensile stress of the mandrel according to the method of the present invention is greatly reduced as compared with that according to the conventional method, and the mandrel of the method of the present invention does not break even after processing 100 pieces. However, it can be seen that the conventional method breaks in a small number.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

Since the present invention is constructed as described above, the tensile force applied to the mandrel can be greatly reduced, and the life of the mandrel can be greatly extended. Further, there is an effect that a pipe-shaped product having a smaller inner diameter can be manufactured as compared with the conventional method.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a device of the present invention.

FIG. 2 is a view showing a pressure distribution received by a mandrel at upper and lower portions of a die bearing portion.

FIG. 3 is a diagram showing an example of dimensions of an intermediate product.

FIG. 4A is a diagram showing the shape of a perforated material, and FIG. 4B is a diagram showing the shape of a pipe-shaped product which is an intermediate product.

FIG. 5 is an explanatory diagram of a conventional device.

[Explanation of symbols]

5 Mandrel 13 tubular 14 Auxiliary cylinder 15 cylinder rod

Claims (2)

[Claims] 1. When manufacturing a pipe-shaped product from a perforated material by extrusion, the mandrel is processed while descending at the same speed as the material flow speed under the bearing portion of the die. Extrusion processing method for shaped products. 2. A cylinder rod of the auxiliary cylinder, wherein a punch is provided at a lower end of a cylindrical body provided at a lower part of the slide, and an auxiliary cylinder is provided by fixing a rear end to an inner diameter portion of the cylindrical body and a lower part of the slide. An extruding apparatus for pipe-shaped products, characterized in that a mandrel is vertically provided at the lower end of the punch through the inner diameter portion of the punch.