JPH078401B2 - Molding device for cup-shaped products with internal teeth - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forming device for forming a cup-shaped product with internal teeth by forging, such as an outer case of a hydraulic clutch or an outer case of a viscous coupling.

(Prior Art) Conventionally, according to Japanese Patent Laid-Open No. 61-269951, a die having an orifice portion formed on the inner periphery thereof and a die supported so as to be movable relative to the die against the cushion pressure of the cushion means. An inner punch on the inner periphery of the inner punch and an outer punch opposite to the inner punch are provided, and the outer punch is moved relative to the die so that the bottom wall of the cup-shaped material is sandwiched between the inner punch and the outer punch from inside and outside. In this state, the material is pushed from the open end side into the orifice portion on the inner circumference of the die, and inner teeth are formed on the inner circumference of the material according to the molding tooth profile formed on the outer circumference of the inner punch. Is known, in which the cushion means comprises a spring.

(Problems to be solved by the invention) By the way, in extrusion molding of a cup-shaped material, when the bottom of the material is close to the orifice part and near the end of the press stroke, the inner punch is pushed down and the surplus material is a hole in the material. It will tend to overhang the bottom corner, and if it is left as it is, the excess meat will bite into the hole bottom when it is finally pressed and it will be damaged, so the biasing force of the inner punch spring will be greater than the pushing down force of the inner punch excess pressure. It is necessary to set the spring constant to a large value so that the excess thickness does not overhang at the corner of the hole bottom, and as a result, as shown by the dotted line in FIG. A large cushion pressure is applied.

Here, in the middle part of the press stroke, the extrusion speed of the material from the orifice is higher than the descending speed of the outer punch, and the pressing force by the friction with the material acts on the inner punch, so the material produced by the inner punch and the outer punch It is necessary to apply a cushion pressure greater than this pushing force to the inner punch so that the holding force of the bottom wall of the cushion does not decrease, but the pushing force by the friction is not as large as the left side, and as described above, the spring of the cushion means If the constant is set to a large value, an excessive cushion pressure by the cushion means acts on the inner punch in the middle part of the press stroke, and the press work of the outer punch must be increased by that amount, resulting in energy loss. There's a problem.

An object of the present invention is to provide a device that solves the above problems.

(Means for Solving the Problems) In order to achieve the above object, the present invention supports a die having an orifice portion formed on the inner periphery thereof and a die capable of moving relative to the die against the cushion pressure of the cushion means. An inner punch on the inner periphery of the die and an outer punch facing the inner punch are provided, and the outer punch is moved relative to the die so that the bottom wall of the cup-shaped material is formed by the inner punch and the outer punch. The material is pushed from the inside and outside into the orifice part on the inner circumference of the die from the open end side, and the inner teeth are formed on the inner circumference of the material, following the molding tooth profile formed on the outer circumference of the inner punch. In the forming apparatus described above, the cushion means is a fluid pressure cylinder, and the pressure adjusting means for adjusting the internal pressure of the fluid pressure cylinder to increase stepwise so as to increase at the end of the press stroke. It is characterized by being composed of and.

(Operation) The cushion pressure acting on the inner punch is controlled by the overhang in the vicinity of the end of the press stroke so that the overhang of the overfill in the hole bottom corner of the material near the end of the press stroke can be prevented. Even if it is set to be larger than the pressing force of the inner punch, the cushion pressure acting on the inner punch in the middle part of the press stroke can be set to be small. This does not act and the pressure work of the outer punch can be reduced.

(Embodiment) In the drawings, (1) shows an upper die, (2) shows a lower die, an outer punch (3) is fixed to the lower surface of the upper die (1), and the upper surface of the lower die (2). In the inner circumference of the orientation part (4a)
The die (4) having the above-mentioned structure is fixed through a die holder (5), and the lower die (2) is provided with a support plate (7) supported by a plurality of cushion means (6). 7), an inner punch (8) having a molding tooth holder (8a) formed on the outer periphery is erected so as to face the orifice portion (4a) of the die (4), and the inner punch (8) is supported by the support plate. The support plate (7) to the stopper portion (5a) forming the die holder (5) at its lowest position while allowing it to descend freely through the (7) against the cushion pressure of these cushion means (6). It was regulated by the contact of.

In the drawing, (9) shows a knockout pin that can freely project from the upper surface of the inner punch (8).

A fluid pressure cylinder (10) is provided for the cushion means (6) and a pressure adjustment means is provided for adjusting the internal pressure of the fluid pressure cylinder (10) so as to increase stepwise so as to increase at the end of the press stroke. 11) and in the embodiment, the pressure adjusting means (11) includes an oil passage (13) for connecting the hydraulic chamber (10a) of the hydraulic slinder, which is a fluid pressure cylinder (10), to the hydraulic tank (12). A first relief valve (11a) that operates at a relatively low pressure and a second relief valve (11b) that operates at a relatively high pressure, and are installed in parallel with each other, and the first relief valve (11a) of the oil passage (13) 1 A solenoid switching valve (11c) is provided on the upstream side of the relief valve (11a), and the switching valve (11c) is interlocked with the press stroke by a limit switch or the like to provide a hydraulic cylinder from its starting end to its intermediate portion. Hydraulic chamber (10a) is the first relief Valve (10a)
The switching position indicated by A in the figure connected to the hydraulic tank (12) via the first relief of the hydraulic chamber (10a) to the hydraulic tank (12) from immediately before the end of the press stroke to the end. The connection via the valve (10a) is broken B in the figure
The switch position is changed to the switch position indicated by. In the drawing (13
a) is a branch passage branched from the upstream side of the solenoid switching valve (11c) of the oil passage (13) and connected to the hydraulic tank (12), and (14) is an inflow passage to the tank (12) side. A check valve provided in the branch passage (13a) for blocking, (15) an air supply source for supplying air to the air chamber above the hydraulic tank (12), and (16) a constant pressure in the air chamber. The relief valve to hold is shown.

Next, the operation of the embodiment will be described.

First, the cup-shaped material W is set on the upper end portion of the inner punch (8) with the open end thereof facing downward (the state shown in FIG. 1), and then the upper die (1) is lowered. The bottom wall of W is sandwiched by the inner punch (8) and the outer punch (3) from above and below, and in this state, the inner punch (8) descends against the cushion pressure of the cushion means (6), and the material W Is pushed into the orifice part (4a) on the inner circumference of the die (4) from the opening end side thereof, and the inner punch (8) is subsequently lowered against the cushion means (6), and the material of the material W is the orifice part ( 4a) is extruded downward while being squeezed inward while being pressed downward from above, so-called front extrusion molding is performed so that the inner circumference of the material W follows the molding tooth profile (8a) on the outer circumference of the inner punch (8). Inner teeth are formed and the inner punch (8) moves to the stopper part (5 The material W is finally pressed at the lowest position regulated in a), and internal teeth are formed up to the bottom of the hole of the material W (state shown in FIG. 2).

In this case, the internal pressure of the hydraulic chamber (10a) of the hydraulic cylinder is adjusted to a relatively low pressure by the first relief valve (11a) from the start end portion to the middle portion of the press stroke, and immediately before the end portion of the press stroke to the end portion. Is adjusted to a relatively high pressure until the inner punch (8) has a relatively low cushion pressure from the start end to the middle of the press stroke and the pressure from just before the end of the press stroke to the end. As a solid line in FIG. 3, the characteristic curve of the change in the cushion pressure with respect to the press stroke changes in two steps, and the cushion acting on the inner punch (8) in the middle of the press stroke is acted on. The pressure can be reduced.

Further, the cushion pressure acting on the inner punch (8) increases immediately before the end portion of the press stroke, and overhang of the excess thickness to the hole bottom corner portion which is likely to occur near the end portion of the press stroke is prevented.

After extrusion molding, if the upper die (1) is raised, the pressure applied by the outer punch (3) of the inner punch (8) disappears, so that the hydraulic pressure is supplied to the hydraulic chamber (10a) of the hydraulic cylinder via the branch passage (13a). The pressure oil of the tank (12) flows in, the inner punch (8) rises to a predetermined position, and the knockout pin (9)
To remove the product.

(Effects of the Invention) As described above, according to the present invention, the cushion pressure acting on the inner punch in the middle portion of the press stroke can be reduced, and the cushion pressure acting on the inner punch immediately before the end portion of the press stroke is rapidly increased. Therefore, there is an effect that the pressure work of the outer punch can be reduced, energy loss can be suppressed, and overhang of excess material to the hole bottom corner portion of the material can be effectively prevented.

[Brief description of drawings]

FIG. 1 is a cut sectional view showing an example of the device of the present invention, FIG. 2 is a cut sectional view showing its operating state, and FIG. 3 is a graph showing the cushion pressure with respect to the press stroke of the cushion means. (3) …… Outer punch, (4) …… Die (4a) …… Orifice part, (6) …… Cushion means (8) …… Inner punch, (8a) …… Formed tooth profile (10) …… Fluid pressure Cylinder, (11) …… Pressure adjusting means W …… Cup-shaped material

Claims (1)

[Claims] 1. A die having an orifice portion formed on the inner periphery thereof, and an inner punch on the inner periphery of the die supported so as to be movable relative to the die against the cushion pressure of the cushioning means.
The inner punch and the outer punch facing each other are provided, and the outer punch is moved relative to the die so that the bottom wall of the cup-shaped material is sandwiched between the inner punch and the outer punch from inside and outside to open the material. In the forming device for pressing the die from the side to the orifice part on the inner circumference of the die and forming the inner teeth on the inner circumference of the material in the shape of the molding tooth profile formed on the outer circumference of the inner punch, the cushion means is a fluid pressure cylinder. And a pressure adjusting means for adjusting the internal pressure of the fluid pressure cylinder so that the internal pressure of the fluid pressure cylinder increases stepwise so as to increase at the end of the press stroke.