JPS60227921A - Metallic mold for rear extrusion - Google Patents

Abstract

PURPOSE:To obtain a titled metallic mold for improving the working accuracy and its life by providing a guide bush for guiding a punch, so as to be freely liftable, guiding the punch in the vicinity of a die, and preventing the eccentricity and breakdown of the punch. CONSTITUTION:First of all, air is fed to an air cylinder 17 of a punch 11, and a plate 14 is energized downward through a piston 18. When the punch 11 having a punch 12 whose tip part is slightly thick is lowered, the plate 14 also descends together with the punch, and the punch 12 and a guide bush 13 for guiding its axial part so as to be freely slidable descend in the same related position. When the punch 11 is lowered after the bush 13 has been fitted by prescribed length into a center hole 7 of a die 8 of a die 5, the punch 12 descends by a guidance of the bush 13, and a blank 6 is pressed and formed. In this regard, the cylinder 17 descends together with the punch 11, but a piston 18 lifts relatively in a state that it remains stopped, and energizes the plate 14 downward. Also, the cylinder 17 sets in advance the upper limit position of the punch 12 to a state led slightly into the bush 13.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to cold forging, and more specifically, a cylindrical blank placed in a lower die is pressurized with an upper punch, ``Conventional technology'' relates to a backward extrusion mold that extrudes the outer circumference of a blank upward to produce a cylindrical container-shaped product with a deep hole. A guide is provided to guide the punch because stress acts on the punch and causes it to become eccentric from the hole in the die, reducing the precision of the molded product and causing it to bend and break. As an example is shown in FIG. 3, a fixed guide (2) was provided with the outer periphery of the lower die (1) as a reference to guide the shaft of the punch (3). However, this fixed guide (2) does not allow the molded product (4) to die (
1) It must be placed at a position higher than the height of the molded product (4) in order to extract it from the molded product (4). Therefore, the molded product (4)
If the height of the punch (3) becomes high or the diameter of the punch (3) is small, the performance of the guide will deteriorate, and the practical limit is when the deep hole ratio (= hole depth / hole diameter) is 2.5 or less. Ta. Therefore, in order to obtain a molded product with a deep hole ratio of 3 or more, a blank product with a small deep hole ratio is made, annealed, etc., and then ironed to form a molded product, which is a multi-step process. I had to.

"Means for Solving the Problem" The purpose of the present invention is to eliminate these drawbacks by providing a guide bush that guides the punch so that it can be raised and lowered, and to move it toward the die in accordance with the movement of the punch, and to It is possible to guide the punch near the die by urging it with the urging force of , thereby preventing eccentricity of the punch and extruding a deep hole with a deep hole ratio of about 3 to 6 in one process. It is an object of the present invention to provide a backward extrusion mold that can perform processing with high precision, prevent breakage of punches, and improve the life of the mold. Embodiments of the present invention will be described below with reference to the drawings.

"Example" FIG. 1 shows the structure of a backward extrusion die of the present invention. The figure shows the upper die near its upper limit. Lower mold (5
) has a central hole (7) that accommodates a cylindrical blank (6).
A die (8) with a center hole (at the bottom of the force is a lower die (5) that can be raised and lowered freely and the lower limit is regulated, and a blank (
6) is provided.

There is a knockout pin 00 below the counter punch (9)
) is provided and is urged upward at a required time to raise the upper surface of the counter punch (9) to an upper limit that coincides with the upper surface of the die (8). The upper mold I is provided with a punch (121) that faces the die (8) concentrically.As shown in Fig. 4, the tip of the punch a-z has a slightly larger diameter so that extrusion of deep holes can be easily performed. A guide push (2) is provided to guide the shaft of the punch edge.

The guide bush A3, which has a slightly larger diameter at the tip of the punch (12+, is split into two pieces to enable assembly) and is fixed to the plate (14). The plate I has a horizontally elongated shape, and both ends of the plate I are guided so as to be raised and lowered by a plurality of guide rods (15) erected on the lower mold (1). punch a3
When the plate αa descends with the guide bush a3
The outer layer of the lower end part is designed to fit into the center hole (force) of the die (8).The length of the fit is regulated by the stopper αe fixed to the lower surface of the plate (14) and the upper surface of the die (8). If the difference in diameter between the center hole (7) and the punch (12) is small and the wall thickness of the guide push-piece (03) is too thin, the center hole (the upper part of the punch should be made slightly larger in diameter. (12 is slightly pulled into the guide push-piece Q3 as shown in the figure at the upper limit), so the guide push-off
For the hole (13), leave some distance from the bottom surface. The upper die OD is provided with an air cylinder (17) that urges the play Q4) downward, and a piston α8) that is compatible with the air cylinder (17). Pole on the tip surface of the piston rod of piston Q81 (11 and concentrically with the collar (20
), fit the hole in the collar (2■ to plate Q4), and insert the spring Cυ between the head of bolt α and plate I.
(14) is brought into contact with the piston (18). At the lower limit position of the air cylinder (piston α8) of the piston α8, the cylinder chamber above the cylinder chamber is provided with an air supply port for constantly supplying air at a constant pressure. is held in a slightly retracted state by the guide bush 03).

Next, we will discuss the effect. When performing backward extrusion processing with this mold, first
Supply air at a constant pressure to urge the piston aal to the lower limit position. The die (
The blank (6) is carried into the center hole of
The punch (12) and the guide bush 03 descend together while being urged by the mallet along the guide rod (151) while maintaining the same relative position. First Guide Pussy-03)
is inserted into the center hole (force) of the die (8), and the stopper (16
) comes into contact with the upper surface of the die (8). At this time, the distance between the lower end (upper end of the recess) of the part guiding the punch 03 of the guide bluff 1α level and the upper surface of the blank (6) can be reduced to about 15 cm. Subsequently, when the upper die αυ descends, the punch (12+) is guided by the guide bush (13) and descends to pressurize the blank (6).Air cylinder a7
) is lowered together with the upper die aυ, but the piston α remains stationary and urges the plate α downward, causing it to rise relatively.

As shown in Figure 2, the outer periphery of the blank (6) is punched (6).
) is pushed up along the center hole (7), and when it comes into contact with the guide bush and shoe 03), the guide push
Play with 03)) Q4) and push up the piston cod. At the lower limit of the upper die Ql shown in the figure, the blank (6
) is molded into a molded article (23). The molded product (23) is moved through the guide punch 09 by the biasing force of the piston α8).
is pushed out from the punch 02, and then the knockout pin (10
) rises and the molded product (2
3) Stick out. As mentioned above, when the punch 02) reaches the blank (6), the guide pusher 03) guides the punch (12) in a position extremely close to the blank (6), so the punch α is not eccentric. Molded products (
23) can be improved and breakage of the punch a2 can be prevented. The machining experience using this mold has confirmed that continuous machining is possible with a deep hole ratio of 6, the punching life is more than 45,000 times, and the life of the die (8) is even longer.

The descending speed of the punch Q2+ during processing is preferably such that the flow rate of the product to be processed is 600 ynvt/sec or less. Normally, the plate 04) is used below the upper limit position of the guide rod (15), but if the upper limit of the punch α is adjusted slightly higher by mistake, or if a hydraulic press with uneven upper limit stop position is used. When plate 04) stops at the upper limit of guide rod (1z), it slightly punches (1z
The spring (21) rises and the spring (21) contracts, so that no force is applied to the piston, and the large diameter part of the tip of the punch (12+) is prevented from being damaged due to the clearance of the lower end of the guide push (I3).

As is clear from the above description, according to the present invention, by providing a guide bush that can be raised and lowered, it is possible to guide the punch at a position extremely close to the blank in the die at the initial stage when the punch is loaded. It has great practical effects and advantages, such as preventing eccentricity and breakage of the punch, improving the precision of the molded product, and extending the life of the mold, thereby improving productivity and reducing costs.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view at the upper die upper limit, FIG. 2 is a longitudinal cross-sectional view at the upper die lower limit, FIG. 3 is an explanatory diagram of a conventional example, and FIG. 4 is an explanatory diagram of the shape of the punch tip. 1 is a die, 2 is a fixed guide, 3 is a punch, 4 is a molded product, 5 is a lower die, 6 is a blank, 7 is a center hole, 8 is a die,
9 is a counter punch, 10 is a punch out pin, 11 is an upper mold, 12 is a punch, 13 is a guide bush, 14 is a plate, 15 is a guide rod, 16 is a stopper, 17 is an air cylinder, 18 is a piston, 19 20 is a bolt, 20 is a collar, 21 is a spring, 22 is an air supply port, and 23 is a molded product. Patent applicant Representative of AIDA ENGINEERING Co., Ltd.
Meeting 1) Keinosuke

Claims (1)

[Claims] A punch with a slightly thicker tip is provided on the upper mold,
A plate in which a two-split guide bush facing that slidably guides the shaft of the punch is fixed) (141 is provided in the lower mold part so as to be movable up and down, and is connected to the plate so that the plate is always directed downward. The upper die is provided with an air cylinder that presses the punch and restricts the upper limit position of the punch within the guide pusher, and the lower die is provided with a die that faces the punch, and the lower end of the guide pusher α3) is lowered together with the upper die. 1. A backward extrusion mold, characterized in that the part fits into the center hole of the die for a certain length.