JP2014079801A - Hot forging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent decline in thickness accuracy of a forged product due to thermal expansion caused by temperature fluctuation of a mold and a bolster, etc.SOLUTION: A hot forging device 1 includes: upper and lower bolsters 3, 4 having tapered recesses 9, 10 formed thereon; tapered upper and lower plates 5, 6 engaging with the recesses 9, 10, respectively; and upper and lower molds 7, 8 mounted to the upper and the lower plates 5, 6, respectively. The upper and the lower plates 5, 6 are formed of a material having a thermal expansion coefficient smaller than that of the upper and the lower bolsters 3, 4. When heat conduction of a hot workpiece causes thermal expansion of the upper and the lower plates 5, 6 and the upper and the lower bolsters 3, 4, increase amount of width of the recesses 9, 10 of the upper and the lower bolsters 3, 4 is made larger than that of width of engagement parts 11, 12 of the upper and the lower plates 5, 6. Thus, engagement positions of the upper and the lower plates 5, 6 with the recesses 9, 10 of the upper and the lower bolsters 3, 4 move to bottom sides of the recesses 9, 10, and the movement amount is offset by the thermal expansion in the height directions of the upper and the lower molds 7, 8. As a result, height of the upper and the lower molds 7, 8 is maintained at a fixed level before and after the thermal expansion, so as to enable prevention of decline in thickness accuracy of a forged product.

Description

  The present invention relates to a hot forging apparatus that prevents a reduction in accuracy of a molded product due to thermal expansion of a forging die in hot forging.

  In hot forging, a molded product is obtained by pressurizing a hot work heated above the recrystallization temperature with a press. A forging device for hot forging generally attaches a forging die (upper die and lower die) to a press machine through a bolster, and sets a hot work between the upper die and the lower die. A forged molded product is formed by clamping.

  In the forging device for hot forging described above, when a hot work is continuously stamped, the temperature of the forging die and the bolster rises due to heat conduction from the hot work, and when the punching is interrupted. The temperature of the forging die and the bolster is lowered. The temperature fluctuations of these forging dies and bolsters cause thermal expansion and contraction, and the distance between the bolsters and the distance between the upper die and the lower die change to change the thickness of the forged product (die There is a problem that the accuracy of the striking direction is reduced.

  Conventionally, as a method for preventing a decrease in thickness accuracy of a forged molded product, for example, a dikis method is known (see Patent Document 1). In this die kiss method, a pre-adjusted die kiss plate is attached to a bolster or a forging die or the like, and the die kiss plates are brought into contact with each other at the time of stamping, thereby adjusting the thickness of the forged molded product to a predetermined thickness. .

JP 2010-247210 A

  However, in the above-described dikis method, there are cases where the forging die and the bolster cannot sufficiently cope with a large temperature fluctuation.

  This invention is made in view of said point, and provides the hot forging apparatus which prevents the fall of the thickness precision of the forging molded product by the thermal expansion accompanying temperature fluctuations, such as a metal mold | die and a bolster. Objective.

An upper bolster and a lower bolster driven by a press machine;
An upper plate and a lower plate respectively attached to the upper bolster and the lower bolster;
An upper mold and a lower mold respectively attached to the upper plate and the lower plate;
The upper bolster and the lower bolster are formed with tapered concave portions, and the upper plate and the lower plate are formed with tapered engaging portions that engage with the tapered concave portions of the upper bolster and the lower bolster, respectively. The thermal expansion coefficients of the upper plate and the lower plate are smaller than the thermal expansion coefficients of the upper bolster and the lower bolster.

  According to the hot forging device according to the present invention, it is possible to prevent a decrease in thickness accuracy of a forged molded product due to thermal expansion accompanying temperature fluctuations of a mold, a bolster, and the like.

It is a schematic sectional drawing of the hot forging apparatus which concerns on one Embodiment of this invention. FIG. 2 is a schematic cross-sectional view showing a state before and after thermal expansion of a lower die, a lower plate, and a lower bolster in the hot forging device shown in FIG. 1. In the hot forging apparatus shown in FIG. 1, it is a schematic sectional drawing which shows the stamping state at the time of thermal expansion. In the hot forging apparatus shown in FIG. 1, it is a schematic sectional drawing which shows the state before and behind thermal expansion when the thermal expansion coefficient of a lower die and a lower bolster is made the same.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
In FIG. 1, the schematic sectional drawing of the hot forging apparatus 1 which concerns on one Embodiment of this invention is shown. As shown in FIG. 1, the hot forging device 1 includes an upper bolster 3, a lower bolster 4, an upper plate 5 and a lower plate 6 engaged with the upper bolster 3 and the lower bolster 4, and an upper plate 5. And an upper die 7 and a lower die 8 attached to the lower plate 6, respectively, and a press machine (not shown) for driving the upper bolster 3 to perform stamping.

  The upper bolster 3 is attached to a ram (not shown) of a press machine, and moves up and down by reciprocation of the ram to perform mold opening and stamping. A tapered recess 9 is formed in the lower portion of the upper bolster 3. The upper plate 5 is engaged with the recess 9 of the upper bolster 3.

  The lower bolster 4 is attached to a bed (not shown) of a press machine, and a tapered recess 10 is formed on the upper portion of the lower bolster 4. The recess 10 is disposed so as to face the recess 9 of the upper bolster 3. The lower plate 6 is engaged with the recess 10 of the lower bolster 4.

  The upper plate 5 and the lower plate 6 are formed with tapered engaging portions 11 and 12 so as to be able to engage with the concave portion 9 of the upper bolster 3 and the concave portion 10 of the lower bolster 4. A gap C is provided between the bottom of the concave portion 9 of the upper bolster 3 and the concave portion 10 of the lower bolster 4 and the upper plate 5 and the lower plate 6 engaged with the concave portions 9 and 10 respectively. The upper plate 5 and the lower plate 6 are made of a material having a smaller thermal expansion coefficient than the upper bolster 3 and the lower bolster 4.

  The upper plate 5, the lower plate 6, the upper bolster 3, and the lower bolster 4 are thermally expanded due to heat conduction from the upper die 7 and the lower die 8 heated by the heat of the hot work 2 at the time of stamping. . At this time, referring to FIG. 4, if the thermal expansion coefficients of the upper plate 5, the lower plate 6, the upper bolster 3 and the lower bolster 4 are the same, the thermal expansion amounts thereof are the same. 3 and the recess 10 of the lower bolster 4 and the upper plate 5 and the lower plate 6 are engaged with each other before the thermal expansion shown in FIG. 4A and during the thermal expansion shown in FIG. It does not change. Therefore, the mounting position of the upper plate 5 and the lower plate 6 at the time of thermal expansion becomes higher by the height H2 than before thermal expansion. FIG. 4 shows only the lower bolster 4 side.

  In the hot forging device 1 of the present embodiment, the coefficients of thermal expansion of the upper plate 5 and the lower plate 6 are made smaller than those of the upper bolster 3 and the lower bolster 4, so The increase amount of the width of the concave portion 10 of the bolster 4 is larger than the increase amount of the width of the engagement portion 11 of the upper plate 5 and the engagement portion 12 of the lower plate 6. Thereby, the engagement position of the upper bolster 3 of the upper plate 5 and the lower plate 6 with the concave portion 9 of the upper bolster 3 and the concave portion 10 of the lower bolster 4 is changed from the position before thermal expansion shown in FIG. Are moved to the bottom side of the recesses 9 and 10 (the gap C becomes smaller). The amount of movement of the upper plate 5 and the lower plate 6 toward the bottom of the recesses 9 and 10 and the amount of thermal expansion in the height direction of the upper plate 5, the lower plate 6, the upper bolster 3 and the lower bolster 4 are offset. Thus, the mounting height H to the upper plate 5 and the lower plate 6 of the upper mold 7 and the lower mold 8 is maintained constant before and during thermal expansion. FIG. 2 shows only the lower bolster 4 side.

  The concave portion 9 of the upper bolster 3, the concave portion 10 of the lower bolster 4, the taper angle of the engaging portion 11 of the upper plate 5 and the engaging portion 12 of the lower plate 6, and the upper bolster 3, the lower bolster, the upper plate 5 and the lower plate The thermal expansion coefficient of 6 is based on the amount of change in temperature, etc., and the mounting height H to the upper plate 5 and the lower plate 6 of the upper mold 7 and the lower mold 8 is kept constant with respect to the thermal expansion occurring in these. Set to be.

  The upper die 7 is attached to the upper plate 5, and a crankshaft-shaped impression portion 7A, which is a forged product, is formed on the lower surface. Further, the upper die 7 moves up and down with the upper bolster 3 through the upper plate 5 by reciprocating movement of the ram, and performs mold opening and punching with respect to the lower die 8.

  The lower mold 8 is attached to the lower plate 6, and a crankshaft-shaped impression portion 8A, which is a forged product, is formed on the upper surface. The impression part 8A of the lower die 8 is disposed so as to face the impression part 7A of the upper die 7.

Next, a process of forming a forged product using the hot forging device 1 configured as described above will be described.
First, the upper die 6 and the lower die 7 are opened, and the hot work 2 is set in the impression part 8A of the lower die 8 (see FIG. 2a). Then, the upper bolster 3 and the upper mold 7 are lowered, and the hot work 2 is sandwiched between the upper mold 7 and the lower mold 8 and pressed (molding). Thereby, the hot work 2 is filled in the impression part 7A of the upper die 7 and the impression part 8A of the lower die 8 (see FIG. 3). And the upper bolster 3 and the upper mold | type 7 are raised, and a forge molded product is released.

  At this time, by continuously stamping the hot work 2, the heat of the hot work 2 is transferred to the upper plate 5, the lower plate 6, the upper bolster 3, and the lower bolster 4 via the upper mold 7 and the lower mold 8. These temperatures increase, and due to the interruption of stamping, these temperatures decrease. As shown in FIGS. 2 (a) and 2 (b), the upper bolster 3 and the lower plate 6, as shown in FIGS. Difference in thermal expansion coefficient between the bolster 4 and the upper plate 5 and the lower plate 6, and engagement between the tapered recesses 9 and 10 and the tapered engaging portions 11 and 12 of the upper plate 5 and the lower plate 6 Thus, the mounting height H to the upper plate 5 and the lower plate 6 of the upper die 7 and the lower die 8 can be kept constant. As a result, as shown in FIG. 3, the distance D between the upper die 7 and the lower die 8 is set regardless of the temperature variation of the upper plate 5, the lower plate 6, the upper bolster 3, and the lower bolster 4 at the time of stamping. It can be kept constant, and a decrease in the accuracy of the thickness of the forged product can be prevented.

  According to the hot forging device 1 according to the present invention, the upper bolster 3 and the lower bolster 4 with respect to the thermal expansion of the upper bolster 3, the lower bolster 4, the upper plate 5, and the lower plate 6 due to the difference in their thermal expansion coefficients. The distance between the upper die 7 and the lower die 8 is changed by changing the engagement positions of the tapered concave portions 9 and 10 and the tapered engaging portions 11 and 12 of the upper plate 5 and the lower plate 6. Can be kept constant. As a result, it is possible to prevent a reduction in the accuracy of the thickness of the forged molded product due to thermal expansion.

  DESCRIPTION OF SYMBOLS 1 ... Hot forging device, 2 ... Hot work, 3 ... Upper bolster, 4 ... Lower bolster, 5 ... Upper plate, 6 ... Lower plate, 7 ... Upper die, 8 ... Lower die, 9, 10 ... Recess, 11 , 12 ... engaging portion

Claims (1)

An upper bolster and a lower bolster driven by a press machine;
An upper plate and a lower plate respectively attached to the upper bolster and the lower bolster;
An upper mold and a lower mold respectively attached to the upper plate and the lower plate;
The upper bolster and the lower bolster are formed with tapered concave portions, and the upper plate and the lower plate are formed with tapered engaging portions that engage with the tapered concave portions of the upper bolster and the lower bolster, respectively. A hot forging device, wherein the thermal expansion coefficients of the upper plate and the lower plate are smaller than the thermal expansion coefficients of the upper bolster and the lower bolster.

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