JP6098493B2 - Forging equipment - Google Patents

Description

  The present invention relates to a forging device.

  Conventionally, in Patent Document 1, a molding die is installed in a pressure vessel filled with a liquid pressure medium such as water or oil, and the pressure mold is lowered to compress the liquid pressure medium, and the upper molding die. A forging technique is described in which the material to be molded is compression-molded by lowering.

  According to this conventional technique, a compressive force by a mold is applied to the material to be molded, and at the same time, a compressive force (hydrostatic pressure) by a liquid pressure medium is also applied to the periphery of the material to be molded. It can be molded without any problems.

Japanese Patent Laid-Open No. 9-277096

  In the above prior art, when compressing the molding material with the upper molding die, tensile stress (stress acting in the circumferential direction of the molding material) acts on the molding material. And the compressive force by a liquid pressure medium acts from the outer periphery of a molding material so that this tensile stress may be canceled. Therefore, it can suppress that a tensile stress exceeds the material strength of a molding material, and a crack (crack) arises in a molding material.

  However, in the above prior art, since the compressive force by the liquid pressure medium increases exponentially, there is a risk that the pressure of the liquid pressure medium will increase excessively and exceed the strength of the molding die, and the molding die may be damaged. (See formulas F1, F2 and FIG. 4 to be described later).

  In view of the above points, an object of the present invention is to suppress an excessive pressure acting on a molding die.

In order to achieve the above object, in the invention described in claim 1,
An upper mold (11) and a lower mold (12) for molding the material to be molded (1);
Drive means (14, 15) for driving the upper mold (11);
A cylindrical storage space forming member (13) that forms a storage space (13a) for storing the working fluid ;
In the storage space (13a), the molding material (1) is arranged,
When the drive means (14, 15) drives the upper mold (11) to the molding material (1) side, the upper mold (11) compresses the working fluid in the storage space (13a) and compresses the working material (1). )
The storage space forming member (13) has a shape in which the cross-sectional area of the storage space (13a) increases as it goes in the pressing direction (Z) in which the upper mold (11) presses the molding material (1). It is characterized by being.

  According to this, since the width (h) of the gap between the upper mold (11) and the storage space forming member (13) increases as the upper mold (11) moves in the pressing direction (Z), the upper mold An increase in pressure loss in the gap between (11) and the storage space forming member (13) can be suppressed (see Formula F1 described later).

As a result, an increase in the pressure of the working fluid in the storage space (13a) can be suppressed, so that the pressure acting on the molding dies (11, 12) can be suppressed from becoming excessive.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is a whole lineblock diagram of a forging device in one embodiment. It is explanatory drawing explaining the outline | summary of the forge process in one Embodiment. It is III-III sectional drawing of FIG. It is a graph showing the relationship between the pressure of hydraulic fluid, and a viscosity. It is a graph showing transition of the pressure of the hydraulic oil in one embodiment. It is sectional drawing which shows the operating state of the forging apparatus in one Embodiment.

  Hereinafter, a forging device in one embodiment will be described. A forging device 10 shown in FIG. 1 is a device for forging a workpiece 1 (material to be molded), and includes a punch 11, a die 12, a storage space forming member 13, a punch driving unit 14, and a control device 15.

  In FIG. 1, the up and down arrows indicate the up and down direction (gravity direction) when the forging device 10 is installed.

  The punch 11 and the die 12 are molding dies for molding the workpiece 1. The punch 11 is an upper mold (movable mold) that presses the work 1, and the die 12 is a lower mold (fixed mold). The workpiece 1 is forged between the punch 11 and the die 12 and formed into a predetermined shape. The punch 11 and the die 12 can form the workpiece 1 into various products.

The storage space forming member 13 has, for example, a cylindrical shape as a whole. The die 12 is disposed at the bottom of the storage space forming member 13. The die 12 and the storage space forming member 13 form a storage space 13a for storing hydraulic oil (working liquid , working fluid ). A sealing member (not shown) is disposed between the die 12 and the storage space forming member 13 so as to ensure liquid tightness. The workpiece 1 is disposed on the die 12. Therefore, the workpiece 1 is disposed in the hydraulic fluid in the storage space 13a.

  The punch driving unit 14 and the control device 15 are driving means for driving the punch 11. The punch drive unit 14 drives the punch 11 to reciprocate in a direction toward and away from the die 12. The punch drive unit 14 is configured by, for example, a hydraulic cylinder.

  The control device 15 is a control unit that controls the operation of the punch driving unit 14. The control device 15 includes, for example, a PLC (programmable logic controller) and its peripheral devices.

  The punch 11 has, for example, a cylindrical shape as a whole. An escape portion 11a is formed in a portion of the punch 11 opposite to the direction Z (hereinafter referred to as the pressing direction) in which the workpiece 1 is pressed (upward portion in FIG. 1). The escape portion 11a has a smaller outer diameter as compared with a portion on the pressing direction Z side (a lower portion in FIG. 1). That is, the punch 11 has a stepped columnar shape in which a portion opposite to the pressing direction Z is thinner than a portion on the pressing direction Z side.

  The storage space forming member 13 has a stepped cylindrical shape that expands stepwise as the diameter of the storage space 13a goes in the pressing direction Z. Therefore, the cross-sectional area of the storage space 13a gradually increases as it goes in the pressing direction Z.

  In the example of FIG. 1, the storage space 13a has a diameter that increases in four stages as d1 → d2 → d3 → d4 in the pressing direction Z. That is, the storage space forming member 13 includes a first step portion 131 having an inner diameter d1, a second step portion 132 having an inner diameter d2, and a third step portion 133 having an inner diameter d3. And a fourth step portion 134 having an inner diameter of d4.

  Next, a forging method using the forging device 10 will be described. FIG. 2 is an explanatory diagram for explaining the outline of the forging process. In FIG. 2, the punch 11 and the die 12 are schematically shown for easy understanding.

  First, the work 1 is placed in the storage space 13a and hydraulic oil is injected. Next, the punch 11 is driven in the pressing direction Z by the punch driving unit 14. In this embodiment, the punch 11 is driven in the pressing direction Z at a constant speed, but the pressing speed of the punch 11 may be varied.

  Thereby, since the punch 11 enters the storage space 13a and the hydraulic oil in the storage space 13a is compressed, the pressure of the hydraulic oil increases. The hydraulic oil pressure Pn at time n is approximately represented by the following formula F1.

  In Formula F1, L is the length in the pressing direction Z of the gap between the punch 11 and the storage space forming member 13. In Formula F1, ηn is the viscosity of the hydraulic oil at time n. In Formula F1, Q is the flow rate of the hydraulic oil in the gap between the punch 11 and the storage space forming member 13. In Formula F1, w is the circumferential length of the edge portion (the portion indicated by the thick line in FIG. 3) of the gap between the punch 11 and the storage space forming member 13 on the punch 11 side. In Formula F1, h is the width of the gap between the punch 11 and the storage space forming member 13 (see FIGS. 1 and 3).

  Formula F1 is based on the pressure loss formula for parallel plates. That is, when the hydraulic oil in the storage space 13 a is pushed by the punch 11, the hydraulic oil flows through the gap between the punch 11 and the storage space forming member 13, and pressure loss occurs in the gap between the punch 11 and the storage space forming member 13. This pressure loss is almost equal to the pressure of hydraulic oil (difference from atmospheric pressure).

  As the pressure of the hydraulic oil increases, the viscosity of the hydraulic oil increases. For example, the viscosity ηn of a predetermined hydraulic oil used in the present embodiment is represented by the following formula F2.

  In Formula F2, k is a temperature coefficient. In Formula F2, Pn-1 is the pressure of the hydraulic oil at time n-1. Time n-1 is a time before time n.

  FIG. 4 is a graph representing Formula F2. As can be seen from Formula F2 and FIG. 4, the viscosity ηn of the predetermined hydraulic oil used in the present embodiment increases exponentially with the increase in the hydraulic oil pressure Pn−1. As can be seen from Formula F1, the pressure loss Pn is proportional to the viscosity ηn of the hydraulic oil.

  Therefore, when the punch 11 enters the storage space 13a and presses the hydraulic oil, pressure loss occurs and the hydraulic oil pressure increases. When the hydraulic oil pressure increases, the hydraulic oil viscosity increases and the hydraulic oil viscosity increases. As the pressure rises, a pressure spiral is generated in which the pressure loss further increases and the hydraulic oil pressure further increases.

  When the punch 11 pressurizes the workpiece 1, a circumferential tensile stress acts on the workpiece 1. Since the compressive stress from the hydraulic oil acts on the workpiece 1, the tensile stress is reduced. Therefore, it can suppress that a tensile stress exceeds the material strength of the workpiece | work 1 and a crack (crack) generate | occur | produces in the workpiece | work 1.

  Moreover, since the pressure of the hydraulic oil increases as the punch 11 pressurizes the workpiece 1, the tensile stress can be sufficiently reduced even if the tensile stress increases as the punch 11 pressurizes the workpiece 1.

  FIG. 5 is a graph showing the transition of the pressure of the hydraulic oil. First, as shown in FIG. 1, in a state where the punch 11 is in the first step portion 131 of the storage space forming member 13 (time t <b> 1 or less in FIG. 5), as the punch 11 enters, the punch 11 and the first step portion 131. And the length L1 of the gap between the pressure increases and the pressure loss P1 increases (see Formula F1). Accordingly, the pressure of the hydraulic oil also increases.

  When the punch 11 further enters, the punch 11 spans both the first step portion 131 and the second step portion 132 of the storage space forming member 13 as shown in FIG. At this time, a pressure loss P1 in the first stage 131 and a pressure loss P2 in the second stage 132 occur. Accordingly, the pressure of the hydraulic oil is substantially equal to the sum of the pressure loss P1 and the pressure loss P2.

  In this state (time t1 or more and time t2 or less in FIG. 5), the length L1 of the gap between the punch 11 and the first step portion 131 decreases as the punch 11 enters, and the punch 11 and the second step portion 132 The gap length L2 increases.

  Since the length L1 of the gap between the punch 11 and the first step portion 131 decreases as the punch 11 enters, an increase in the pressure loss P1 in the first step portion 131 is suppressed (see Formula F1).

  The length L2 of the gap between the punch 11 and the second step portion 132 increases as the punch 11 enters, but the width h2 of the gap between the punch 11 and the second step portion 132 is set to the punch 11 and the first step portion 131. Therefore, the pressure loss P2 in the second step portion 132 can be kept small (see Formula F1). Therefore, an increase in hydraulic oil pressure is suppressed.

  When the punch 11 further enters, the punch 11 straddles both the second step portion 132 and the third step portion 133 of the storage space forming member 13 (not shown). At this time, a pressure loss P2 in the second step portion 132 and a pressure loss P3 in the third step portion 133 occur. Accordingly, the pressure of the hydraulic oil is substantially equal to the sum of the pressure loss P2 and the pressure loss P3.

  In this state (time t2 or more and time t3 or less in FIG. 5), the length L2 of the gap between the punch 11 and the second step portion 132 decreases as the punch 11 enters, and the punch 11 and the third step portion 133 The length L3 of the gap increases.

  Since the length L2 of the gap between the punch 11 and the second step portion 132 decreases as the punch 11 enters, an increase in the pressure loss P2 in the second step portion 132 is suppressed (see Formula F1).

  The length L3 of the gap between the punch 11 and the third step portion 133 increases as the punch 11 enters, but the width of the gap between the punch 11 and the third step portion 133 is different from that of the punch 11 and the second step portion 132. Therefore, the pressure loss P3 in the third step portion 133 can be kept small (see Formula F1). Therefore, an increase in hydraulic oil pressure is suppressed.

  When the punch 11 further enters, the punch 11 straddles both the third step portion 133 and the fourth step portion 134 of the storage space forming member 13 (not shown). At this time, a pressure loss P3 in the third step portion 133 and a pressure loss P4 in the fourth step portion 134 occur. Accordingly, the pressure of the hydraulic oil is substantially equal to the sum of the pressure loss P3 and the pressure loss P4.

  In this state (time t3 or more and time t4 or less in FIG. 5), the length L3 of the gap between the punch 11 and the third step portion 133 decreases as the punch 11 enters, and the punch 11 and the fourth step portion 134 The gap length L4 increases.

  Since the length L3 of the gap between the punch 11 and the third step portion 133 decreases as the punch 11 enters, an increase in the pressure loss P3 in the third step portion 133 is suppressed (see Formula F1).

  The length of the gap between the punch 11 and the fourth step portion 134 increases as the punch 11 enters, but the width of the gap between the punch 11 and the fourth step portion 134 is between the punch 11 and the third step portion 133. Since it is larger than the width of the gap, the pressure loss P4 in the fourth step portion 134 can be kept small (see Formula F1). Therefore, an increase in hydraulic oil pressure is suppressed.

  In FIG. 5, the two-dot chain line of the hydraulic oil pressure indicates a comparative example corresponding to the prior art. In this comparative example, the diameter of the storage space 13a is constant at d1 throughout the entire pressing direction Z1. In this comparative example, since the width of the gap between the punch 11 and the storage space forming member 13 is constant over the entire pressing direction Z1, the pressure of the hydraulic oil increases exponentially. Therefore, the pressure acting on the mold (punch 11 and die 12) becomes excessive, and the life of the mold is shortened or the mold is damaged.

  On the other hand, in this embodiment, the storage space forming member 13 has a shape in which the cross-sectional area of the storage space 13a increases as it goes in the pressing direction Z.

  According to this, since the width h of the gap between the punch 11 and the storage space forming member 13 increases as the punch 11 moves in the pressing direction Z, the pressure loss in the gap between the punch 11 and the storage space forming member 13 increases. Can be suppressed. As a result, an increase in the pressure of the hydraulic oil in the storage space 13a can be suppressed, so that the pressure acting on the molding dies 11 and 12 can be suppressed from becoming excessive.

  For example, the storage space forming member 13 only needs to have a stepped cylinder shape in which the cross-sectional area of the storage space 13a gradually increases in the pressing direction Z. The storage space forming member 13 may have a tapered column shape in which the cross-sectional area of the storage space 13a continuously expands in the pressing direction Z.

  In the present embodiment, the punch 11 has a shape in which a portion opposite to the pressing direction Z is thinner than a portion on the pressing direction Z side.

  According to this, since the length L of the gap between the punch 11 and the storage space forming member 13 is smaller than when the thickness of the punch 11 is constant, the gap between the punch 11 and the storage space forming member 13 is reduced. An increase in pressure loss can be suppressed. As a result, an increase in the pressure of the hydraulic oil in the storage space 13a can be suppressed, so that the pressure acting on the molding dies 11 and 12 can be suppressed from becoming excessive.

  For example, the punch 11 only needs to have a stepped pillar shape with a step between a portion opposite to the pressing direction Z and a portion on the pressing direction Z side. The punch 11 may have a taper shape that becomes continuously thinner toward the opposite side of the pressing direction Z.

(Other embodiments)
The above embodiment can be variously modified as follows, for example. Each embodiment can be appropriately combined.

  (1) When driving the punch 11 to the workpiece 1 side, the punch driving unit 14 and the control device 15 may decrease the driving speed of the punch 11 over time.

  Here, the flow rate Q of the hydraulic oil flowing through the gap between the punch 11 and the storage space forming member 13 is expressed by the following formula F3.

Q = v × A−ΔQ F3
In Formula F3, v is the drive speed (push-in speed) of the punch 11. In Formula F3, A is a cross-sectional area of the gap between the punch 11 and the storage space forming member 13. In Formula F3, ΔQ is a leakage reduction amount due to viscous resistance when hydraulic oil (working liquid , working fluid ) flows through the gap between the punch 11 and the storage space forming member 13.

  Considering the case where the cross-sectional area A of the gap between the punch 11 and the storage space forming member 13 is constant, the punch 11 is driven toward the workpiece 1 when the drive speed v of the punch 11 is decreased with time. Accordingly, the flow rate Q of the hydraulic oil flowing through the gap between the punch 11 and the storage space forming member 13 is reduced.

  Therefore, as can be seen from the above-described mathematical formula F1, since an increase in pressure loss in the gap between the punch 11 and the storage space forming member 13 can be suppressed, an increase in the pressure of hydraulic oil in the storage space 13a can be suppressed, and as a result, a molding die It can suppress that the pressure which acts on 11 and 12 becomes excess.

  (2) In the above embodiment, the punch 11 has a cylindrical shape as a whole, and the storage space forming member 13 has a cylindrical shape as a whole. However, the present invention is not limited to this. 11 may have various column shapes (for example, prismatic shapes), and the storage space forming member 13 may have various tube shapes (for example, rectangular tube shapes).

  (3) In the above embodiment, the storage space forming member 13 is a separate member from the die 12, but the storage space forming member 13 may be a member integrated with the die 12.

(4) In the above embodiment, the hydraulic oil is used as working liquid for storing the storage space 13a (the working fluid), it is not limited thereto, various liquid working liquid such as water (working (Fluid) .

1 Workpiece (molding material)
11 Punch (upper die)
12 Die (lower mold)
13 storage space forming member 13a storage space 14 punch drive unit (drive means)
15 Control device (drive means)
Z pressing direction

Claims (5)

An upper mold (11) and a lower mold (12) for molding the material to be molded (1);
Drive means (14, 15) for driving the upper mold (11);
A cylindrical storage space forming member (13) that forms a storage space (13a) for storing the working fluid ;
In the storage space (13a), the molding material (1) is arranged,
When the driving means (14, 15) drives the upper mold (11) to the molding material (1) side, the upper mold (11) compresses the working fluid in the storage space (13a). While pressing the molding material (1),
The storage space forming member (13) has a shape in which the cross-sectional area of the storage space (13a) increases as it goes in the pressing direction (Z) in which the upper mold (11) presses the molding material (1). A forging device characterized by comprising:   The said upper metal mold | die (11) has the shape where the site | part on the opposite side to the said press direction (Z) became thin compared with the site | part on the said press direction (Z) side, It is characterized by the above-mentioned. Item 2. The forging device according to Item 1.   The said storage space formation member (13) has a stepped cylinder shape where the cross-sectional area of the said storage space (13a) expands in steps as it goes to the said pressing direction (Z). Item 3. The forging device according to Item 1 or 2.   The upper mold (11) has a stepped columnar shape with a step between a portion opposite to the pressing direction (Z) and a portion on the pressing direction (Z) side. The forging device according to claim 1.   The drive means (14, 15) reduces the drive speed of the upper mold (11) with time when driving the upper mold (11) toward the molding material (1). The forging device according to any one of claims 1 to 4.

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