JP2000263179A - Die forging method and die forging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a die forging method and a die forging apparatus capable of forging a molded product having a projecting part and a recessed part by forging in high material yield, productivity and precision hardly causing forging defects. SOLUTION: Firstly, a cavity 12 is formed at the side part of the upper end part of the forging blank 5. Successively, the forging blank 5 is pressed from its lower end side to allow the one end part of the blank 5 to project toward the cavity 12, then the cavity 12 is filled with the blank 5 to form the outer-shape thereof, thereby obtaining the projecting part. Thereafter, the recessed part is formed in the projecting part by punching the projecting part in the axial direction from the one end surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a die forging method and a die forging apparatus. In particular, the present invention relates to a die forging method and a die forging apparatus capable of accurately and accurately forging a molded product having an overhang portion and a concave portion.

[0002]

2. Description of the Related Art Conventionally, a brass hand shower support 6 as shown in FIG. 6 has been widely used. The hand shower support 6 has a cylindrical shape provided with a deep concave portion 1 for inserting a hand shower and a shallow concave portion 2 having a larger diameter than the concave portion.
Three. A small projection 4 is provided at the other end. In order to manufacture a product having such a complicated shape, casting is generally used. However, for this type of housing parts, the appearance is beautiful (they must be shiny), but for cast products, the amount of work involved in the process of polishing the surface becomes enormous, which increases the manufacturing cost. Would.

In order to solve such a problem, Japanese Patent Laid-Open Publication No. Hei 7-236937 discloses a forging method which enables high-precision forging to improve product quality. I have. According to this forging method, the forging material is accommodated in the cavity formed by the upper mold and the lower mold, and when the upper mold is lowered and brought into close contact with the lower mold, the cavity is formed by the upper punch of the upper mold. The forging material in the inside is subjected to primary forging to fluidly deform at least to the root of the bevel gear, and then the forging material is subjected to secondary forging by the lower punch by lowering the upper mold and the lower mold in close contact. The bevel gear is forged by flowing deformation to the tip of the bevel gear.

On the other hand, Japanese Patent Publication (JP-B) No. 7-
No. 16751 discloses a forging method and a forging device for a product having an overhang portion and a concave portion. In this forging device, a fixed plate, a die, and a die spin are provided as a lower die, and a movable plate, a base, a holder, a punch body, a spring for elastically biasing the punch body, and a movable plate as an upper die. Pins are provided. The overhang of the product is formed by molding or machining, and then the recess is formed by forging. This forging device is provided with a die retreat mechanism for applying a pressing force (or holding force) to the die spin, and when the movable pin is driven downward while the punch body is lowered to clamp the molded material, The concave portion is forged by lowering the die spin by a volume equal to the pushing volume of the movable pin. It is described that a recess having a depth of at least 20 times the forming hole diameter can be forged by this. Examples of the die retreat mechanism include a mechanism configured to apply hydraulic pressure to the pressure receiving portion of the holder supporting the die spin, and a rack-pinion type interlock mechanism that reduces the moving speed of the movable platen and transmits it to the die spin. Things are listed.

[0005]

However, according to the forging method disclosed in Japanese Patent Application Laid-Open No. Hei 7-236937, it is possible to forge a protruding portion of a product but not to form a concave portion. On the other hand, Tokiko 7-1675
According to the forging method described in No. 1, it is difficult to increase the yield and productivity of the material because the overhang of the product must be formed by molding or machining.

Therefore, if the overhanging portion and the concave portion of the product are to be forged at the same time, there is a problem that the formability of forming the overhanging portion is deteriorated and a forging defect is easily generated. In particular, in the case where there is a wall-shaped portion that needs to be filled with a material in a direction opposite to the direction in which the concave portion is formed in order to form the overhang, the formability of forming the wall-shaped portion is deteriorated, and forging is performed. Defects are likely to occur. The reason is considered as follows.

When a substantially constant and low back pressure is applied to the die spin, the die spin is prevented from retreating by the lower die or the lower fixing plate fixing the lower die when the recess is formed. Eventually, the pressure of the material rises and the overhanging portion is filled with the material, so that the material flows so as to return from the tip of the concave portion. That is, since the material is deformed by the backward extrusion, a pressing force for overcoming the frictional force is required in addition to the pressing force necessary for filling the material. In addition, since the material is liable to be entangled due to the backward extrusion, the shape of the overhanging portion may be large.
And it is difficult to shape the overhang portion into a sharp shape.

On the other hand, when a substantially constant and high back pressure is applied to the die spin, the pressing force required to press the upper punch becomes extremely large, so that not only the upper punch is easily buckled, but also In addition, there is a problem that the material flows in the clearance between the punch and the die, and many burrs are generated on the surface of the component.

In view of the above, the present invention relates to a die forging method for forging a molded article having an overhanging portion and a concave portion, which has high material yield, high productivity and high molding accuracy, and which hardly generates forging defects. And a die forging device.

[0010]

In order to solve the above problems, a die forging method according to the present invention forms a predetermined shape by plastically flowing a forged material in an forging die by pressing the material in an axial direction. A forging method comprising: a first step of defining a cavity on one side of an axial direction of a forged material; and pressing the forged material from the other axial side of the forged material to form one end of the forged material. A second step of forming the outer shape by filling the overhang into the overhanging cavity, thereby obtaining an overhang, and after the second step, projecting from the end face of one end and punching the body in the axial direction to overhang the body. And forming a recess in the body.

A die forging apparatus according to the present invention is a die forging apparatus for forming a predetermined shape by plastically flowing a forged material by axially pressing the forged material in a forging die; A first die and a second die that can be combined so as to define a cavity on one side, and first driving means for driving at least one of the first and second dies. The first die is supported movably in the axial direction by the second die, and presses the forged material when the first and second dies are combined, thereby filling one end of the forged material into the cavity and projecting. A die spin for forming the portion, a second driving means for driving the die spin, and a concave portion formed on the forged material, which is supported by the first die so as to be movable in the axial direction and has an overhang portion. Characterized by comprising a punch for, and a third drive means for driving the punch.

According to the present invention, by continuously forming the overhang portion and the concave portion on the forged material, it is possible to increase the material yield, the productivity and the forming accuracy, and to suppress the occurrence of forging defects. Further, the outer shape of the overhang portion can be accurately formed.

After forming the first concave portion, a second concave portion having a diameter larger than the first concave portion and shallower than the first concave portion is continuously formed in the overhang portion by using the second punch disposed on the outer peripheral portion of the punch. May be formed. In this case, the flow inhibition of the material which occurs when the first concave portion and the second concave portion are simultaneously formed does not occur, and it is possible to prevent the overhanging portion from being cut off.

Further, a notch may be provided in a part of the die spin for pressing the forging material from the other end side. In this case, at the same time as forming the overhanging portion, a convex portion can be formed on a part of the other end surface of the forged material.

Here, when forming the recess, the die spin contacting the other end of the forged material may be retracted while applying back pressure. In this case, the so-called flow-back, in which the volume in the concave portion of the forged material is pushed up in the opposite direction to the punch, does not occur, and the forged material flows continuously and smoothly, so that the product does not have micro cracks .
Further, since the pressing force of the punch may be substantially equal to the material processing force, the depth of the concave portion can be freely set without buckling of the punch. A die forging method according to another aspect of the present invention is a die forging method in which a forged material is plastically flowed by being axially pressed in a forging die to form a predetermined shape; A step of punching a punch in the forging material in the axial direction from the end face of one end to form a concave portion, and thereafter, a second step disposed on the outer peripheral portion of the punch.
The punch further includes a B step of forming a second concave portion having a diameter larger than the concave portion and shallower than the concave portion on the end face. In the A step, the die spin contacting the other end of the forged material is subjected to a back pressure. And retreating while applying Also in this case, the so-called flow-back in which the volume in the concave portion of the forged material is pushed up in the direction opposite to the punch does not occur, and the forged material flows continuously and smoothly, so that a fine crack does not occur in the product. Also,
Since the pressing force of the punch may be substantially equal to the material processing force, the depth of the concave portion can be freely set without buckling of the punch.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 are views showing a die forging method according to the present invention in the order of steps. FIG. 1A shows the die forging device in a standby state, and the temperature of a predetermined portion of the die forging device is adjusted to obtain an optimal crystal structure of a molded product.

First, a die forging apparatus according to the present invention will be described. A lower die 10 fixed to a main body frame (not shown) supports a die pin 11 so as to be movable in the axial direction. The die spin 11 is driven up and down by a hydraulic cylinder 14 as driving means. For this reason, the upper end of the piston rod 14 a of the hydraulic cylinder 14 is connected to the die pin 11. A notch is provided in a part of the upper surface of the die spin 11. Reference numeral 61 in the figure denotes a heater for heating the die, and reference numeral 62 denotes a heater for heating the die.
Is a temperature sensor, and reference numeral 63 is a temperature controller. These operations will be described later.

On the other hand, the upper die 20 is driven up and down by a hydraulic cylinder 22 as driving means. Therefore, the lower end of the piston rod 22 a of the hydraulic cylinder 22 is connected to the upper die 20. The hydraulic cylinder 2
The number of 2 may be one or more, but here two hydraulic cylinders 22 are used. The inner die 21 is supported by the upper die 20 so as to be movable in the axial direction. The inner punch 21 is driven up and down by a hydraulic cylinder 23 as driving means. Therefore, the lower end of the piston rod 23 a of the hydraulic cylinder 23 is connected to the inner punch 21. An outer punch 24 is supported on the outer periphery of the inner punch 21 so as to be movable in the axial direction. The outer punch 24 is elastically urged upward by a compression spring 25.

In FIG. 1B, a forging material 5 is put into a lower die 10 (above a die spin 11).

In FIG. 1C, the upper die 20, the inner punch 21, and the outer punch 24 are integrally lowered, and the lower surface of the upper die 20 is brought into close contact with the upper surface of the lower die 10, so that the forging material 5 is formed. A cavity 12 surrounding the upper end is defined (clamping). At this stage, the forged material 5 is not compressed.

In FIG. 2 (D), when the die spin 11 rises, the forged material 5 flows and deforms, forming an overhang 3 on the upper part of the forged material 5 and a part of the lower surface of the forged material 5. A projection (convex portion) 4 is formed on the substrate.

2 (E) to 2 (F), the inner punch 21 is lowered, and the formation of the deep first concave portion proceeds.
At that time, the die spin 11 retreats downward while applying back pressure to the forged material 5. Here, the die spin 11 is lowered by a volume equal to the pressed volume of the inner punch 21.

In FIG. 3G, the inner punch 21
The lower surface 21a of the large diameter portion and the upper surface 2 of the outer punch 24
4a, the outer punch 24 starts to descend together with the inner punch 21. Thus, the shaping of the shallow second concave portion is started. At that time, die spin 11
Moves the forged material 5 downward while applying back pressure.
Here, the die spin 11 is lowered by a volume equal to the pressed volume of the inner punch 21 and the outer punch 24.

In FIG. 3H, the inner punch 21
And the lowering of the outer punch 24 stops, and the first recess 1
And the molding of the second concave portion 2 is completed. Next, FIG.
In FIG. 4, the inner punch 21 is pulled up,
In (J), the upper die 20, the inner punch 21,
The outer punch 24 rises as a unit (mold opening). Further, in FIG. 4 (K), by raising the die spin 11, the hand shower support bracket 6 is removed from the lower die (knock out), and the entire process is completed.

Next, a hydraulic control system of the die forging apparatus according to the present embodiment will be described with reference to FIG.
As shown in FIG. 5, the hydraulic control system includes a hydraulic supply device 41 for supplying hydraulic pressure to the cylinders 14, 22, and 23.
And a hydraulic circuit including electromagnetic directional switching valves 42 to 44, electromagnetic proportional relief valves 45 and 46, a plurality of detection switches 47, and a control unit 48. The hydraulic supply device 41 has a hydraulic pump, a drive motor, and an oil tank.

Here, the electromagnetic type directional control valve 42 is installed in an oil path for supplying hydraulic pressure to the cylinder 22, and the electromagnetic directional control valve 43 is installed in an oil path for supplying hydraulic pressure to the cylinder 14. The direction switching valve 44 is installed in an oil passage that supplies oil pressure to the cylinder 23.

The electromagnetic proportional relief valve 45 is connected to an oil passage for supplying hydraulic pressure to the cylinder 14,
Is supplied with a hydraulic pressure set by an electromagnetic proportional relief valve 45. By setting the electromagnetic proportional relief valve 45,
The back pressure of the die spin 11 is also set. Similarly, the electromagnetic proportional relief valve 46 is connected to an oil passage that supplies oil pressure to the cylinder 23, and the electromagnetic proportional relief valve 4 is connected to the cylinder 23.
The hydraulic pressure set at 6 is supplied.

The plurality of detection switches 47 are connected to the upper die 20.
And a detection switch for detecting the upper limit position and the lower limit position of the inner punch 21, and the like.

The control unit 48 has a microcomputer and an input / output interface. Based on detection signals from the plurality of detection switches 47, the ROM of the microcomputer stores the hydraulic pressure supply device 41, the electromagnetic directional change valves 42 to 44, and the electromagnetic proportional relief valves 45 and 46.
Is stored, and the microcomputer performs a control operation in accordance with the control program.

In the above embodiment, the lower die 1
The upper die 20 was moved with 0 fixed, but conversely,
The upper die 20 may be fixed and the lower die 10 may be moved.

In the die forging method and the die forging apparatus described above, brass having good workability is desirable as a material of the forging material, but conventional brass has a problem in corrosion resistance and the like as compared with bronze. Therefore, as a preferred embodiment, it is desirable that the molded article after cooling satisfies at least one of the following crystal structures (1) to (3).

(1) The area ratio of α + β phase and β phase is 20
% Or more, the average crystal grain size of the α phase and the β phase is 15 μm or less, and the Sn concentration in the β phase is 1.5 wt.
% Crystal structure. (2) The area ratio of the α + γ phase and the γ phase is 3 to 30%, the average crystal grain size of the α phase is 15 μm or less, the average crystal grain size (minor axis) of the γ phase is 8 μm or less, and γ A crystal structure in which the Sn concentration in the phase is 8 wt% or more and the γ phase is scattered at the grain boundaries of the α phase. (3) The area ratio of α + β + γ phase and α phase is 40 to 94
%, The area ratio of the β phase and the α phase is 3 to 30%, respectively, the average crystal grain size of the α phase and the β phase is 15 μm or less, and the average crystal grain size (minor axis) of the γ phase is 8 μm or less. Therefore, the Sn concentration in the γ phase is 8 wt% or more,
Crystal structure surrounding the phase.

According to the crystal structures (1) to (3),
The first feature is that the Japan Copper and Brass Association Technical Standard (JBMA)
In the dezincification corrosion test according to T-303), the maximum dezincification depth is 100 μm or less when parallel to the processing direction, and 70 μm or less when perpendicular to the processing direction. As a second feature, when the cylindrical sample is exposed to an ammonia atmosphere on a 14% aqueous ammonia solution for 24 hours while applying a load of stress 180 N / mm ² , the sample has an SCC resistance that the sample is not broken.

As a third feature, it has a 0.2% proof stress or a yield stress of 300 N / mm ² or more. As a fourth feature, it has erosion corrosion resistance.

In order to obtain the above crystal structure, a forged material having an apparent Zn content of 37 to 50 wt% and a Sn content of 1.7 to 2.2 wt% is used. Here, the term “apparent Zn content” means that A is the Cu content (wt%), and B is the Zn content (wt%).
%), The Zn equivalent of the third element (for example, Sn) to which t is added, and Q is the content (wt%) of the third element.
“{(B + t · Q) / (A + B + t · Q)} × 100”
Used in the sense of

According to the above composition, a γ phase having a short-axis average crystal grain size of 15 μm or less can be present in the crystal structure of the forged material during forging. Due to such a crystal structure during processing, sufficient ductility can be ensured even when plastic deformation occurs while recrystallization occurs in a low temperature range of 300 to 550 ° C. Further, by setting the temperature difference between the start of forging and the end of forging within 20 degrees, the ductility of the material can be made substantially constant between the start of processing and the end of processing, thereby improving the formability.

The above effects can also be achieved by reducing the temperature difference between the forged material and the punch or die to 20 degrees or less, or by heating the punch or die to 300 to 550 ° C. In order to control the temperature of the punch or the die in this way, a heater and a temperature sensor (61 and 62 in FIG. 1A) are incorporated in the punch or the die, and the heater or the heater is controlled based on a detection signal output from the temperature sensor. The amount of heat generated may be controlled by a temperature controller (63 in FIG. 1A).

[0038]

As described above, according to the present invention, when forging a molded article having an overhang portion and a concave portion, the material yield, productivity and molding accuracy are increased, and forging defects are less likely to occur. be able to.

[Brief description of the drawings]

FIG. 1 is a view showing steps (A) to (C) in a die forging method according to an embodiment of the present invention.

FIG. 2 is a view showing steps (D) to (F) in a die forging method according to an embodiment of the present invention.

FIG. 3 is a view showing steps (G) to (I) in the die forging method according to one embodiment of the present invention.

FIG. 4 is a view showing steps (J) to (K) in a die forging method according to an embodiment of the present invention.

FIG. 5 is a diagram showing a hydraulic system used in the die forging device according to one embodiment of the present invention.

FIG. 6 is a view showing the shape of a hand shower support.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Deep concave part 2 Shallow concave part 3 Overhang part 4 Projection 5 Forging material 6 Hand shower support metal fitting 10 Lower die 11 Diespin 12 Cavity 14, 2
2, 23 Hydraulic cylinders 14a, 22a, 23a Piston rod 20 Upper die 21 Inner punch 22 Hydraulic cylinder 24 Outer punch 41 Hydraulic supply device 42-44
Electromagnetic directional change valve 45, 46 Electromagnetic proportional relief valve 47 Detection switch 48 Control unit 61 Heater 62 Temperature sensor 63 Temperature controller

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) B21J 13/02 B21J 13/02 M (72) Inventor Jun Yamauchi 2-chome Nakajima, Kokurakita-ku, Kitakyushu-shi, Fukuoka No.1 F-term (reference) in Tohoku Kikai Co., Ltd. 4E087 AA04 AA08 AA10 BA07 CA11 CA14 CA24 CA27 CA33 CB03 CB04 CB11 DA04 DA05 DB15 DB16 DB24 EA11 EB03 EC12 EC14 EC18 EC22 EC37 EC41 EC50 EC54 EC57 ED12 EE02 GA03 GA20 HA29B HB13

Claims (15)

[Claims] 1. A die forging method in which a forged material is plastically flowed by being axially pressed in a forging die to form a predetermined shape; a cavity is formed at one axial side of the forged material. A first step of defining, and pressing the forging material from the other axial end of the forging material, thereby projecting the one end of the forging material to fill the cavity and form the outer shape of the same. A second step of obtaining an overhang by this, a third step of, after the second step, axially punching a punch into the overhang from the end surface of the one end to form a recess in the overhang. A die forging method, comprising: 2. After the third step, a second concave portion having a diameter larger than the concave portion and shallower than the concave portion is formed in the overhanging portion of the overhanging body by using a second punch arranged on an outer peripheral portion of the punch. The method according to claim 1, further comprising a fourth step of performing the following. 3. The method according to claim 2, wherein the second step includes forming a projection on a part of the other end surface of the forging material by using a notch provided in a part of a die spin for pressing the forging material from the other end side. The method according to claim 1, further comprising molding. 4. The die forging method according to claim 1, wherein said third step includes retreating a die spin in contact with said other end of said forging material while applying back pressure. 5. The molded product after forging and cooling has an α + β phase and a β phase area ratio of 20% or more, an α phase and a β phase having an average crystal grain size of 15 μm or less, and a β phase The die forging method according to any one of claims 1 to 4, wherein the tin forging method is made of a brass material having a crystal structure having a Sn concentration of 1.5 wt% or more. 6. The molded article after forging and cooling has an α + γ phase and γ phase area ratio of 3 to 30%, an average crystal grain size of α phase of 15 μm or less, and an average of short axes of γ phase. The crystal grain size is 8 μm or less, and the Sn concentration in the γ phase is 8 wt.
% Or more, and is made of a brass material having a crystal structure in which a γ phase is scattered at a grain boundary of an α phase.
4. The die forging method according to any one of 4 above. 7. The molded product after forging and cooling is α + β +
The area ratio of the γ phase and the α phase is 40 to 94%, the area ratio of the β phase and the α phase is 3 to 30%, respectively, the average crystal grain size of the α phase and the β phase is 15 μm or less, The average crystal grain size of the axis is 8 μm or less, the Sn concentration in the γ phase is 8 wt% or more, and the γ phase is made of a brass material having a crystal structure surrounding the α phase. Item 1
The die forging method according to any one of claims 1 to 4. 8. The method according to claim 1, wherein the forging material is a brass material,
5. The die forging according to claim 1, wherein the third step includes heating the contact portion between the forging die and the forging material to 300 to 550 ° C. for forging. 6. Method. 9. A forging apparatus for forming a predetermined shape by plastically flowing a forged material in an forging direction by pressurizing the forged material in an axial direction; a cavity is formed at one axial side of the forged material. A first die and a second die that can be combined in a defined manner; first driving means for driving at least one of the first and second dies; and a second die. It is supported movably in the axial direction, and by pressing the forged material when the first and second dies are combined, one end of the forged material is filled in the cavity to form an overhang portion. A die spin for molding, a second driving means for driving the die spin, and the forging material, which is supported by the first die so as to be movable in an axial direction, and in which the overhang portion is formed. Die forging apparatus characterized by comprising a punch for forming a recess, and a third drive means for driving the punch, the. 10. A second concave portion having a diameter larger than the concave portion and shallower than the concave portion is formed inside the forged material, which is disposed on the outer peripheral portion of the punch so as to be movable in the axial direction, and in which the overhang portion is formed. The die forging device according to claim 9, further comprising a second punch. 11. The die forging apparatus according to claim 9, wherein the die spin has a notch for forming a convex part in a part of the forging material. 12. When the punch forms a recess in the forged material, the second driving means drives the die spin in contact with the forged material to retreat while applying back pressure. The die forging apparatus according to claim 9, wherein 13. A heating means for heating the punch, a temperature detecting means for detecting a temperature of a predetermined portion of the punch and outputting a detection signal, and a detection signal outputted from the temperature detecting means. And a temperature control means for controlling the heating means.
13. The die forging apparatus according to any one of 12. 14. A heating means for heating at least one of the first and second dies, a temperature detecting means for detecting a temperature of a predetermined portion of the dies and outputting a detection signal, The die forging apparatus according to any one of claims 9 to 12, further comprising: a temperature control unit that controls the heating unit based on a detection signal output from the temperature detection unit. 15. A die forging method in which a forged material is plastically flowed by being axially pressed in a forging die and formed into a predetermined shape; said forged material being cut from an end face at one axial end of said forged material. A step of forming a concave portion by driving a punch in the axial direction into the inside, and then using a second punch disposed on the outer peripheral portion of the punch, forming a second shallower, larger diameter and shallower than the concave portion on the end face. A die forging method, further comprising a B step of forming a concave portion, wherein in the A step, the die spin contacting the other end of the forging material is retracted while applying back pressure.