EP1884299A1 - Punching method and punching device - Google Patents
Punching method and punching device Download PDFInfo
- Publication number
- EP1884299A1 EP1884299A1 EP06756578A EP06756578A EP1884299A1 EP 1884299 A1 EP1884299 A1 EP 1884299A1 EP 06756578 A EP06756578 A EP 06756578A EP 06756578 A EP06756578 A EP 06756578A EP 1884299 A1 EP1884299 A1 EP 1884299A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- hole punching
- punch
- raw material
- scheduled portion
- hole
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
- B21J5/06—Methods for forging, hammering, or pressing; Special equipment or accessories therefor for performing particular operations
- B21J5/10—Piercing billets
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D28/00—Shaping by press-cutting; Perforating
- B21D28/02—Punching blanks or articles with or without obtaining scrap; Notching
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
- B21J5/02—Die forging; Trimming by making use of special dies ; Punching during forging
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
- B21J5/06—Methods for forging, hammering, or pressing; Special equipment or accessories therefor for performing particular operations
- B21J5/08—Upsetting
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
- B21K1/00—Making machine elements
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
- B21K1/00—Making machine elements
- B21K1/14—Making machine elements fittings
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
- B21K1/00—Making machine elements
- B21K1/76—Making machine elements elements not mentioned in one of the preceding groups
- B21K1/761—Making machine elements elements not mentioned in one of the preceding groups rings
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
- B21K1/00—Making machine elements
- B21K1/76—Making machine elements elements not mentioned in one of the preceding groups
- B21K1/766—Connecting rods
Definitions
- the present invention relates to a method and an apparatus for hole punching for use in manufacturing hole punched products, such as, e.g. , arms or connecting rods for vehicles (e.g., automobiles, or railroad vehicles).
- holes punched products such as, e.g. , arms or connecting rods for vehicles (e.g., automobiles, or railroad vehicles).
- Japanese Unexamined Laid-open Patent Publication No. H11-147157 discloses a method in which a preform is roughly molded in a cavity (molding space) of a closed die in one press cycle, then a hole punching scheduled portion is forged with a punch inserted in the closed die so that a thin material remains, and lastly the remained material is removed by punching processing with a punch (see Patent Document 1).
- Patent Document 1 Japanese Unexamined Laid-open Patent Publication No. H11-147157
- the remained material is required to be removed by punching after the full enclosed die forging, which requires a high forming load to prevent occurrence of underfill at the time of forging and results in low yield of materials.
- the present invention was made in view of the aforementioned technical background, and aims to provide a hole punching method capable of executing hole punching at a low load with high yield of materials and further preventing occurrence of underfill, a hole punched product obtained by the method, and a hole punching apparatus for use in the aforementioned hole punching method.
- the present invention has the following means.
- a hole punching method comprising:
- the method further includes a diameter expanding step of expanding the hole punching scheduled portion of the raw material with an upsetting apparatus in advance to the expanding step, the upsetting apparatus being provided with a fixing die for securing the raw material, the fixing die being connected to the closed die, a guide having an insertion hole for inserting and holding the hole punching scheduled portion of the raw material in a buckling preventing state, and a pressure punch, and the guide having a pair of diameter expansion preventing protruded portions each protruded in an axial direction of the guide and integrally formed at opposed portions of the tip end portion of the guide across the insertion hole, wherein, at the diameter expansion step, the hole punching scheduled portion of the raw material secured to the fixing die is disposed in the cavity and the hole punching scheduled portion of the raw material is inserted
- a hole punching apparatus comprising:
- the apparatus further includes an upsetting apparatus for expanding the hole punching scheduled portion of the raw material before expanding the hole punching scheduled portion of the raw material, wherein the upsetting apparatus is provided with a fixing die for securing the raw material, the fixing die being connected to the closed die, a guide having an insertion hole for inserting and holding the hole punching scheduled portion of the raw material in a buckling preventing state, and a pressure punch for axially pressing the hole punching scheduled portion of the raw material inserted in the insertion hole of the guide, and a punch driving apparatus for moving the guide in a direction opposite to a moving direction of the pressure punch, the guide having a pair of diameter expansion preventing protruded portions each protruded in an axial direction of the guide and integrally formed at opposed portions of the tip end portion of the
- the present invention has the following effects.
- the hold punching scheduled portion of the raw material disposed within the cavity of the closed die is pressed from the opposite sides thereof across the hold punching scheduled portion with the pair of large and small diameter punches to expand the hole punching scheduled portion so that unfilled portions remain in the cavity. Therefore, the hole punching scheduled portion can be expanded within the cavity at a low load.
- a hole can be formed by a relatively small load since a small diameter hole is opened in the hole punching scheduled portion by penetrating the small diameter punch into the hole punching scheduled portion of the raw material. Furthermore, the penetration operation of the small diameter punch causes the material of the hole punching scheduled portion of the raw material to be filled in the unfilled portions located at the penetration front side of the small diameter punch among the unfilled portions in the cavity.
- the small diameter hole can be expanded by penetrating the large diameter punch into the small diameter hole formed in the hole punching scheduled portion of the raw material to thereby form a large diameter hole in the hole punching scheduled portion, the hole can be opened at a relatively low load. Furthermore, the penetration operation of the large diameter punch causes the material of the hole punching scheduled portion of the raw material to be filed in the unfilled portions located at the penetration front side of the large diameter punch among the unfilled portions in the cavity. Consequently, almost all of the unfilled portions in the cavity disappear and the entire cavity is filled with the material, which in turn prevents occurrence of underfill.
- the hole punching method of this invention is not a method in which a hole is formed by punching and removing the material of the hole punching scheduled portion of the raw material, and therefore the yield of material is high.
- the tapered tip end portion of the small diameter punch enables penetration of the hole punching scheduled portion of the raw material at a low load. Furthermore, since the peripheral surface of the tip end portion of the small diameter punch is formed by plural stepped taper surfaces arranged so as to decrease in taper angle gradually stepwise toward the tip of the small diameter punch, the forming load can be adjusted to a prescribed value by setting the plural stepped taper angles of the small diameter punch.
- the penetration operation of the small diameter punch enables an effective radially outward expansion of the hole punching scheduled portion of the raw material, which enables assured filling of the material of the hole punching scheduled portion of the raw material in the unfilled portions located at the penetration front side of the small diameter punch among the unfilled portions in the cavity.
- the tapered tip end portion of the large diameter punch enables penetration of the large diameter punch into the hole punching scheduled portion of the raw material at a low load. Furthermore, since the peripheral surface of the tip end portion of the large diameter punch is formed by tapered surfaces with the number of steps fewer than N, the tapered surfaces being arranged so as to decrease the taper angle gradually stepwise toward the tip end of the large diameter portion, or formed by a single step of a taper surface, the forming load can be adjusted to a prescribed value.
- the penetration operation of the large diameter punch enables effective radially outward expansion of the hole punching scheduled portion of the raw material, thereby enabling assured filling of the material of the hole punching scheduled portion of the material in the unfilled portions located at the penetration front side of the large diameter punch among the unfilled portions in the cavity.
- the excessive material can be prevented from flowing out of the closed die.
- a hole punching apparatus which can be preferably used for the hole punching method of the present invention can be provided.
- Fig. 1 is an exploded perspective view of a hole punching apparatus according to an embodiment of the present invention.
- Fig. 2 is a cross-sectional perspective view of the hole punching apparatus in the state before expanding the hole punching scheduled portion of the raw material with the hole punching apparatus.
- Fig. 3 is a horizontal cross-sectional view of the hole punching apparatus in the state shown in Fig. 2.
- Fig. 4 is a cross-sectional view taken along the line A-A in Fig. 2.
- Fig. 5 is a cross-sectional perspective view of the hole punching apparatus in the middle of expanding the hole punching scheduled portion of the raw material with the hole punching apparatus.
- Fig. 6 is a horizontal cross-sectional view of the hole punching apparatus in the state shown in Fig. 5.
- FIG. 7 is a cross-sectional perspective view of the hole punching apparatus in the state after expanding the hole punching scheduled portion of the raw material with the hole punching apparatus.
- Fig. 8 is a horizontal cross-sectional view of the hole punching apparatus in the state shown in Fig. 7.
- Fig. 9 is a cross-sectional view taken along the line B-B in Fig. 7.
- Fig. 10 is a cross-sectional view of the hole punching apparatus in the state in which the hole punching scheduled portion of the raw material was expanded with the hole punching apparatus.
- Fig. 11 is a cross-sectional view of the hole punching apparatus in the state in which the hole punching scheduled portion of the raw material was penetrated by a small diameter punch with the hole punching apparatus.
- Fig. 8 is a horizontal cross-sectional view of the hole punching apparatus in the state shown in Fig. 7.
- Fig. 9 is a cross-sectional view taken along the line B-B in Fig. 7.
- Fig. 10 is
- FIG. 12 is a cross-sectional view of the hole punching apparatus in the state in which the hole punching scheduled portion of the raw material was penetrated by a large diameter punch with the hole punching apparatus.
- Fig. 13 is a perspective view of the punched member obtained by the hole punching apparatus.
- Fig. 1 denotes a hole punching apparatus according to this embodiment, and “1” denotes a raw material. Furthermore, in Fig. 13, “6” denotes a hole punched product (hole punched article) manufactured with the hole punching apparatus 1. This hole punched product 6 is used as a preform for manufacturing arms for vehicles, such as, e. g. , automobiles or railroad vehicles.
- the raw material 1 is a straight bar-shaped member made of, e.g., aluminum (including its alloy).
- the raw material 1 is circular in cross-section and constant in cross-sectional area along the axial direction.
- the quality of material of the raw material 1 is not limited to aluminum, and can be metal, such as, e.g., brass, copper, or stainless steel, or plastic.
- the cross-sectional configuration of the raw material 1 is not limited to a circle configuration, and can be a polygonal configuration, such as, e. g. , a square configuration or a hexagonal configuration.
- the hole punching scheduled portion 2 of this raw material 1 is located at each of the axial end portions of the raw material 1. More specifically, it is located at both end portions of the raw material 1. In other words, both the end portions of the raw material 1 are defined as hole punching scheduled portions 2.
- Each of the hole punching scheduled portions 2 of the raw material 1 is expanded into an approximate circular plate shape, and thereafter the expanded hole punching scheduled portion is punched to thereby obtain a hole punched product 6 as shown in Fig. 13.
- a hole punched portion 5 corresponds to a connecting portion to be connected with other component of an arm for vehicles.
- the hole 3 formed in this hole punched portion 5 corresponds to, e. g. , a bush mounting hole. This hole 3 is penetrated in the thickness direction of the hole punching scheduled portion 2 expanded into a circular plate shape, and is circular in cross-sectional configuration.
- each hole punched portion 5 is 70 mm in diameter, 24 mm in thickness, the hole 3 is 30 mm in diameter, and the length between the hole punched portions 5 and 5 is 300 mm.
- the raw material 1 is 18 mm in diameter.
- the dimension of each portion of the punched product 6 and the diameter of the raw material 1 are not limited to the above-mentioned dimension.
- the dimension of each portion and the diameter of the raw material 1 can be set so that the purpose of the present invention can be attained in accordance with the manufacture of the punched product 6, such as, e.g., an arm for vehicles (e.g., cars, or railroad vehicles), or a connecting rod.
- the hole punching apparatus 10 of this embodiment is for forming a hole 3 in the hole punching scheduled portion 2 of the raw material 1, and, as shown in Fig. 1, is equipped with a closed die 11 (closed die assembly), two pairs of punches 13 and 15 (i.e., hole punches), a punch driving apparatus 30 for moving each punch 13 and 15, and an upsetting apparatus 20.
- a closed die 11 closed die assembly
- two pairs of punches 13 and 15 i.e., hole punches
- a punch driving apparatus 30 for moving each punch 13 and 15, and an upsetting apparatus 20.
- the closed die 11 has two cavities 12 and 12 each for forming each hole punching scheduled portion 2 of the raw material 1 into a prescribed configuration (i.e., a circular plate). Both the cavities 12 and 12 are disposed apart from each other in the axial direction of the closed die 11. Furthermore, this closed die 11 is divided into two pieces, or upper and lower pieces, along the axial direction.
- the hole punching scheduled portions 2 of the raw material 1 are to be placed.
- the pair of punches 13 and 15 are formed into a circular configuration in cross-section, respectively. Each punch 13 and 15 is for forming a hole 3 in the corresponding hole punching scheduled portion 2 of the raw material 1. Both the punches 13 and 15 are different in diameter. Both the punches 13 and 15 are disposed so as to face each other across the hole punching scheduled portion 2 of the raw material 1 placed in the cavity 12. In other words, both the punches 13 and 15 are placed so as to face each other at opposite sides across the cavity 12. In this embodiment, the punches 13 and 15 are vertically faced each other.
- the punch having a larger diameter will be referred to as “large diameter punch 15”
- the punch having a smaller diameter will be referred to as “small diameter punch 13.”
- the diameter of the large diameter punch 15 is set to the same diameter as the diameter of the prescribed hole 3.
- the diameter of the small diameter punch 13 is set to a diameter smaller than the diameter of the large diameter punch 15, and is decided by calculation depending on various conditions, such as, e.g., the ability of the punch driving apparatus 30 for driving the small diameter punch 13, the stroke of the small diameter punch 13 required for punching the hole punching scheduled portion 2, or the taper angle of the peripheral surface of the tip end portion of the small diameter punch 13.
- the diameter of the small diameter punch 13 is set so as to fall within the range of 0.4 times or more of the diameter of the large diameter punch 15 and less than 1 time of the diameter of the larger diameter punch 15 (preferably, from 0.66 to 0.95 times). In the present invention, however, the diameter of the small diameter punch 13 is not necessarily required to fall within the aforementioned range.
- the tip end portion 14 of the small diameter punch 13 is formed into a tapered shape as shown in Fig. 4. Furthermore, the peripheral surface of the tip end portion 14 of the small diameter punch 13 is formed by plural stepped taper surfaces 14a and 14b gradually decreasing stepwise in taper angle ⁇ 1 and ⁇ 2 toward the tip end of the small diameter punch 13. In this embodiment, the number of steps of the taper surfaces 14a and 14b is two. Therefore, among these taper angles ⁇ 1 and ⁇ 2 of these taper surfaces 14a and 14b, the taper angle ⁇ 1 of the first step counted from the tip end of the small diameter punch 13 and the taper angle ⁇ 2 of the second step counted therefrom are set to ⁇ 1 ⁇ 2.
- the tip end portion 16 of the large diameter punch 15 is formed into a tapered shape.
- N the number of steps of the taper surfaces 14a and 14b forming the peripheral surface of the tip end portion 14 of the small diameter punch 13
- the peripheral surface of the tip end portion 16 of the large diameter punch 15 is formed by taper surfaces having the number of steps smaller than N and arranged so that the taper angle decreases gradually stepwise toward the tip end of the large diameter punch 15.
- N 2
- the peripheral surface of the tip end portion 16 of the large diameter punch 15 is formed by a single step taper surface 16a.
- " ⁇ 1" denotes a taper angle of this taper surface 16a.
- the taper angle ⁇ 1, ⁇ 2 or ⁇ 1 of the taper surface 14a, 14b or 16a denotes an angle of the taper surface 14a, 14b or 16a to the axis of the punch 13 or 15.
- each punch 13 and 15 is formed into a flat configuration. In the present invention, however, it is not limited that the tip end face of each punch 13 and 15 is formed into a flat configuration, and can be formed into, for example, a convex configuration.
- Both the punches 13 and 15 are connected to punch driving apparatuses 30, respectively. It is configured such that the operation of the punch driving apparatus 30 causes frontward and backward movements of the corresponding punch 13 and 15, or the punch 13 and 15 can be advanced into and retreated from the cavity 12.
- the punch driving apparatus 30 is configured to give driving force to the punch 13 and 15 by, e.g., machine cams using a pressing machine, fluid pressure (e.g., oil pressure, or gas pressure), or an electric motor.
- fluid pressure e.g., oil pressure, or gas pressure
- Punch insertion holes 17 and 17 each for fitting the corresponding punch 13 and 15 are formed in the opposite portions (upper and lower portions in this embodiment) of the closed die 11 facing across the cavity 12 so as to communicate with the cavity 12.
- Each punch 13 and 15 is inserted in the corresponding punch insertion hole 17 and 17 in a vertically movable manner.
- a gap 18 and 18 is formed between the peripheral surface of each punch 13 and 15 and the peripheral surface of each punch insertion hole 17 and 17 (the so-called clearance between the punch 13 and 15 and the punch insertion hole 17 and 17) along the entire periphery of each punch 13 and 15 in the peripheral direction thereof.
- a dam portion 13a and 15b for preventing the excessive material 2a flowed into the gap 18 from being flowed out of the closed die 11 is integrally formed radially outwardly along the entire periphery of the punch 13 and 15.
- the upsetting apparatus 20 is for simultaneously expanding both the hole punching scheduled portions 2 and 2 of the raw material 1.
- This upsetting apparatus 20 is equipped with, as shown in Figs. 1 to 3, a fixing die 21 for fixing the raw material 1, the fixing die 21 being connected to the closed die 11, two guides 22 and 22, two pressure punches 25 and 25 (i.e. , upsetting punches), two guide driving apparatuses 32 and 32, and two pressure punch driving apparatuses 33 and 33.
- the fixing die 21 consists of a portion of the closed die 11 located between both the cavities 12 and 12, and is integrally formed with the closed die 11.
- the fixing die 21 is divided into upper and lower halves along the axial direction.
- the divided members of the closed die 11 and the fixing die 21 are held by a die holding member (not illustrated) in a mutually assembled manner, so that the closed die 11 and fixing die 21 cannot be disassembled unexpectedly.
- the closed die 11 and the fixing die 21 can be separated members.
- the fixing die 21 is for securing the raw material 1 so as not to move in the axial direction unexpectedly at the time of the diameter expansion.
- the fixing die 21 is provided with a raw material fixing insertion hole 21a for securing an axial intermediate portion 4 of the raw material 1 as a non-hole punching scheduled portion in a fitted manner.
- the insertion hole 21a is extended in an axial direction of the fixing die 21 and communicated with both the cavities 12 and 12.
- the two guides 22 and 22 are the same in structure.
- Each guide 22 has an insertion hole 23 for fitting and holding the corresponding hole punching scheduled portion 2 of the raw material 1 in a buckling preventing state.
- This insertion hole 23 is extended in the axial direction of the guide 20 and penetrated in the guide 20.
- the diameter of this insertion hole 23 is set to a size capable of closely fitting and axially slidably inserting the hole punching scheduled portion 2 of the raw material 1.
- a pair of diameter expansion preventing protruded portions 24 are integrally protruded from the tip end portion of the guide 22 in the axial direction of the guide 22, so that the protruded portions 24 are moved together with the guide 22 in accordance with the movement of the guide 22.
- a part of the peripheral surface of the hole punching scheduled portion 2 of the raw material 1 inserted in the insertion hole 23 of the guide 22 comes into contact with the side surface 24a of each protruded portion 24 facing to the insertion hole 23 at the time of expanding the hole punching scheduled portion 2, whereby the expansion of the contacting portion of the hole punching scheduled portion 2 in contact with the protruded portion 24 is controlled.
- a slide groove portion 19 extended in the axial direction of the closed die 11 is formed, respectively, so that the protruded portion 24 of the guide 22 is slidably inserted in this slide groove portion 19 in the axial direction of the closed die 16.
- the side surface 24a of the protruded portion 24 of the guide 22 with which a part of the peripheral surface of the hole punching scheduled portion 2 of the raw material 1 comes into contact is formed into a surface corresponding to the peripheral surface configuration of the hole punching scheduled portion 2 where the raw material is expanded in diameter.
- the side surface 24a of the protruded portion 24 is flush with the upper or lower surface of the cavity 12.
- the side surface 24a of this protruded portion 24 is formed into a flat configuration corresponding to the surface of the circle configuration of the thickness direction both sides of the hole punching scheduled portion 2 expanded into an approximately circular plate.
- each guide 22 is divided into two pieces, i.e., upper and lower pieces, divided by a dividing plane longitudinally dividing the insertion hole 23.
- the divided members of each guide 22 are held by a guide holding member (not illustrated) in a mutually assembled manner, so that the guide 22 is not disassembled unexpectedly.
- Each pressure punch 25 is for axially pressurizing a corresponding hole punching scheduled portion 2 of the raw material 1. Both the pressure punches 25 and 25 are disposed at the axial both end portions of the raw material 1 so as to face each other.
- Each pressure punch driving apparatus 33 is for moving each pressure punch 25 in the axial direction of the raw material 1 to thereby give driving force for pressurizing the hole punching scheduled portion 2 of the raw material 1 to the pressure punch 25.
- Each pressure punch driving apparatus 33 is connected to the corresponding pressure punch 25.
- the pressure punch driving apparatus 33 is configured to give driving force to the pressure punch 25 with machine cams using, e.g. , a pressing machine, fluid pressure (e.g., oil pressure, gas pressure), or electric motors.
- Each guide driving apparatus 32 is for moving each guide 22 in a direction 27 opposite to the moving direction 28 of the corresponding pressure punch 25 (i.e., in the pressurizing direction to the raw material hole punching scheduled portion 2 by the pressure punch 25) (see Fig. 6).
- Each guide driving apparatus 32 is connected to the corresponding guide 22.
- the guide driving apparatus 32 is configured to give driving force to the guide 22 with machine cams or fluid pressure using, e.g., pressing machines (e.g., oil pressure or gas pressure), electric motors, or springs.
- each hole punching scheduled portion 2 of the raw material 1 is preliminarily expanded in diameter by the upsetting apparatus 20 of the hole punching apparatus 10 [DIAMETER EXPANSION STEP].
- both the hole punching scheduled portions 2 and 2 of the raw material 1 will be simultaneously expanded in diameter.
- the raw material 1 is secured to the fixing die 21 so that the raw material 1 cannot be unexpectedly moved in the axial direction while disposing each hole punching scheduled portion 2 of the raw material 1 in the corresponding cavity 12.
- the hole punching scheduled portion 2 of the raw material 1 is placed in the cavity 12 in a penetrated manner. Therefore, only the portions of the hole punching scheduled portion 2 of the raw material 1 near the axial intermediate portion of the raw material 1 are placed in the cavities 12, and the end portions of the hole punching scheduled portions 2 are placed so as to protrude from the cavities 12.
- each hole punching scheduled portion 2 of the raw material 1 is inserted in the corresponding insertion hole 23 of the guide 22 to thereby hold each hole punching scheduled portion 2 in a buckling preventing state. Furthermore, the corresponding protruded portion 24 of the guide 22 is inserted into each slide groove portion 19 of the closed die 11. In this state, the opposing portions of the peripheral surface of each hole punching scheduled portion 2 of the raw material 1 are in contact with the side surfaces 24a and 24a of both the protruded portions 24 and 24 of the guide 22.
- both the guides 22 and 22 are simultaneously moved in a direction 27 opposite to the moving direction 28 of the corresponding pressure punch 25 by simultaneously operating both the guide driving apparatuses 32 and 32.
- the traveling speed of the pressure punch 25 and the traveling speed of the guide 22 are set depending on the diameter expansion designed shape of the hole punching scheduled portion 2 of the raw material 1. Such traveling speed can be constant or variable.
- the hole punching scheduled portion 2 of the raw material 1 is gradually expanded in the cavity 12 and the material of the hole punching scheduled portion 2 is filed in the cavity 12 in a state in which the contacting portions of the hole punching scheduled portion 2 in contact with the guide protruded portions 24 and 24 are restricted from being expanded in diameter.
- Both the hole punching scheduled portions 2 and 2 of the raw material 1 are expand in diameter as mentioned above.
- hole punching is executed to each hole punching scheduled portion 2 formed by expanding the raw material 1 according to the following procedures.
- both the punches 13 and 15 simultaneously press the hole punching scheduled portion 2 from the opposite sides across the hole punching scheduled portion 2 so that the tip ends of both the punches 13 and 15 do not come into contact with each other.
- both the punches 13 and 15 press the hole punching scheduled portion 2 from the expansion restriction direction sides of the hole punching scheduled portion 2 by the protruded portions 24 and 24 of the guide 22 (i.e., both thickness sides of the hole punching scheduled portion 2).
- the tip end portions 14 and 16 of both the punches 13 and 15 are pressed into the hole punching scheduled portion 2 to thereby expand the hole punching scheduled portion 2 within the cavity 12 [EXPANDING STEP].
- portions in the cavity 12 where the material of the hole punching scheduled portion 2 is not filled i. e. , unfilled portions M, remain in the state where the hole punching scheduled portion 2 of the raw material 1 has been extended.
- the hole punching scheduled portion 2 it is preferable to simultaneously press the hole punching scheduled portion 2 with both the punches 13 and 15. If the pressurization of the hole punching scheduled portion 2 with both the punches 13 and 15 is not performed simultaneously, the inflow amount of the material of the hole punching scheduled portion 2 into the gaps 18 and 18 between the peripheral surfaces of the punches 13 and 15 and the peripheral surfaces of the punch insertion holes 17 and 17 increases, which may cause deterioration of the material yield. In the present invention, however, it is not always required to simultaneously perform the pressurization of the hole punching scheduled portion 2 with both the punches 13 and 15.
- the tip end portion 14 of the small diameter punch 13 is pressed into the hole punching scheduled portion 2 more deeply to penetrate the small diameter punch 13 into the hole punching scheduled portion 2 in the thickness direction [PENETRATION STEP BY SMALL DIAMETER PUNCH 13]. Consequently, a small diameter through-hole 3a corresponding to the diameter of the small diameter punch 13 is formed in the hole punching scheduled portion 2.
- the small diameter punch 13 can penetrate the hole punching scheduled portion 2 after releasing the pressurization to the hole punching scheduled portion 2 of the raw material 1 by the large diameter punch 15.
- the penetration operation of the small diameter punch 13 into the hole punching scheduled portion 2 causes the excessive material 2a of the hole punching scheduled portion 2 to be flowed into the gaps 18 and 18 between the peripheral surfaces of the punches 13 and 15 and the peripheral surfaces of the punch insertion holes 17 and 17 from the inside of the cavity 12.
- This inflow excessive material 2a cause burrs.
- the inflow excessive material 2a is dammed by the dam portions 13a and 15a to thereby prevent the discharge of the excessive material 2a to the outside.
- the front side unfilled portion M1 located at the front side of the penetration direction of the small diameter punch 13 will be filled with the material of the hole punching scheduled portion 2 of the raw material 1.
- the tip end portion 16 of the large diameter punch 15 is pressed into the small diameter hole 3a formed in the hole punching scheduled portion 2 to thereby penetrate the large diameter punch 15 in the hole punching scheduled portion 2 [PENETRATION STEP BY LARGE DIAMETER PUNCH 15].
- the small diameter hole 3a is expanded, which in turn can form a desired large diameter hole 3 corresponding to the diameter of the large diameter punch 15 in the hole punching scheduled portion 2.
- the penetration of the large diameter punch 15 into the hole punching scheduled portion 2 can be performed after pulling out the small diameter punch 13 from the hole punching scheduled portion 2.
- the penetration operation of the large diameter punch 15 into the hole punching scheduled portion 2 causes the excessive material 2a of the hole punching scheduled portion 2 to flow into the gaps 18 and 18 between the peripheral surfaces of punches 13 and 15 and the peripheral surfaces of the punch insertion holes 17 and 17 from the inside of the cavity 12.
- the inflow excessive material 2a cause burrs.
- the inflow excessive material 2a is dammed by the dam portions 13a and 15a of the punches 13 and 15 to thereby prevent the discharge of the excessive material 2a to the outside.
- the large diameter punch 15 is retreated from the cavity 12 to pull out the large diameter punch 15 penetrated in the hole punching scheduled portion 2 from the hole punching scheduled portion 2.
- the closed die 11 and the fixing die 21 are disassembled to remove the raw material 1 from the inside of the cavity 12. Thereafter, burrs 2a formed on the periphery of the hole 3 are removed as need arises to obtain a prescribed hole punched product (preform) as shown in Fig. 13.
- the hold punching scheduled portion 2 of the raw material 1 disposed within the cavity 12 of the closed die 11 is pressed from the opposite sides thereof across the hold punching scheduled portion 2 with the pair of large and small diameter punches 13 and 15 to expand the hole punching scheduled portion 2 so that unfilled portions M remain in the cavity 12. Therefore, the hole punching scheduled portion 2 can be expanded within the cavity 12 at a low load.
- a hole 2a can be formed by a relatively small load since a small diameter hole 2a is opened in the hole punching scheduled portion 2 by penetrating the small diameter punch 13 into the hole punching scheduled portion 2 of the raw material 1. Furthermore, the penetration operation of the small diameter punch 13 causes the material of the hole punching scheduled portion 2 of the raw material 1 to be filled in the unfilled portion M1 located at the penetration front side of the small diameter punch 13 among the unfilled portions M in the cavity 12.
- the small diameter hole 2a is expanded by penetrating the large diameter punch 15 into the small diameter hole 2a formed in the hole punching scheduled portion 2 of the raw material 1 to form a large diameter hole 3 in the hole punching scheduled portion 2, the hole 3 can be opened at a relatively low load. Furthermore, the penetration operation of the large diameter punch 15 causes the material of the hole punching scheduled portion 2 of the raw material 1 to be filed in the unfilled portion M2 located at the penetration front side of the large diameter punch 15 among the unfilled portions M in the cavity 12. Consequently, all the unfilled portions M in the cavity 12 disappear and the entire cavity 12 is filled with the material, which prevents occurrence of underfill.
- the tapered tip end portion 14 of the small diameter punch 13 enables penetration of the hole punching scheduled portion 2 of the raw material 1 at a low load. Furthermore, since the peripheral surface of the tip end portion 14 of the small diameter punch 13 is formed by two stepped taper surfaces 14a and 14b arranged so as to decrease in taper angle ⁇ 1 and ⁇ 2 gradually stepwise toward the tip of the small diameter punch 13, the forming load can be adjusted to a prescribed value by setting the two stepped taper angles ⁇ 1 and ⁇ 2 of the small diameter punch 13.
- the penetration operation of the small diameter punch 13 enables an effective radially outward expansion of the hole punching scheduled portion 2 of the raw material 1, which enables assured filling of the material of the hole punching scheduled portion 2 of the raw material 1 to the small diameter punch penetration front side portion M1 of the unfilled portions M in the cavity 12.
- the tapered tip end portion 16 of the large diameter punch 15 enables penetration of the large diameter punch 15 into the hole punching scheduled portion 2 of the raw material 1 at a low load. Furthermore, the one step taper surface 16a of the peripheral surface of the tip end portion 16 of the large diameter punch 15 enables adjustment of the forming load to a prescribed value by setting the taper angle ⁇ 1 of the taper surface 16a. And, the penetration operation of the large diameter punch 15 enables effective radially outward expansion of the hole punching scheduled portion 2 of the raw material 1, thereby enabling assured filling of the material of the hole punching scheduled portion 2 of the material 1 to the large diameter punch penetration front side portion M2 of the unfilled portions M in the cavity 12, which assuredly prevents occurrence of underfill.
- dam portion 13a and 15a for preventing the outward flow of the excessive material 2a flowed into the gap 18 is formed at the peripheral surface of each punch 13 and 15, the excessive material 2a can be prevented from flowing out of the closed die 11.
- the hole punching scheduled portion 2 of the raw material 1 is pressed by both the punches 13 and 15 so that the tip ends of the punches 13 and 15 do not come into contact with each other. Therefore, occurrence of breakages and/or damages of the punch tip end portions 14 and 16, which may occur due to the contact of the tips of both the punches 13 and 15, can be prevented.
- the hole punching method of this embodiment includes, before the expanding step, a diameter expansion step in which the hole punching scheduled portion 2 of the raw material 1 is expanded in diameter in advance.
- a diameter expansion step in which the hole punching scheduled portion 2 of the raw material 1 is expanded in diameter in advance.
- the hole punching scheduled portion 2 is pressed with both the punches 13 and 15 from the diameter expansion restriction sides by the guide protruded portions 24 and 24. Therefore, in the case where the hole punching scheduled portion 2 of the raw material 1 is expanded in diameter beforehand and then hole punching is executed to the hole punching scheduled portion 2, these processing can be performed effectively.
- the hole punching method and the hole punching apparatus according to the present invention are not limited to a method and an apparatus for manufacturing a preform for manufacturing arms of vehicles, and can also be used to manufacture various preforms for industrial products, such as, e.g., a preform for connecting rods or a preform for gears with a shaft hole.
- the hole punching scheduled portion 2 of the raw material 1 can be only one place, such as, e.g., an axial intermediate portion or an axial one end portion of the raw material 1.
- the shape of the raw material 1 is not limited to a bar shape, and the present invention can be applied to raw materials 1 of various configurations.
- the raw material 1 can be an extruded material, a rolled material, such as, e.g., a continuously cast rolled material manufactured by a Properzi method, or can be any material manufactured by any other production methods.
- the present invention can be applied to a hole punching method and a hole punching apparatus for manufacturing a hole punched product, such as, e.g., an arm or a connecting rod for vehicles (e.g., automobiles, railroad vehicles).
- a hole punching method for manufacturing a hole punched product
- a hole punching apparatus for manufacturing a hole punched product, such as, e.g., an arm or a connecting rod for vehicles (e.g., automobiles, railroad vehicles).
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Abstract
Description
- The present invention relates to a method and an apparatus for hole punching for use in manufacturing hole punched products, such as, e.g. , arms or connecting rods for vehicles (e.g., automobiles, or railroad vehicles).
- Conventionally, in manufacturing hole punched products by forging, from the viewpoint of die life and safety, in place of directly executing hole punching of a hole punching scheduled portion of a raw material, it is common to initially form and shape the hole punching scheduled portion of the raw material so that a thin wall remains and then to remove the thin wall by, e.g., trimming.
- On the other hand,
Japanese Unexamined Laid-open Patent Publication No. H11-147157
Patent Document 1: Japanese Unexamined Laid-open Patent PublicationNo. H11-147157 - In the aforementioned conventional hole punching method, the remained material is required to be removed by punching after the full enclosed die forging, which requires a high forming load to prevent occurrence of underfill at the time of forging and results in low yield of materials.
- The present invention was made in view of the aforementioned technical background, and aims to provide a hole punching method capable of executing hole punching at a low load with high yield of materials and further preventing occurrence of underfill, a hole punched product obtained by the method, and a hole punching apparatus for use in the aforementioned hole punching method.
- The present invention has the following means.
- [1] A hole punching method, comprising:
- a step of expanding a hole punching scheduled portion of a raw material disposed in a cavity of a closed die by pressing the hole punching scheduled portion from opposite sides thereof across the hole punching scheduled portion with a pair of large diameter punch and small diameter punch different in diameter and arranged so as to face each other so that unfilled portions remain in the cavity;
- a step of penetrating the small diameter punch into the hole punching scheduled portion of the raw material while releasing or after releasing pressurization by the large diameter punch to the hole punching scheduled portion; and
- a step of penetrating the large diameter punch into the hole punching scheduled portion of the raw material while pulling out or after pulling out the small diameter punch penetrated in the hole punching scheduled portion of the raw material from the hole punching scheduled portion of the raw material.
- [2] The hole punching method as recited in the
aforementioned Item 1, wherein a tip end portion of the small diameter punch is formed into a tapered shape, and wherein a peripheral surface of the tip end portion of the small diameter punch is formed by plural stepped taper surfaces arranged so as to decrease in taper angle gradually stepwise toward the tip end portion of the small diameter punch. - [3] The hole punching method as recited in the
aforementioned Item 2, wherein, when the number of steps of the taper surfaces forming the peripheral surface of the tip end portion of the small diameter punch is N (N≧2), a tip end portion of the large diameter punch is formed into a tapered shape, and a peripheral surface of the tip end portion of the large diameter punch is formed by stepped taper surfaces whose step number is smaller than N and arranged so as to decrease a taper angle gradually stepwise toward the tip end portion of the large diameter punch, or formed by a single step taper surface. - [4] The hole punching method as recited in any one of the
aforementioned Items 1 to 3, wherein the closed die is provided with punch insertion holes each for inserting each punch, each punch insertion hole being communicated with the cavity, and
wherein, in a state in which each punch is inserted in the corresponding punch insertion hole, gaps for receiving excessive material of the hole punching scheduled portion of the raw material from the cavity are formed between peripheral surfaces of the punches and peripheral surfaces of the punch insertion holes. - [5] The hole punching method as recited in the
aforementioned Item 4, wherein a dam portion for preventing the excessive material flowed into the gaps from discharging to an outside is formed at the peripheral surface of the punch so as to expand toward a radially outward of the punch. - [6] The hole punching method as recited in any one of the
aforementioned Items 1 to 5, wherein, at the step of expanding, the hole punching scheduled portion is pressed from opposite sides thereof across the hole punching scheduled portion with both the punches so that the tip ends of both the punches do not come into contact with each other. - [7] The hole punching method as recited in any one of the
aforementioned Items 1 to 6, wherein the raw material is a bar shaped material in which an axial prescribed portion of the raw material is defined as the hole punching scheduled portion,
wherein the method further includes a diameter expanding step of expanding the hole punching scheduled portion of the raw material with an upsetting apparatus in advance to the expanding step, the upsetting apparatus being provided with a fixing die for securing the raw material, the fixing die being connected to the closed die, a guide having an insertion hole for inserting and holding the hole punching scheduled portion of the raw material in a buckling preventing state, and a pressure punch, and the guide having a pair of diameter expansion preventing protruded portions each protruded in an axial direction of the guide and integrally formed at opposed portions of the tip end portion of the guide across the insertion hole,
wherein, at the diameter expansion step, the hole punching scheduled portion of the raw material secured to the fixing die is disposed in the cavity and the hole punching scheduled portion of the raw material is inserted and held in the insertion hole of the guide, and then, the guide is moved in a direction opposite to a moving direction of the pressure punch while axially pressing the hole punching scheduled portion of the raw material with the pressure punch by moving the pressure punch, to thereby expand the hole punching scheduled portion of the raw material exposed between the tip end portion of the guide and the fixing die in the cavity in a state in which contacting portions of the hole punching scheduled portion in contact with the guide protruded portions are prevented from being expanded in diameter, and
wherein, at the expanding step, the expanded hole punching scheduled portion of the raw material is pressed with both the punches from both sides of the hole punching scheduled portion prevented in diameter expansion by the guide protruded portions in a state in which the hole punching scheduled portion expanded in diameter is disposed in the cavity. - [8] A hole punched product obtained by the hole punching method as recited in any one of the
aforementioned Items 1 to 7. - [9] A hole punching apparatus, comprising:
- a closed die having a cavity; and
- a pair of large diameter punch and small diameter punch different in diameter and disposed at opposite sides across a hole punching scheduled portion of a raw material disposed in the cavity of the closed die,
- [10] The hole punching apparatus as recited in the aforementioned Item 9, wherein a tip end portion of the small diameter punch is formed into a tapered shape, and wherein a peripheral surface of the tip end portion of the small diameter punch is formed by plural stepped taper surfaces arranged so as to decrease in taper angle gradually stepwise toward the tip end portion of the small diameter punch.
- [11] The hole punching apparatus as recited in the
aforementioned Item 10, wherein, when the number of steps of the taper surfaces forming the peripheral surface of the tip end portion of the small diameter punch is N (N≧2), a tip end portion of the large diameter punch is formed into a tapered shape, and a peripheral surface of the tip end portion of the large diameter punch is formed by stepped taper surfaces whose step number is smaller than N and arranged so as to decrease a taper angle gradually stepwise toward the tip end portion of the large diameter punch, or formed by a single step taper surface. - [12] The hole punching apparatus as recited in any one of the aforementioned Items 9 to 11, wherein the closed die is provided with punch insertion holes each for inserting each punch, each punch insertion hole being communicated with the cavity, and wherein, in a state in which each punch is inserted in the corresponding punch insertion hole, gaps for receiving excessive material of the hole punching scheduled portion of the raw material from the cavity are formed between peripheral surfaces of the punches and peripheral surfaces of the punch insertion holes.
- [13] The hole punching apparatus as recited in the
aforementioned Item 12, wherein a dam portion for preventing the excessive material flowed into the gaps from discharging to an outside is formed at the peripheral surface of the punch so as to expand toward a radially outward of the punch. - [14] The hole punching apparatus as recited in any one of the aforementioned Items 9 to 13, wherein the raw material is a bar shaped material in which an axial prescribed portion of the raw material is defined as the hole punching scheduled portion,
wherein the apparatus further includes an upsetting apparatus for expanding the hole punching scheduled portion of the raw material before expanding the hole punching scheduled portion of the raw material,
wherein the upsetting apparatus is provided with a fixing die for securing the raw material, the fixing die being connected to the closed die, a guide having an insertion hole for inserting and holding the hole punching scheduled portion of the raw material in a buckling preventing state, and a pressure punch for axially pressing the hole punching scheduled portion of the raw material inserted in the insertion hole of the guide, and a punch driving apparatus for moving the guide in a direction opposite to a moving direction of the pressure punch, the guide having a pair of diameter expansion preventing protruded portions each protruded in an axial direction of the guide and integrally formed at opposed portions of the tip end portion of the guide across the insertion hole, and
wherein a part of a peripheral surface of the hold punching scheduled portion is brought into contact with side surfaces of the protruded portions of the guide at the time of expanding the hole punching scheduled portion of the raw material to thereby prevent a contacting portion of the hole punching scheduled portion in contact with the protruded portions from being expanded. - The present invention has the following effects.
- According to the invention as recited in the aforementioned Item [1], the hold punching scheduled portion of the raw material disposed within the cavity of the closed die is pressed from the opposite sides thereof across the hold punching scheduled portion with the pair of large and small diameter punches to expand the hole punching scheduled portion so that unfilled portions remain in the cavity. Therefore, the hole punching scheduled portion can be expanded within the cavity at a low load.
- Furthermore, a hole can be formed by a relatively small load since a small diameter hole is opened in the hole punching scheduled portion by penetrating the small diameter punch into the hole punching scheduled portion of the raw material. Furthermore, the penetration operation of the small diameter punch causes the material of the hole punching scheduled portion of the raw material to be filled in the unfilled portions located at the penetration front side of the small diameter punch among the unfilled portions in the cavity.
- Furthermore, since the small diameter hole can be expanded by penetrating the large diameter punch into the small diameter hole formed in the hole punching scheduled portion of the raw material to thereby form a large diameter hole in the hole punching scheduled portion, the hole can be opened at a relatively low load. Furthermore, the penetration operation of the large diameter punch causes the material of the hole punching scheduled portion of the raw material to be filed in the unfilled portions located at the penetration front side of the large diameter punch among the unfilled portions in the cavity. Consequently, almost all of the unfilled portions in the cavity disappear and the entire cavity is filled with the material, which in turn prevents occurrence of underfill.
- The hole punching method of this invention is not a method in which a hole is formed by punching and removing the material of the hole punching scheduled portion of the raw material, and therefore the yield of material is high.
- According to the invention as recited in the aforementioned Item [2], the tapered tip end portion of the small diameter punch enables penetration of the hole punching scheduled portion of the raw material at a low load. Furthermore, since the peripheral surface of the tip end portion of the small diameter punch is formed by plural stepped taper surfaces arranged so as to decrease in taper angle gradually stepwise toward the tip of the small diameter punch, the forming load can be adjusted to a prescribed value by setting the plural stepped taper angles of the small diameter punch. Furthermore, the penetration operation of the small diameter punch enables an effective radially outward expansion of the hole punching scheduled portion of the raw material, which enables assured filling of the material of the hole punching scheduled portion of the raw material in the unfilled portions located at the penetration front side of the small diameter punch among the unfilled portions in the cavity.
- According to the invention as recited in the aforementioned Item [3], the tapered tip end portion of the large diameter punch enables penetration of the large diameter punch into the hole punching scheduled portion of the raw material at a low load. Furthermore, since the peripheral surface of the tip end portion of the large diameter punch is formed by tapered surfaces with the number of steps fewer than N, the tapered surfaces being arranged so as to decrease the taper angle gradually stepwise toward the tip end of the large diameter portion, or formed by a single step of a taper surface, the forming load can be adjusted to a prescribed value. And, the penetration operation of the large diameter punch enables effective radially outward expansion of the hole punching scheduled portion of the raw material, thereby enabling assured filling of the material of the hole punching scheduled portion of the material in the unfilled portions located at the penetration front side of the large diameter punch among the unfilled portions in the cavity.
- According to the invention as recited in the aforementioned Item [4], in the state where each punch is inserted in the corresponding punch insertion hole, a gap for receiving excessive material of the hole punching scheduled portion of the raw material from the cavity is formed between the peripheral surface of the punch and the peripheral surface of the punch insertion hole. Therefore, the material of the hole punching scheduled portion of the raw material can be filled in the unfilled portion in the cavity at a relatively low load.
- According to the invention as recited in the aforementioned Item [5], the excessive material can be prevented from flowing out of the closed die.
- According to the invention as recited in the aforementioned Item [6], occurrence of breakages and/or damages of the punch tip end portions, which may occur due to the contact of the tips of the punches, can be prevented.
- According to the invention as recited in the aforementioned Item [7], in the case where the hole punching scheduled portion of the raw material is expanded in diameter beforehand and then hole punching is executed to the hole punching scheduled portion, these processing can be performed effectively.
- According to the invention as recited in the aforementioned Item [8], a hole punched product with no or almost no underfill can be obtained.
- According to the invention as recited in the aforementioned Item [9] to [14], a hole punching apparatus which can be preferably used for the hole punching method of the present invention can be provided.
- Fig. 1 is an exploded perspective view of a hole punching apparatus according to an embodiment of the present invention.
Fig. 2 is a cross-sectional perspective view of the hole punching apparatus in the state before expanding the hole punching scheduled portion of the raw material with the hole punching apparatus.
Fig. 3 is a horizontal cross-sectional view of the hole punching apparatus in the state shown in Fig. 2.
Fig. 4 is a cross-sectional view taken along the line A-A in Fig. 2.
Fig. 5 is a cross-sectional perspective view of the hole punching apparatus in the middle of expanding the hole punching scheduled portion of the raw material with the hole punching apparatus.
Fig. 6 is a horizontal cross-sectional view of the hole punching apparatus in the state shown in Fig. 5.
Fig. 7 is a cross-sectional perspective view of the hole punching apparatus in the state after expanding the hole punching scheduled portion of the raw material with the hole punching apparatus.
Fig. 8 is a horizontal cross-sectional view of the hole punching apparatus in the state shown in Fig. 7.
Fig. 9 is a cross-sectional view taken along the line B-B in Fig. 7.
Fig. 10 is a cross-sectional view of the hole punching apparatus in the state in which the hole punching scheduled portion of the raw material was expanded with the hole punching apparatus.
Fig. 11 is a cross-sectional view of the hole punching apparatus in the state in which the hole punching scheduled portion of the raw material was penetrated by a small diameter punch with the hole punching apparatus.
Fig. 12 is a cross-sectional view of the hole punching apparatus in the state in which the hole punching scheduled portion of the raw material was penetrated by a large diameter punch with the hole punching apparatus.
Fig. 13 is a perspective view of the punched member obtained by the hole punching apparatus. -
- 1... raw material
- 2... hole punching scheduled portion
- 3... hole
- 6... hole punched product (preform)
- 10... hole punching apparatus
- 11... closed die
- 12... cavity
- 13... small diameter punch
- 14... tip end portion
- 15... large diameter punch
- 16... tip end portion
- 17... punch insertion hole
- 18... gap
- 19... slide groove portion
- 20... upsetting apparatus
- 21... fixing die
- 22... guide
- 23... insertion hole
- 24... diameter expansion preventing protruded portion
- 24a... side surface
- 25... pressure punch
- 27... guide moving direction
- 28... pressure punch moving direction
- 30... punch driving apparatus
- 32... guide driving apparatus
- 33... pressure punch driving apparatus
- M... unfilled portion
- Next, an embodiment of the present invention will be explained below with reference to the attached drawings.
- In Fig. 1, "10" denotes a hole punching apparatus according to this embodiment, and "1" denotes a raw material. Furthermore, in Fig. 13, "6" denotes a hole punched product (hole punched article) manufactured with the
hole punching apparatus 1. This hole punchedproduct 6 is used as a preform for manufacturing arms for vehicles, such as, e. g. , automobiles or railroad vehicles. - As shown in Fig. 1, the
raw material 1 is a straight bar-shaped member made of, e.g., aluminum (including its alloy). Theraw material 1 is circular in cross-section and constant in cross-sectional area along the axial direction. - In the present invention, the quality of material of the
raw material 1 is not limited to aluminum, and can be metal, such as, e.g., brass, copper, or stainless steel, or plastic. Moreover, the cross-sectional configuration of theraw material 1 is not limited to a circle configuration, and can be a polygonal configuration, such as, e. g. , a square configuration or a hexagonal configuration. - The hole punching scheduled
portion 2 of thisraw material 1 is located at each of the axial end portions of theraw material 1. More specifically, it is located at both end portions of theraw material 1. In other words, both the end portions of theraw material 1 are defined as hole punching scheduledportions 2. Each of the hole punching scheduledportions 2 of theraw material 1 is expanded into an approximate circular plate shape, and thereafter the expanded hole punching scheduled portion is punched to thereby obtain a hole punchedproduct 6 as shown in Fig. 13. - In this hole punched
product 6, the portion to which hole punching was executed, i.e., a hole punchedportion 5, corresponds to a connecting portion to be connected with other component of an arm for vehicles. Thehole 3 formed in this hole punchedportion 5 corresponds to, e. g. , a bush mounting hole. Thishole 3 is penetrated in the thickness direction of the hole punching scheduledportion 2 expanded into a circular plate shape, and is circular in cross-sectional configuration. - In this hole punched
product 6, for example, each hole punchedportion 5 is 70 mm in diameter, 24 mm in thickness, thehole 3 is 30 mm in diameter, and the length between the hole punchedportions raw material 1 is 18 mm in diameter. In the present invention, however, the dimension of each portion of the punchedproduct 6 and the diameter of theraw material 1 are not limited to the above-mentioned dimension. For example, the dimension of each portion and the diameter of theraw material 1 can be set so that the purpose of the present invention can be attained in accordance with the manufacture of the punchedproduct 6, such as, e.g., an arm for vehicles (e.g., cars, or railroad vehicles), or a connecting rod. - The
hole punching apparatus 10 of this embodiment is for forming ahole 3 in the hole punching scheduledportion 2 of theraw material 1, and, as shown in Fig. 1, is equipped with a closed die 11 (closed die assembly), two pairs ofpunches 13 and 15 (i.e., hole punches), apunch driving apparatus 30 for moving eachpunch apparatus 20. - The closed die 11 has two
cavities portion 2 of theraw material 1 into a prescribed configuration (i.e., a circular plate). Both thecavities closed die 11. Furthermore, this closed die 11 is divided into two pieces, or upper and lower pieces, along the axial direction. - In the
cavities 12 of theclosed die 11, the hole punching scheduledportions 2 of theraw material 1 are to be placed. - The pair of
punches punch hole 3 in the corresponding hole punching scheduledportion 2 of theraw material 1. Both thepunches punches portion 2 of theraw material 1 placed in thecavity 12. In other words, both thepunches cavity 12. In this embodiment, thepunches - In this specification, among both the
punches large diameter punch 15," and the punch having a smaller diameter will be referred to as "small diameter punch 13." - The diameter of the
large diameter punch 15 is set to the same diameter as the diameter of theprescribed hole 3. On the other hand, the diameter of thesmall diameter punch 13 is set to a diameter smaller than the diameter of thelarge diameter punch 15, and is decided by calculation depending on various conditions, such as, e.g., the ability of thepunch driving apparatus 30 for driving thesmall diameter punch 13, the stroke of thesmall diameter punch 13 required for punching the hole punching scheduledportion 2, or the taper angle of the peripheral surface of the tip end portion of thesmall diameter punch 13. For example, the diameter of thesmall diameter punch 13 is set so as to fall within the range of 0.4 times or more of the diameter of thelarge diameter punch 15 and less than 1 time of the diameter of the larger diameter punch 15 (preferably, from 0.66 to 0.95 times). In the present invention, however, the diameter of thesmall diameter punch 13 is not necessarily required to fall within the aforementioned range. - The
tip end portion 14 of thesmall diameter punch 13 is formed into a tapered shape as shown in Fig. 4. Furthermore, the peripheral surface of thetip end portion 14 of thesmall diameter punch 13 is formed by plural steppedtaper surfaces small diameter punch 13. In this embodiment, the number of steps of the taper surfaces 14a and 14b is two. Therefore, among these taper angles α1 and α2 of thesetaper surfaces small diameter punch 13 and the taper angle α2 of the second step counted therefrom are set to α1<α2. - The
tip end portion 16 of thelarge diameter punch 15 is formed into a tapered shape. For convenience of explanation, it is assumed that the number of steps of the taper surfaces 14a and 14b forming the peripheral surface of thetip end portion 14 of thesmall diameter punch 13 is N (N≧2). In this case, the peripheral surface of thetip end portion 16 of thelarge diameter punch 15 is formed by taper surfaces having the number of steps smaller than N and arranged so that the taper angle decreases gradually stepwise toward the tip end of thelarge diameter punch 15. In this embodiment, since N=2, the peripheral surface of thetip end portion 16 of thelarge diameter punch 15 is formed by a singlestep taper surface 16a. "β1" denotes a taper angle of thistaper surface 16a. - In the present invention, "N" is not limited to 2 (N=2), and can be, for example, 3, 4 or 5, as long as N≧2. Furthermore, the number of steps of the
taper surface 16a forming the peripheral surface of thetip end portion 16 of thelarge diameter punch 15 is not limited to one, and can be, for example, 1 or 2 in the case of N=3, 1 to 3 in the case of N=4, or 1 to 4 in the case of N=5, as long as the number of steps is smaller than N. - In this specification, the taper angle α1, α2 or
β 1 of thetaper surface taper surface punch - The tip end face of each
punch punch - Both the
punches apparatuses 30, respectively. It is configured such that the operation of thepunch driving apparatus 30 causes frontward and backward movements of the correspondingpunch punch cavity 12. - The
punch driving apparatus 30 is configured to give driving force to thepunch - Punch insertion holes 17 and 17 each for fitting the
corresponding punch closed die 11 facing across thecavity 12 so as to communicate with thecavity 12. Eachpunch punch insertion hole gap punch punch insertion hole 17 and 17 (the so-called clearance between thepunch punch insertion hole 17 and 17) along the entire periphery of eachpunch portion 2 of theraw material 1 flows into thisgap 18 from the cavity 12 (see Fig. 11 and Fig. 12). Theexcessive material 2 flowed into thisgap 18 will remain at the periphery of thehole 3 as burrs. - At the peripheral surface of each
punch dam portion 13a and 15b for preventing theexcessive material 2a flowed into thegap 18 from being flowed out of theclosed die 11 is integrally formed radially outwardly along the entire periphery of thepunch - The upsetting
apparatus 20 is for simultaneously expanding both the hole punching scheduledportions raw material 1. - This upsetting
apparatus 20 is equipped with, as shown in Figs. 1 to 3, a fixingdie 21 for fixing theraw material 1, the fixing die 21 being connected to theclosed die 11, twoguides guide driving apparatuses punch driving apparatuses - The fixing die 21 consists of a portion of the
closed die 11 located between both thecavities closed die 11. The fixing die 21 is divided into upper and lower halves along the axial direction. The divided members of theclosed die 11 and the fixing die 21 are held by a die holding member (not illustrated) in a mutually assembled manner, so that theclosed die 11 and fixing die 21 cannot be disassembled unexpectedly. In the present invention, theclosed die 11 and the fixing die 21 can be separated members. - The fixing die 21 is for securing the
raw material 1 so as not to move in the axial direction unexpectedly at the time of the diameter expansion. The fixing die 21 is provided with a raw material fixinginsertion hole 21a for securing an axialintermediate portion 4 of theraw material 1 as a non-hole punching scheduled portion in a fitted manner. Theinsertion hole 21a is extended in an axial direction of the fixing die 21 and communicated with both thecavities intermediate portion 4 of theraw material 1 is fitted in the raw material fixinginsertion hole 21a, theraw material 1 is immovably secured in the axial direction, and the diameter expansion and buckling of the axialintermediate portion 4 of theraw material 1 are prevented. - The two guides 22 and 22 are the same in structure. Each
guide 22 has aninsertion hole 23 for fitting and holding the corresponding hole punching scheduledportion 2 of theraw material 1 in a buckling preventing state. Thisinsertion hole 23 is extended in the axial direction of theguide 20 and penetrated in theguide 20. The diameter of thisinsertion hole 23 is set to a size capable of closely fitting and axially slidably inserting the hole punching scheduledportion 2 of theraw material 1. - A pair of diameter expansion preventing protruded
portions 24 are integrally protruded from the tip end portion of theguide 22 in the axial direction of theguide 22, so that the protrudedportions 24 are moved together with theguide 22 in accordance with the movement of theguide 22. A part of the peripheral surface of the hole punching scheduledportion 2 of theraw material 1 inserted in theinsertion hole 23 of theguide 22 comes into contact with theside surface 24a of each protrudedportion 24 facing to theinsertion hole 23 at the time of expanding the hole punching scheduledportion 2, whereby the expansion of the contacting portion of the hole punching scheduledportion 2 in contact with the protrudedportion 24 is controlled. - On the other hand, on the upper and lower surfaces of the
cavity 12 of theclosed die 11, aslide groove portion 19 extended in the axial direction of theclosed die 11 is formed, respectively, so that the protrudedportion 24 of theguide 22 is slidably inserted in thisslide groove portion 19 in the axial direction of theclosed die 16. - Furthermore, the
side surface 24a of the protrudedportion 24 of theguide 22 with which a part of the peripheral surface of the hole punching scheduledportion 2 of theraw material 1 comes into contact is formed into a surface corresponding to the peripheral surface configuration of the hole punching scheduledportion 2 where the raw material is expanded in diameter. In the state in which the protrudedportion 24 is inserted in theslide groove portion 19, theside surface 24a of the protrudedportion 24 is flush with the upper or lower surface of thecavity 12. In this embodiment, theside surface 24a of this protrudedportion 24 is formed into a flat configuration corresponding to the surface of the circle configuration of the thickness direction both sides of the hole punching scheduledportion 2 expanded into an approximately circular plate. - Furthermore, each
guide 22 is divided into two pieces, i.e., upper and lower pieces, divided by a dividing plane longitudinally dividing theinsertion hole 23. The divided members of eachguide 22 are held by a guide holding member (not illustrated) in a mutually assembled manner, so that theguide 22 is not disassembled unexpectedly. - Each
pressure punch 25 is for axially pressurizing a corresponding hole punching scheduledportion 2 of theraw material 1. Both the pressure punches 25 and 25 are disposed at the axial both end portions of theraw material 1 so as to face each other. - Each pressure
punch driving apparatus 33 is for moving eachpressure punch 25 in the axial direction of theraw material 1 to thereby give driving force for pressurizing the hole punching scheduledportion 2 of theraw material 1 to thepressure punch 25. Each pressurepunch driving apparatus 33 is connected to thecorresponding pressure punch 25. The pressurepunch driving apparatus 33 is configured to give driving force to thepressure punch 25 with machine cams using, e.g. , a pressing machine, fluid pressure (e.g., oil pressure, gas pressure), or electric motors. - Each
guide driving apparatus 32 is for moving eachguide 22 in adirection 27 opposite to the movingdirection 28 of the corresponding pressure punch 25 (i.e., in the pressurizing direction to the raw material hole punching scheduledportion 2 by the pressure punch 25) (see Fig. 6). Eachguide driving apparatus 32 is connected to thecorresponding guide 22. Theguide driving apparatus 32 is configured to give driving force to theguide 22 with machine cams or fluid pressure using, e.g., pressing machines (e.g., oil pressure or gas pressure), electric motors, or springs. - Now, a hole punching method using the aforementioned
hole punching apparatus 10 will be explained below. - Initially, as shown in Figs. 2 to 7, each hole punching scheduled
portion 2 of theraw material 1 is preliminarily expanded in diameter by the upsettingapparatus 20 of the hole punching apparatus 10 [DIAMETER EXPANSION STEP]. In this embodiment, both the hole punching scheduledportions raw material 1 will be simultaneously expanded in diameter. - This diameter expansion method will be explained below.
- As shown in Figs. 2 to 4, by fitting the axial
intermediate portion 4 which is a non-hole punching scheduled portion of theraw material 1 in the raw material fixinginsertion hole 21a of the fixing die 21, theraw material 1 is secured to the fixing die 21 so that theraw material 1 cannot be unexpectedly moved in the axial direction while disposing each hole punching scheduledportion 2 of theraw material 1 in the correspondingcavity 12. In this embodiment, the hole punching scheduledportion 2 of theraw material 1 is placed in thecavity 12 in a penetrated manner. Therefore, only the portions of the hole punching scheduledportion 2 of theraw material 1 near the axial intermediate portion of theraw material 1 are placed in thecavities 12, and the end portions of the hole punching scheduledportions 2 are placed so as to protrude from thecavities 12. - Furthermore, each hole punching scheduled
portion 2 of theraw material 1 is inserted in thecorresponding insertion hole 23 of theguide 22 to thereby hold each hole punching scheduledportion 2 in a buckling preventing state. Furthermore, the corresponding protrudedportion 24 of theguide 22 is inserted into eachslide groove portion 19 of theclosed die 11. In this state, the opposing portions of the peripheral surface of each hole punching scheduledportion 2 of theraw material 1 are in contact with the side surfaces 24a and 24a of both the protrudedportions guide 22. - Next, as shown in Figs. 5 and 6, while simultaneously axially pressurizing the hole punching scheduled
portions raw material 1 with the corresponding pressure punches 25 and 25 by moving both the pressure punches 25 and 25 by simultaneously operating both the pressurepunch driving apparatuses guides direction 27 opposite to the movingdirection 28 of thecorresponding pressure punch 25 by simultaneously operating both theguide driving apparatuses portion 2 of theraw material 1 exposed between the tip end portion of eachguide 22 and the fixing die 21 is brought into contact with the side surfaces 24a and 24a of the protrudedportions 24 of theguide 22 and therefore the contacting portion of the hole punching scheduledportion 2 in contact with the guide protrudedportions portion 2 in contact with the guide protruded portions 24) will be expanded in thecavity 12. - In the present invention, the traveling speed of the
pressure punch 25 and the traveling speed of theguide 22 are set depending on the diameter expansion designed shape of the hole punching scheduledportion 2 of theraw material 1. Such traveling speed can be constant or variable. - In accordance with the movement of the
pressure punch 25 and theguide 22, the hole punching scheduledportion 2 of theraw material 1 is gradually expanded in thecavity 12 and the material of the hole punching scheduledportion 2 is filed in thecavity 12 in a state in which the contacting portions of the hole punching scheduledportion 2 in contact with the guide protrudedportions - As shown in Figs. 7 to 9, when each hole punching scheduled
portion 2 of theraw material 1 is expanded into a prescribed configuration, the movements of the pressure punches 25 and theguides 22 are terminated. At this time, there remains a portions not filled with the material of the hole punching scheduledportion 2 of theraw material 1, i.e. , unfilled portions M, in thecavity 12. In this state, the hole punching scheduledportion 2 of theraw material 1 has been expanded into an approximately circular shape only in the widthwise directions, almost not in the thickness direction. - Both the hole punching scheduled
portions raw material 1 are expand in diameter as mentioned above. - Next, as shown in Fig. 10, hole punching is executed to each hole punching scheduled
portion 2 formed by expanding theraw material 1 according to the following procedures. - Without removing each expanded hole punching scheduled
portion 2 of theraw material 1 from thecavity 12, or in a state in which each expanded hole punching scheduledportion 2 remains in thecavity 12, thesmall diameter punch 13 and thelarge diameter punch 15 are simultaneously advanced into thecavity 12 by operating thepunch driving apparatuses punches portion 2 from the opposite sides across the hole punching scheduledportion 2 so that the tip ends of both thepunches punches portion 2 from the expansion restriction direction sides of the hole punching scheduledportion 2 by the protrudedportions tip end portions punches portion 2 to thereby expand the hole punching scheduledportion 2 within the cavity 12 [EXPANDING STEP]. - At this expanding step, however, as shown in this figure, portions in the
cavity 12 where the material of the hole punching scheduledportion 2 is not filled, i. e. , unfilled portions M, remain in the state where the hole punching scheduledportion 2 of theraw material 1 has been extended. - At this expanding step, it is preferable to simultaneously press the hole punching scheduled
portion 2 with both thepunches portion 2 with both thepunches portion 2 into thegaps punches portion 2 with both thepunches - Subsequently, as shown in Fig. 11, while releasing the pressurization to the hole punching scheduled
portion 2 of theraw material 1 with thelarge diameter punch 15 by retreating thelarge diameter punch 15 from thecavity 12, thetip end portion 14 of thesmall diameter punch 13 is pressed into the hole punching scheduledportion 2 more deeply to penetrate thesmall diameter punch 13 into the hole punching scheduledportion 2 in the thickness direction [PENETRATION STEP BY SMALL DIAMETER PUNCH 13]. Consequently, a small diameter through-hole 3a corresponding to the diameter of thesmall diameter punch 13 is formed in the hole punching scheduledportion 2. In the present invention, thesmall diameter punch 13 can penetrate the hole punching scheduledportion 2 after releasing the pressurization to the hole punching scheduledportion 2 of theraw material 1 by thelarge diameter punch 15. - The penetration operation of the
small diameter punch 13 into the hole punching scheduledportion 2 causes theexcessive material 2a of the hole punching scheduledportion 2 to be flowed into thegaps punches cavity 12. This inflowexcessive material 2a cause burrs. Furthermore, the inflowexcessive material 2a is dammed by thedam portions excessive material 2a to the outside. Furthermore, in accordance with the penetration operation of thissmall diameter punch 13, among the unfilled portions M in thecavity 12, the front side unfilled portion M1 located at the front side of the penetration direction of thesmall diameter punch 13 will be filled with the material of the hole punching scheduledportion 2 of theraw material 1. - Next, as shown in Fig. 12, while pulling out the
small diameter punch 13 penetrated in the hole punching scheduledportion 2 by retreating thesmall diameter punch 13 from thecavity 12, thetip end portion 16 of thelarge diameter punch 15 is pressed into thesmall diameter hole 3a formed in the hole punching scheduledportion 2 to thereby penetrate thelarge diameter punch 15 in the hole punching scheduled portion 2 [PENETRATION STEP BY LARGE DIAMETER PUNCH 15]. With this, thesmall diameter hole 3a is expanded, which in turn can form a desiredlarge diameter hole 3 corresponding to the diameter of thelarge diameter punch 15 in the hole punching scheduledportion 2. In the present invention, the penetration of thelarge diameter punch 15 into the hole punching scheduledportion 2 can be performed after pulling out thesmall diameter punch 13 from the hole punching scheduledportion 2. - The penetration operation of the
large diameter punch 15 into the hole punching scheduledportion 2 causes theexcessive material 2a of the hole punching scheduledportion 2 to flow into thegaps punches cavity 12. The inflowexcessive material 2a cause burrs. Furthermore, the inflowexcessive material 2a is dammed by thedam portions punches excessive material 2a to the outside. Furthermore, in accordance with the penetration operation of thislarge diameter punch 15, among the unfilled portions M in thecavity 12, the front side unfilled portion M2 located at the front side of the penetration direction of thelarge diameter punch 15 will be filled with the material of the hole punching scheduledportion 2 of theraw material 1. Consequently, all of the unfilled portions M in thecavity 12 disappear, and theentire cavity 12 is filled with the material. - Next, the
large diameter punch 15 is retreated from thecavity 12 to pull out thelarge diameter punch 15 penetrated in the hole punching scheduledportion 2 from the hole punching scheduledportion 2. - Next, the
closed die 11 and the fixing die 21 are disassembled to remove theraw material 1 from the inside of thecavity 12. Thereafter,burrs 2a formed on the periphery of thehole 3 are removed as need arises to obtain a prescribed hole punched product (preform) as shown in Fig. 13. - Thus, in the hole punching method of the aforementioned embodiment, the hold punching scheduled
portion 2 of theraw material 1 disposed within thecavity 12 of theclosed die 11 is pressed from the opposite sides thereof across the hold punching scheduledportion 2 with the pair of large and small diameter punches 13 and 15 to expand the hole punching scheduledportion 2 so that unfilled portions M remain in thecavity 12. Therefore, the hole punching scheduledportion 2 can be expanded within thecavity 12 at a low load. - Furthermore, a
hole 2a can be formed by a relatively small load since asmall diameter hole 2a is opened in the hole punching scheduledportion 2 by penetrating thesmall diameter punch 13 into the hole punching scheduledportion 2 of theraw material 1. Furthermore, the penetration operation of thesmall diameter punch 13 causes the material of the hole punching scheduledportion 2 of theraw material 1 to be filled in the unfilled portion M1 located at the penetration front side of thesmall diameter punch 13 among the unfilled portions M in thecavity 12. - Furthermore, since the
small diameter hole 2a is expanded by penetrating thelarge diameter punch 15 into thesmall diameter hole 2a formed in the hole punching scheduledportion 2 of theraw material 1 to form alarge diameter hole 3 in the hole punching scheduledportion 2, thehole 3 can be opened at a relatively low load. Furthermore, the penetration operation of thelarge diameter punch 15 causes the material of the hole punching scheduledportion 2 of theraw material 1 to be filed in the unfilled portion M2 located at the penetration front side of thelarge diameter punch 15 among the unfilled portions M in thecavity 12. Consequently, all the unfilled portions M in thecavity 12 disappear and theentire cavity 12 is filled with the material, which prevents occurrence of underfill. - In the hole punching method of this embodiment, no step of punching and removing the material of the hole punching scheduled
portion 2 of theraw material 1, is included, resulting in high material yield. - Furthermore, the tapered
tip end portion 14 of thesmall diameter punch 13 enables penetration of the hole punching scheduledportion 2 of theraw material 1 at a low load. Furthermore, since the peripheral surface of thetip end portion 14 of thesmall diameter punch 13 is formed by two steppedtaper surfaces taper angle α 1 and α2 gradually stepwise toward the tip of thesmall diameter punch 13, the forming load can be adjusted to a prescribed value by setting the two stepped taper angles α1 and α2 of thesmall diameter punch 13.
The penetration operation of thesmall diameter punch 13 enables an effective radially outward expansion of the hole punching scheduledportion 2 of theraw material 1, which enables assured filling of the material of the hole punching scheduledportion 2 of theraw material 1 to the small diameter punch penetration front side portion M1 of the unfilled portions M in thecavity 12. - Furthermore, the tapered
tip end portion 16 of thelarge diameter punch 15 enables penetration of thelarge diameter punch 15 into the hole punching scheduledportion 2 of theraw material 1 at a low load. Furthermore, the onestep taper surface 16a of the peripheral surface of thetip end portion 16 of thelarge diameter punch 15 enables adjustment of the forming load to a prescribed value by setting the taper angle β1 of thetaper surface 16a. And, the penetration operation of thelarge diameter punch 15 enables effective radially outward expansion of the hole punching scheduledportion 2 of theraw material 1, thereby enabling assured filling of the material of the hole punching scheduledportion 2 of thematerial 1 to the large diameter punch penetration front side portion M2 of the unfilled portions M in thecavity 12, which assuredly prevents occurrence of underfill. - Furthermore, in the state where each punch 13 and 15 is inserted in the corresponding
punch insertion hole gaps excessive material 2a of the hole punching scheduledportion 2 of theraw material 1 are formed between the peripheral surfaces of thepunches portion 2 of theraw material 1 can be filled in the unfilled portions M in thecavity 12 at a relatively low load. - In addition, since the
dam portion excessive material 2a flowed into thegap 18 is formed at the peripheral surface of eachpunch excessive material 2a can be prevented from flowing out of theclosed die 11. - At the expansion step, the hole punching scheduled
portion 2 of theraw material 1 is pressed by both thepunches punches tip end portions punches - The hole punching method of this embodiment includes, before the expanding step, a diameter expansion step in which the hole punching scheduled
portion 2 of theraw material 1 is expanded in diameter in advance. At the expanding step, in the state where the hole punching scheduledportion 2 of theraw material 1 expanded in diameter at the diameter expansion step is disposed in thecavity 12, the hole punching scheduledportion 2 is pressed with both thepunches portions portion 2 of theraw material 1 is expanded in diameter beforehand and then hole punching is executed to the hole punching scheduledportion 2, these processing can be performed effectively. - Although an embodiment of the present invention was explained above, the present invention is not limited to the aforementioned embodiment and can be modified in various manners.
- For example, the hole punching method and the hole punching apparatus according to the present invention are not limited to a method and an apparatus for manufacturing a preform for manufacturing arms of vehicles, and can also be used to manufacture various preforms for industrial products, such as, e.g., a preform for connecting rods or a preform for gears with a shaft hole.
- Furthermore, in the present invention, the hole punching scheduled
portion 2 of theraw material 1 can be only one place, such as, e.g., an axial intermediate portion or an axial one end portion of theraw material 1. Needless to say, in the present invention, the shape of theraw material 1 is not limited to a bar shape, and the present invention can be applied toraw materials 1 of various configurations. Furthermore, in the present invention, theraw material 1 can be an extruded material, a rolled material, such as, e.g., a continuously cast rolled material manufactured by a Properzi method, or can be any material manufactured by any other production methods. - This application claims priority to
Japanese Patent Application No. 2005-153770 filed on May 26, 2005 U.S. Provisional Application No. 60/685,870 filed on June 1, 2005 - It should be understood that the terms and expressions used herein are used for explanation and have no intention to be used to construe in a limited manner, do not eliminate any equivalents of features shown and mentioned herein, and allow various modifications falling within the claimed scope of the present invention.
- The present invention can be applied to a hole punching method and a hole punching apparatus for manufacturing a hole punched product, such as, e.g., an arm or a connecting rod for vehicles (e.g., automobiles, railroad vehicles).
then, while releasing or after releasing pressurization by the large diameter portion to the hole punching scheduled portion, the small diameter punch is penetrated into the hole punching scheduled portion of the raw material,
thereafter, while pulling out or after pulling out the small diameter punch penetrated in the hole punching scheduled portion of the raw material from the hole punching scheduled portion, the hole punching scheduled portion of the raw material is penetrated by the large diameter punch.
Claims (14)
- A hole punching method, comprising:a step of expanding a hole punching scheduled portion of a raw material disposed in a cavity of a closed die by pressing the hole punching scheduled portion from opposite sides thereof across the hole punching scheduled portion with a pair of large diameter punch and small diameter punch different in diameter and arranged so as to face each other so that unfilled portions remain in the cavity;a step of penetrating the small diameter punch into the hole punching scheduled portion of the raw material while releasing or after releasing pressurization by the large diameter punch to the hole punching scheduled portion; anda step of penetrating the large diameter punch into the hole punching scheduled portion of the raw material while pulling out or after pulling out the small diameter punch penetrated in the hole punching scheduled portion of the raw material from the hole punching scheduled portion of the raw material.
- The hole punching method as recited in claim 1, wherein a tip end portion of the small diameter punch is formed into a tapered shape, and wherein a peripheral surface of the tip end portion of the small diameter punch is formed by plural stepped taper surfaces arranged so as to decrease in taper angle gradually stepwise toward the tip end portion of the small diameter punch.
- The hole punching method as recited in claim 2, wherein, when the number of steps of the taper surfaces forming the peripheral surface of the tip end portion of the small diameter punch is N (N≧2), a tip end portion of the large diameter punch is formed into a tapered shape, and a peripheral surface of the tip end portion of the large diameter punch is formed by stepped taper surfaces whose step number is smaller than N and arranged so as to decrease a taper angle gradually stepwise toward the tip end portion of the large diameter punch, or formed by a single step taper surface.
- The hole punching method as recited in claim 1, wherein the closed die is provided with punch insertion holes each for inserting each punch, each punch insertion hole being communicated with the cavity, and
wherein, in a state in which each punch is inserted in the corresponding punch insertion hole, gaps for receiving excessive material of the hole punching scheduled portion of the raw material from the cavity are formed between peripheral surfaces of the punches and peripheral surfaces of the punch insertion holes. - The hole punching method as recited in claim 4, wherein a dam portion for preventing the excessive material flowed into the gaps from discharging to an outside is formed at the peripheral surface of the punch so as to expand toward a radially outward of the punch.
- The hole punching method as recited in claim 1, wherein, at the step of expanding, the hole punching scheduled portion is pressed from opposite sides thereof across the hole punching scheduled portion with both the punches so that the tip ends of both the punches do not come into contact with each other.
- The hole punching method as recited in any one of claims 1 to 6, wherein the raw material is a bar shaped material in which an axial prescribed portion of the raw material is defined as the hole punching scheduled portion,
wherein the method further includes a diameter expanding step of expanding the hole punching scheduled portion of the raw material with an upsetting apparatus in advance to the expanding step, the upsetting apparatus being provided with a fixing die for securing the raw material, the fixing die being connected to the closed die, a guide having an insertion hole for inserting and holding the hole punching scheduled portion of the raw material in a buckling preventing state, and a pressure punch, and the guide having a pair of diameter expansion preventing protruded portions each protruded in an axial direction of the guide and integrally formed at opposed portions of the tip end portion of the guide across the insertion hole,
wherein, at the diameter expansion step, the hole punching scheduled portion of the raw material secured to the fixing die is disposed in the cavity and the hole punching scheduled portion of the raw material is inserted and held in the insertion hole of the guide, and then, the guide is moved in a direction opposite to a moving direction of the pressure punch while axially pressing the hole punching scheduled portion of the raw material with the pressure punch by moving the pressure punch, to thereby expand the hole punching scheduled portion of the raw material exposed between the tip end portion of the guide and the fixing die in the cavity in a state in which contacting portions of the hole punching scheduled portion in contact with the guide protruded portions are prevented from being expanded in diameter, and
wherein, at the expanding step, the expanded hole punching scheduled portion of the raw material is pressed with both the punches from both sides of the hole punching scheduled portion prevented in diameter expansion by the guide protruded portions in a state in which the hole punching scheduled portion expanded in diameter is disposed in the cavity. - A hole punched product obtained by the hole punching method as recited in any one of claims 1 to 7.
- A hole punching apparatus, comprising:a closed die having a cavity; anda pair of large diameter punch and small diameter punch different in diameter and disposed at opposite sides across a hole punching scheduled portion of a raw material disposed in the cavity of the closed die,wherein the hole punching scheduled portion of the raw material disposed in the cavity of the closed die is expanded with both the punches by pressing the hole punching scheduled portion from opposite sides across the hole punching scheduled portion,
then, while releasing or after releasing pressurization by the large diameter portion to the hole punching scheduled portion, the small diameter punch is penetrated into the hole punching scheduled portion of the raw material,
thereafter, while pulling out or after pulling out the small diameter punch penetrated in the hole punching scheduled portion of the raw material from the hole punching scheduled portion, the hole punching scheduled portion of the raw material is penetrated by the large diameter punch. - The hole punching apparatus as recited in claim 9, wherein a tip end portion of the small diameter punch is formed into a tapered shape, and wherein a peripheral surface of the tip end portion of the small diameter punch is formed by plural stepped taper surfaces arranged so as to decrease in taper angle gradually stepwise toward the tip end portion of the small diameter punch.
- The hole punching apparatus as recited in claim 10, wherein, when the number of steps of the taper surfaces forming the peripheral surface of the tip end portion of the small diameter punch is N (N≧2), a tip end portion of the large diameter punch is formed into a tapered shape, and a peripheral surface of the tip end portion of the large diameter punch is formed by stepped taper surfaces whose step number is smaller than N and arranged so as to decrease a taper angle gradually stepwise toward the tip end portion of the large diameter punch, or formed by a single step taper surface.
- The hole punching apparatus as recited in claim 9, wherein the closed die is provided with punch insertion holes each for inserting each punch, each punch insertion hole being communicated with the cavity, and wherein, in a state in which each punch is inserted in the corresponding punch insertion hole, gaps for receiving excessive material of the hole punching scheduled portion of the raw material from the cavity are formed between peripheral surfaces of the punches and peripheral surfaces of the punch insertion holes.
- The hole punching apparatus as recited in claim 12, wherein a dam portion for preventing the excessive material flowed into the gaps from discharging to an outside is formed at the peripheral surface of the punch so as to expand toward a radially outward of the punch.
- The hole punching apparatus as recited in any one of claims 9 to 13, wherein the raw material is a bar shaped material in which an axial prescribed portion of the raw material is defined as the hole punching scheduled portion,
wherein the apparatus further includes an upsetting apparatus for expanding the hole punching scheduled portion of the raw material before expanding the hole punching scheduled portion of the raw material,
wherein the upsetting apparatus is provided with a fixing die for securing the raw material, the fixing die being connected to the closed die, a guide having an insertion hole for inserting and holding the hole punching scheduled portion of the raw material in a buckling preventing state, and a pressure punch for axially pressing the hole punching scheduled portion of the raw material inserted in the insertion hole of the guide, and a punch driving apparatus for moving the guide in a direction opposite to a moving direction of the pressure punch, the guide having a pair of diameter expansion preventing protruded portions each protruded in an axial direction of the guide and integrally formed at opposed portions of the tip end portion of the guide across the insertion hole, and
wherein a part of a peripheral surface of the hold punching scheduled portion is brought into contact with side surfaces of the protruded portions of the guide at the time of expanding the hole punching scheduled portion of the raw material to thereby prevent a contacting portion of the hole punching scheduled portion in contact with the protruded portions from being expanded.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2005153770 | 2005-05-26 | ||
US68587005P | 2005-06-01 | 2005-06-01 | |
PCT/JP2006/310418 WO2006126622A1 (en) | 2005-05-26 | 2006-05-25 | Punching method and punching device |
Publications (2)
Publication Number | Publication Date |
---|---|
EP1884299A1 true EP1884299A1 (en) | 2008-02-06 |
EP1884299A4 EP1884299A4 (en) | 2010-03-31 |
Family
ID=37452046
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP06756578A Withdrawn EP1884299A4 (en) | 2005-05-26 | 2006-05-25 | Punching method and punching device |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP1884299A4 (en) |
KR (1) | KR20080011299A (en) |
WO (1) | WO2006126622A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2010108486A2 (en) * | 2009-03-25 | 2010-09-30 | Gustav Meyer Stanztechnik Gmbh & Co. Kg | Stamping method and workpiece produced therewith |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4792536B1 (en) * | 2010-12-17 | 2011-10-12 | 弘士 小川 | Manufacturing method of door hinge for automobile |
JP2019003763A (en) * | 2017-06-13 | 2019-01-10 | 矢崎総業株式会社 | Method of manufacturing flat conductor |
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US1007941A (en) * | 1909-11-11 | 1911-11-07 | Forged Steel Wheel Company | Manufacture of car-wheels. |
JPS56134036A (en) * | 1980-03-20 | 1981-10-20 | Kawasaki Yukou Kk | Closed forging method of marked forging |
US4477537A (en) * | 1982-09-23 | 1984-10-16 | Blase Tool And Manufacturing Co., Inc. | Method for producing burr-free blanks and the blanks produced thereby |
JPS59197336A (en) * | 1983-04-22 | 1984-11-08 | Mitsubishi Heavy Ind Ltd | Forming method of link |
US4916798A (en) * | 1988-08-26 | 1990-04-17 | Jack Toering | Method of applying applique or like object to a baseplate |
FR2665382A1 (en) * | 1990-08-06 | 1992-02-07 | Akebono Brake Ind | Method and press for chamfering metal objects |
US5218853A (en) * | 1992-04-16 | 1993-06-15 | General Motors Corporation | Single-cycle closed die metal forging method |
US6427326B1 (en) * | 1999-06-17 | 2002-08-06 | Honda Giken Kogyo Kabushiki Kaisha | Method of manufacturing connecting rod |
US20050050935A1 (en) * | 2002-11-20 | 2005-03-10 | Hideyuki Miyahara | Shearing method for thin plate |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3657468B2 (en) * | 1999-08-06 | 2005-06-08 | 本田技研工業株式会社 | Method and apparatus for forming perforated products |
JP4819329B2 (en) * | 2003-07-31 | 2011-11-24 | 昭和電工株式会社 | Forging method, forged product and forging device |
-
2006
- 2006-05-25 KR KR1020077027254A patent/KR20080011299A/en not_active Application Discontinuation
- 2006-05-25 EP EP06756578A patent/EP1884299A4/en not_active Withdrawn
- 2006-05-25 WO PCT/JP2006/310418 patent/WO2006126622A1/en active Application Filing
Patent Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1007941A (en) * | 1909-11-11 | 1911-11-07 | Forged Steel Wheel Company | Manufacture of car-wheels. |
JPS56134036A (en) * | 1980-03-20 | 1981-10-20 | Kawasaki Yukou Kk | Closed forging method of marked forging |
US4477537A (en) * | 1982-09-23 | 1984-10-16 | Blase Tool And Manufacturing Co., Inc. | Method for producing burr-free blanks and the blanks produced thereby |
JPS59197336A (en) * | 1983-04-22 | 1984-11-08 | Mitsubishi Heavy Ind Ltd | Forming method of link |
US4916798A (en) * | 1988-08-26 | 1990-04-17 | Jack Toering | Method of applying applique or like object to a baseplate |
FR2665382A1 (en) * | 1990-08-06 | 1992-02-07 | Akebono Brake Ind | Method and press for chamfering metal objects |
US5218853A (en) * | 1992-04-16 | 1993-06-15 | General Motors Corporation | Single-cycle closed die metal forging method |
US6427326B1 (en) * | 1999-06-17 | 2002-08-06 | Honda Giken Kogyo Kabushiki Kaisha | Method of manufacturing connecting rod |
US20050050935A1 (en) * | 2002-11-20 | 2005-03-10 | Hideyuki Miyahara | Shearing method for thin plate |
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Title |
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2010108486A2 (en) * | 2009-03-25 | 2010-09-30 | Gustav Meyer Stanztechnik Gmbh & Co. Kg | Stamping method and workpiece produced therewith |
WO2010108486A3 (en) * | 2009-03-25 | 2011-03-17 | Gustav Meyer Stanztechnik Gmbh & Co. Kg | Stamping method and workpiece produced therewith |
Also Published As
Publication number | Publication date |
---|---|
EP1884299A4 (en) | 2010-03-31 |
KR20080011299A (en) | 2008-02-01 |
WO2006126622A1 (en) | 2006-11-30 |
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