JP2011177762A - Extruding die - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an extruding die in which a mandrel ring is externally fitted to a shaft, the mandrel ring being stably fixed and the extruding die being easily maintained. <P>SOLUTION: In the extruding die, the mandrel 30 for forming the inside surface of an extruded material has the shaft 32 and the mandrel ring 35 which is externally fitted to the shaft 32 via an intermediate tightening ring 40. The intermediate tightening ring 40 is composed of a material the thermal expansion coefficient of which is larger than that of the shaft and the mandrel ring 35; and the outer peripheral surface of the shaft 32, the inner peripheral surface of the intermediate tightening ring 40, the outer peripheral surface of the intermediate tightening ring 40 and the inner peripheral surface of the mandrel ring 35 are set so that there are clearances S<SB>1</SB>, S<SB>2</SB>on at least one side between the shaft 32 and the intermediate tightening ring 40 and between the intermediate tightening ring 40 and the mandrel ring 35 at ordinary temperature. The clearances S<SB>1</SB>, S<SB>2</SB>are eliminated in at least a part in the axial direction of the mandrel at die temperature at extrusion and both of them are brought into contact with each other. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an extrusion die used for extrusion of a hollow material.

  In the description of the present specification and claims, the direction in which the extruded material and the extruded material travel is referred to as downstream or downstream side, and the reverse direction is referred to as upstream or upstream side.

  In an extrusion die, a cemented carbide material such as cemented carbide or ceramic is used for a part of the die including the bearing unit in order to give wear resistance to the bearing unit (see Patent Documents 1 to 3).

  Patent Document 1 describes a die in which a ring-shaped die made of a super hard material is shrink-fitted in a recess of a die case made of tool steel. In Patent Document 2, a mandrel mandrel is formed of tool steel, a mandrel ring made of a super hard material is fitted on the mandrel, and a retaining nut is attached to the tip of the mandrel to fix the mandrel ring to the mandrel. The male type of the porthole die configured as described above is described. Further, the die described in Patent Document 3 is a mandrel ring that is shrink-fitted with a sleeve softer than the mandrel interposed between the mandrel and the mandrel ring. This is to suppress cracking.

JP-A-6-15348 JP 2003-181525 A Japanese Examined Patent Publication No. 4-69009

  However, the type of die for shrink-fitting a super hard material has a problem that it takes time and effort for the preparation process and maintenance of extrusion.

  In addition, cemented carbide has a characteristic that its thermal expansion coefficient is smaller than that of tool steel, and it is weaker in tensile force than tool steel. For this reason, when a mandrel ring made of a super hard material is externally fitted to a mandrel made of tool steel, the mandrel expands during hot extrusion and may be damaged if the clamping force against the mandrel ring is too strong. On the other hand, if the tightening force is too weak, the mandrel ring is not firmly fixed, and there is a possibility that the piecing portion of the extruded material may be wavy or uneven. Further, the mandrel ring may come off the mandrel due to the flow of the extruded material.

  In addition, since the die of Patent Document 3 compresses and deforms the sleeve, the sleeve has to be replaced every time the extrusion is performed, which requires maintenance and cost. In addition, when the difference between the thermal expansion coefficients of the mandrel ring and mandrel is small, or when the mandrel ring has a larger coefficient of thermal expansion than the mandrel ring, the mandrel ring cannot be sufficiently tightened and the mandrel ring is fixed. Stability is lowered, causing uneven thickness of the extruded material and breakage of the mandrel ring.

  In view of the above-described technical background, an object of the present invention is to provide an extrusion die in which a mandrel ring can be stably fixed and maintenance can be easily performed in an extrusion die for externally fitting a mandrel ring to a mandrel.

  That is, this invention has the structure as described in following [1]-[6].

[1] A mandrel for molding the inner surface of the extruded material has a mandrel and a mandrel ring that is externally fitted to the mandrel via an intermediate fastening ring.
The intermediate fastening ring is made of a material having a larger coefficient of thermal expansion than the mandrel and mandrel ring,
When the outer peripheral surface of the mandrel, the inner peripheral surface of the intermediate tightening ring, the outer peripheral surface of the intermediate tightening ring, and the inner peripheral surface of the mandrel ring are externally fitted to the mandrel via the intermediate tightening ring, the mandrel at normal temperature There is a gap between at least one of the ring and the intermediate ring and between the intermediate ring and the mandrel ring so that the gap disappears in at least a part of the mandrel in the axial direction at the time of the die temperature at the time of extrusion. Extrusion dies characterized by being set to.

  [2] The volume of the intermediate tightening ring is smaller than the volume of the space formed at a normal temperature with respect to the volume of the space formed between the mandrel and the mandrel ring, and the volume of the space at the die temperature during extrusion. The extrusion die according to the preceding item 1, which is set to be larger than that.

  [3] A tapered surface in which at least one of the outer peripheral surface of the mandrel, the inner peripheral surface of the intermediate tightening ring, the outer peripheral surface of the intermediate tightening ring, and the inner peripheral surface of the mandrel ring is inclined with respect to the axis of the mandrel. 3. The extrusion die according to 1 or 2 above, which is formed.

[4] the thermal expansion coefficient of the mandrel (alpha _1), the thermal expansion coefficient of the mandrel ring (alpha _2), the thermal expansion coefficient of the intermediate clamping ring (alpha ₃₎ satisfies α ₂ ≦ α ₁ <α ₃ the relationship The extrusion die according to any one of the preceding items 1 to 3.

  [5] The extrusion die according to any one of [1] to [4], wherein the length of the mandrel is set shorter than the length of the intermediate tightening ring and the mandrel ring in the axial direction of the mandrel.

[6] Using the extrusion die according to any one of items 1 to 5,
An extrusion method characterized by performing extrusion at a temperature at which there is no gap between the mandrel and the intermediate fastening ring and between the intermediate fastening ring and the mandrel ring in at least a part of the mandrel in the axial direction.

  In the invention described in [1], in the mandrel in which the mandrel ring is externally fitted to the mandrel via the intermediate tightening ring, the intermediate tightening ring is made of a material having a larger thermal expansion coefficient than the mandrel and the mandrel ring. For this reason, when the die reaches the temperature at the time of extrusion and the three expand based on their respective thermal expansion coefficients, the intermediate tightening ring that is constrained by the mandrel ring on the outer side in the radial direction also expands in the direction in which the inner diameter decreases. In combination with the expansion of the outer diameter of the mandrel, the intermediate tightening ring changes in the direction in which it is tightened with respect to the mandrel. Further, since the outer diameter expansion amount of the intermediate tightening ring exceeds the inner diameter expansion amount of the mandrel ring, the mandrel ring changes in a direction to be tightened with respect to the intermediate tightening ring. Such thermal expansion eliminates the gap between the mandrel and the intermediate tightening ring and the gap between the intermediate tightening ring and the mandrel ring at room temperature, and the mandrel ring is brought into contact with the mandrel via the intermediate tightening ring when they come into contact with each other. Fixed. Thus, when extrusion is performed with the mandrel ring fixed to the mandrel, uneven thickness of the extruded material is suppressed, and a high-quality extruded material can be produced. In addition, since there is a gap between the mandrel and the intermediate tightening ring and at least one of the intermediate tightening ring and the mandrel ring at normal temperature, the mandrel ring can be easily attached to and detached from the mandrel, and maintenance such as replacement of the mandrel ring Can be done easily.

  According to the invention described in [2] above, the mandrel ring can be attached and detached particularly smoothly at room temperature, and high position stability of the mandrel ring can be obtained at the temperature during extrusion.

  According to the invention described in [3] above, the mandrel ring can be prevented from coming off and the position stability of the mandrel ring can be improved.

  According to the invention described in [4] above, the clamping force for the mandrel ring can be increased and the position stability of the mandrel ring can be increased.

  According to the invention described in [5] above, it is possible to improve the position stability of the mandrel ring in the axial direction of the mandrel, and to efficiently guide the thermal expansion of the intermediate fastening ring in the radial direction.

  According to the invention described in [6] above, since extrusion is performed in a state where the mandrel ring is fixed to the mandrel, uneven thickness of the extruded material can be suppressed.

It is a disassembled perspective view which shows the porthole die provided with the male type | mold which is one Embodiment of this invention. It is sectional drawing which shows the assembly | attachment state of the porthole die of FIG. It is sectional drawing which shows the decomposition | disassembly state of the mandrel in the porthole of FIG. It is sectional drawing which shows a state with a clearance gap in a mandrel. It is sectional drawing which shows the other state with a clearance gap in a mandrel. It is sectional drawing which shows a state without a clearance gap in a mandrel. FIG. 4 is a cross-sectional view showing a state of the mandrel of FIG. 3 at normal temperature. FIG. 4 is a cross-sectional view showing another state of the mandrel of FIG. 3 at room temperature. It is sectional drawing which shows the further another state at the time of normal temperature of the mandrel of FIG. It is sectional drawing which shows the state in the die temperature at the time of extrusion of the mandrel of FIG. It is sectional drawing which shows the preferable dimension example in the axial direction of a mandrel. It is sectional drawing which shows the other example of a dimension in the axial direction of a mandrel. It is sectional drawing which shows the state at the time of normal temperature of the mandrel which has a taper surface. It is explanatory drawing which shows the pressure distribution at the time of extrusion of the mandrel of FIG. 8A. It is sectional drawing which shows the state at the time of normal temperature of the other mandrel which has a taper surface. It is sectional drawing which shows the state at the time of extrusion of the mandrel of FIG. 9A. It is sectional drawing which shows the decomposition | disassembly state of the mandrel which has a detachable mandrel. It is sectional drawing which shows the assembly state at the time of normal temperature of the mandrel of FIG.

  The port hole die (10) shown in FIGS. 1 and 2 is a combination of a female die (11) for molding the outer peripheral surface of the hollow extruded material (1) and a male die (20) for molding the inner peripheral surface. The male mold (20) is an embodiment of the extrusion die of the present invention.

  The female mold (11) has a bearing hole (12) in the center, a relief hole (13) is formed on the downstream side of the bearing hole (12), and a recess (14) for the welding chamber is formed on the upstream side. Is formed.

  The male mold (20) has a plurality of port holes (22) penetrating in the extrusion direction around the mandrel (30), with a mandrel (30) protruding downstream from the center of the die base (21). ing. Between adjacent port holes (22) and (22), leg portions (23) for supporting the mandrel (30) protruding downstream are supported at the base end portions.

  As shown in FIG. 3, the mandrel (30) includes a mandrel (32), a mandrel ring (35), and an intermediate tightening ring (40). In the mandrel (30), a mandrel (32) having a small diameter is integrally formed on the distal end side of the pedestal (31) that integrally extends from the base portion (21) of the die, and the pedestal (31) Due to the difference in diameter, a step (33) is formed between them. The distal end side of the mandrel (32) is further reduced in diameter, and a bolt portion (34) having a helical thread groove formed on the outer peripheral surface is integrally formed. The base (31), the mandrel (32) and the bolt part (34) are formed coaxially. The mandrel ring (35) is an annular body in which a bearing portion (36) for forming the inner peripheral surface of the extruded material (1) projects from the outer peripheral surface. The intermediate fastening ring (40) is an annular body disposed between the mandrel (32) and the mandrel ring (35). The outer peripheral surface of the mandrel (32), the inner and outer peripheral surfaces of the intermediate fastening ring (40), and the inner peripheral surface of the mandrel ring (35) are all parallel to the axis of the mandrel (30). The nut (37) is a holding member, and has a screw hole (38) screwed into the screw groove of the bolt part (34). Thus, the intermediate tightening ring (40) and the mandrel ring (35) are externally fitted to the mandrel (32) and brought into contact with the stepped portion (33), and the screw portion of the nut (37) is inserted into the bolt portion (34). When (38) is screwed together, the intermediate tightening ring (40) and the mandrel ring (35) are sandwiched between the step portion (33) and the nut (37), and are arranged at predetermined positions in the axial direction. The material properties and dimensions of the mandrel (32), intermediate fastening ring (40) and mandrel ring (35) will be described in detail later.

  When the female mold (11) and the male mold (20) are combined, the bearing portion (36) of the mandrel ring (35) of the male mold (20) is fitted into the bearing hole (12) of the female mold (11). An annular molding gap (not shown) is formed between them, and a part of the recess (14) for the welding chamber of the female mold (11) is blocked by the end face of the male mold (20), and the port hole ( 22) A welding chamber that communicates with is formed. Then, the extruded materials that have flowed into the respective port holes (22) merge in the welding chamber and are extruded from the forming gap as an extruded material (1) having a hollow portion (2).

[Gap between mandrel, intermediate tightening ring and mandrel ring]
The mandrel (30) is obtained by externally fitting a mandrel ring (35) to a mandrel (32) through an intermediate tightening ring. There is a gap in at least one of the mandrel (32) and the intermediate tightening ring (40) and between the intermediate tightening ring (40) and the mandrel ring (35) at normal temperature, and the mandrel at the die temperature during extrusion. It is set so that there is no gap in at least a part of the axial direction of (30) and the two contact each other.

  The “die temperature at the time of extrusion” in the present invention refers to the temperature at which the mandrel (32), the intermediate fastening ring (40) and the mandrel ring (35) reach a predetermined temperature during high temperature extrusion.

Also, the presence or absence of the gap (S ₂₎ between the mandrel (32) and the gap between the intermediate clamping ring (40) (S ₁₎ and the intermediate clamping ring (40) and the mandrel ring (35), and a clearance ( The magnitude of S ₁ ) (S ₂ ) is defined by the difference in diameter. That is, at an arbitrary die temperature (T), the outer diameter of the mandrel (32) calculated from the thermal expansion coefficient is A _T , the inner diameter of the mandrel ring (35) is B _T , and the inner diameter of the intermediate tightening ring (40) is C _{When T} and the outer diameter of the intermediate tightening ring (40) are represented by _DT , they are defined as follows.

As shown in FIG. 4A, a state where there is a gap (S ₁ ) between the mandrel (32) and the intermediate tightening ring (40) means that the outer diameter (A _T ) of the mandrel (32) <intermediate tightening ring (40 ) Satisfying the relationship of the inner diameter (C _T ), which means that there is a clearance between them and the intermediate tightening ring (40) is loose with respect to the mandrel (32). Further, a gap difference between the outer diameter _{(A T)} of the size of the _{(S 1)} is the inner diameter of the intermediate clamping ring (40) _{(C T)} and the mandrel _{(32) (C T -A T} ), S 1 = C _T -A _T > 0. FIG. 4A shows a state in which the mandrel (32) and the intermediate tightening ring (40) are aligned with each other, and the distance between the outer peripheral surface of the mandrel (32) and the inner peripheral surface of the intermediate tightening ring (40). Is constant in the circumferential direction. However, when the axis is not aligned, the distance between the two changes in the circumferential direction, and for example, both may contact in part of the circumferential direction as shown in FIG. 4B. In the latter case as well, there is a gap (S ₁ > 0) between the mandrel (32) and the intermediate tightening ring (40), and the intermediate tightening ring (40) is loose with respect to the mandrel (32). is there.

On the other hand, the state where the clearance (S ₁ ) is eliminated and the outer peripheral surface of the mandrel (32) and the inner peripheral surface of the intermediate tightening ring (40) are in contact with each other as shown in FIG. 4C. In this state, the relationship of the outer diameter (A _T ) ≧ the inner diameter (C _T ) of the intermediate fastening ring (40) is satisfied, and S ₁ = C _T −A _T ≦ 0. Mandrel (32) the outer diameter of _{(A T)} and the inside diameter _{(C T)} is equal to the intermediate clamping ring _{(40) (A T = C} T) when is _S 1 = 0, both clamping is in contact Power is not good. When the outer diameter (A _T ) of the mandrel (32) is larger than the inner diameter (C _T ) of the intermediate tightening ring (40) (A _T > C _T ), S ₁ <0, It is in a state of being tightened on the mandrel (32), and the difference in diameter (C _T -A _T ) acts as a force for tightening the intermediate tightening ring (40) from the inside, and the intermediate tightening ring (40) is pulled in the circumferential direction. As force is applied, it becomes more difficult to come off the mandrel (32) and it is firmly fixed.

Similarly, the state where there is a gap (S ₂ ) between the intermediate tightening ring (40) and the mandrel ring (35) means that the outer diameter of the intermediate tightening ring (40) (see FIG. 4A and FIG. 4B). D _T ) <the inner diameter (B _T ) of the mandrel ring (35) is satisfied, which means that there is a clear rinse between the two and looseness. The size of the gap (S ₂ ) is represented by (B _T -D _T ), and the loose state is S ₂ = B _T -D _T > 0. Moreover, as shown in FIG. 4C, the state in which the clearance (S ₂ ) disappears and the outer peripheral surface of the intermediate tightening ring (40) and the inner peripheral surface of the mandrel ring (35) are in contact with each other. 40) Outer diameter (D _T ) ≧ Mandrel ring (35) where inner diameter (B _T ) is satisfied, D _T = B _T is in contact with both but not tightening force (S ₂ = 0), D _T > B _T is a state where the mandrel ring (35) is fastened to the intermediate fastening ring (40) (S ₂ <0), and the diameter difference (D _T -B _T ) Acts as a force to tighten the mandrel ring (35) from the inside, and a tensile force is applied to the mandrel ring (35) in the circumferential direction. .

There is no gap (S ₁ ) between the mandrel (32) and the intermediate fastening ring (40), and there is no gap (S ₂ ) between the intermediate fastening ring (40) and the mandrel ring (35). The state is a state in which the mandrel ring (35) is fixed to the mandrel (32) through the intermediate fastening ring (40). That is, when S ₁ ≦ 0 and S ₂ ≦ 0 are satisfied, the mandrel ring (35) is fixed to the mandrel (32) via the intermediate tightening ring (40), and high positional stability can be obtained.

[Materials for mandrels]
In the present invention, the outer peripheral surface of the mandrel (32), the inner peripheral surface and outer peripheral surface of the intermediate fastening ring (40), and the inner peripheral surface of the mandrel ring (35) have the gaps (S ₁ ) and (S ₂ ) described above at room temperature. In addition, it is necessary to design the gap (S ₁ ) (S ₂ ) to be eliminated by the thermal expansion of the three at the time of the die temperature when the die temperature rises. The state in which there is no gap (S ₁ ) (S ₂ ) is a state in which the space between the mandrel (32) and the mandrel ring (35) is filled with the intermediate tightening ring (40) in the radial direction. To achieve this condition, the thermal expansion coefficient of the intermediate clamping ring ₍₄₀₎ (α ₃₎ that is greater than the mandrel coefficient of thermal expansion ₍₃₂₎ (α ₁₎ and the thermal expansion coefficient of the mandrel ring (alpha ₂₎ It becomes a condition. That is, the three coefficients of thermal expansion have a relationship of α ₃ > α ₁ and α ₃ > α ₂ . The relationship between the thermal expansion coefficient of the mandrel (32) and the mandrel ring (35) is not limited, but to obtain high positional stability by using the clamping force on the mandrel ring (35), the thermal expansion of the mandrel ring (35) The coefficient (α ₂ ) is preferably smaller than or equal to the thermal expansion coefficient (α ₁ ) of the mandrel (32). Therefore, a preferable relationship between the three thermal expansion coefficients is intermediate tightening ring (α ₃ )> mandrel (α ₁ ) ≧ mandrel ring (α ₂ ).

Further, since the mandrel ring (35) is required to have excellent wear resistance, it is desirable to use a super hard material. Examples of the cemented carbide material include cemented carbide alloys such as WC-Co, high-speed tool steel, powdered high-speed tool steel, and ceramics. Table 1 shows examples of tool steels used as materials for these cemented carbide materials and mandrels (32) and their thermal expansion coefficients, and their thermal expansion coefficients are larger than these materials, making them suitable for intermediate fastening rings (40). Examples of materials and their thermal expansion coefficients are shown. The present invention only needs to satisfy the condition that the thermal expansion coefficient (α ₃ ) of the intermediate fastening ring (40) is larger than the thermal expansion coefficient (α ₁ ) of the mandrel and the thermal expansion coefficient (α ₂ ) of the mandrel ring. Therefore, the exemplified materials are not limited to the uses described in Table 1. For example, the present invention includes a case where a mandrel ring (35) of cemented carbide or ceramics is combined with a mandrel ring (35) of powder high-speed tool steel and an intermediate fastening ring (40) exemplified in Table 1 is combined.

[Mandrel at normal temperature]
In the present invention, the mandrel (30) can be easily attached to or detached from the mandrel (32) at room temperature (T ₁ ), and the mandrel ring (35 using the difference in thermal expansion coefficient during extrusion). ) To the mandrel (32). Therefore, to easily attach and detach the mandrel ring (35) to the mandrel (32), between the mandrel (32) and the intermediate tightening ring (40), between the intermediate tightening ring (40) and the mandrel ring (35) It is a condition that there is a gap in at least one of the above. “Easy to attach and detach” means that attachment and detachment are possible without applying pressure at room temperature.

5A to 5C, three modes that the mandrel (30) can take at normal temperature (T ₁ ), namely, between the mandrel (32) and the intermediate fastening ring (40), the intermediate fastening ring (40) and the mandrel A state where there is a gap in at least one of the rings (35) is shown.

FIG. 5A shows that there is a gap (S ₁ ) between the mandrel (32) and the intermediate fastening ring (40), and there is a gap (S ₂ ) between the intermediate fastening ring (40) and the mandrel ring (35). The outer diameter (A _T1 ) of the mandrel (32) <the inner diameter (C _T1 ) of the intermediate fastening ring (40), the outer diameter (D _T1 ) of the intermediate fastening ring (40) <the mandrel ring (35). The relationship of the inner diameter (B _T1 ) is satisfied. Therefore, the intermediate fastening ring (40) can be easily attached to and detached from the mandrel (32), and the mandrel ring (35) can be easily attached to and detached from the intermediate fastening ring (40).

  As shown in FIG. 5B and FIG. 5C, even if the intermediate tightening ring (40) is in contact with either the mandrel ring (32) or the mandrel ring (35) without a gap, there is a gap between them. If necessary, the mandrel ring (35) can be easily attached to and detached from the mandrel (32).

FIG. 5B shows that the intermediate tightening ring (40) is mounted in a state where there is no gap (S ₁ ) with respect to the mandrel (32) and the two are in contact with each other, and between the mandrel ring (35) and the intermediate tightening ring (40). Indicates a state in which there is a gap (S ₂ ). The dimensions of the three members in FIG. 5B are A _T1 ≧ C _T1 and D _T1 <B _T1 .

FIG. 5C shows that there is a gap (S ₁ ) between the intermediate fastening ring (40) and the mandrel (32), and there is no gap (S ₂ ) between the mandrel ring (35) and the intermediate fastening ring (40). It shows a state of being attached in a contact state. The dimensions of the three members in FIG. 5C are A _T1 <C _T1 and D _T1 ≧ B _T1 .

It should be noted that the intermediate tightening ring (40) is fitted on the mandrel (32) so as to satisfy the relationship of A _T1 ≧ C _T1 , or the mandrel ring (35) is satisfied so as to satisfy the relationship of D _T1 ≧ B _T1. A method of externally fitting the intermediate fastening ring (40) is not limited, and is appropriately performed by press fitting or shrink fitting.

[Mandrel at die temperature during extrusion]
(Fixing in the radial direction of the mandrel ring)
As shown in FIG. 6, when a predetermined die temperature (T ₂ ) is reached during extrusion, the mandrel (32), the intermediate fastening ring (40), and the mandrel ring (35) are thermally expanded based on their respective thermal expansion coefficients.

Although the thermal expansion coefficient (α ₃ ) of the intermediate fastening ring (40) is larger than the thermal expansion coefficient (α ₁ ) of the mandrel (32), the intermediate fastening ring (40) Since it is constrained by a mandrel ring (35) having a smaller coefficient of thermal expansion than the mandrel ring (35), the intermediate tightening ring (40) expands in the direction of decreasing the inner diameter, coupled with the mandrel (32) that increases the outer diameter. The intermediate fastening ring (40) changes in the tightening direction. In other words, by constraining the intermediate fastening ring (40) from the outside by the mandrel ring (35), the expansion direction of the intermediate fastening ring (40) is guided in a direction in which the inner diameter becomes smaller. On the other hand, since the thermal expansion coefficient (α ₃ ) of the intermediate fastening ring (40) is larger than the thermal expansion coefficient (α ₂ ) of the mandrel ring (35), the amount of expansion of the outer diameter of the intermediate fastening ring (40) is mandrel ring ( It exceeds the inner diameter expansion amount of 35) and changes in the direction in which the mandrel ring (35) is tightened with respect to the intermediate tightening ring (40). When there is a gap (S ₁ ) (S ₂ ) at room temperature (T ₁ ) due to such thermal expansion, the gap becomes smaller as the temperature rises and the diameters become equal (A _T2 = C _T2 D _T2 = B _T2 ) and the gap (S ₁ ) (S ₂ ) disappears, and when the die temperature (T ₂ ) at the time of extrusion is higher, A _T2 > C _T2 , D _T2 > B _T2 , The difference in diameter acts as a force for fastening the mandrel ring (35) and the intermediate fastening ring (40) from the inside. Further, when there is no gap (S ₁ ) (S ₂ ) at room temperature (T ₁ ), the clamping force from the inside increases at the die temperature (T ₂ ) during extrusion. In either case, the mandrel ring (35) is tightened in the radial direction and fixed to the mandrel (32) via the intermediate tightening ring (40).

Moreover, since the mandrel ring (35) is fixed to the mandrel ring (35) by the volume expansion of the intermediate tightening ring (40), the thermal expansion coefficient (α ₁ ) of the mandrel (32) is the thermal expansion of the mandrel ring (35). The mandrel ring (35) can be fixed even when it is smaller than the coefficient (α ₂ ).

  In this way, the mandrel ring is firmly fixed to the mandrel and the position stability of the mandrel ring is increased, whereby the thickness of the extruded material can be stabilized. And if the dimension of an extrusion material is stable, the product quality after post-processing will also become stable. For example, when drawing is performed after extrusion, if the extruded material has no uneven thickness and the thickness is constant, the thickness of the drawn material is also constant. In addition, if the thickness of the extruded material is constant, the length of drawing is also constant. Therefore, the extruded material produced by using the extrusion die of the present invention is excellent not only in quality as an extruded material but also in quality as a post-processing material.

When the extrusion die is finished and cooled to room temperature (T ₁ ), the extrusion die returns to the gap (S ₁ ) (S ₂ ) at room temperature (T ₁ ) and loosens, so that the mandrel ring ( 35) or the mandrel ring (35) and the intermediate fastening ring (40) can be removed. Accordingly, maintenance such as removal of a worn mandrel ring and installation of a new mandrel ring can be easily performed.

Three aspects of the normal temperature _{(T 1)} shown in FIG. 5A~5C are both mandrel ring (35) at a die temperature during the extrusion _{(T 2)} is fixed to the mandrel (32) (Fig. 6) However, depending on the position of the gap at normal temperature (T ₁ ), there are the following specific effects.

(FIG. 5A: When S ₁ > 0, S ₂ > 0)
Since the intermediate fastening ring (40) and the mandrel ring (35) can be easily attached to and detached from each other, they can be exchanged.

(FIG. 5B: When S ₁ ≦ 0 and S ₂ > 0)
Since the intermediate tightening ring (40) is fixed to the mandrel (32), only the mandrel ring (35) can be replaced. Further, since the intermediate tightening ring (40) is fixed to the mandrel (32) in advance, the accuracy of alignment is good. As a result, an extruded material having a small uneven thickness and high dimensional accuracy can be extruded. Furthermore, since the force applied to the mandrel ring (35) only needs to consider the thermal expansion of the intermediate tightening ring (40), the design of the mandrel ring (35) can be simplified compared to the embodiment of FIG. 5A.

(FIG. 5C: When S ₁ > 0 and S ₂ ≦ 0)
The intermediate tightening ring (40) can be replaced with the mandrel ring (35). Further, since the intermediate fastening ring (40) can be replaced, it is advantageous when the intermediate fastening ring (40) is easily damaged.

From the above, the outer peripheral surface (outer diameter of the mandrel: A _T1 ) of the mandrel (32) at normal temperature (T ₁ ), the inner peripheral surface and the outer peripheral surface of the intermediate tightening ring (40) (inner diameter of the intermediate tightening ring: C _T1 , outer diameter: D _T1), the inner peripheral surface of the mandrel ring (35) (mandrel ring inner diameter: B _T1), based on the thermal expansion coefficient of each material, at least one of the gaps in the normal temperature (T ₁₎ (S ₁ ) and (S ₂ ), and the _two gaps (S ₁ ) and (S ₂ ) are eliminated during extrusion, and the two are in contact with each other.

  4A to 4C, FIGS. 5A to 5C, and FIG. 6 are schematic diagrams for explaining the thermal expansion in the radial direction, and the thermal expansion in the axial direction is not shown.

(Fixed in the axial direction of the mandrel ring)
At the die temperature (T ₂ ) at the time of extrusion, the mandrel ring (35) is fixed by being clamped in the radial direction by the intermediate clamping ring (40) and the mandrel (32). The power of. Therefore, in the mandrel (30) of the above-described embodiment, the nut (37) is attached to reliably prevent the mandrel ring (35) from falling off and to improve the fixing stability. Also, by attaching a nut (37) and applying axial restraining force, the tightening force can be reduced compared to the case of fixing only by radial tightening due to the expansion force of the intermediate tightening ring (40) and mandrel (32). Therefore, the risk of breakage of the mandrel ring (35) due to an increase in tightening force can be avoided.

In the mandrel (30) for restraining the mandrel ring (35) in the axial direction, the mandrel (32), a normal temperature to the dimension in the axial direction of the intermediate clamping ring and the mandrel ring (35) (T ₁₎ a difference provided when The mandrel ring (35) and the intermediate fastening ring (40) are brought into contact with the nut (37) at the time of the die temperature (T ₂ ) at the time of extrusion, and the mandrel ring (35) and the intermediate fastening ring (40) are put into the nut. It is preferable that the inner ring is securely restrained by (37) and the volume expansion of the intermediate tightening ring (40) is reliably guided in the radial direction.

FIG. 7A shows an example of a mandrel (30) having a gap (S ₂ ) only between the intermediate tightening ring (40) and the mandrel ring (35) of FIG. 5B, and a mandrel (32 at room temperature (T ₁ )). ), An example of a preferable dimensional relationship in the axial direction of the intermediate fastening ring (40) and the mandrel ring (35). In this figure, the lengths of the intermediate tightening ring (40) and mandrel ring (35) are equal, and the mandrel (32) is shorter than the intermediate tightening ring (40) and mandrel ring (35), The screwed nut (37) tightens the intermediate tightening ring (40) and the mandrel ring (35), and there is a gap (S ₃ ) between the mandrel (32) and the nut (37). The tensile force corresponding to the magnitude of the gap (S ₃₎ is assigned to the mandrel (32), an intermediate fastening ring (40) and the mandrel ring (35) is restrained in the axial direction.

In the present invention, the outer side of the intermediate fastening ring (40) is restrained by the mandrel ring (35), and the mandrel ring (35) is fixed by guiding the volume expansion of the intermediate fastening ring (40) in the radial direction. 7B, when the mandrel (32) is shorter than the intermediate tightening ring (40) and the intermediate tightening ring (40) is not restrained in the axial direction at room temperature (T ₁ ), the volume expansion is axial. The amount of change in the radial direction decreases and the effect of fixing the mandrel ring (35) decreases. Further, although the thermal expansion coefficient (α ₃ ) of the intermediate tightening ring (40) is larger than the thermal expansion coefficients (α ₁ , α ₂ ) of the mandrel (32) and the mandrel ring (35), it is surely positioned in the axial direction. In order to obtain stability, the mandrel ring (35) must be constrained in the axial direction even at the die temperature (T ₂ ) during extrusion.

From the above, the preferable relationship of the length in the axial direction at normal temperature (T ₁ ) is mandrel <intermediate tightening ring ≦ mandrel ring. In addition, when the mandrel ring (35) is longer than the intermediate tightening ring (40), the volume expansion of the intermediate tightening ring (40) escapes in the axial direction and the efficiency of expanding the diameter is reduced, so the mandrel ring (35) Is preferably not shorter than the intermediate fastening ring (40). Accordingly, it is preferable that the lengths of the intermediate tightening ring (40) and the mandrel ring (35) are equal, and the most preferable relationship between the axial lengths at normal temperature (T ₁ ) is mandrel <intermediate tightening ring = mandrel ring. Yes (see FIG. 7A).

[Right for mandrel ring]
The degree of loosening or tightening of the mandrel ring (35) with respect to the mandrel (32) at an arbitrary temperature (T) depends on the space formed between the outer peripheral surface of the mandrel (32) and the inner peripheral surface of the mandrel ring (35). it can be expressed by the volume (V2 _T) ratio of the intermediate clamping ring (40) with respect to the volume (V1 _T). Here, V1 _T and V2 _T are values calculated based on temperature (T), thermal expansion coefficients (α ₁ , α ₂ , α ₃ ) and dimensions at normal temperature. The tightening allowance (P _T ) indicating the degree of tightening is expressed by the following equation (i).

P _T (%) = V2 _T / V1 _T × 100 (i)
In the above formula (i), when V1 _T > V2 _T , P _T <100%, between the mandrel (32) and the intermediate fastening ring (40), and between the intermediate fastening ring (40) and the mandrel ring (35 )), And the mandrel ring (35) is loose with respect to the mandrel (32). When the intermediate tightening ring (40) is not in contact with either the mandrel (32) or the mandrel ring (35) (see FIG. 5A) or in contact with either one (see FIGS. 5B and 5C), The interference (P _T ) is P _T <100%. When V1 _T = V2 _T , P _T = 100%, and the mandrel (32), the intermediate tightening ring (40), and the mandrel ring (35) are in contact with each other but the tightening force is not effective. is there. When V1 _T <V2 _T , P _T > 100%, the mandrel (32), the intermediate tightening ring (40), and the mandrel ring (35) are in contact with each other and the tightening force is applied, and P _T The larger the is, the stronger the tightening force.

Therefore, at normal temperature (T ₁ ), V1 _T1 > V2 _T1 and _the interference (P _T1 ) is smaller than 100%. Further, the fastening allowance (P _T1 ) suitable for smoothly attaching and detaching the mandrel ring (35) at room temperature (T ₁ ) is 99.5 to 97.5%, and further 99.0 to 98.0%. Is preferred. Further, at the time of the die temperature (T ₂ ) at the time of extrusion, V1 _T2 ≧ V2 _T2 is satisfied, and the interference (P _T2 ) is P _T2 ≧ 100%. Further, in order to securely fix the mandrel ring (35) and obtain high positional stability, it is preferable that V1 _T2 > V2 _T2 and P _T2 > 100%. As the tightening allowance (P _T2 ) increases, the tightening force also increases, and the mandrel ring (35) is firmly fixed and is difficult to come off. Further, during extrusion, a force in the extrusion direction is also applied due to the material flow. Considering these, the fastening allowance (P _T2 ) at the time of extrusion is preferably 100.5 to 102.5%, and more preferably 101.0 to 102.0%.

[Other shapes of mandrels]
1 to 7A, the mandrel (30) has an outer peripheral surface of the mandrel (32), an inner peripheral surface and an outer peripheral surface of the intermediate fastening ring (40), and an inner peripheral surface of the mandrel ring (35) all on the axis of the mandrel. The gaps (S ₁ ) and (S ₂ ) that are parallel to each other at normal temperature (T ₁ ) are parallel to the axis and have a constant size in the axis direction. However, the present invention is not limited to the fact that the three peripheral surfaces are axial lines, and that the size of the gap is constant in the axial direction. Moreover, it is not limited to the mandrel (32) being integrally formed with the base (31) of the base part (21) of the male mold (20).

  Accordingly, at least one of the outer peripheral surface of the mandrel, the inner peripheral surface of the intermediate tightening ring, the outer peripheral surface of the intermediate tightening ring, and the inner peripheral surface of the mandrel ring is formed by a tapered surface inclined with respect to the axis, or A mandrel in which the size of the gap changes in the axial direction due to the tapered surface is also included in the present invention. Furthermore, a mandrel in which the mandrel is detachable from the pedestal is also included in the present invention.

  The mandrel having the above shape will be described in detail below. In addition, in the following FIGS. 8A to 11, the same reference numerals as those in FIGS.

(1) Mandrel in which the size of the gap narrows toward the downstream side The mandrel (50) shown in FIG. 8A has an outer peripheral surface (32a) and a mandrel ring (35) of the mandrel (32) at room temperature (T ₁ ). The inner peripheral surface (35a) of the intermediate fastening ring (60) is parallel to the axis, and the inner peripheral surface (61) and the outer peripheral surface (62) of the intermediate fastening ring (60) are formed with tapered surfaces that are inclined outward toward the downstream side. Yes. Thus, the gap between the mandrel (32) and the gap between the intermediate clamping ring (60) (S ₁₎ and the intermediate clamping ring (60) and the mandrel ring (35) (S ₂₎ is toward the downstream side Narrower and wider toward the upstream side.

In the process of increasing the die temperature, the mandrel first has no gap at the downstream end, and both come into contact with each other, and the contact area expands upstream. Since the gap (S ₁ ) (S ₂ ) at the normal temperature (T ₁ ) is narrower toward the downstream side, the gap (S ₁ ) (S ₂ ) disappears at the die temperature (T ₂ ) during extrusion in FIG. 8B. In this state, the interface between the outer peripheral surface (32a) of the mandrel (32) and the inner peripheral surface (61) of the intermediate tightening ring (60) and the outer peripheral surface (62) of the intermediate tightening ring (60) and the mandrel ring (35 ) In the pressure field applied to the interface with the inner peripheral surface (35a), and the pressure is higher on the downstream side and lower on the upstream side. Then, due to such a difference in pressure distribution, a force (F ₁ ) (F ₂ ) opposite to the extrusion direction acts. This reverse force (F ₁ ) (F ₂ ) acts against the force that the extruded material pushes the mandrel ring (35) and intermediate clamping ring (60) downstream, so that the mandrel ring (35 ) And the intermediate tightening ring (60) are restrained from moving to the downstream side, so that a retaining effect can be obtained. As a result, the positional stability of the mandrel ring (35) is improved.

The above-described effect can be obtained if at least one of the gaps (S ₁ ) (S ₂ ) is narrowed toward the downstream side and widened toward the upstream side at room temperature (T ₁ ). It is done. Therefore, as a modification of the mandrel (50) of FIGS. 8A and 8B, a mandrel in which only one of the inner peripheral surface (61) and the outer peripheral surface (62) of the intermediate fastening ring (60) is a tapered surface can be mentioned. . Further, if the gaps (S ₁ ) and (S ₂ ) are narrowed toward the downstream side, the above-mentioned effect can be obtained. The present invention also includes a case where one or both of the inner peripheral surfaces are formed with a tapered surface. Further, the gaps (S ₁ ) and (S ₂ ) can be narrowed toward the downstream side by inclining the two opposing surfaces in opposite directions, and the two opposing surfaces are inclined in the same direction at different angles. Accordingly, the gaps (S ₁ ) and (S ₂ ) can be narrowed toward the downstream side.

  FIG. 8B shows a state in which the mandrel (32) and the intermediate tightening ring (60), and the intermediate tightening ring (60) and the mandrel ring (35) are in contact with the upstream end. It is not a requirement to make contact in all directions. The present invention also includes a case where a portion that does not contact the upstream side remains due to the setting of the taper angle, the material thermal expansion coefficient, the thickness of each member, and the like. This is because the mandrel ring is fixed if the mandrel, the intermediate tightening ring, and the mandrel ring are in contact with each other at least in the axial direction.

(2) Mandrel whose contact surface during extrusion is an inclined surface At the die temperature (T ₂ ) during extrusion, the contact surface between the mandrel and the intermediate tightening ring, the contact surface between the intermediate tightening ring and the mandrel ring If at least one is inclined outwardly toward the mandrel axis toward the downstream side, the outwardly inclined surface prevents the movement even if the flow of extruded material tries to push the mandrel ring downstream. Therefore, the effect of preventing the mandrel ring from coming off can be obtained.

The mandrel (51) shown in FIG. 9A shows an example of a state at normal temperature (T ₁ ) for making the contact surface at the extrusion die temperature (T ₂ ) outward toward the downstream side. The outer peripheral surface (32a) of the mandrel (32) and the inner peripheral surface (71) of the intermediate fastening ring (70) are parallel to the axis. Further, the outer peripheral surface (72) of the intermediate tightening ring (70) and the inner peripheral surface (76) of the mandrel ring (75) are inclined in the direction in which the diameter increases on the downstream side and are parallel to each other. When the mandrel (51) in FIG. 9A reaches the die temperature (T ₂ ) during extrusion, as shown in FIG. 9B, the contact surface (77) between the intermediate tightening ring (70) and the mandrel ring (75) is on the downstream side. It becomes a taper surface inclined outward.

  To make the contact surface between the mandrel (32) and the intermediate tightening ring (75) tapered, the outer peripheral surface (32) of the mandrel (32) and the inner peripheral surface (71) of the intermediate tightening ring (75) What is necessary is just to incline in the direction which a diameter expands in the downstream. Further, if only one of the two opposing surfaces is a tapered surface, the contact surface is slightly inclined even when the other is parallel to the axis. Such a case is also included in the present invention.

  From the above (1) and (2), at least one of the outer peripheral surface of the mandrel at normal temperature, the inner peripheral surface of the intermediate tightening ring, the outer peripheral surface of the intermediate tightening ring, and the outer peripheral surface of the mandrel ring is used as the mandrel axis. By forming it with a tapered surface that is inclined with respect to the mandrel ring, the mandrel ring can be prevented from coming off and the position stability of the mandrel ring can be enhanced.

(3) Mandrel with removable mandrel The mandrel (52) shown in FIG. 10 is detachable from the base (21) of the male mold (20) referred to in FIG. A mandrel (80) attached to the mandrel, and an intermediate fastening ring (90) and a mandrel ring (95) fitted on the mandrel (80).

  The mandrel (80) has a bolt shape, and the mandrel (80) is attached to the pedestal (31) on the upstream side of the main body (82), which is a mounting portion of the intermediate fastening ring (90) and the mandrel ring (95). A convex portion (83) is provided coaxially with the main body portion (82), and a head portion (84) for suppressing the mandrel ring (95) is integrally provided on the downstream side.

  The mandrel (80) is formed with a tapered surface in which the outer peripheral surface (82a) of the main body (82) is inclined outward toward the downstream side, and the convex (83) is a cylindrical shape following the main body (82). The centering portion (85) and the upstream male screw portion (86) are formed. The head (84) suppresses the mandrel ring (95) and the intermediate fastening ring (90) fitted to the main body (82) from the downstream side, and a large-diameter flange ( 87) is formed. On the other hand, the recess (25) of the pedestal (31) is formed by a centering part (26) corresponding to the centering part (85) of the mandrel (80) and a female thread part (27) corresponding to the male thread part (86). Has been.

  The inner peripheral surface (91) and outer peripheral surface (92) of the intermediate tightening ring (90) and the inner peripheral surface (96) of the mandrel ring (95) are each formed by a tapered surface inclined outward toward the downstream side. Has been.

Then, as shown in FIG. 11, the mandrel (52) is assembled at room temperature (T ₁ ), and the intermediate tightening ring (90) and the mandrel ring (95) are attached from the convex portion (83) side of the mandrel (80). When the fitting (83) is attached to the pedestal (31), the intermediate tightening ring (90) and mandrel ring (95) that are externally fitted to the main body (82) ) Between the head (84) and the head (84). Clearances (S) between the main body (82) of the mandrel (80) and the intermediate fastening ring (90) and between the intermediate fastening ring (90) and the mandrel ring (95) are inclined with respect to the axis. ₁ ) (S ₂ ) is formed.

  In the structure in which the mandrel (80) is detachably attached as described above, the mandrel (80) can be replaced and maintenance can be performed more easily. Further, since the intermediate tightening ring (90) and the mandrel ring (95) can be fitted from the upstream side of the mandrel (80), the peripheral surfaces (82a) (91) (92) (96) are directed toward the downstream side. The degree of freedom in designing the taper angle when tilting outward is high. For this reason, it is possible to set a taper angle that cannot be assembled with a mandrel formed integrally with the base (31) and fitted with an intermediate tightening ring and a mandrel ring from the downstream side. Also, the axial tightening force applied to the intermediate tightening ring (80) and mandrel ring (95) is the degree of tightening between the male threaded part (86) of the mandrel (80) and the female threaded part (27) of the base (31). Can be adjusted. Further, even in a detachable mandrel, if the head (nut) is detached from the mandrel as in the mandrel in FIG. 1 or the like, the intermediate tightening ring and mandrel ring can be fitted from either the upstream side or the downstream side of the mandrel. As a result, the mandrel design is more flexible.

  The extrusion die of the present invention can be applied not only to the extrusion of a hollow material having a closed hollow portion, but also to the extrusion of a semi-hollow material having a part of the hollow portion opened.

  Moreover, as long as the material shape | molded using the extrusion die of this invention is a metal, it will not be limited at all, and aluminum, copper, iron, and these alloys can be illustrated.

  The extrusion die of the present invention can be used for producing various extruded materials having a hollow portion or a semi-hollow portion.

1 ... Extruded material
10 ... Porthole Dice
11 ... Female
20 ... Male mold (extrusion die)
30, 50, 51, 52 ... mandrels
31 ... pedestal
32, 80 ... mandrel
32a… Outer peripheral surface
33 ... Step
34… Bolt part
35, 75 ... Mandrel ring
35a, 76, 96 ... inner peripheral surface
36… Bearing part
37 ... Nut (holding member)
40, 60, 70 ... Intermediate fastening ring
61, 71 ... Inner peripheral surface
62, 72 ... outer peripheral surface
82 ... Main body of mandrel
82 ... outer peripheral surface S ₁ , S ₂ ... gap

Claims (6)

A mandrel that molds the inner surface of the extruded material has a mandrel and a mandrel ring that is externally fitted to the mandrel via an intermediate tightening ring;
The intermediate fastening ring is made of a material having a larger coefficient of thermal expansion than the mandrel and mandrel ring,
When the outer peripheral surface of the mandrel, the inner peripheral surface of the intermediate tightening ring, the outer peripheral surface of the intermediate tightening ring, and the inner peripheral surface of the mandrel ring are externally fitted to the mandrel via the intermediate tightening ring, the mandrel at normal temperature There is a gap between at least one of the ring and the intermediate ring and between the intermediate ring and the mandrel ring so that the gap disappears in at least a part of the mandrel in the axial direction at the time of the die temperature at the time of extrusion. Extrusion dies characterized by being set to.   The volume of the intermediate fastening ring is smaller than the volume of the space at room temperature and larger than the volume of the space at the die temperature during extrusion, with respect to the volume of the space formed between the mandrel and the mandrel ring. The extrusion die according to claim 1, which is set to be   At least one of the outer peripheral surface of the mandrel, the inner peripheral surface of the intermediate tightening ring, the outer peripheral surface of the intermediate tightening ring, and the inner peripheral surface of the mandrel ring is formed by a tapered surface that is inclined with respect to the axis of the mandrel. The extrusion die according to claim 1 or 2. Thermal expansion coefficient of the mandrel (alpha _1), the thermal expansion coefficient of the mandrel ring (alpha _2), the thermal expansion coefficient of the intermediate clamping ring (alpha _3), a request meets the α ₂ ≦ α _{1 <α 3} the relationship Item 4. The extrusion die according to any one of Items 1 to 3.   The extrusion die according to any one of claims 1 to 4, wherein the length of the mandrel is set shorter than the length of the intermediate fastening ring and the mandrel ring in the axial direction of the mandrel. Using the extrusion die according to any one of claims 1 to 5,
An extrusion method characterized by performing extrusion at a temperature at which there is no gap between the mandrel and the intermediate fastening ring and between the intermediate fastening ring and the mandrel ring in at least a part of the mandrel in the axial direction.

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