Extrusion die for molding Anti-slip patterned bumper and Anti-slip patterned bumper

Abstract

To provide an extrusion die for molding a bumper with a non-slip pattern and the bumper with the non-slip pattern for molding the non-slip pattern by reducing pressure even in the bumper composed of a large-sized hollow shape in which the extrusion pressure becomes large.SOLUTION: This device is provided with an upper die 10 provided with a mandrel 13 having an inside bearing part 15 for forming a hollow part shape in an introduced metal M and an intermediate bearing part 16 for forming a reinforcing rib, an intermediate die 20 having an outside bearing part 25 for forming the outer shape of the metal and a lower die 30 for supporting the upper die through the intermediate die. The lower die is provided with a pattern forming tool 40 that rotates together with the movement of the product member formed by the bearing portion and forms a non-slip pattern on the short side surface of the product member, the intermediate die is provided with a recessed portion 21 to be filled with the metal introduced into the upper die, and the recessed portion is provided with an inclined portion 22 from the outer edge of the recessed portion to the opening portion side inward from the outer end of the pattern forming tool.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to an extrusion die for molding a bumper with an anti-slip pattern, and more specifically to an extrusion die for molding a bumper with an anti-slip pattern, which molds an anti-slip pattern on the short side surface of a hollow rectangular product component having a reinforcing rib within the hollow portion, and to a bumper with an anti-slip pattern. [Background technology]

[0002] Conventionally, aluminum hollow sections with reinforcing ribs inside the hollow are used for rear and side bumpers of trucks, trailers, etc. These types of bumpers are required to absorb energy during a collision and also function as a stepping stone.

[0003] Conventionally, aluminum profiles have slippery surfaces, so to provide a non-slip surface for the step, a checkered aluminum plate is laid on the surface of the profile to prevent slipping. However, this structure increases the weight, increases the assembly process, and increases costs.

[0004] As a technology for solving the above problems, an extrusion die for forming a patterned product is known, which produces a patterned product by forming a predetermined pattern on the surface of a product component, which is a hollow extrusion made of an aluminum alloy as a thermoplastic material (see, for example, Patent Document 1).

[0005] The extrusion die described in Patent Document 1 comprises a male die having a mandrel that forms a hollow shape in the thermoplastic member, and a female die that forms the outer shape of the product member. The female die has a recess into which the extruded metal is filled, and this recess allows the formation of a stable outer shape. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2022-45464 Summary of the Invention [Problem to be solved by the invention]

[0007] However, when the technology disclosed in Patent Document 1 is applied to hollow extrusions with long sides, such as bumpers for trucks, the die diameter becomes large and the extrusion force also increases. This increase in extrusion force may cause the recesses to deform, leading to contact with the pattern forming tool and preventing the rotation of the pattern forming tool.

[0008] One way to prevent contact between the recess and the pattern forming tool is to leave a gap between the pattern forming tool and the bottom of the female mold, but this raises the concern that metal could get into the gap and similarly prevent the pattern forming tool from rotating.

[0009] The present invention has been made in view of the above circumstances, and has as its object to provide an extrusion die for molding a bumper with an anti-slip pattern, which can reduce the pressure required to form an anti-slip pattern even in a bumper made of a large hollow extrusion material, which is subject to a large extrusion pressure, and a bumper with an anti-slip pattern. [Means for solving the problem]

[0010] In order to achieve the above object, the extrusion die for molding bumpers with anti-slip patterns of the present invention is an extrusion die for molding anti-slip patterns on the short side surfaces of a product component having a rectangular cross section and a reinforcing rib within a hollow portion, which is formed from a thermoplastic material continuously extruded from a material supply side, and which molds an anti-slip pattern on the short side surfaces of the product component, the product component having a rectangular cross section and a reinforcing rib within the hollow portion, and which comprises: an upper die into which the thermoplastic material is introduced and which is integrally formed with a mandrel having a bearing portion that molds the hollow portion shape and the reinforcing rib in the thermoplastic material; an intermediate die having a bearing portion that molds the outer shape of the thermoplastic material; and a lower die that supports the upper die via the intermediate die, the lower die comprising a pattern former that rotates with the movement of the product component molded by the bearing portion and molds the anti-slip pattern on the short side surfaces of the product component, the intermediate die having a recess into which the thermoplastic material introduced into the upper die is filled, and a sloped portion that extends from the outer edge of the recess toward an opening side inward from the outer end of the pattern former (claim 1).

[0011] This configuration allows the inclined portion extending from the outer edge of the recess to the opening side inward from the outer edge of the pattern former to supply sufficient thermoplastic material for molding while reducing the pressure. Also, reducing the extrusion pressure can suppress deformation of the recess.

[0012] In this invention, it is preferable that a second inclined portion is provided in the recess of the intermediate mold at a position opposite to the neck of the mandrel, and that the inclination angle of the second inclined portion is smaller than the inclination angle of the neck of the mandrel (Claim 2).

[0013] This configuration allows the thermoplastic material to flow smoothly toward the opening on the mandrel side, thereby reducing accumulation of the thermoplastic material.

[0014] In addition, in this invention, it is preferable that a flat portion is formed continuing from the lower end of the inclined portion of the intermediate mold, a second inclined portion is provided at a position on the flat portion opposite the neck portion of the mandrel, and the inclination angle of the second inclined portion is formed smaller than the inclination angle of the neck portion of the mandrel (Claim 3).

[0015] With this configuration, the flat portion maintains an appropriate flow path to the opening on the mandrel side, allowing the thermoplastic material to flow smoothly.

[0016] In addition, in this invention, it is preferable that the inclination angle of the second inclined portion is greater than the inclination angle of the inclined portion extending from the outer edge of the recess to the opening side inward from the outer end of the pattern forming tool (Claim 4).

[0017] This configuration allows the thermoplastic material filled in the recess to flow more easily toward the mandrel.

[0018] In addition, it is preferable that the thickness of the recess of the intermediate mold directly above the pattern forming tool is 0.5 to 1.0 times the diameter of the pattern forming tool (claim 5). If the thickness directly above the pattern-forming tool is less than 0.5 times the diameter of the pattern-forming tool, the area directly above the pattern-forming tool is most susceptible to contact, which can cause deformation of the recess and lead to contact between the recess and the pattern-forming tool. Furthermore, if the thickness directly above the pattern-forming tool is more than 1.0 times the diameter of the pattern-forming tool, the thickness of the intermediate die becomes large, resulting in a thick die overall. Furthermore, a longer mandrel is required, which can lead to concerns about strength issues.

[0019] The bumper with an anti-slip pattern of this invention is a bumper with an anti-slip pattern formed by the above-mentioned extrusion die for molding bumpers with an anti-slip pattern, characterized in that an uneven anti-slip pattern is formed on the short side surface of the bumper body, which has a rectangular cross section and whose hollow portion is partitioned by one or more reinforcing ribs, along the longitudinal direction of the bumper body and at intervals in the width direction (Claim 6).

[0020] In this invention, the anti-slip pattern may be provided on the entire surface of the short side of the bumper body (claim 7), or on a portion of the bumper body along the longitudinal direction where no pattern is left (claim 8). In this case, it is preferable that the anti-slip pattern is formed by a plurality of convex rib portions formed along the longitudinal direction of the bumper body and at predetermined intervals in the width direction, and intersecting recesses formed on the surface of the convex rib portions so as to intersect with the longitudinal direction (Claim 9).

[0021] By providing reinforcing ribs within the hollow portion, the bumper made of a large hollow extrusion can be given an energy absorbing function. Also, by forming an uneven anti-slip pattern along the length of the bumper body and spaced apart in the width direction on the short side surface of the bumper body, an anti-slip function can be given to the step portion. [Effects of the Invention]

[0022] (1) According to the invention described in claim 1, the inclined portion extending from the outer edge of the recess to the opening side inward from the outer end of the pattern forming tool allows a sufficient amount of thermoplastic material to be supplied for forming and reduces pressure, thereby suppressing deformation of the recess. Therefore, even in bumpers made of large hollow extrusions, which are subject to large extrusion pressures, the pressure can be reduced and an anti-slip pattern can be formed.

[0023] (2) According to the invention described in claim 2, the flow of the thermoplastic material to the opening on the mandrel side can be improved and accumulation of the thermoplastic material can be reduced. Therefore, in addition to the above (1), a sufficient amount of thermoplastic material can be supplied to the molding and the pressure can be reduced, thereby suppressing deformation of the recess.

[0024] (3) According to the invention described in claim 3, the flat portion can adequately maintain the flow path to the opening on the mandrel side, and the flow of the thermoplastic material can be made smooth.

[0025] (4) According to the invention described in claim 4, the flow of the thermoplastic material toward the mandrel side can be improved, so that a sufficient amount of thermoplastic material can be supplied when molding the product component.

[0026] (5) According to the invention described in claim 5, deformation of the recesses due to the extrusion pressure during molding of a bumper made of a large hollow extrusion can be reliably suppressed without increasing the thickness of the entire die.

[0027] (6) According to the inventions set forth in claims 6 to 9, the bumper made of a large hollow extrusion having reinforcing ribs can be endowed with an energy absorbing function, and the step portion can be endowed with an anti-slip function. [Brief explanation of the drawings]

[0028] [Figure 1] 1A is a perspective view showing an extrusion die for molding a bumper with an anti-slip pattern according to the present invention, and FIG. 1B is a longitudinal cross-sectional view thereof. [Figure 2] FIG. 2 is an exploded perspective view of the extrusion die for molding the bumper with the anti-slip pattern. [Figure 3] 1A is a perspective view showing an upper die of the present invention, FIG. 1B is a longitudinal cross-sectional view thereof, FIG. 1C is an enlarged cross-sectional view of part I of FIG. 1B, and FIG. 1D is a cross-sectional view taken along line II-II of FIG. 1C. [Figure 4] 1A is a perspective view showing an intermediate mold of the present invention, FIG. 1B is a longitudinal sectional view thereof, and FIG. 1C is an enlarged sectional view of part III of FIG. 1B. [Figure 5] FIG. 2 is a plan view showing a lower die housing a pattern forming tool according to the present invention. [Figure 6] FIG. 6 is a cross-sectional perspective view taken along line IV-IV in FIG. 5. [Figure 7] 1A is an enlarged cross-sectional view showing the main part of an extrusion die for molding a bumper with an anti-slip pattern according to the present invention, and FIG. 1B is an enlarged view of a V part in FIG. 1A. [Figure 7A] 3 is a schematic cross-sectional view showing the relationship between a first inclined portion, a second inclined portion, and an inclined portion of a mandrel in the present invention. FIG. [Figure 8]FIG. 2 is a cross-sectional view showing the use of the extrusion die for molding the bumper with the anti-slip pattern. [Figure 8A] 1A is a cross-sectional view showing another state of use of the extrusion die for molding a bumper with an anti-slip pattern, and FIG. 1B is a perspective view of another pattern forming tool. [Figure 9] FIG. 9 is an enlarged cross-sectional view showing a main part of FIG. 8. [Figure 9A] FIG. 10 is an enlarged cross-sectional view showing a main part of the extrusion die for molding a bumper with an anti-slip pattern in still another state of use. [Figure 10] 1A shows the pressure adjustment mechanism of the present invention, in which (a) shows the state in which the pattern forming tool is fully inserted into the hollow member, and (b) is a plan view showing a partial cross section in a state in which the pattern forming tool is slightly inserted into the hollow member. [Figure 11] FIG. 10(b) is a cross-sectional view taken along line VI-VI in FIG. [Figure 12] 1 is an enlarged cross-sectional view showing a main portion of another embodiment of an extrusion die for molding a bumper with an anti-slip pattern according to the present invention. [Figure 13] 10 is an enlarged cross-sectional view showing a main portion of yet another embodiment of an extrusion die for molding a bumper with an anti-slip pattern according to the present invention. FIG. [Figure 14] 1 is a perspective view showing an example of a bumper with an anti-slip pattern according to the present invention. [Figure 15] 15(a) is an enlarged cross-sectional view taken along line VII-VII in FIG. 14, and FIG. 15(b) is an enlarged view of part VIII in FIG. [Figure 16] FIG. 10 is a perspective view showing another example of a bumper with an anti-slip pattern according to the present invention. [Figure 16A] FIG. 10 is a perspective view showing yet another example of a bumper with an anti-slip pattern according to the present invention. [Figure 17] 17A is an enlarged cross-sectional view taken along line IX-IX in FIG. 16 and FIG. 17B is an enlarged view of part X in FIG. [Figure 18] 1 is a perspective view showing an example of a state in which the bumper with an anti-slip pattern according to the present invention is used. DETAILED DESCRIPTION OF THE INVENTION

[0029] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0030] The extrusion die 1 for molding a bumper with an anti-slip pattern (hereinafter simply referred to as the extrusion die 1) of this invention is used to mold an anti-slip pattern P (hereinafter referred to as the anti-slip pattern P) on the short side surface of a bumper 4, which is a product made of a hollow extrusion material with a rectangular cross section having a reinforcing rib 4b inside a hollow portion 4a, as shown in Figure 14, for example.

[0031] The extrusion die 1 is equipped with an upper die 10 which is integral with a mandrel 13 having an inner bearing portion 15 for introducing a thermoplastic material (hereinafter referred to as metal M) and forming the hollow shape in the metal M and an intermediate bearing portion 16 for forming reinforcing ribs 4b, an intermediate die 20 which has an outer bearing portion 25 for forming the outer shape of the metal M, and a lower die 30 which supports the upper die 10 via the intermediate die 20.

[0032] The lower die 30 is equipped with a pattern forming tool 40 that rotates with the movement of the product component formed by the inner bearing portion 15, the intermediate bearing portion 16, and the outer bearing portion 25, and forms an anti-slip pattern P on the short side surface of the product component.

[0033] In this case, the upper die 10 and the intermediate die 20 are connected by fitting an annular recess 10a provided on the outer periphery of the lower surface of the upper die 10 with an annular protrusion 20b provided on the outer periphery of the upper surface of the intermediate die 20, and the intermediate die 20 and the lower die 30 are connected by fitting an annular recess 20a provided on the outer periphery of the lower surface of the intermediate die 20 with an annular protrusion 30b provided on the outer periphery of the upper surface of the lower die 30. The upper die 10, the intermediate die 20, and the lower die 30 are connected by connecting bolts (not shown) inserted from the back surface of the lower die 30. In this state, the intermediate die 20 is connected while being sandwiched between the upper die 10 and the lower die 30, and therefore bending and deformation are suppressed.

[0034] As shown in FIG. 8, the container 2 is placed on the upper surface of the upper die 10, and is configured to accommodate the metal M and to maintain the temperature of the metal M at 400 to 500°C.

[0035] 1 and 2, the upper die 10 has four fan-shaped introduction holes 11 formed at predetermined angles around the central axis of the upper die 10. The introduction holes 11 are for allowing the metal M to pass through, and two bridges 12 are provided to cross each other so as to separate the introduction holes 11.

[0036] These bridges 12 are parts for supporting the mandrel 13, and a support shaft 14 is connected to the back side of their central part (the part where the bridges 12 intersect) so as to hang down below in the axial direction of the upper die 10, and the mandrel 13 is formed integrally at the tip of the support shaft 14.

[0037] The mandrel 13 is formed so that its lower end surface extends below a position horizontal to the outer bearing portion 25 of the intermediate mold 20 and the center of rotation of the pattern forming tool 40 provided on the lower die 30. In other words, the mandrel 13 is formed downstream in the direction of movement of the product member 3 from a position where the pattern forming tool 40 presses the product member 3 as described below (see Figures 8 and 9).

[0038] A neck portion 13b is provided above the mandrel 13, extending inward from the tip of the support shaft 14 via an inclined portion 13a. As shown in FIG. 3, the neck portion 13b is provided with an inner bearing portion 15 having a rectangular cross-sectional shape substantially identical to the inner shape of the product 4, and two pairs of intermediate bearing portions 16 that form the two reinforcing ribs 4b. Furthermore, a recess 17 is formed below the outer bearing portion 25 at a position corresponding to the side surface of the product component 3 to prevent an uneven shape from being formed on the inner surface when the outer surface of the product component 3 is pressed by the pattern former 40 (see FIG. 9). The recess 17 extends to the tip of the mandrel 13.

[0039] As shown in Figure 4, the intermediate mold 20 is formed with a slight recess in the center to accommodate the upper die 10, and in this recessed portion is formed a recess 21 for storing the metal M, which has approximately the same shape as the outer edge of the introduction hole 11.

[0040] As shown in Fig. 7, recess 21 has an inclined portion 22 (hereinafter referred to as first inclined portion 22) extending from the outer edge of recess 21 toward the opening side inward from the outer end of pattern forming tool 40. A horizontal flat portion 23 is provided continuing to the lower end of first inclined portion 22, and a second inclined portion 24 is provided at a position of flat portion 23 facing neck portion 13b of mandrel 13. As shown in Figs. 7 and 7A, the inclination angle α of second inclined portion 24 is smaller than the inclination angle β of neck portion 13b of mandrel 13. As shown in Fig. 7A, the inclination angle α of second inclined portion 24 is larger than the inclination angle γ of first inclined portion 22.

[0041] With this configuration, the first inclined portion 22, which is provided from the outer edge of the recess 21 to the opening side inward from the outer end of the pattern forming tool 40, allows a sufficient amount of metal M to be supplied to the forming process while reducing the pressure. Furthermore, reducing the extrusion pressure can suppress deformation of the recess 21. Furthermore, by forming the inclination angle α of the second inclined portion 24 to be larger than the inclination angle γ of the first inclined portion 22, the flow of the metal M toward the mandrel side can be improved, and therefore a sufficient amount of metal can be supplied when forming the product component.

[0042] Furthermore, the provision of the flat portion 23 maintains an appropriate flow path to the opening on the mandrel side, resulting in a smooth flow of the metal M. Furthermore, by forming the inclination angle α of the second inclined portion 24 to be smaller than the inclination angle β of the neck portion 13b of the mandrel 13, the flow of the metal M to the opening on the mandrel side can be improved, and accumulation of the metal M can be reduced.

[0043] Furthermore, downstream of the recess 21 and facing the inner bearing portion 15 of the mandrel 13 described above, an outer bearing portion 25 is formed which is continuous with the recess 21 and has an opening which is gradually narrower than the recess 21. This outer bearing portion 25 is a portion for finishing the outer shape of the metal M to the outer shape of the product 4, and the inner dimensions of the outer bearing portion 25 are formed to be approximately the same as the outer dimensions of the product 4. Furthermore, as described above, the inner bearing portion 15 is formed to be approximately the same as the inner shape of the product 4, and therefore, as the metal M passes between the inner bearing portion 15 and the outer bearing portion 25, the shape of the metal M is formed to be the same as the shape of the product 4 except for the anti-slip pattern P.

[0044] Furthermore, below the outer bearing portion 25, an upper guide portion 26 is formed which is continuous with this outer bearing portion 25. This upper guide portion 26 is a portion which guides the metal M (hereinafter, the formed metal M will be referred to as the product member 3) which is formed by the inner bearing portion 15 and the outer bearing portion 25 and extruded, toward the lower die 30 side.

[0045] More specifically, a protrusion 27 that protrudes downstream is provided on the lower side of the outer bearing portion 25, on the side corresponding to the portion where the pattern former 40 (described later) is provided, or on the side located above the pattern former 40. This protrusion 27 is formed along and covers part of the outer periphery of the upper side of the pattern former 40. The surface of this protrusion 27 facing the product member 3 is formed so as to leave a predetermined gap between it and the product member 3. In addition, the side on which this protrusion 27 is not formed is formed at an angle so that the gap between it and the product member 3 increases as the product member 3 advances, and this inclined surface is configured to function as the upper guide portion 26.

[0046] 7, the thickness T of the recess 21 of the intermediate die 20 directly above the pattern-forming tool 40 is set to 0.5 to 1.0 times the diameter D of the pattern-forming tool 40. The reason for this is that if the thickness T directly above the pattern-forming tool 40 is less than 0.5 times the diameter D of the pattern-forming tool 40, the area directly above the pattern-forming tool 40 is most likely to come into contact, which may cause deformation of the recess 21 and contact between the recess 21 and the pattern-forming tool 40. If the thickness T directly above the pattern-forming tool 40 is more than 1.0 times the diameter D of the pattern-forming tool 40, the thickness of the intermediate die 20 becomes large, resulting in a thick die as a whole. Furthermore, the mandrel 13 must be long, which may cause strength problems if the mandrel 13 is made longer.

[0047] 5 and 6, the lower die 30 is formed in a cylindrical shape, and an annular protrusion 30b is formed on the outer periphery of its upper surface to fit into an annular recess 20a formed on the back surface of the intermediate die 20. The lower die 30 is formed with a pattern-forming tool arrangement space 32 (hereinafter referred to as arrangement space 32) having a substantially rectangular cross section near the approximate center of its plane, for arranging a pattern-forming tool 40.

[0048] The lower die 30 is formed with a lower guide portion 31 that guides the product member 3. The lower guide portion 31 is formed from its upper end surface to its lower end surface. As shown in Figures 8 and 9, the lower guide portion 31 is formed with an opening area larger than the opening area of ​​the lower end side of the upper guide portion 26, and is formed along the axial direction of the lower die 30.

[0049] A pattern forming tool 40 for forming an anti-slip pattern P on the opposing surface of the product member 3 is disposed in the arrangement space 32 on the upper side of the lower die 30, i.e., on the side of the intermediate die 20.

[0050] On both sides along the length of the arrangement space 32 on the upper side (intermediate mold 20 side) of the lower die 30, installation recesses 33 for installing the attachment members 41 of the pattern forming tool 40 are formed. Note that Fig. 6 shows one of the installation recesses 33. This installation recess 33 is provided along the length of the arrangement space 32 and is formed in a rectangular shape with a predetermined width and a predetermined depth. The attachment members 41 are inserted into the installation recesses 33 formed in this way.

[0051] 10 and 11, through holes 34 communicating with the installation recesses 33 are formed in the outer peripheral surface of the lower die 30 at positions on the extension lines of the installation recesses 33. The inner diameter of the through holes 34 on the installation recess 33 side is smaller than the inner diameter on the outer peripheral side of the lower die 30, and a female thread 34a is formed in the portion with the smaller inner diameter. A pressure adjustment bolt 51 constituting a pressure adjustment mechanism of the pattern forming tool 40, which will be described later, is screwed into this female thread 34a. Two through holes 34 with female threads 34a are formed so as to press against two locations, the upper and lower, on the side surface of the mounting member 41.

[0052] The pattern former 40 forms an uneven anti-slip pattern P on the short side surface of the hollow rectangular product member 3, and is formed by a roller with peaks and valleys provided at appropriate intervals on the outer circumferential surface. The anti-slip pattern P formed on the short side surface of the product member 3 by the pattern former 40 formed in this way has convex ridges Pa and intersecting recesses Pb, which will be described later, that correspond to the peaks and valleys of the pattern former 40, and is formed by sandwiching the short side surface of the product member 3 between the pattern former 40 and the relief portion 17.

[0053] Specifically, with regard to the pattern former 40 shown in FIG. 9 , when the side surface of the product member 3 formed to a predetermined thickness between the inner bearing portion 15 and the outer bearing portion 25 hangs down without receiving any load, the recess 17 is formed so that a predetermined gap S is formed between the inner surface of the side surface and the recess 17. This gap S is configured to release the pressing force of the top of the pattern former 40 when the pattern former 40 forms the non-slip pattern P with a continuous uneven shape on the surface of the side surface. Therefore, when the top of the pattern former 40 presses the side surface when it forms the non-slip pattern P with a continuous uneven shape on the surface of the side surface with its top, the pressing force of the pattern former 40 is absorbed by the recess 17, and the side surface is pressed against the recess 17. As a result, the inner surface of the side surface and the recess 17 are in close contact with each other, which prevents the formation of an uneven shape on the inner surface of the side surface.

[0054] Next, the mounting structure of the pattern forming tool 40 will be described. As described above, the pattern forming tool 40 is disposed at a position facing the recess 17. As shown in Fig. 6, a bearing 43 is fitted into the mounting member 41, and a shaft 44 for supporting the pattern forming tool 40 is fitted into the bearing 43. As shown in Fig. 10, the mounting member 41 is inserted into the installation recess 33 and slidably fitted into the product member 3 (metal M). The pattern forming tool 40 and the shaft 44 are connected by a key 45.

[0055] Next, the structure of the pressure adjustment mechanism will be described with reference to Fig. 10. The pressure adjustment mechanism is composed of a pressure adjustment bolt 51 that abuts against one end of the mounting member 41 in the longitudinal direction, and an adjustment spacer 52 that is provided in the installation recess 33 so as to be insertable and detachable.

[0056] These pressure adjustment bolts 51 are configured to be screwed into female threads 34a provided in through holes 34 formed from the outer periphery of the lower die 30 toward the side of the mounting member 41, so that the tip of each pressure adjustment bolt 51 abuts against one end of the mounting member 41 in the longitudinal direction.

[0057] For example, as shown in Figure 10(a), when the pressure adjustment bolt 51 is screwed into the female thread 34a, the mounting member 41 slides in the installation recess 33 in the direction of arrow Y, thereby adjusting the amount by which the top of the pattern former 30 bites into a predetermined surface of the product member 3, i.e., the distance between the pattern former 40 and the surface. Note that Figure 10(a) shows a state in which the pressure adjustment bolt 51 is screwed in to the maximum extent, with the other side surface of the mounting member 41 abutting against the end of the installation recess 33. There is also a predetermined gap L between one side surface of the mounting member 41 and one side surface of the installation recess 33.

[0058] 10(b) shows an adjustment method for reducing the amount by which the top of the pattern forming tool 40 bites into the surface of the product member 3. In this case, turning the pressure adjustment bolt 51 in the reverse direction allows the mounting member 41 to slide freely within the installation recess 33. Therefore, first, turn the pressure adjustment bolt 51 in the reverse direction until the gap L of the above-mentioned predetermined dimension disappears.

[0059] Next, the pattern forming tool 40 is grasped by hand and pulled toward the pressure adjustment bolt 51. After that, an adjustment spacer 52 is inserted into the gap L1 dimension on the other side surface so that the top of the pattern forming tool 40 bites into the product member 3 to the set amount, and the pressure adjustment bolt 51 is screwed in until it abuts against the side surface of the mounting member 41. At this time, the combined dimension of the gap L1 between the mounting member 41 and the side surface of the installation recess 33 and the gap L2 between the mounting member 41 and the other side surface of the installation recess 33 is the same as the gap L (= L1 + L2) in Figure 10(a) above.

[0060] As shown in Fig. 11, the adjustment spacer 52 is formed from a plate finished to a predetermined thickness, and a plurality of types of plates with different thicknesses are prepared in advance so that the amount of bite of the top of the pattern forming tool 40 into the product member 3 can be adjusted. The adjustment spacer 52 is formed to have a length that is approximately the same as the thickness of the mounting member 41. Note that, as shown in Fig. 11, the upper end of the adjustment spacer 52 has gripping portions 53 formed on both ends in the width direction. The gripping portions 53 are formed so that the adjustment spacer 52 can be clamped with a predetermined clamping tool (jig) when being inserted into the installation recess 33.

[0061] Next, we will explain the method for forming the product 4 (bumper with an anti-slip pattern) using the extrusion die 1 configured as above. Prior to this operation, a pattern forming tool 40 for forming an anti-slip pattern P having a concave-convex shape on the short side surface of the product member 3 is set in the lower die 30.

[0062] Specifically, the pattern forming tool 40 is set by inserting the mounting member 41 into the installation recess 33 provided on the upper side (intermediate mold side) of the lower die 30. At this time, the position of the pattern forming tool 40 is set in advance using the pressure adjustment bolt 51 so that the amount by which the top of the pattern forming tool 40 bites into the side surface of the product member 3, i.e., the height dimensions of the ridge portion Pa and the recess 21, are the desired dimensions.

[0063] After the pattern forming tool 40 is set, the upper die 10, the intermediate die 20 and the lower die 30 are connected by connecting bolts (not shown) inserted from the back surface of the lower die 30.

[0064] With the pattern-forming tool 40 set as described above, the metal M is introduced from the container 2 into the upper die 10 and extruded downstream through the introduction hole 11 via the first inclined portion 22, the flat portion 23, and the second inclined portion 24 formed in the recess 21 of the intermediate die 20. As the metal M passes between the inner bearing portion 15 of the mandrel 13 of the upper die 10 and the outer bearing portion 25 of the intermediate die 20, and between the intermediate bearing portion 16 of the intermediate die 20, the outer shape of the metal M is formed to the outer shape of the product 4, and a hollow shape having two reinforcing ribs 4b is formed in the metal M. The metal M formed into a hollow rectangular shape, i.e., the product member 3, is extruded toward the lower die 30 along the upper guide portion 26 of the intermediate die 20.

[0065] As described above, the intermediate mold 20 has the protrusion 27 formed so as to cover the pattern forming tool 40 provided on the lower die 30, which in particular prevents the tip portion of the metal M from coming into contact with the pattern forming tool 40 before it is sandwiched between the pattern forming tool 40 and the mandrel 13 when the extrusion of the metal M begins. In other words, the pressing force of the pattern forming tool 40 can be applied to the intended position of the product member 3.

[0066] Then, while the product member 3 extruded into the lower die 30 is being guided downward within the arrangement space 32 of the lower die 30, the pattern former 40 rotates in conjunction with the extrusion of the product member 3, and an uneven anti-slip pattern P is continuously formed on the opposing surface of the short side of the product member 3. In other words, the pattern former 40 is configured to rotate by utilizing the load that presses the metal M against the extrusion die 1.

[0067] As described above, when the top of the pattern-forming tool 40 bites into the side of the product member 3 being extruded from the intermediate mold 20, the pressing force is transmitted to the product member 3, pushing the side toward the opposite side from the pattern-forming tool 40. However, as shown in FIG. 9 , a wide gap S is provided between the surface of the mandrel 13 facing the pattern-forming tool 40, i.e., the recess 17, and the inner surface of the product member 3. As a result, the inner surface of the pressed product member 3 is pressed against the recess 17. In other words, the pressing force of the pattern-forming tool 40 on the side of the product member 3 is absorbed by the recess 17. Furthermore, even if part of the product member 3 (metal M) flows into the part that has already passed through the pattern-forming tool 40 due to being pressed by the pattern-forming tool 40, the inner surface of the part that has passed through the pattern-forming tool 40 also abuts the recess 17, preventing the material from flowing toward the hollow portion. This allows the inner surface of the product member 3 to be maintained smooth. In other words, the occurrence of irregularities on the inner surface of the product member 3 can be suppressed.

[0068] As described above, the uneven anti-slip pattern P is formed on the opposing surfaces of the short sides of the product member 3 by the pattern forming tool 40. Then, this process is continued until the product reaches a predetermined length.

[0069] In the above embodiment, the recess 21 formed in the intermediate mold 20 has the first inclined portion 22 extending from the outer edge of the recess 21 to the portion immediately above the pattern-forming tool 40 on the opening side inward from the outer end of the pattern-forming tool 40, as shown in Fig. 7. However, the first inclined portion 22 may have another configuration as long as it extends at least from the outer end of the pattern-forming tool 40 toward the opening side inward. For example, as shown in Fig. 12, a first inclined portion 22A having a gradient greater than that of the first inclined portion 22 may be provided from the outer edge of the recess 21 to the opening side inward from the outer end of the pattern-forming tool 40, and a flat portion 23A connected to the lower end of this first inclined portion 22A and extending from the center of the pattern-forming tool 40 toward the inner end, and a second inclined portion 24 may be provided at a position of the flat portion 23A facing the neck portion 13b of the mandrel 13. Alternatively, as shown in Figure 13, a first inclined portion 22B having a gradient smaller than that of the first inclined portion 22 may be provided from the outer edge of the recess 21 to the opening side inward from the outer end of the pattern forming tool 40, and a second inclined portion 24 may be provided at the tip of this first inclined portion 22B in a position facing the neck portion 13b of the mandrel 13. Note that other parts of the other embodiment shown in Figures 12 and 13 are similar to those of the above embodiment, so description thereof will be omitted.

[0070] The product 4 molded as described above, i.e., the bumper 4 with an anti-slip pattern, has a bumper body 5 with a rectangular cross section, the hollow portion 4a of which is partitioned by two reinforcing ribs 4b, and on the entire surface of the short side of the bumper body 5, as shown in Figures 14 and 15, an anti-slip pattern P in the shape of protrusions and recesses is formed along the longitudinal direction of the bumper body 5 and spaced apart in the width direction.

[0071] Specifically, the anti-slip pattern P is formed by a plurality of ridges Pa formed along the longitudinal direction of the bumper body 5 and at predetermined intervals in the width direction, and intersecting recesses Pb formed on the surfaces of the ridges Pa, intersecting the longitudinal direction. The depth of the intersecting recesses Pb is shallower than the height of the ridges Pa.

[0072] The bumper 4 with an anti-slip pattern formed as described above has reinforcing ribs 4b provided within the hollow portion, thereby enabling the bumper 4, which is made of a large hollow extrusion, to have an energy absorption function. Furthermore, by providing the anti-slip pattern P on the short side surfaces of the bumper body 5, which is formed with a plurality of ridges Pa formed along the longitudinal direction of the bumper body 5 and at predetermined intervals in the width direction, and intersecting recesses Pb formed on the surfaces of the ridges Pa so as to intersect in the longitudinal direction, the step portion can have an anti-slip function. Furthermore, by forming the depth of the intersecting recesses Pb shallower than the height of the ridges Pa, drainage can be improved, further improving the anti-slip function.

[0073] The bumper 4 with the anti-skid pattern constructed as described above is attached to the rear of a van-type truck 60 by means of a pair of brackets 70, as shown in FIG. The bumper 4 attached as described above has reinforcing ribs 4b provided in the hollow portion 4a of the bumper body 5 formed from a hollow extrusion, thereby providing an energy absorbing function. In addition, by forming uneven anti-slip patterns P along the length of the bumper body 5 and spaced apart in the width direction on the short side surfaces of the bumper body 5, it is possible to provide an anti-slip function to the step portion.

[0074] In the above description, an example has been described in which the bumper 4 with anti-skid patterns is used as the rear bumper of a van-type truck 60, but the present invention is not limited to this. For example, the present invention can also be applied to vehicles other than van-type trucks, such as trucks and trailers.

[0075] In the above embodiment, two reinforcing ribs 4b are provided within the hollow portion 4a of the bumper body 5, and an anti-slip pattern P is provided over the entire short side of the bumper body 5. However, the present invention is not necessarily limited to this. For example, as shown in FIGS. 16 and 17 , the hollow portion 4a of the bumper body 5 may be partitioned by a single reinforcing rib 4b, and an anti-slip pattern PA may be provided in the portion of the short side surface of the bumper body 5 where a no-pattern P0 is left along the longitudinal direction of the bumper body 5, as described above, which is formed of a plurality of convex rib portions Pa formed along the longitudinal direction of the bumper body 5 at predetermined intervals in the width direction, and intersecting concave portions Pb formed on the surface of the convex rib portion Pa so as to intersect in the longitudinal direction. This makes it possible to form an anti-slip patterned bumper 4A in which the anti-slip pattern P is provided in the portion of the short side surface of the bumper body 5 where a no-pattern P0 is left along the longitudinal direction of the bumper body 5 and where a single reinforcing rib 4b is provided within the hollow portion 4b.

[0076] When molding the anti-slip patterned bumper 4A having the anti-slip pattern PA, as shown in Figure 8A, a mandrel 13A equipped with a pair of intermediate bearing portions 16 is used instead of the mandrel 13 of the above embodiment. Also, instead of the pattern-forming tool 40 of the above embodiment, a pattern-forming tool 40A is used, as shown in Figure 8A(b), which has pattern-forming teeth 47 on both sides, leaving a blank pattern-forming portion 46 for forming a blank pattern P0 in the axial center. This allows the anti-slip pattern P to be formed on the short side surface of the bumper body 5 having one reinforcing rib 4b in the portion where the blank pattern P0 remains. Note that since the other parts in Figure 8A are the same as those of the above embodiment, the same parts are designated by the same reference numerals and their description will be omitted.

[0077] The bumper 4A with an anti-slip pattern molded as described above has one reinforcing rib 4b, but because a thick non-patterned portion P0 is provided on the short side surface of the bumper body 5 along the longitudinal direction of the bumper body 5, it can have the same rigidity as a bumper 4 with an anti-slip pattern having two reinforcing ribs 4b.

[0078] Alternatively, instead of the above embodiment, as shown in Fig. 9A, a pattern forming tool 40B may be used that has wide convex teeth 47a between concave and convex pattern forming teeth 47 that are arranged at predetermined intervals in the circumferential direction. A bumper 4B formed using this pattern forming tool 40B has wide intersecting recesses Pc that are spaced apart from the intersecting recesses Pb at predetermined intervals in a direction perpendicular to the longitudinal direction of the bumper 4B, as shown in Fig. 16A. Note that, since the other parts in Figs. 9A and 16A are the same as those in the above embodiment, the same parts are designated by the same reference numerals and their description will be omitted.

[0079] In the above embodiment, the recesses 21 constituting the anti-slip patterns P, PA are described as being rectangular in shape and intersecting the convex stripe portion Pa at right angles, but the recesses 21 are not limited to being rectangular in shape and may be formed into patterns of other shapes such as X-shape or V-shape, for example, recesses having a semicircular or polygonal cross section.

[0080] In the above embodiment, an extrusion die for molding a bumper with an anti-slip pattern and a bumper with an anti-slip pattern molded by this extrusion die have been described. However, this invention can also be applied to a hollow extrusion member with a rectangular cross section having a reinforcing rib inside the hollow portion and having an anti-slip pattern on the surface of the short side, such as a step stool for an outdoor staircase or a step ladder. [Explanation of symbols]

[0081] 1. Extrusion die 3. Product materials 4, 4A, 4B bumper 4a Hollow part 4b Reinforcing rib 5 Bumper body 10 Upper die 13,13A Mandrel 13a Slope 13b Neck 15 Inner bearing part 16 Intermediate bearing part 17 Relief area 20 Intermediate type 21 Recess 22, 22A, 22B First inclined portion 23,23A flat part 24 Second inclined section 25 Outer bearing part 30 Lower die 40, 40A, 40B Pattern forming tool M Metal P Anti-slip pattern P0 Plain Pa convex part Pb,Pc intersection recess α Inclination angle of the second inclined portion β Inclination angle of metal neck γ: Inclination angle of the first inclined portion T Thickness directly above the recessed pattern forming tool D Diameter of pattern former

Claims

1. An extrusion die for molding a bumper with an anti-slip pattern, which molds an anti-slip pattern on a short side surface of a product member having a rectangular cross section and a reinforcing rib in a hollow portion, the product member being formed from a thermoplastic material continuously extruded from a material supply side, an upper die having integrally formed therewith a mandrel having a bearing portion for introducing the thermoplastic member and for forming the hollow portion shape and the reinforcing rib in the thermoplastic member; an intermediate die having a bearing portion for forming the outer shape of the thermoplastic member; and a lower die for supporting the upper die via the intermediate die, the lower die includes a pattern forming tool that rotates with the movement of the product member formed by the bearing portion and forms an anti-slip pattern on the short side surface of the product member; The intermediate mold is provided with a recess into which the thermoplastic material introduced into the upper mold die is filled, and the recess is provided with a sloped portion from the outer edge of the recess to an opening side inward from the outer end of the pattern forming tool. An extrusion die for molding bumpers with anti-slip patterns.

2. The extrusion die for molding a bumper with an anti-slip pattern according to claim 1, a second inclined portion is provided in the recess of the intermediate mold at a position facing the neck portion of the mandrel, and the inclination angle of the second inclined portion is smaller than the inclination angle of the neck portion of the mandrel; An extrusion die for molding bumpers with anti-slip patterns.

3. The extrusion die for molding a bumper with an anti-slip pattern according to claim 1, a flat portion connected to a lower end of the inclined portion of the intermediate mold is formed, and a second inclined portion is provided at a position of the flat portion facing the neck portion of the mandrel, and the inclination angle of the second inclined portion is formed smaller than the inclination angle of the neck portion of the mandrel; An extrusion die for molding bumpers with anti-slip patterns.

4. The extrusion die for molding a bumper with an anti-slip pattern according to claim 2 or 3, The inclination angle of the second inclined portion is larger than the inclination angle of the inclined portion provided from the outer edge of the recess to the opening side inward from the outer end of the pattern forming tool. An extrusion die for molding bumpers with anti-slip patterns.

5. The extrusion die for molding a bumper with an anti-slip pattern according to claim 1, The thickness of the recess of the intermediate mold directly above the pattern forming tool is 0.5 to 1.0 times the diameter of the pattern forming tool; An extrusion die for molding bumpers with anti-slip patterns.

6. A bumper with an anti-slip pattern formed by the extrusion die for forming a bumper with an anti-slip pattern according to claim 1, The bumper body has a rectangular cross section and the hollow portion is divided by one or more reinforcing ribs. On the short side surfaces of the bumper body, uneven anti-slip patterns are formed along the longitudinal direction of the bumper body and at intervals in the width direction. A bumper with an anti-slip pattern.

7. 7. The bumper with an anti-slip pattern according to claim 6, The anti-slip pattern is provided on the entire surface of the short side of the bumper body. A bumper with an anti-slip pattern.

8. 7. The bumper with an anti-slip pattern according to claim 6, The anti-slip pattern is provided on a portion of the bumper body that is left unpatterned along the longitudinal direction of the bumper body. A bumper with an anti-slip pattern.

9. A bumper with an anti-slip pattern according to any one of claims 6 to 8, The anti-slip pattern is formed by a plurality of ridges formed along the longitudinal direction of the bumper body and at predetermined intervals in the width direction, and intersecting recesses formed on the surface of the ridges intersecting the longitudinal direction. A bumper with an anti-slip pattern.

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