Manufacturing method of inner clamping plate for fixing

Abstract

A method for manufacturing an inner splint for fixation is characterized in that after a metal material of a round rod is heated, a blank comprising a head part having a large diameter and a shaft part having a small diameter and integrally formed with the head part is formed by a forward extrusion device, and after the blank is heated, the shaft part is extruded by the forward extrusion device to form the inner splint for fixation. A die-forged product having a shape similar to the shape of a plate-shaped inner clamping plate (plate) for fixing, which is a final product, is formed by die forging using a die, and the die-forged product is annealed.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an internal splint (plate) for fixing a fracture site, and in particular to a method for manufacturing an internal splint (plate) for fixing a fracture site which has a complex shape matching the shape of a bone end. Background Art

[0002] Starting with Japan, many countries in the world are facing an aging population, and the demand for internal splints (plates) used for fixing fracture accidents caused by falls of the elderly is increasing. Here, the internal splints (plates) used for fixing the bone end parts are complicated in shape and thin-walled, so they are manufactured from metal blocks as materials by cutting. At this time, a large amount of cutting chips is generated, and low yield rate becomes a problem.

[0003] Therefore, non-patent document 1 discloses a high-temperature forming technology without cutting for the purpose of suppressing the generation of cutting chips and improving the yield of metal materials. This technology uses a heating furnace to heat a round bar as a metal material to a high temperature, and forms the round bar into the shape of a fixed inner clamping plate (plate) by forging in two stages of rough forming and fine forming using a die.

[0004] High temperature forming significantly improves the yield rate compared to cutting, but the width of the internal splint (plate) used for fixation at the bone end is often uneven, and in the round bar material, more burrs are generated in the narrow width part, which deteriorates the yield rate. In order to reduce the generation of burrs in the narrow width part, it is necessary to change the diameter of the round bar corresponding to the wide width part and the narrow width part, but this requires cutting of the round bar, making it difficult to improve the yield rate.

[0005] Prior art literature

[0006] Non-patent literature

[0007] Non-patent document 1: Report on research and development results, etc. of Strategic Basic Technology Advancement and Collaboration Support Project in 2011 Strategic Basic Technology Advancement Support Project "Development of High-quality and Low-cost Forming Processing Technology for Bone End Plates" May 1991 Reiwa Bureau Kanto Bureau of Economy, Industry and Trade Support Project Fujinokuni Medical Castle Town Promotion Organization

[0008] https: / / www.chusho.meti.go.jp / keiei / sapoin / portal / seika / 2016 / 2831803029h.pdf Summary of the invention

[0009] Problems to be solved by the invention

[0010] On the other hand, as a method of changing the diameter of the round bar of the wide width portion and the narrow width portion of the fixing inner clamping plate (plate) without cutting the round bar, front extrusion forging is known. However, in front extrusion forging, since the grains are elongated in the extrusion direction, there is a problem that it is difficult to achieve the equiaxed structure required by ISO20160.

[0011] Therefore, the present invention proposes a method for manufacturing a fixing inner plate (plate) that uses front extrusion forging and can achieve an equiaxed structure required by ISO20160.

[0012] Means used to solve problems

[0013] According to the present invention, the above-mentioned problems are solved as follows.

[0014] (1) The manufacturing method of the fixing inner clamp (plate) of the present invention is characterized in that after heating the metal material of the round rod, a front extrusion device is used to form a blank consisting of a head portion with a large diameter and a shaft portion with a small diameter formed integrally with the head portion, and after heating the blank, a die forging product close to the shape of the plate-shaped fixing inner clamp (plate) as the final product is formed by die forging using a die, and the die forging product is annealed.

[0015] By using the manufacturing method of the fixed inner clamp (plate) based on the present invention, a blank formed with grains elongated in the extrusion direction by a front extrusion device is transformed into a die forging product with increased strain of the elongated grains by die forging using a die. By annealing the die forging product, the strain can be released and the grains can be refined.

[0016] Generally, annealing can release internal strain and restore coarsened grains to standard structure, but in the present invention, the strain generated by elongating the grains by front extrusion is further increased by die forging, and annealing is performed from this state, thereby more effectively refining the grains. In this way, the equiaxed structure required by ISO20160 can be achieved.

[0017] (2) In the above-mentioned item (1), the blank is subjected to die forging using a die once or twice or more.

[0018] By making a product of a desired shape by die forging once, the process can be simplified. Furthermore, by performing die forging in multiple times, a product of a complex shape can be made by die forging.

[0019] (3) Based on the above item (1) or (2), it is characterized in that the head portion of the blank corresponds to the wide portion of the fixing inner clamp (plate) as a product, and the shaft portion of the blank corresponds to the narrow portion of the fixing inner clamp (plate).

[0020] By making the shape of the blank correspond to the shape of the fixing inner plate (plate) as a product, the material yield can be improved.

[0021] (4) Based on the above item (1) or (2), it is characterized in that the metal material of the round rod is pure titanium or titanium alloy.

[0022] (5) Based on the above item (1) or (2), it is characterized in that the metal material of the round rod is cobalt-chromium-molybdenum alloy.

[0023] (6) In the above-mentioned item (1) or (2), the metal material of the round bar is austenitic stainless steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a process diagram of a method for manufacturing the fixing inner clamping plate (plate) of the present invention.

[0025] Figure 2 is used for Figure 1 Schematic diagram of the front extrusion device of the front extrusion.

[0026] Figure 3 is used for Figure 1 Front view of the die forging mold.

[0027] Figure 4A These are photos of equiaxed structures A1-A6 as required by ISO20160.

[0028] Figure 4B This is the A7-A12 photo of the equiaxed structure required by ISO20160.

[0029] Figure 5 These are photos of the metal structure after extrusion, die forging, and annealing. DETAILED DESCRIPTION

[0030] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, in each of the drawings, the same reference numerals are given to the same parts.

[0031] Figure 1 The process diagram of the manufacturing method of the fixing inner clamping plate (plate) 100 of the present invention is shown. The process consists of step 1: material cleaning, step 2: material heating, step 3: front extrusion, step 4: blank heating, step 5: die forging, step 6: annealing, step 7: deburring, and step 8: cutting.

[0032] In the manufacturing method of the fixing inner clamping plate (plate) 100 (hereinafter, appropriately referred to as "plate 100") of the present invention, the material 10 used in step 1 is a round bar of metal, specifically, a round bar of Ti-6Al-4V ELI titanium alloy, cobalt-chromium-molybdenum alloy, austenitic stainless steel, etc. In step 1, impurities and greases attached to the material 10 are removed. Specifically, mineral oil-based greases are the target, so a quasi-aqueous cleaning agent of the type composed of a white spirit mixed with a surfactant and water is generally used.

[0033] The heating in step 2 is performed by heating a round bar as the material 10 to a temperature below the β transformation point, using Ti-6Al-4V ELI titanium alloy as an example. It is preferable to heat the round bar to a uniform temperature at the center thereof while taking sufficient time.

[0034] The front extrusion in step 3 is performed by using a front extrusion device 20 to load a round rod (material) 10 heated to a temperature below the β transformation point into a cylindrical die 25 (see Figure 2 ) through the punch 21 (refer to Figure 2 ) is extruded forward to produce a billet 30 having a shape suitable for die forging. Figure 2 Step 3 will be further described.

[0035] Figure 2 (a) in the figure represents a round rod as material 10, Figure 2 (b) and Figure 2 (c) in the figure represents the front extrusion device 20, Figure 2 (d) in the figure shows a blank 30 produced by front extrusion. The dimensions of the round bar of the material 10 are, for example, 19.2 mm in outer shape and 48 mm in length. Figure 2 In the case of the material shown in (a), the size of the billet 30 produced by front extrusion is that the head portion with a larger diameter has an outer shape of 20 mm, the shaft portion with a smaller diameter has an outer shape of 11.5 mm, and the total length is 110 mm.

[0036] Figure 2 (b) is a schematic diagram of the front extrusion device 20 in a state where the material 10 is loaded. By applying a force to extrude "forward" to the punch 21 via the gasket 24, the loaded material 10 is formed to match the shape of the die 25. In the front extrusion device 20, the punch 21 is held by the punch guide 23 assembled to the punch housing 22. In addition, the die 25 is assembled to the die housing 28, and its lower part is blocked by the backing block 29.

[0037] Figure 2(c) in the figure shows a forward extrusion device in which the material 10 is extruded forward by the punch 21 to form a blank 30. By adopting forward extrusion in this way, the blank 30 having a head portion 30a with a large diameter and a shaft portion 30b with a small diameter can be formed integrally, and the loss of material caused by cutting can be reduced.

[0038] Figure 2 (d) in FIG. 3 shows a blank 30 formed by the front extruder. Figure 1 In step 4, the steel is heated to a temperature below the β transformation point in the same manner as in step 2, and then used for die forging using a die 40 in step 5.

[0039] Figure 3 express Figure 1 4 is a front view of a die 40 used for die forging in step 5. The die 40 is paired in upper and lower parts and is respectively mounted on a press 50. A blank 30 is assembled between the upper and lower pairs of the die, and the blank 30 is deformed into the shape of the die by the pressing force of the press 50.

[0040] exist Figure 3 In the embodiment, the upper die set 41 of the die 40 is mounted on the slide 51 of the press machine 50, and the upper die set 41 moves up and down together with the punch plate 43 and the punch 42 along with the vertical movement of the press machine 50. On the other hand, the lower die set 46 of the die 40 is fixed to the backing plate 52 of the press machine 50, and the lower die set 46 receives the pressing force of the press machine 50 together with the die plate 45 and the die 44 through the punch 42.

[0041] In addition, the die 40 forms a burr avoidance portion 47 between the upper and lower pairs of the die 40 to avoid burrs generated when the blank 30 is deformed. The gap of the burr avoidance portion 47 varies depending on the degree of deformation of the blank 30, but is usually adjusted within a range of 1 to 3 mm. Figure 1 As shown in step 5 of the die forging, the die forging product 60 formed by die forging has burrs 61 formed on the entire circumference thereof.

[0042] In the present invention, annealing is performed in step 6 and deburring is performed in step 7. By annealing, in the case of Ti-6Al-4VELI titanium alloy, the uniform α-β two-phase metal structure of the material 10 can be restored, and the hardness of the metal structure increased by die forging can be reduced. Therefore, in the deburring of step 7 in which the burrs 61 as unnecessary protrusions are removed by machining, the tool life can be improved. Annealing is performed at 700 to 750°C for 1 to 4 hours. By deburring in step 7, the die forging product 60 becomes an intermediate product 70 before cutting.

[0043] Alternatively, annealing may be performed in step 7 after deburring is performed in step 6 .

[0044] The pre-cut intermediate product 70 is subjected to cutting processing in step 8 as the final step. In cutting processing, two types of processing are performed: surface processing and hole processing. Surface processing is an operation of removing oxide scale generated on the surface of the pre-cut intermediate product 70 by front extrusion and die forging, and processing it to a target size as a product. Hole processing is an operation of cutting a threaded hole for inserting a fixing screw for fastening the plate 100 as a product to a bone.

[0045] A machining center is used in the cutting process of step 8. The machining center is an NC milling machine with an automatic tool changing function. A plurality of cutting tools are stored in the tool library, and the machine automatically changes the tools according to the instructions of the computer numerical control, thereby being able to continuously perform various processes such as milling, boring, drilling, and tapping. Through the cutting process, the plate 100 as the final product is completed.

[0046] Furthermore, surface treatment (sterilization treatment) may be performed after cutting.

[0047] By the manufacturing method of the fixing inner clamping plate (plate) 100 of the present invention, in the process of manufacturing the blank from the round bar of the material 10, the front extrusion forging without cutting is adopted, and the problem of the grain elongation in the extrusion direction, which is the disadvantage of the front extrusion forging, is used on the contrary. By die forging after the front extrusion forging, the strain generated by the front extrusion forging is increased, and annealing is performed from this state, thereby making the grains more effectively fine. In this way, by using the manufacturing method of the fixing inner clamping plate (plate) 100 of the present invention, the yield rate of the material 10 can be further improved, and the equiaxed structure required by ISO20160 can be achieved.

[0048] In addition, Figure 1 In the process diagram of FIG. 1 , the die forging of step 5 is performed once, but the die forging may be performed twice or more. In this case, the heating of step 4 and the die forging of step 5 are repeated twice or more. The intermediate product 70 before cutting as an intermediate product can be formed by one die forging, but by performing the die forging multiple times, a product with a complex shape can be produced by die forging.

[0049] Figure 4A and Figure 4B The microstructure of the ISO20160 international standard surgical implant-metal material-α+β titanium alloy rod is shown in the figure. Figure 4A In the A2 photo, the α+β type double-layer organization constitutes an equiaxial organization.

[0050] Figure 5 1 is a photograph of the microstructure after being processed through each step of the manufacturing method of the fixing inner splint (plate) 100 according to the present invention. Figure 5As shown on the left side of , this photograph is the microstructure of the central portion of the vertical cross section in the stretching direction of the material 10. Figure 5 (a) is a photo of the metal structure after extrusion. Figure 5 (b) is a photo of the metal structure after die forging. Figure 5 (c) is a photograph of the metal structure after annealing.

[0051] exist Figure 5 In (a), it is shown that the microstructure is extended in the extrusion direction by front extrusion. Figure 5 The photo on the right side of (a) is a microstructure at a magnification of 2000 times, and the photo on the left side is a microstructure at a magnification of 200 times. Figure 4A and Figure 4B The same magnification as the ISO20160 international standard photos. Figure 5 (b) shows that the strain of the microstructure elongated in the extrusion direction increases due to die forging. Figure 5 (c) clearly shows that the strain of the microstructure enlarged by annealing disappears, the grains become finer, and an equiaxed structure is formed. Figure 5 The left side of the photo in (c) becomes Figure 4A The equiaxial structure of A1~A2 is the same as that of the other.

[0052] In addition, in the present embodiment, the manufacturing method of the fixing inner plate (plate) 100 using Ti-6Al-4V ELI titanium alloy as the material is mainly described, but the manufacturing method of the fixing inner plate (plate) of the present application, that is, the method of die forging after front extrusion, can also be applied to other materials that can be used as the fixing inner plate (plate) in addition to Ti-6Al-4V ELI titanium alloy. For example, the same manufacturing method can also be applied to pure titanium (CP-Ti), Ti-6Al-4V, Ti-6Al-2Nb-1Ta, Ti-15Zr-4Nb-4Ta, Ti-6Al-7Nb, Ti-3Al-2.5V, Ti-13Nb-13Zr as titanium alloys, cobalt-chromium-molybdenum alloys, cobalt-chromium-tungsten-nickel alloys, austenitic stainless steel, austenitic low-nickel stainless steel, etc.

[0053] Description of Reference Numerals

[0054] 10: Materials;

[0055] 20: front extrusion device;

[0056] 21: Punch;

[0057] 22: Punch housing;

[0058] 23: Punch guide;

[0059] 24: Gasket;

[0060] 25: die pressing;

[0061] 28: die-cast housing;

[0062] 29: backing block;

[0063] 30: blank;

[0064] 30a: head;

[0065] 30b: shaft;

[0066] 40: Mould;

[0067] 41: upper die of die set;

[0068] 42: Punch;

[0069] 43: Punch plate;

[0070] 44: die pressing;

[0071] 45: Pressing plate;

[0072] 46: lower die of die set;

[0073] 50: Pressing machine;

[0074] 51: Slider;

[0075] 52: pad;

[0076] 60: Die forgings;

[0077] 61: burr;

[0078] 70: Intermediate product before cutting;

[0079] 100: Inner splint (plate) for fixation.

Claims

1. A method for manufacturing a fixing inner splint, characterized in that: After the metal material of the round rod is heated, a front extrusion device is used to form a billet consisting of a head portion with a large diameter and a shaft portion with a small diameter formed integrally with the head portion. After the billet is heated, a die forging using a die is used to form a die forging product that is close to the shape of a plate-shaped fixing inner clamp (plate) as a final product, and the die forging product is annealed.

2. The method for manufacturing the fixing inner plate according to claim 1 or 2, characterized in that: The blank is subjected to die forging using a die once or twice or more.

3. The method for manufacturing the fixing inner plate according to claim 1 or 2, characterized in that: The head portion of the blank corresponds to a wide portion of the fixing inner plate (plate) as a final product, and the shaft portion of the blank corresponds to a narrow portion of the fixing inner plate (plate).

4. The method for manufacturing the fixing inner plate according to claim 1 or 2, characterized in that: The metal material of the round rod is pure titanium or titanium alloy.

5. The method for manufacturing the fixing inner plate according to claim 1 or 2, characterized in that: The metal material of the round rod is cobalt-chromium-molybdenum alloy.

6. The method for manufacturing the fixing inner plate according to claim 1 or 2, characterized in that: The metal material of the round bar is austenitic stainless steel.

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