Manufacturing method for cutter bit

Abstract

To propose a manufacturing method for a cutter bit for improving wear resistance of the cutter bit and extending its life.SOLUTION: A manufacturing method for a cutter bit includes a coating removal step of removing a hard coating on a surface of a hard tip 5, a tip arrangement step of aligning a plurality of hard tips 5, 5, ... at a top inside a mold 7, a wear-resistant material formation step of injecting molten metal 40 into the mold 7 to form a wear-resistant material 4, and a blade material fixing step of fixing the wear-resistant material 4 to the surface of a base material 2 and fixing a blade material 3 to the tip of the base material 2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method of manufacturing a cutter bit for use in an excavator. [Background technology]

[0002] Tunnel construction using the shield tunneling method, jacking method, TBM, etc. is carried out by a tunnel boring machine equipped with a cutter bit. The cutter bit is equipped with a carbide tip as a cutting material and a base material that holds the carbide tip at a set angle. The base material is easily worn away by cutting the natural ground, and the cutter bit may fall off the boring machine due to the wear of the base material. If the cutter bit falls off or becomes worn away, it is necessary to stop the excavation work and replace the cutter bit, but stopping the excavation work prevents the shortening of the construction period. Therefore, there are cases where the wear resistance of the cutter bit is improved to extend its life. For example, Patent Document 1 discloses a cutter bit in which build-up welding is applied to the outer surface of a base material that holds a blade material. According to the cutter bit of Patent Document 1, the build-up welding suppresses wear of the base material, and the risk of the blade material peeling off can be reduced. However, the work of applying build-up welding to the outer surface of the base material is time-consuming.

[0003] Therefore, Patent Document 2 discloses a technique of disposing a hard tip (cermet tip) at a predetermined location on the surface of a base material as a wear countermeasure for equipment that requires wear resistance. The hard tip is disposed in a mold in advance, but may be broken due to heat shock when molten metal is poured into the mold. The broken hard tip may move in the mold and may not be disposed in the desired position. Therefore, in the manufacturing method of Patent Document 2, multiple plating layers are laminated on the hard tip to reduce heat shock caused by sudden heating when molten metal is poured into the mold. On the other hand, the plating process requires time and costs. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-087426 A [Patent Document 2] JP 2014-083577 A Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to propose a method for manufacturing a cutter bit that improves the wear resistance of the cutter bit and extends its life. [Means for solving the problem]

[0006] In order to solve these problems, the present invention provides a method for manufacturing a cutter bit to be attached to an excavator, which includes a chip arrangement process in which a plurality of hard chips are arranged at the top of a mold, a wear-resistant material formation process in which molten metal is injected into the mold to form a wear-resistant material, and a fixing process in which the wear-resistant material is fixed to the surface of a base material and a blade material is fixed to the tip of the base material. The cutter bit obtained by this manufacturing method can have a long life because the wear of the base material is suppressed by the hard tips. In addition, the hard tips are arranged in a predetermined position by fixing the wear-resistant material to the base material, so the manufacturing process requires little effort. In addition, since the hard tips are arranged in advance on the upper part of the mold (on the surface side of the wear-resistant material), they remain on the surface side of the base material even after being cast-in with molten metal. In addition, since the specific gravity of the hard tips is smaller than that of the base material, they move to the upper part of the mold (on the surface side of the base material) even if they are broken due to heat shock.

[0007] When the hard tip has a through hole, it is preferable to insert the same mounting member into the through holes of the hard tips and mount the mounting member in the mold in the tip arrangement step. By doing so, even after the molten metal (casting insert material) is poured into the mold, the hard tips can be maintained in a line, so that the hard tips can be prevented from being unevenly arranged. It is preferable to use a material (molybdenum, tungsten, etc.) with a higher melting point than the metal (e.g., SS material) constituting the base material for the mounting member, but stainless steel, etc. may also be used.

[0008] By forming an injection hole in the lower part of the side wall of the mold and injecting molten metal through the injection hole in the wear-resistant material forming process, even if the hard tip breaks due to heat shock, the movement of the hard tip can be minimized and the hard tip can be prevented from being positioned unevenly. If the hard tip is a cermet tip (used cermet tip) used in a cutting tool or the like, it is possible to reduce material costs and to effectively utilize waste materials. In this case, if a coating removal process is provided for removing the hard coating on the surface of the hard tip, the bonding between the hard tip and the metal constituting the wear-resistant material is improved. The hard coating is preferably removed by air blasting. Effect of the Invention

[0009] A cutter bit manufactured by the cutter bit manufacturing method of the present invention can be manufactured relatively easily and inexpensively, and is also wear-resistant and can have a long life. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a cross-sectional view showing a cutter bit according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view showing an example of a hard tip. [Diagram 3] 1 is a flowchart showing a method for manufacturing a cutter bit. [Figure 4]FIG. [Diagram 5] FIG. 11 is a perspective view showing a chip placement step. [Figure 6] 6A to 6C are diagrams showing a chip placement step following FIG. 5, in which (a) is a plan view, (b) is a XX sectional view of (a), and (c) is a YY sectional view of (a). [Figure 7] 1A to 1C are diagrams showing a process for forming an abrasion-resistant material, in which (a) is a plan view, (b) is a sectional view taken along line XX of (a), and (c) is a sectional view taken along line YY of (a). [Figure 8] FIG. [Figure 9] 1A to 1C are cross-sectional views showing the experimental conditions for confirming the arrangement of hard tips of the wear-resistant material of this embodiment, where (a) is Example 1, (b) is Comparative Example 1, and (c) is Comparative Example 2. [Figure 10] 6A to 6C are photographs showing the results of an experiment conducted to confirm the arrangement of hard tips in the wear-resistant material of the present embodiment, where (a) is Example 1, (b) is Comparative Example 1, and (c) is Comparative Example 2. [Figure 11] 6A and 6B are photographs showing the results of confirming the effect of removing the hard film on the surface of a hard tip, where (a) is Example 2 and (b) is Comparative Example 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] In this embodiment, a cutter bit 1 that is fixed to a cutter head of a shield machine and cuts natural ground will be described. Fig. 1 shows the cutter bit 1. As shown in Fig. 1, the cutter bit 1 includes a base material 2, and a blade material 3 and a wear-resistant material 4 brazed to the base material 2. In this embodiment, silver brazing is used as the brazing material used for brazing. The base material 2 is a member fixed to an excavator (cutter head) to support the blade material 3, and is a so-called shank material. The base material 2 holds the blade material 3 at a determined angle and prevents it from falling off. The base material 2 in this embodiment is made of a material that has a larger expansion coefficient than the blade material 3 and has sufficient rigidity and strength as a structural member. In this embodiment, SS material, SKC material, etc. are used as the material for the base material 2, but the material for the base material 2 is not limited.

[0012] The front surface 22 of the base material 2 is the surface on the front side in the moving direction of the cutter bit 1, and as shown in FIG. 1, it is inclined so as to move away from the rear surface 24 toward the tip portion (blade material 3) side. The rear surface 23 of the base material 2 is the surface facing the natural ground (cutting surface), and is inclined so as to move away from the bottom surface 25 toward the tip portion (blade material 3) side. The corner where the extended surface of the rear surface 23 and the extended surface of the front surface 22 intersect is an acute angle. The rear surface 24 of the base material 2 is the surface on the rear side in the moving direction of the cutter bit 1, and the bottom surface 25 is the surface that abuts against a cutter head (not shown). The rear surface 24 and the bottom surface 25 of the base material 2 of this embodiment intersect at a right angle. The rear surface 24 and the bottom surface 25 do not necessarily have to be at a right angle. In addition, the shape of the base material 2 is not limited. A continuous recess 21 that opens to the tip side is formed on the front surface 22 and the back surface 23 of the base material 2. In this specification, the tip of the base material 2 refers to a corner portion sandwiched between the extended surface of the front surface 22 and the extended surface of the back surface 23 of the base material 2. The recess 21 is a missing portion with a V-shaped cross section formed on the tip of the base material 2. The blade material 3 and the wear-resistant material 4 are fixed (brazed) to the recess 21.

[0013] The blade material 3 is made of a carbide tip having a rectangular cross section, and is arranged along the extended surface of the front surface 22 and the extended surface of the back surface 23 of the base material 2, as shown in FIG. 1. In the blade material 3 of this embodiment, the front surface 31 and the back surface 32 are exposed at the tip of the base material 2, and the back surface 33 and the bottom surface 34 are brazed to the recess 21 (base material 2) or the wear-resistant material 4. The intersection of the front surface 31 and the back surface 32 of the blade material 3 forms an acute angle. On the other hand, the intersection of the front surface 31 and the bottom surface 34 of the blade material 3 and the intersection of the bottom surface 34 and the back surface 33 of the blade material 3 form a right angle, and the intersection of the back surface 32 and the back surface 33 forms an obtuse angle. The cross-sectional shape of the blade material 3 is determined appropriately according to the shapes of the base material 2 (recess 21) and the wear-resistant material 4, and is not limited to the shape shown in the figure.

[0014] The wear-resistant material 4 is a member in which multiple hard tips 5, 5, ... are embedded facing the surface, and as shown in Fig. 1, is brazed to the recess 21 in a state where it is flush with the front surface 22 or the back surface 23 of the base material 2. That is, multiple hard tips 5, 5, ... are fixed to the base material 2 in a state where they are flush with the front surface 22 and the back surface 23. The tip end surface of the base material 2 of the wear-resistant material 4 is brazed in a state where it is in contact with the bottom surface 34 or the back surface 33 of the blade material 3. The wear-resistant material 4 may also be fixed to the back surface 24 or the side surface (the surface on the front or back of the paper in Fig. 1) of the base material.

[0015] The hard tip 5 of this embodiment is a cermet tip mainly composed of titanium carbide or titanium carbonitride, and is reused from a cutting tool or the like. The hard tip 5 is shown in FIG. 2. As shown in FIG. 2, a through hole 51 is formed in the center of each hard tip 5 for mounting to a cutting tool or the like. In this embodiment, a hard tip 5 having a triangular shape (triangular prism shape) in a plan view is used, but the shape of the hard tip 5 is not limited. The specific gravity of the hard tip 5 is smaller than the specific gravity of the molten metal of the wear-resistant material 4.

[0016] The manufacturing method of the cutter bit 1 of this embodiment will be described below. Fig. 3 shows the manufacturing method of the cutter bit 1. As shown in Fig. 3, the manufacturing method of the cutter bit 1 includes a coating removing step S1, a mold forming step S2, a tip arranging step S3, an abrasion resistant material forming step S4, and a blade material fixing step S5.

[0017] In the coating removal step S1, the hard coating is removed from the surface of the hard tip 5. In this embodiment, the hard coating is removed from the surface of the hard tip 5 by air blasting. In the mold formation step S2, a mold 7 for the wear-resistant material 4 is formed. The mold 7 is shown in FIG. 4. The mold 7 in this embodiment is a sand mold, and is formed by hardening sand in a state in which a cavity 71 corresponding to the shape of the wear-resistant material 4 is formed, as shown in FIG. 4. The mold 7 is composed of a main body 72 in which the cavity 71 is formed, and a bottom plate 73 covering the lower surface of the main body 72. The cavity 71 is formed so as to open downward, and the bottom plate 73 covers the cavity 71. An injection hole (groove) 74 leading to the cavity 71 is formed in the lower part of the side wall of the main body 72.

[0018] In the chip arrangement step S3, a plurality of hard chips 5, 5, ... are arranged at the top of the mold 7 (cavity 71). The chip arrangement step is shown in Fig. 5 and Fig. 6. In the chip arrangement step S3, first, as shown in Fig. 5, the same attachment member 6 is inserted into the through holes 51 of the plurality of hard chips 5, 5, .... Next, as shown in Figs. 6(a) to (c), the attachment member 6 is attached to the mold 7 (cavity 71). At this time, it is preferable to arrange the hard chips 5 without any gaps so that the surfaces facing the outer surface of the wear-resistant material 4 (base material 2) are aligned. The attachment member 6 that has been inserted into the plurality of hard chips 5, 5, ... is fixed to the inner surface of the mold 7 (cavity 71 of the main body 72) by a jig 61. When the hard tips 5, 5, ... are arranged, the body 72 is placed so that the opening of the cavity 71 faces up, and the hard tips 5 are arranged in the cavity 71 from above. The mounting member 6 and the jig 61 are made of a material such as molybdenum or tungsten, which has a higher melting point than the cast-in material (e.g., SS material) constituting the wear-resistant material 4, to prevent melting when the cast-in material (molten metal) is poured into the mold 7. Stainless steel or the like may also be used for the mounting member 6. After the mounting member 6 is fixed to the body 72, the body 72 is turned over and placed on the bottom plate 73 with the opening of the cavity 71 facing down (see FIG. 7).

[0019] In the wear-resistant material forming step S4, the molten metal (casting insert material) 40 is poured into the mold 7 (cavity 71) to form the wear-resistant material 4. FIG. 7 shows the wear-resistant material forming step S4. The molten metal 40 is poured from a pouring hole 74 formed in the lower part of the side of the mold 7. The pouring hole 74 is connected to a pouring port 41 that opens on the upper surface of the mold 7. In this embodiment, high chromium cast iron (melting point 1400 to 1700°C) that has a lower melting point than the hard tip and the mounting member 6 is used as the molten metal. When the molten metal 40 poured into the mold 7 solidifies, the wear-resistant material 4 is removed from the mold 7. Thereafter, the surface of the wear-resistant material is polished as necessary. In the blade fixing process S5, the wear-resistant material 4 is fixed to the surface of the base material 2, and the blade material 3 is fixed to the tip of the base material 2. The blade fixing process S5 is shown in Fig. 8. The wear-resistant material 4 is brazed to the recess 21 of the base material 2 as shown in Fig. 8. In addition, the blade material 3 is brazed to the recess 21 and the end face of the wear-resistant material 4.

[0020] As described above, according to the cutter bit 1 of this embodiment, the wear-resistant material 4 with the hard tips 5 embedded therein is disposed facing the outer surface of the base material 2, so that wear of the base material 2 is suppressed and the cutting ability can be extended. Therefore, the frequency of replacing the cutter bit 1 can be reduced, and the labor required can be reduced. In addition, the wear-resistant material 4 with the multiple hard tips 5, 5, ... dispersed in a planar shape prevents partial wear of the base material 2. The molten metal 40 is injected through an injection hole 74 formed in the lower part of the side wall of the mold 7, so that even if the hard tip 5 is broken due to heat shock, the movement of the hard tip 5 can be minimized, preventing the hard tip 5 from being positioned unevenly.

[0021] In addition, since the multiple hard tips 5, 5, ... are arranged with one face aligned with the surface of the base material 2 (wear-resistant material 4), the resistance during cutting is not increased by the hard tips 5. In addition, by arranging the hard tips 5 without any gaps, the wear resistance of the base material 2 is further improved. Furthermore, since the hard tip 5 is disposed at a predetermined position by fixing the wear-resistant material 4 to the base material 2, the labor required for manufacturing is small.

[0022] In addition, since the hard film is removed from the surface of the hard tip 5, the bonding strength between the hard tip 5 and the molten metal 40 is excellent. The hard chips 5 are arranged in advance in the upper part of the mold 7, and therefore remain disposed on the surface side of the base material 2 even after being cast-in with the molten metal 40. Since the hard chips 5 have a smaller specific gravity than the base material 2, they move (float) to the upper part of the mold 7 (the surface side of the base material 2) even if they are broken due to heat shock.

[0023] The hard tips 5 are positioned in the mold 7 via the mounting member 6 inserted into the through hole 51, so that even after the molten metal 40 (casting filler material) is injected into the mold 7, the multiple hard tips 5 can be maintained in a row, thereby preventing the hard tips 5 from being positioned unevenly. Reduction in material costs and effective use of waste materials are realized by using a used cermet tip as the hard tip 5. In addition, since a used cermet tip can be used as it is as the hard tip 5 without processing (except for removing the hard coating), the effort required for processing can be omitted.

[0024] Next, the results of an experiment carried out to confirm the effects of the manufacturing method of the cutter bit 1 (wear-resistant material 4) of this embodiment will be shown. FIG. 9 shows an outline of the experimental conditions. In this experiment, as shown in FIG. 9(a), the state of the hard tip 5 was confirmed when the molten metal 40 was injected from an injection hole 74 formed on the lower side of the side wall of the mold 7 with multiple hard tips arranged on the upper side of the cavity 71 of the mold 7 (Example 1). As Comparative Example 1, as shown in FIG. 9(b), the state of the hard tip 5 was confirmed when the molten metal 40 was injected from the upper part of the side wall with the hard tip 5 arranged on the bottom of the cavity 71. Furthermore, as Comparative Example 2, as shown in FIG. 9(c), the state of the hard tip 5 was confirmed when the molten metal 40 was injected from above with the hard tip 5 arranged on the bottom of the cavity 71.

[0025] 10(a) shows a photograph of the wear-resistant material with the polished surface in Example 1, (b) in Comparative Example 1, and (c) in Comparative Example 2. The dotted line in Fig. 1 indicates the position of the hard tip 5 before the molten metal 40 is poured. 10(a), in Example 1, the hard tips 5 were cracked by the heat of the molten metal 40, but because the specific gravity of the hard tips 5 was lighter than that of the molten metal 40, they rose to the surface side. As a result, the hard tips 5 were disposed on the surface of the wear-resistant material 4. In addition, by injecting the molten metal 40 from below, the flow of the injected molten metal did not directly sweep away the hard tips 5, and the hard tips 5 were disposed relatively evenly. In Comparative Example 1 and Comparative Example 2, the hard chips 5 cracked by the heat of the molten metal 40 float in the cavity 71 and float up on the opposite side to the surface of the wear-resistant material 4. Therefore, as shown in Figs. 10(b) and (c), the number of hard chips 5 arranged on the surface of the wear-resistant material 4 was reduced compared to Example 1. In Comparative Example 1, the molten metal 40 was injected from the upper side of the mold 7, so the hard chips 5 were carried away by the flow of the molten metal 40, and as shown in Fig. 10(b), the hard chips 5 tended to be biased to the opposite side of the injection hole (upper side in Fig. 10(b)). Furthermore, in Comparative Example 2, the molten metal 40 was injected from above the cavity 71, so the hard chips 5 were carried away by the flow of the molten metal 40, and almost no hard chips 5 remained in the center of the wear-resistant material 4, as shown in Fig. 10(c). From the above results, it was confirmed that the manufacturing method of the cutter bit 1 of this embodiment makes it possible to manufacture a cutter bit 1 in which the hard tips 5 are evenly arranged on the surface of the base material 2.

[0026] Next, the effect was confirmed by removing the hard coating on the surface of the hard tip 5. The bondability with the welding material (welding material) 42 was confirmed for the case where the hard coating was removed from the surface of the hard tip 5 (Example 2) and the case where the hard coating was not removed (Comparative Example 3). Fig. 11 shows enlarged photographs of the bonded portion between the hard tip (cermet tip) 5 and the welding material 42 of Example 2 and Comparative Example 3. As shown in Fig. 11(a), it was confirmed that the hard tip 5 and the welding material 42 were joined without any gaps in Example 1. On the other hand, as shown in Fig. 11(b), in Comparative Example 3, a gap G was formed between the hard film (coating layer C) and the welding material 42. Therefore, it was confirmed that by removing the hard film on the surface of the hard tip 5, the bonding strength between the hard tip 5 and the molten metal 40 was improved.

[0027] Although an embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and each component can be appropriately modified without departing from the spirit of the present invention. In the above embodiment, the cutter bit 1 is described as being used in a shield machine, but the excavation machine using the cutter bit 1 is not limited, and it may be used, for example, in a tunnel boring machine or a tunnel excavator used in a jacking construction method. The method of fixing the blade material 3 and the wear-resistant material 4 to the base material 2 is not limited to brazing. Moreover, the brazing material used for brazing is not limited to silver brazing. In the above embodiment, a used cermet tip is reused as the hard tip 5, but the hard tip 5 may be made of a new material. The material of the hard tip 5 is not limited. The configuration of the mounting member 6 used when installing the hard tip 5 in the mold is not limited. The coating removal step S1 may be performed as necessary. [Explanation of symbols]

[0028] 1 cutter bit 2 Base material 21 Recess 3 Blade material 4 Wear-resistant material 5 Hard Tip 51 Through hole 6 Mounting material 7. Mold 71 Cavity 72 Main body 73 Bottom plate 74 Injection hole S1 Film removal process S2 Mold forming process S3 Chip placement process S4 Wear-resistant material formation process S5 Blade material fixing process

Claims

1. A chip arrangement process for arranging a plurality of hard chips in an upper portion of the mold; a wear-resistant material forming step of injecting molten metal into the mold to form a wear-resistant material; and a blade material fixing step of fixing the wear-resistant material to a surface of a base material and fixing a blade material to a tip of the base material.

2. The hard tip has a through hole formed therein, The method for manufacturing a cutter bit according to claim 1, characterized in that the tip arrangement process includes the steps of inserting an identical mounting member into the through holes of a plurality of the hard tips and attaching the mounting member to the mold.

3. An injection hole is formed in a lower portion of a side wall of the mold, 2. The method for manufacturing a cutter bit according to claim 1, wherein in the wear-resistant material forming step, a molten metal is poured through the pouring hole.

4. 3. The method for manufacturing a cutter bit according to claim 1, wherein the hard tip is a cermet tip.

5. The method for manufacturing a cutter bit according to claim 4, further comprising a coating removal step of removing a hard coating on a surface of the hard tip.

6. The method for manufacturing a cutter bit according to claim 5, wherein the hard coating is removed by air blasting in the coating removing step.

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