Guide bar manufacturing method, guide bar, and work machine

Abstract

To provide a manufacturing method of a guide bar capable of relatively easily manufacturing the guide bar having excellent joining strength between a guide bar body and a coating layer, the guide bar having such characteristics, and a working machine equipped with the guide bar.SOLUTION: According to an aspect of the present invention, there is provided a method for manufacturing a guide bar around which a saw chain is to be wound, the method including a first step of preparing a guide bar body made of a first metallic material and powder made of a second metallic material having higher heat resistance and wear resistance than the first metallic material, and a second step of forming a coating layer that coats at least a front end portion of the guide bar body by performing an operation of melting the powder by irradiation with a laser beam at least once while supplying the powder to at least the front end portion of the guide bar body.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a guide bar, a guide bar, and a work machine. [Background technology]

[0002] The cutting blade (working part) of a chainsaw is constructed by wrapping a saw chain around the outer periphery of a guide bar. The tip of the guide bar, i.e., the part that is subject to high thermal stress when the saw chain rotates, is designed to have high heat resistance and wear resistance (see Patent Document 1). Patent document 1 discloses a method in which a guide bar (base material) with its tip pre-processed is placed in a recess in a mold, the space created between them is filled with a powdered wear-resistant material, and the wear-resistant material is fused by heating and melting.

[0003] Alternatively, guide bars may be manufactured by manually adding buildup to the tip of the base material using a filler (welding rod). However, there is a demand for further improvement in the bonding strength between the base material and the wear-resistant member. Also, manual build-up work requires high skill from the worker. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 4-119801 Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above circumstances, the present invention provides a method for manufacturing a guide bar that can relatively easily manufacture a guide bar having excellent bonding strength between the guide bar body and the coating layer, a guide bar having such characteristics, and a work machine equipped with this guide bar. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided a method for manufacturing a guide bar that is used by wrapping a saw chain around it, the method comprising: a first step of preparing a guide bar body made of a first metal material and powder made of a second metal material that is more heat-resistant and wear-resistant than the first metal material; and a second step of supplying the powder to at least the tip of the guide bar body and melting it by irradiating it with laser light at least once to form a coating layer that covers at least the tip of the guide bar body.

[0007] According to this aspect, a guide bar having excellent bonding strength between the guide bar body and the coating layer can be manufactured relatively easily. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a right side view showing the appearance of the chain saw. [Figure 2] FIG. 2 is a left side view showing the appearance of the chain saw. [Figure 3] FIG. 2 is a top view showing the chainsaw with some parts omitted. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA in FIG. [Figure 5] 1A and 1B are diagrams showing a guide bar ((a) is a right side view, (b) is a front view). [Figure 6] 1A to 1C are diagrams illustrating a manufacturing process of a guide bar. [Figure 7] 1 is a schematic diagram showing the configuration of a nozzle head of a laser coating device used to form a coating layer. FIG. [Figure 8] 5A and 5B are schematic diagrams ((a) side view, (b) front view) showing the configuration of the guide bar body in a state where a coating layer is formed. [Figure 9] 10 is a photograph showing the appearance of the guide bar body after the coating layer is formed. [Figure 10] 1 is a photograph showing the appearance of guide bars manufactured in Examples and Comparative Examples. [Figure 11]1 is a graph showing changes in hardness of guide bars manufactured in Examples and Comparative Examples. [Figure 12] 1 shows characteristic X-ray images and line analysis results of a guide bar manufactured in a comparative example. [Figure 13] 1 shows characteristic X-ray images and line analysis results of a guide bar manufactured in an example. [Figure 14] 6A and 6B are photographs showing the appearance of the guide bars manufactured in the examples and comparative examples before and after a strength test. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present embodiment will be described below with reference to the drawings. Various features shown in the following embodiment can be combined with each other. <Chainsaw> First, a chainsaw 1 according to one embodiment of a work machine will be described. The chainsaw 1 is a work machine for cutting, milling, processing, etc. (hereinafter simply referred to as "processing") work objects such as trees and branches, and is powered by, for example, a motor or an engine. The following description will be given taking as an example a chainsaw 1 that uses a motor as its power source.

[0010] FIG. 1 is a right side view showing the appearance of a chainsaw. FIG. 2 is a left side view showing the appearance of the chainsaw. FIG. 3 is a top view showing the chainsaw with some parts omitted. FIG. 4 is a cross-sectional view taken along line AA in FIG. 3. FIG. 5 is a diagram showing a guide bar ((a) right side view, (b) front view). FIG. 6 is a diagram showing a manufacturing process of a guide bar. In the following description, the directions of the chainsaw 1 and the members that make up the chainsaw 1 are defined based on "up," "down," "left," "right," "front," and "rear" shown in FIGS.

[0011] The chainsaw 1 shown in Figures 1 and 2 is a small chainsaw known as a top-handle saw. This chainsaw 1 includes a main body 2 and a battery 8. The main body 2 includes a working unit 3, a handle 4, a housing 5, and a motor 6 and a control unit 7 housed in the housing 5.

[0012] (Working Section 3) The working unit 3 is configured to process a work object and is connected to the housing 5. In the illustrated configuration, the working unit 3 is a chain cutter and includes a guide bar 31, a saw chain 32, and a drive sprocket 33. 1 and 2, the guide bar 31 is a plate-shaped member extending in the front-rear direction, and the rear end of the guide bar 31 is attached to the front right part of the housing 5. As shown in FIG. 4, the guide bar 31 is disposed in front of the drive sprocket 33.

[0013] The saw chain 32 is configured in an annular shape and has a blade on its outer periphery for treating a work object. In the state shown in the figure, the saw chain 32 is engaged with the guide bar 31 at the front end side of the guide bar 31, and is engaged (meshed) with the drive sprocket 33 connected to the rotary shaft 61 of the motor 6 at the rear end side of the guide bar 31. In other words, the saw chain 32 is wound around the guide bar 31 and the drive sprocket 33. In addition, the saw chain 32 is configured to rotate along the outer periphery of the guide bar 31 and the drive sprocket 33 when the drive sprocket 33 rotates due to the rotational power generated by the motor 6.

[0014] The drive sprocket 33 is generally disk-shaped and has a plurality of protrusions (teeth) 33c that protrude outward from its outer periphery. The tips of the protrusions 33c are configured to engage (mesh) with a portion of the saw chain 32. The drive sprocket 33 also has a shaft hole 33b in the center of the generally disk-shaped sprocket. The drive sprocket 33 has a rotation shaft 33a at the center of the shaft hole 33b. The rotation shaft 33a is disposed behind the guide bar 31 and aligned in the left-right direction of the main body 2.

[0015] The shaft hole 33b is fitted with the rotating shaft 61 of the motor 6. This allows the drive sprocket 33 to rotate due to the rotational power generated by the motor 6. As shown in Fig. 4, the shaft hole 33b and the rotating shaft 61 are specifically configured to have flat surfaces on the front and rear sides, preventing the rotating shaft 61 from rotating within the shaft hole 33b. As the drive sprocket 33 rotates (clockwise in FIG. 4), it sequentially engages with the saw chain 32 at its lower front end, while sequentially disengaging from the saw chain 32 at its upper front end. With this configuration, the rotation of the drive sprocket 33 causes the saw chain 32 to move along the guide bar 31. The shaft hole 33b and the rotary shaft 61 may be any mechanism capable of transmitting rotational power, and may be, for example, a spline mechanism, a key and key groove mechanism, or the like.

[0016] (Handle 4) 1 and 2, the handle 4 has a top handle 41 provided above the housing 5 and a side handle 42 provided on the left side of the housing 5. An operator performs work by holding the top handle 41 and the side handle 42 with each hand.

[0017] ((Top handle 41)) The top handle 41 is disposed above the housing 5. The top handle 41 is formed contiguous with the top surface of the housing 5 and extends in the front-to-rear direction above the housing 5. The front side of the top handle 41 is fixed to a front end portion 53 of the housing 5 that protrudes upward from the housing 5. A drive switch (not shown) is provided inside the front end 53 of the housing 5. This drive switch controls the operation of the working unit 3. Specifically, the drive switch controls the rotation speed of the motor 6 according to the amount of depression of the head, thereby increasing or decreasing the rotation speed of the saw chain 32. The rear side of the top handle 41 is fixed to the battery attachment / detachment section 54 of the housing 5. When the battery 8 is attached to the battery attachment / detachment section 54, the upper end of the battery 8 protrudes above the rear end of the top handle 41.

[0018] A grip portion 411 extending in the front-to-rear direction is provided between the front end and rear end of the top handle 41. The grip portion 411 is inclined slightly downward from the front end to the rear end of the top handle 41. The grip portion 411 is the part that an operator holds when holding the chainsaw 1. The operator's hand is inserted into the space between the grip portion 411 and the top surface of the housing 5. A trigger lever 412 is disposed on the underside of the front end of the grip part 411 as an operating means for increasing or decreasing the rotation speed of the saw chain 32. In other words, the trigger lever 412 is configured to control the operation of the working unit 3 via a drive switch (not shown). The operator can operate the trigger lever 412 while holding the grip part 411.

[0019] Furthermore, a lockout lever 413 is provided on the upper surface of the grip portion 411 so as to be displaceable relative to the trigger lever 412. Specifically, the lockout lever 413 is disposed so as to be able to freely appear and disappear from the grip portion 411 (top handle 41). When an operator grips the grip portion 411, the lockout lever 413 is pushed by the palm of the operator's hand and retracts into the grip portion 411. This allows the lockout lever 413 and the trigger lever 412 to be operatively connected within the grip portion 411, enabling the trigger lever 412 to be operated for the first time. As a result, an operation mechanism is made up of a trigger lever 412 and a lockout lever 413, both of which are provided on the grip part 411 (top handle 41). By operating this operation mechanism, the operation of the working part 3 can be controlled, i.e., the rotation speed of the saw chain 32 can be increased or decreased.

[0020] ((Horizontal handle 42)) The side handle 42 extends in the front-to-rear direction from the front end to the rear end on the left side of the housing 5. The side handle 42 may be made of resin, or may be formed by bending a lightweight metal pipe. The front end of the side handle 42 is attached to the left side of the front end of the top handle 41. The rear end of the side handle 42 is located rearward and downward of the housing 5, and is attached to the left wall of the battery attachment / detachment section 54. The portion between the front and rear ends of the side handle 42 is curved so as to bulge outward from the left side of the housing 5 (see FIG. 3).

[0021] (Case 5) The housing 5 is a resin box that houses mechanical and electrical devices that operate the chainsaw 1. As shown in Fig. 2, specifically, the housing 5 houses a motor 6 and a control unit 7. The housing 5 also has a battery attachment / detachment section 54 to which a battery 8 can be attached / detached. As shown in FIG. 1, the battery attachment / detachment section 54 has a cylindrical shape extending from the bottom to the top. The battery attachment / detachment section 54 is formed at the rear of the housing 5 and is inclined so that its lower portion is positioned further forward than its upper portion. The battery attachment / detachment section 54 is provided with a metal connection terminal (not shown). The connection terminal is electrically connected to the motor 6 and the control unit 7. When the connection terminal of the battery attachment / detachment section 54 is connected to the connection terminal of the battery 8, power is supplied from the battery 8 to the motor 6 and the control unit 7.

[0022] 3, the housing 5 is made up of a left cover 51 and a right cover 52, and can be separated in the left-right direction. The left cover 51 and the right cover 52 are joined together to form a space for accommodating the motor 6 and the control unit 7. Furthermore, as shown in FIG. 3, a sprocket cover 55 is detachably attached to the right side surface of the right cover 52. The sprocket cover 55 is a box-shaped member configured to cover the components arranged in the right cover 52. As shown in FIG. 4, on the right side of the right cover 52, there are arranged the rotating shaft 61 of the motor 6 protruding to the right from the right cover 52, the drive sprocket 33 fitted to the tip of the rotating shaft 61, the guide bar 31 arranged in front of the drive sprocket 33, and the saw chain 32 wound around the guide bar 31 and the drive sprocket 33. The sprocket cover 55 is attached to the right cover 52 so as to cover the rotating shaft 61, the drive sprocket 33, part of the saw chain 32, and part of the guide bar 31.

[0023] (Motor 6) The motor 6 is a known electric motor configured to generate rotational power for driving the working unit 3. As shown in Fig. 2, the motor 6 has a rotating shaft 61. The rotating shaft 61 extends in the left-right direction, and as shown in Fig. 4, its right end is connected to the drive sprocket 33. (Control Unit 7) 2, the control unit 7 has a box shape and is fixed to the housing 5. The control unit 7 is electrically connected to the motor 6 and the battery 8 by wires, connectors, etc., and controls the supply of electricity from the battery 8 to the motor 6. The control unit 7 is configured to electrically control the rotation of the motor 6.

[0024] (8 batteries) As shown in FIG. 1, battery 8 is a known battery, configured by housing a secondary battery such as a lithium-ion secondary battery in a rectangular parallelepiped case extending in the vertical direction. The height of battery 8 is greater than the height of the rear end of housing 5. Battery 8 is larger in size than batteries that are housed in housing 5. Battery 8 has a sufficiently high output and charging capacity suitable for work. When attaching the battery 8 to the battery attachment / detachment section 54, the battery 8 is fitted into the battery attachment / detachment section 54 by sliding the battery 8 from above toward below relative to the battery attachment / detachment section 54. Then, when the battery 8 is moved to a position where it is supported by the battery attachment / detachment section 54, the engagement section of the battery 8 engages with the battery attachment / detachment section 54, and the battery 8 is fixed to the battery attachment / detachment section 54.

[0025] The battery 8 attached to the battery attachment / detachment part 54 is disposed at an angle so that its lower part is positioned further forward than its upper part. The battery 8 has a connection terminal (not shown), and when the battery 8 is fixed to the battery attachment / detachment part 54, the connection terminal of the battery 8 and the connection terminal (not shown) of the battery attachment / detachment part 54 are electrically connected. When the connection terminal of the battery 8 is connected to the connection terminal of the battery attachment / detachment part 54, power is supplied from the battery 8 to the motor 6 and the control unit 7. When removing the battery 8 from the battery attachment / detachment section 54, the connection lever (not shown) of the battery 8 is pulled up, which disengages the battery attachment / detachment section 54 from the engagement section, allowing the battery 8 to be slid upward relative to the battery attachment / detachment section 54.

[0026] The guide bar 31 will now be described in more detail. ((Guide bar 31)) As described above, the guide bar 31 is used by wrapping the saw chain 32 around it. The guide bar 31 shown in Fig. 5 comprises a guide bar body 311 made of a first metallic material, and a coating layer 312 made of a second metallic material that covers at least the tip of the guide bar body 311 and has higher heat resistance and wear resistance than the first metallic material. This configuration makes it possible to impart excellent heat resistance and high wear resistance to the tip, which is subject to high thermal stress when the saw chain 32 is rotated.

[0027] Furthermore, the guide bar 31 has a region on the coating layer 312 side of the guide bar body 311 where metal elements contained in the second metal material are diffused into the first metal material, and / or a region on the guide bar body 311 side of the coating layer 312 where metal elements contained in the first metal material are diffused into the second metal material. With this configuration, even if a large force is continuously applied to the coating layer 312 when the saw chain 32 is rotated, breakage at the interface between the coating layer 312 and the guide bar body 311 can be suitably prevented. It is preferable that the above-mentioned region exists in both the guide bar body 311 and the coating layer 312, in other words, exists across the guide bar body 311 and the coating layer 312. In this case, the region can also be called a mixed region (diffusion region) where components of the first metallic material and components of the second metallic material are mixed.

[0028] The first metallic material is preferably carbon steel. Carbon steel is preferred because it has high hardness and is easily available. Examples of carbon steel include low carbon steel, medium carbon steel, and high carbon steel (so-called SK material), with high carbon steel being preferred. The second metallic material may be any metallic material having higher heat resistance and wear resistance than the first metallic material, but is preferably at least one selected from the group consisting of Co-based alloys, Ni-based alloys, Fe-based alloys, and mixtures of these alloys with at least one of oxide ceramics and carbide ceramics. By selecting such a second metallic material, the above effects can be further improved. Examples of oxide ceramics include alumina (Al2O3), silica (SiO2), etc. Examples of carbide ceramics include diamond, titanium nitride (TiN), silicon carbide (SiC), tungsten carbide (WC), etc. Among these, the second metallic material is preferably a Co-based alloy (Stellite) alone, an Fe-based alloy (Fe—Cr—Ni alloy) alone, or a mixture of a Co-based alloy and an Fe-based alloy, because they are easy to handle. 5(a), it is preferable that the circumferential surface of the guide bar body 311 and the circumferential surface of the coating layer 312 form a continuous surface (a surface without steps). This allows the saw chain 32 to rotate smoothly along the outer circumferential surface of the guide bar 31.

[0029] 5(b), the guide bar 31 has a groove 313 formed around the entire circumference midway in the thickness direction (central portion). A part of the saw chain 32 is inserted into this groove 313, thereby guiding the rotation of the saw chain 32 relative to the guide bar 31. The width W of the groove 313 is not particularly limited, but is preferably about 1.1 mm or more and 1.6 mm or less. With this configuration, the covering layer 312 is provided on the wall portions on both sides of the groove 313 of the guide bar body 311 . The groove 313 may be formed in at least a portion of the circumferential direction of the guide bar body 311, including the tip end portion (for example, excluding the portion facing the drive sprocket 33).

[0030] The guide bar main body 311 is formed with elongated holes 311a through which bolts or pins can be inserted for fixing to the housing 5. The guide bar main body 311 also has three through holes (lightening holes) 311b formed therein to reduce weight. As shown in FIG. 5(a), the total length L of the guide bar 31 is not particularly limited, but is preferably about 240 mm or more and 1170 mm or less. As shown in FIG. 5(b), the thickness T of the guide bar 31 is not particularly limited, but is preferably about 3.1 mm or more and 4.9 mm or less.

[0031] ((Manufacturing Method of Guide Bar 31)) The guide bar 31 used by wrapping the saw chain 32 as described above can be manufactured as follows. The manufacturing method of the guide bar in this embodiment includes: [1] a preparation process (first process) of preparing a guide bar body 311 made of a first metal material and powder P made of a second metal material that has higher heat resistance and wear resistance than the first metal material; [2] a groove formation process of forming grooves 313 in the middle of the thickness direction of the guide bar body 311, at least in a part of the circumferential direction (in this embodiment, the entire circumference), including the tip; and [3] a coating layer formation process (second process) of supplying powder P to the tip portion of the guide bar body 311 and melting it by irradiating it with laser light LB at least once, to form a coating layer 312 that covers the tip portion of the guide bar body 311.

[0032] [1] Preparation process In this step, the guide bar body 311 and the powder P are prepared. These may be commercially available products or may be manufactured by the user. The first metal material and the second metal material are the same as those described above. The average particle size of the particles constituting the powder P is preferably about 15 μm or more and 250 μm or less, and more preferably about 45 μm or more and 150 μm or less. If the powder P containing particles with such an average particle size is used, it is easy to form a dense coating layer 312 that has high bonding strength to the guide bar body 311. The average particle size of the particles means the particle size at 50% of the cumulative volume in the particle size distribution determined by the laser diffraction / scattering method.

[0033] [2] Groove formation process In this step, the groove 313 is formed in at least a portion of the circumferential direction (in this embodiment, the entire circumference) including the tip end, midway in the thickness direction of the guide bar body 311. Note that the formation of the groove 313 may be omitted in a location where the saw chain 32 does not come into contact (for example, the rear end of the guide bar body 311). The grooves 313 can be formed by, for example, laser processing, cutting processing, etc. By using the laser additive manufacturing method in the next step [3], the coating layer 312 can be formed accurately even on the narrow wall portions on both sides of the groove 313 of the guide bar body 311.

[0034] [3] Covering layer formation process As shown in FIG. 6(a), a U-shaped cutout 311c is formed at the tip of the guide bar body 311 in the area where the coating layer 312 is to be formed. Powder P is supplied to this defect portion 311c while being irradiated with laser light LB to melt the powder P. For example, a laser coating device is suitably used for this operation. That is, preferably, the supply of powder P and the irradiation of laser light LB are performed using a single nozzle head 10. FIG. 7 is a schematic diagram showing the configuration of the nozzle head of a laser coating device used to form the coating layer. The nozzle head 10 shown in Figure 7 has a tapered opening 101 formed in the center to allow the laser light LB to pass through, and a passage 102 formed inside the peripheral wall of the nozzle head 10 to allow the powder P to pass through.

[0035] A shielding gas SG is supplied along the inner circumferential surface of the opening 101. The nozzle head 10 is also configured to be cooled by a coolant (for example, water). According to this configuration, the powder P is ejected in a cone shape from the tip of the nozzle head 10 and supplied onto the surface of the missing portion 311c of the guide bar body 311. At the same time, a laser beam LB is irradiated onto the vicinity of the apex of the cone of the powder P. Then, the nozzle head 10 is moved relative to the guide bar body 311. As a result, the powder P is melted, and a first coating layer (unit coating layer) 312a is formed on the surface of the tip of the guide bar body 311.

[0036] The number of times the above operation is repeated is not particularly limited, but is preferably about 1 to 10 times, and more preferably about 3 to 7 times. In this embodiment, the above operation is repeated three times to stack the unit coating layers 312a, 312b, and 312c (so-called laser additive manufacturing), thereby obtaining the coating layer 312. By slightly shifting the formation start and end positions of the unit coating layers 312a, 312b, and 312c, it is easy to form the circumferential surface of the guide bar body 311 and the circumferential surface of the coating layer 312 as a continuous surface.

[0037] In the coating layer forming step (second step), the thickness t (see FIG. 6(b)) of each of the coating layers (unit coating layers) 312a-312c formed in one operation is preferably about 0.1 mm to 1 mm, more preferably about 0.3 mm to 0.7 mm, which makes it easier to form a more uniform coating layer 312. Furthermore, by adjusting the amount of powder P ejected from the nozzle head 10 per unit time (powder feed rate), the intensity and / or wavelength of the laser light LB, the focal diameter of the laser light LB, the moving speed of the nozzle head 10, the type and / or flow rate of the shielding gas SG, etc., it is possible to create a region on the coating layer 312 side of the guide bar body 311 where the metal elements contained in the second metal material are diffused into the first metal material, and / or a region on the guide bar body 311 side of the coating layer 312 where the metal elements contained in the first metal material are diffused into the second metal material.

[0038] Specifically, the powder feed rate is preferably about 5 g / min or more and 20 g / min or less, and more preferably about 10 g / min or more and 15 g / min or less. The focal diameter of the laser light LB is preferably about 1 mm or more and 2.5 mm or less, and more preferably about 1.5 mm or more and 2 mm or less. The flow rate of the shielding gas SG (shielding gas flow rate) is preferably about 1 L / min or more and 25 L / min or less, and more preferably about 3 L / min or more and 20 L / min or less. Increasing the number of times the unit coating layers are stacked makes it easier to increase the welding strength and durability, but the above-mentioned conditions are appropriately set taking into consideration productivity (cost, processing time, etc.), the size of the guide bar 31, etc.

[0039] The coating layer forming step may be followed by a post-treatment step, such as cleaning, polishing, cutting, and possibly heat treatment of the guide bar 31. Fig. 8 is a schematic diagram ((a) side view, (b) front view) showing the configuration of the guide bar main body after the coating layer has been formed. Fig. 9 is a photograph showing the appearance of the guide bar main body after the coating layer has been formed. 8 and 9, when the circumferential surface of the guide bar body 311 and the circumferential surface of the coating layer 312 do not form a continuous surface (when there are irregularities at the boundary or in the vicinity thereof), it is preferable to grind, cut, etc. the circumferential surface of the guide bar 31. This can improve the sliding ability of the saw chain 32 relative to the guide bar 31.

[0040] The coating layer 312 may be provided not only at the tip of the guide bar body 311 but also over the entire periphery. Furthermore, the guide bar body 311 may be a laminate type (three-piece joint type), in which case the formation of the groove 313 in the guide bar body 311 can be omitted. In the above embodiment, a small chain saw 1 called a top handle saw has been described as an example of a work machine, but the work machine may be a pruner or the like. Furthermore, the device for forming the coating layer 312 is not limited to a laser coating device equipped with the nozzle head 10 shown in FIG. 7, but various devices capable of forming a coating layer 312 having the same characteristics as those described above can be used, such as a device that supplies powder P in a linear form while irradiating laser light LB. Furthermore, it may be provided in the following aspects.

[0041] (1) A method for manufacturing a guide bar for use by wrapping a saw chain around it, comprising: a first step of preparing a guide bar body made of a first metal material and powder made of a second metal material that is more heat-resistant and wear-resistant than the first metal material; and a second step of supplying the powder to at least the tip of the guide bar body and melting it by irradiating it with laser light at least once to form a coating layer that covers at least the tip of the guide bar body.

[0042] (2) The method for manufacturing a guide bar according to (1) above, wherein the supply of the powder and the irradiation of the laser light are performed using a single nozzle head.

[0043] (3) The method for manufacturing a guide bar according to (1) or (2) above, wherein the average particle size of the particles constituting the powder is 15 μm or more and 250 μm or less.

[0044] (4) A method for manufacturing a guide bar according to any one of (1) to (3) above, further comprising, prior to the second step, a step of forming a groove in the thickness direction of the guide bar body, including the tip end, in at least a part of the circumferential direction.

[0045] (5) The method for manufacturing a guide bar according to any one of (1) to (4) above, wherein the first metallic material is carbon steel.

[0046] (6) In the method for manufacturing a guide bar described in any one of (1) to (5) above, the second metal material is at least one selected from the group consisting of a Co-based alloy, a Ni-based alloy, an Fe-based alloy, and a mixture of these alloys with at least one of oxide-based ceramics and carbide-based ceramics.

[0047] (7) A method for manufacturing a guide bar described in any one of (1) to (6) above, wherein in the second step, the thickness of the coating layer formed in one operation is 0.1 mm or more and 1 mm or less.

[0048] (8) The method for manufacturing a guide bar according to any one of (1) to (7) above, wherein the circumferential surface of the guide bar body and the circumferential surface of the coating layer form a continuous surface.

[0049] (9) A guide bar used by wrapping a saw chain around it, comprising: a guide bar body made of a first metallic material; and a coating layer covering at least the tip of the guide bar body and made of a second metallic material having higher heat resistance and wear resistance than the first metallic material, wherein the guide bar has a region on the coating layer side of the guide bar body where metal elements contained in the second metallic material are diffused into the first metallic material, and / or a region on the guide bar body side of the coating layer where metal elements contained in the first metallic material are diffused into the second metallic material.

[0050] (10) The guide bar according to (9) above, wherein the guide bar body has a groove in at least a portion of the circumferential direction including the tip portion, and the coating layer is provided on wall portions on both sides of the groove.

[0051] (11) A work machine having a working section configured to process a work object, the working section comprising the guide bar described in (10) above and a saw chain wound around the guide bar. Of course, this is not the case.

[0052] As described above, various embodiments of the present invention have been described, but these are presented as examples and do not limit the scope of the invention in any way. The novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Such embodiments and their modifications are intended to be included within the scope and spirit of the invention, as well as within the scope of the inventions and their equivalents as set forth in the claims. [Example]

[0053] The guide bar and the manufacturing method thereof will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0054] 1. Guide Bar Preparation (Example) The guide bar was manufactured by forming a coating layer (second metal material: Stellite) on the tip of the guide bar body (first metal material: SKS51) shown in Figure 6(a) by laser additive manufacturing. The guide bar body had a total length of 700 mm, a thickness of 4.0 mm, and a width of the groove 313 of 1.4 mm. The coating layer was formed using a laser coating device having a nozzle head (manufactured by Laserline, "OTZ-5 VC") and an oscillator (manufactured by Laserline, "LDM2000-40") configured as shown in FIG. The average volume diameter of the particles constituting the powder was approximately 100 μm.

[0055] The conditions for forming the coating layer are as follows. Laser beam focal diameter: 2.0 mm Laser light output: 500W Powder feed rate: 15g / min Nozzle head movement speed: 500mm / min Shielding gas flow rate: 20L / min

[0056] (Comparative Example) The guide bar was manufactured by forming a coating layer on the tip of the guide bar body (first metal material: SKS51) shown in Figure 6(a) by manual build-up using a filler (second metal material: Stellite).

[0057] 2. Evaluation Various evaluations were carried out on the guide bars manufactured in the examples and comparative examples. 2-1.External observation The appearance of each guide bar was observed using a digital microscope (KEYENCE Corporation, "VHX-2000"), and the photographs are shown in Figure 11. FIG. 10 is a photograph showing the appearance of the guide bars manufactured in the example and comparative example. As shown in FIG. 10, there was no significant difference in appearance between the guide bars manufactured in the example and the guide bars manufactured in the comparative example.

[0058] 2-2.Hardness measurement The hardness of each guide bar was measured from front to rear using a micro Vickers hardness tester (manufactured by MATSUZAWA, "mmT-X") The results are shown in Figure 11. FIG. 11 is a graph showing the change in hardness of the guide bars manufactured in the examples and comparative examples. As shown in Figure 11, the hardness of the guide bar manufactured in the example changes gradually, whereas the hardness of the guide bar manufactured in the comparative example changes significantly.

[0059] 2-3.Component analysis The components of each guide bar were analyzed using an energy dispersive X-ray analyzer (Horiba, Ltd., "X-max (50 mm 2 The results are shown in Figures 12 and 13. Figure 12 shows a characteristic X-ray image and line analysis results of the guide bar manufactured in the comparative example. Figure 13 shows a characteristic X-ray image and line analysis results of the guide bar manufactured in the example. As shown in Fig. 13, in the guide bar manufactured in Example, a region where both metal materials were diffused could be confirmed at the boundary between the guide bar body and the coating layer and in the vicinity thereof (approximately 300 µm). In contrast, as shown in Fig. 12, in the guide bar manufactured in Comparative Example, the boundary between the guide bar body and the coating layer was clear.

[0060] 2-4. Checking welding strength The weld strength of each guide bar was checked using a precision universal testing machine (Shimadzu Corporation, "AGX-V"), and the results are shown in Figure 14. FIG. 14 is a photograph showing the appearance of the guide bars manufactured in the examples and comparative examples before and after the strength test. As shown in Fig. 14, the guide bars manufactured in the examples did not break at the interface between the guide bar body and the coating layer, whereas the guide bars manufactured in the comparative examples broke at the interface between the guide bar body and the coating layer. [Explanation of symbols]

[0061] 1: Chainsaw 2: Main body 3: Working section 31: Guide bar 311: Guide bar body 311a: Long hole 311b:Through hole 311c: Missing part 312: Covering layer 312a: Unit coating layer 312b: Unit coating layer 312c: Unit coating layer 313: Groove 32: Saw chain 33: Drive sprocket 33a: Rotating axis 33b: Shaft hole 33c:Protrusion 4: Handle 41: Top handle 411: Grip part 412: Trigger lever 413: Lockout lever 42: Horizontal handle 5: Housing 51: Left cover 52: Right cover 53: Front end 54: Battery attachment / detachment section 55: Sprocket cover 6: Motor 61: Rotation axis 7: Control unit 8: Battery 10: Nozzle head 101: Opening 102: Passageway SG: Shielding gas LB: Laser light L: Total length T: Thickness P; powder

Claims

1. A method for manufacturing a guide bar used by wrapping a saw chain around it, A first step of preparing a guide bar body made of a first metal material and powder made of a second metal material having higher heat resistance and wear resistance than the first metal material; a second step of supplying the powder to at least the tip portion of the guide bar body and performing an operation of melting the powder by irradiating it with laser light at least once to form a coating layer that covers at least the tip portion of the guide bar body.

2. 2. The method for manufacturing a guide bar according to claim 1, A method for manufacturing a guide bar, wherein the supply of the powder and the irradiation of the laser light are performed using a single nozzle head.

3. 2. The method for manufacturing a guide bar according to claim 1, The method for manufacturing a guide bar, wherein the average particle size of the particles constituting the powder is 15 μm or more and 250 μm or less.

4. 2. The method for manufacturing a guide bar according to claim 1, The method for manufacturing a guide bar further includes, prior to the second step, a step of forming a groove in the middle of the thickness direction of the guide bar body, at least in a part of the circumferential direction, including the tip end.

5. 2. The method for manufacturing a guide bar according to claim 1, A method for manufacturing a guide bar, wherein the first metal material is carbon steel.

6. 2. The method for manufacturing a guide bar according to claim 1, A method for manufacturing a guide bar, wherein the second metal material is at least one selected from the group consisting of a Co-based alloy, a Ni-based alloy, an Fe-based alloy, and a mixture of these alloys with at least one of an oxide-based ceramic and a carbide-based ceramic.

7. 2. The method for manufacturing a guide bar according to claim 1, A method for manufacturing a guide bar, wherein in the second step, the thickness of the coating layer formed in one operation is 0.1 mm or more and 1 mm or less.

8. 2. The method for manufacturing a guide bar according to claim 1, The method for manufacturing a guide bar, wherein the peripheral surface of the guide bar body and the peripheral surface of the coating layer form a continuous surface.

9. A guide bar used by wrapping a saw chain around it, a guide bar body made of a first metal material; a coating layer covering at least the tip portion of the guide bar body and made of a second metal material having higher heat resistance and wear resistance than the first metal material, The guide bar has a region on the coating layer side of the guide bar body where metal elements contained in the second metal material are diffused into the first metal material, and / or a region on the coating layer side of the guide bar body where metal elements contained in the first metal material are diffused into the second metal material.

10. 10. The guide bar according to claim 9, the guide bar body has a groove in at least a portion of its circumferential direction, including the tip end portion, The coating layer is provided on both wall portions of the guide bar that sandwich the groove.

11. A work machine, a working unit configured to process a work object; A work machine, wherein the working unit comprises the guide bar according to claim 10 and a saw chain wound around the guide bar.

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