Cutting element for a tool chain, method for producing a cutting element for a tool chain, tool chain, and chain tool

Abstract

The invention relates to a cutting element (1) for a tool chain, comprising a main body (2) and a cutting tooth (3) formed on the main body (2), wherein the cutting tooth (3) at least partially has a chromium coating (10), wherein the chromium coating (10) has a crack density of ≤ 300 cracks per centimeter. The invention also relates to a method for producing a cutting element (1) for a tool chain. The invention further relates to a tool chain and a chain tool.

Description

[0001] P 62098 WO 17 December 2025

[0002] - 1 - CG / CG

[0003] Cutting link for a tool chain, method for manufacturing a cutting link for a tool chain, tool chain and chain tool

[0004] SCOPE OF APPLICATION AND STATE OF THE ART

[0005] The invention relates to a cutting link for a tool chain, in particular a saw chain, a method for manufacturing a cutting link for a tool chain, in particular a saw chain, a tool chain, in particular a saw chain, and a chain tool, in particular a chainsaw.

[0006] It is known to coat the cutting teeth of saw chain links with a chrome plating to improve the cutting and wear properties of the saw chain. Due to the manufacturing process, the chrome plating exhibits cracks on its surface.

[0007] A method for depositing chromium on cutting elements for saws or other cutting tools is known from US 5,194,100.

[0008] It is also known that the hardness of the chrome coating decreases with decreasing crack density.

[0009] TASK AND SOLUTION

[0010] The invention is based on the objective of providing a cutting link for a tool chain, in particular a saw chain, and a method for manufacturing a cutting link for a tool chain, in particular a saw chain, wherein the cutting link has improved properties compared to cutting links known from the prior art, in particular improved cutting performance and improved wear behavior. Furthermore, the invention is based on the objective of providing a tool chain, in particular a saw chain, and a chain tool, in particular a chainsaw.

[0011] The invention solves these problems by means of a cutting link for a tool chain according to independent claim 1, a method for manufacturing a cutting link for a tool chain according to claim 6, a tool chain according to claim 9, and a chain tool according to claim 10. Advantageous embodiments of the invention are described in the dependent claims. The wording of all claims is hereby incorporated by express reference into the description. According to a first aspect, the invention relates to a cutting link for a tool chain, preferably a cutting chain, in particular a saw chain. The cutting link has a base body and a cutting tooth, in particular formed on the base body. The cutting tooth can be integrally formed or attached to the base body. In particular, the base body and the cutting tooth can be formed in one piece or as a single unit, i.e.,The cutting element must be monolithic, in particular formed as a single-piece or one-part tool component. In particular, the cutting element may be a one-piece or multi-piece, in particular two-piece, cutting element. The cutting tooth must have at least a partial chrome coating or be at least partially provided with a chrome coating.

[0012] The cutting element is particularly distinguished by the fact that the chrome coating has a crack density of < 300, i.e. 300 or < 300 cracks / cm.

[0013] For the purposes of the present invention, the term "chrome coating" shall be understood to mean a coating which contains chromium or consists of chromium.

[0014] The invention is based in particular on the surprising finding that both the cutting performance and the wear behavior of cutting elements whose cutting teeth are provided with a chromium coating can be improved with decreasing crack density of the chromium coating. Moreover, it has been advantageously found that correspondingly coated cutting teeth can be resharpened in such a way that essentially the original cutting performance is restored. This was not to be expected given the previous expert knowledge, according to which the hardness, which is decisive for the cutting performance of the cutting teeth, decreases with decreasing crack density.

[0015] According to the invention, the cutting tooth can have the chrome coating only partially or completely, i.e., entirely.

[0016] Furthermore, in particular only, the incisor roof and / or the incisor tip and / or the incisor breast of the incisor may have the chrome coating.

[0017] In an embodiment of the invention, the chrome coating has a crack density of < 200, i.e.

[0018] 200 or < 200 cracks / cm, in particular < 150, i.e. 150 or < 150 cracks / cm. In a further embodiment of the invention, the chrome coating has a crack density of 30 cracks / cm to 150 cracks / cm, in particular 30 cracks / cm to 120 cracks / cm, preferably 30

[0019] Cracks / cm up to < 100, i.e. 100 or < 100 cracks / cm.

[0020] The crack density of the chrome coating can be determined in particular using the method described below.

[0021] The crack density of the chrome coating is determined using a light microscope and the so-called intersection point method. First, a light-microscopically magnified image of the chrome coating or a portion thereof is generated. A magnification of 100x to 500x, particularly 100x, 200x, or 500x, is selected for generating this image. A magnification of 500x is preferably chosen when more than 400 cracks are expected. A grid of lines is then superimposed on the light-microscopically magnified image, particularly after prior calibration. This superimposition can be performed using software. The grid has a number of lines, preferably 10.The grid lines are arranged parallel to each other and horizontally to the long sides of the light-microscopically magnified image and have a defined or known distance between them. The distance between the grid lines depends on the magnification of the image. At 100x magnification and an image size of 1078 x 1716 pm. 2 The distance between the grid lines is 104.4 pm. At 200x magnification and an image size of 539 x ​​858.1 pm 2 The distance between the grid lines is 52.2 pm. At 500x magnification and an image size of 215.6 x 343.3 pm 2 The distance between the grid lines is 20.88 pm.

[0022] To determine the crack density, the number of cross-sections is calculated, i.e., the number of points where cracks in the chrome coating intersect the grid lines. Cross-sections of cracks that run parallel to and below the grid lines in the light microscopically magnified image, i.e., that coincide with the grid lines in the light microscopically magnified image, are counted only once.

[0023] The crack density is then calculated according to the following formula: where the number of cuts corresponds to the number of cracks identified.

[0024] To better detect cracks on the surface of the chrome plating, the surface can be electropolished and / or etched before determining the crack density, in particular electropolishing followed by etching, for example with sulfuric acid or another suitable acid. Electropolishing the chrome plating can be carried out, for example, at a voltage of 10 V for a time of 8 s. Etching the chrome plating can be carried out, for example, at a voltage of 15 V for a time of 2 s.

[0025] In a further embodiment of the invention, the chromium coating has a layer thickness of 2 pm to 24 pm, in particular 4 pm to 16 pm, preferably 6 pm to 10 pm. The layer thickness of the chromium coating can be constant or variable. Preferably, the chromium coating has a constant layer thickness.

[0026] In a further embodiment of the invention, the chromium coating has a Vickers hardness (HV) of 900 HV to 1200 HV.

[0027] Furthermore, the base body of the cutting element can have a Vickers hardness (HV) of 620 HV to 650 HV.

[0028] Furthermore, the base body of the cutting element can be made of a metal or alloy, or consist of a metal or alloy. The alloy can be, in particular, steel, preferably stainless steel.

[0029] Furthermore, the cutting tooth of the cutting element may, in addition to the chromium of the chrome plating, contain another metal or alloy, or consist of another metal or alloy in addition to the chromium of the chrome plating. The alloy may, in particular, be steel, preferably stainless steel.

[0030] According to a second aspect, the invention relates to a method for manufacturing a cutting element for a tool chain, preferably a cutting chain, in particular a saw chain. In particular, according to the second aspect, the invention relates to a method for manufacturing a cutting element according to the first aspect of the invention.

[0031] The process comprises the following step: a) electroplating of chromium from a chromium electrolyte or from a bath of chromium electrolyte onto a surface of a cutting tooth of the cutting element, forming a chromium coating.

[0032] In this respect, the chrome coating according to the present invention can also be referred to as a so-called hard chrome coating or hard chrome layer. This refers to a chrome layer applied using electroplating. The chrome layer can serve, in particular, to protect against wear and / or corrosion and, especially, to improve cutting performance.

[0033] For the purposes of the present invention, the term “chromium electrolyte” or “chromium electrolyte bath” shall be understood to mean an aqueous solution based on chromic acid (H2CrO4) which is used in electroplating to produce a chromium coating on metal and / or plastic objects.

[0034] The chromium electrolyte or the bath of the chromium electrolyte preferably contains sulfuric acid or sulfate, particularly as a primary catalyst.

[0035] Furthermore, the chromium electrolyte or the chromium electrolyte bath can contain, in addition to sulfuric acid or sulfate as the primary catalyst, another catalyst, i.e., a so-called secondary catalyst. The secondary catalyst can, in particular, be a sulfonic acid salt, preferably a methanesulfonic acid salt.

[0036] In a further embodiment of the invention, polishing and / or etching of the cutting tooth is carried out before step a). This results in better adhesion of the chrome plating to the surface of the cutting tooth and, in particular, the formation of a more homogeneous chrome plating. The polishing can be carried out, in particular, with a mineral acid as the polishing agent. Preferably, the polishing agent or mineral acid is selected from the group consisting of sulfuric acid, nitric acid, hydrochloric acid, and mixtures of at least two of the aforementioned polishing agents or mineral acids. Polishing with sulfuric acid is particularly preferred. Furthermore, the polishing can be carried out once or several times, i.e., repeatedly. Generally, the cutting tooth can be immersed in the polishing and / or etching agent or sprayed, brushed, or otherwise treated with the polishing and / or etching agent.Regarding further features and advantages of the method, particularly with respect to the cutting element and the cutting tooth of the cutting element, reference is made in full to the explanations given in connection with the first aspect of the invention. The features and advantages described therein also apply mutatis mutandis to the method according to the second aspect of the invention.

[0037] According to a third aspect, the invention relates to a tool chain, preferably a cutting chain, in particular a saw chain. The tool chain has at least one cutting link according to the first aspect of the invention. Alternatively, the tool chain has at least one cutting link which is manufactured or manufacturable according to a method according to the second aspect of the invention.

[0038] Regarding further features and advantages of the cutting element, reference is made in full to the explanations given in connection with the first and second aspects of the invention. The features and advantages described therein also apply mutatis mutandis to the tool chain according to the third aspect of the invention.

[0039] According to a fourth aspect, the invention relates to a chain tool.

[0040] The chain tool can be, in particular, a hand-held, especially hand-carried, and / or motor-driven chain tool. Specifically, the chain tool can be a garden, forestry, and / or construction chain tool. Preferably, the chain tool is a cutting chain tool, especially a chainsaw.

[0041] The chain tool comprises at least one cutting link according to the first aspect of the invention. Alternatively, the chain tool comprises at least one cutting link which is manufactured or manufacturable according to a method according to the second aspect of the invention. Alternatively, the chain tool comprises a tool chain according to the third aspect of the invention.

[0042] Regarding further features and advantages of the cutting element and the tool chain, reference is made in full to the previous description. The features and advantages described therein also apply analogously to the chain tool according to the fourth aspect of the invention.

[0043] According to a fifth aspect, the invention relates to a method for determining the crack density of a chromium coating of a cutting tooth of a tool chain cutting link, the method comprising the following steps: a) generating a light-microscopically magnified image of the chromium coating or a partial area of ​​the chromium coating, b) superimposing the light-microscopically magnified image with a grid of lines, c) determining the number of intersections with the grid lines, i.e., the number of points where cracks in the chromium coating intersect the grid lines, and d) calculating the crack density according to the following formula: where the number of cuts corresponds to the number of cracks identified.

[0044] It is advantageous to calibrate the light microscopically magnified image before performing step b), in particular by specifying the light microscope used or the type of light microscope and the magnification selected for the light microscopically magnified image.

[0045] The grid has a number of grid lines with a defined or known spacing between them. The spacing between the grid lines depends on the selected magnification. For example, at 100x magnification and an image size of 1078 x 1716 µm... 2 The distance between the grid lines is 104.4 pm, at a 200x magnification and an image size of 539 x ​​858.1 pm. 2 The distance between the grid lines is 52.2 pm, and at a 500x magnification and an image size of 215.6 x 343.3 pm 2The distance between the grid lines is 20.88 pm. The number of grid lines is preferably arranged parallel to each other and, in particular, horizontally to the longitudinal sides of the light-microscopically magnified image. The grid particularly preferably comprises 10 grid lines arranged parallel to each other and horizontally to the longitudinal sides of the light-microscopically magnified image. Advantageously, sections of cracks that run parallel to and below the grid lines on the light-microscopically magnified image, i.e., that coincide with the grid lines on the light-microscopically magnified image, are counted only once.

[0046] The surface of the chromium coating can be electropolished and / or etched before determining the crack density, in particular electropolishing followed by etching, for example with sulfuric acid or another suitable acid. This advantageously improves the detectability of cracks on the surface of the chromium coating. Electropolishing of the chromium coating can be carried out, for example, at a voltage of 10 V for a time of 8 s. Etching of the chromium coating can be carried out, for example, at a voltage of 15 V for a time of 2 s.

[0047] Regarding further features and advantages of the method, reference is also made in full to the previous description. The features and advantages described therein also apply mutatis mutandis to the method according to the fifth aspect of the invention.

[0048] Further advantages and aspects of the invention will become apparent from the claims and from the following description of preferred embodiments of the invention, which are explained below with reference to a figure and an example part.

[0049] FIGURE DESCRIPTION

[0050] Fig. 1 schematically shows a cutting link 1 for a saw chain in a side view. The cutting link 1 has a base body 2 and a cutting tooth 3. The cutting tooth 3 can be attached to the base body 2 by brazing. The arrow A indicates the direction of rotation of the cutting link 1 when the saw chain is in use. This is a right-hand cutting tooth 3 with respect to the direction of rotation A.

[0051] The base body 2 is provided with two rivet holes 4 in its lower half. A depth stop 5 is arranged above the front rivet hole 4 at the upper edge of the base body 2, relative to the direction of travel A. Behind the depth stop 5, the base body has a recess 6 for chip evacuation.

[0052] The incisor 3 comprises an incisor roof 7, which extends over the top of the base body 2, and an incisor breast 8. Furthermore, the incisor roof 7 and the incisor breast 8 form a common incisor tip 9.

[0053] The incisor tooth 3 is at least partially, in particular only partially, but preferably completely, provided with a chrome coating 10.

[0054] The chromium coating 10 has a crack density of < 300 cracks per centimeter. In particular, the chromium coating 10 can have a crack density of < 200 cracks / cm, more specifically < 150 cracks / cm. Preferably, the chromium coating 10 has a crack density of 30 cracks / cm to 150 cracks / cm, more specifically 30 cracks / cm to 120 cracks / cm, and more preferably 30 cracks / cm to < 100 cracks / cm.

[0055] Furthermore, the chromium coating 10 can have a layer thickness of 2 pm to 24 pm and, in particular, a hardness of 900 HV to 1200 HV.

[0056] Regarding further features and advantages of the cutting element, and in particular the chrome plating, please refer to the general description. The features and advantages described therein relating to the cutting element, and especially the chrome plating, apply accordingly.

[0057] Figure 2 schematically shows another cutting element 1, in particular in the form of a full chisel tooth, for a saw chain in a longitudinal side view (Fig. 2a), a top view (Fig. 2b), a front view (Fig. 2c) and a rear view (Fig. 2d).

[0058] The cutting element 1 is preferably a one-piece cutting element. The cutting element 1 has a base body 2 and a cutting tooth 3. The base body 2 is provided with two rivet holes 4 in its lower half.

[0059] Furthermore, the cutting element 1 has a depth limiter 5 at the front upper edge of the base body 2. Behind the depth limiter 5, the base body 2 has a recess 6 for chip evacuation.

[0060] The incisor 3 comprises an incisor roof 7, which extends over the top of the base body 2, and an incisor breast 8. Furthermore, the incisor roof 7 and the incisor breast 8 form a common incisor tip 9.

[0061] The incisor tooth 3 is at least partially, in particular only partially, but preferably completely, provided with a chrome coating.

[0062] The chrome plating has a crack density of < 300 cracks per centimeter. In particular, the chrome plating can have a crack density of < 200 cracks / cm, more specifically < 150 cracks / cm. Preferably, the chrome plating has a crack density of 30 cracks / cm to 150 cracks / cm, more specifically 30 cracks / cm to 120 cracks / cm, and more preferably 30 cracks / cm to < 100 cracks / cm.

[0063] Furthermore, the chrome coating can have a layer thickness of 2 pm to 24 pm and, in particular, a hardness of 900 HV to 1200 HV.

[0064] Regarding further features and advantages of the cutting element, and in particular the chrome plating, please refer to the general description. The features and advantages described therein relating to the cutting element, and especially the chrome plating, apply accordingly.

[0065] Fig. 3 schematically shows a light microscopically magnified image 100 of a chrome coating 10 of a cutting tooth of a saw chain cutter link. The chrome coating 10 has cracks 20. A grid of 10 lines is superimposed on the light microscopically magnified image 100, the grid lines 30 being arranged parallel to each other and horizontally to the long sides of the light microscopically magnified image 100. The number of grid lines is 10.

[0066] The spacing between the grid lines 30 depends on the selected magnification. For example, at 100x magnification and an image size of 1078 x 1716 µm 2 The distance between the grid lines is 104.4 pm, at a 200x magnification and an image size of 539 x ​​858.1 pm. 2 The distance between the grid lines is 52.2 pm, and at a 500x magnification and an image size of 215.6 x 343.3 pm 2 The distance between the grid lines should be 20.88 pm.

[0067] To determine the crack density, the number of sections 40, i.e., the number of points where the cracks 20 in the chrome coating 10 intersect the grid lines 30, is determined. Sections of cracks that run parallel to and below the grid lines 30 on the light microscopically magnified image, i.e., that coincide with the grid lines 30 on the light microscopically magnified image 1, are counted only once.

[0068] The crack density is then calculated according to the following formula: where the number of cuts corresponds to the number of cracks identified.

[0069] To better detect the cracks 20 on the surface of the chromium coating 10, the surface of the chromium coating 10 can be electropolished and etched before determining the crack density, for example with sulfuric acid or another suitable acid. Electropolishing of the chromium coating 10 can be carried out, for example, at a voltage of 10 V for a time of 8 s. Etching of the chromium coating 10 can be carried out, for example, at a voltage of 15 V for a time of 2 s.

[0070] Determination of cutting performance

[0071] Using a chainsaw according to the invention, i.e., a chainsaw with cutting links having a chrome coating and a crack density of < 300 cracks per cm³, beech logs with a diameter of 30 cm to 40 cm were sawn. To prevent non-reproducible dulling due to dirt, the wood was cleaned beforehand. To accelerate the dulling process, the saw was cut at an angle to the wood grain. The initial cutting power and, after a specific operating time, the remaining cutting power were measured. Subsequently, so-called dulling gradients were determined. For the cutting power loss (cm³), the following parameters were used: 2 The cross-section of the wood and the cutting time were measured (in / s). The cutting performance was defined as 100 percent when the wood was new.

[0072] The results obtained are shown in Figure 4.

[0073] Figure 4 graphically illustrates the cutting performance obtained. Curve 1 represents the reference, i.e., the cutting performance in new condition. Curve 3 shows the cutting performance of a chainsaw known from the prior art. Curve 2 represents the cutting performance of the chainsaw according to the invention.

[0074] As can be seen from Figure 4, the use of a chainsaw according to the invention advantageously allows for approximately a doubling of the sawing time. Moreover, the dulling of the cutting edge of the chainsaw according to the invention is significantly less than that of the chainsaw from the

[0075] The chainsaw according to the invention – unlike the chainsaw known from the prior art – can even achieve its original cutting performance again by resharpening.

Claims

Patent claims 1. Cutting element (1) for a tool chain, in particular for a saw chain, with a base body (2) and a cutting tooth (3) formed on the base body (2), wherein the cutting tooth (3) has at least partially a chromium coating (10), characterized in that the chromium coating (10) has a crack density of < 300 cracks / cm.

2. Cutting element (1) according to claim 1 , characterized in that the chromium coating (10) has a crack density of < 200 cracks / cm, in particular < 150 cracks / cm.

3. Cutting element (1) according to claim 1 or 2, characterized in that the chrome coating (10) has a crack density of 30 cracks / cm to 150 cracks / cm, in particular 30 cracks / cm to 120 cracks / cm, preferably 30 cracks / cm to < 100 cracks / cm.

4. Cutting element (1) according to one of the preceding claims, characterized in that the chromium coating (10) has a layer thickness of 2 pm to 24 pm, in particular 4 pm to 16 pm, preferably 6 pm to 10 pm.

5. Cutting element (1) according to one of the preceding claims, characterized in that the chromium coating (10) has a hardness of 900 HV to 1200 HV.

6. Method for manufacturing a cutting element (1) for a tool chain, in particular for a saw chain, in particular a cutting element (1) according to one of the preceding claims, comprising the following step: Electroplating chromium from a chromium electrolyte onto a surface of a cutting tooth (3) of the cutting element (1) forming a chromium coating (10).

7. Method according to claim 6, characterized in that the chromium electrolyte comprises, in addition to the sulfuric acid or sulfate as primary catalyst, a secondary catalyst, in particular a sulfonic acid salt, preferably a methanesulfonic acid salt.

8. Method according to claim 6 or 7, characterized in that polishing and / or etching of the cutting tooth (3) is carried out before step a).

9. Tool chain, in particular saw chain, comprising - at least one cutting element (1) according to one of claims 1 to 5 or - at least one cutting element (1) which is manufactured or can be manufactured according to a method according to any one of claims 6 to 8.

10. Chain tool, in particular chainsaw, comprising - at least one cutting element (1) according to one of claims 1 to 5 or at least one cutting element (1) which is manufactured or can be manufactured according to a method according to one of claims 6 to 8, or a tool chain, in particular a saw chain, according to claim 9.

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