Hard tooth surface compound gear and machining method thereof

Abstract

The invention discloses a hard tooth surface compound gear and a machining method thereof.The compound gear comprises a gear body and a tooth surface, the working face of the gear body is provided with a gear part, the gear body is made of a metal material with certain strength and hardness, and the gear body has good plastic performance; the gear surface is made of a metal material with higher strength and hardness, the wear resistance of the gear surface is better than that of the gear body, the gear surface is deposited on the outer surface of the working surface of the gear body by adopting an electroplating process to form the compound gear, and the gear body is prepared based on the high-strength and high-hardness material through an efficient machining process; and a layer of tooth surface is deposited on the outer surface of the working surface of the gear body, so that composite material combination is firmer, the production efficiency is high, machining is convenient, thermal deformation and subsequent grinding finish machining processes are omitted, and meanwhile, the machining process is better in economical efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of gear processing, and particularly relates to a hard tooth surface composite gear and a processing method thereof. Background Art

[0002] At present, gears are mainly made of metal or engineering plastics. Metal materials are mainly used to make gears with higher strength and hardness. For gears with higher requirements for hardness and precision, most of them are processed and made of metal materials. Metal gears are mainly manufactured by hobbing, and the processing cost is relatively high, resulting in a relatively high cost of metal gears. Engineering plastic materials are mainly used to make gears with relatively low requirements for strength, hardness, etc. Engineering plastic gears are mainly obtained by injection molding. The production rate of engineering plastic gears is generally high and the cost is low, but the transmitted force is relatively small and the application fields are limited. Ordinary metal gears have a relatively low processing productivity, a relatively high cost, and poor economy.

[0003] Existing gears and their processing methods, such as the Chinese invention patent application with the application number CN201610895798 and the invention name "Forging Method of a 17CrNiMo6 Steel Wind Power Gear" by Taiyuan University of Science and Technology, provide a process route in which the whole gear is forged and blanked with 17CrNiMo6 material and then heat-treated and processed into a gear. The gear body and the gear ring of the gear manufactured in this way are of the same material, with a relatively large weight, which will reduce the mechanical efficiency of the transmission system and have a relatively high manufacturing cost. The Chinese invention patent application with the application number CN201610549713 and the invention name "Aluminum Matrix Composite Material for Automotive Transmission Gears and Preparation Method Thereof" by Anhui Ruilin Auto Parts Co., Ltd. In its embodiments, it is prepared from the following raw materials in parts by weight: aluminum 95 - 98, germanium 0.1 - 0.14, manganese 1 - 1.2, titanium 0.13 - 0.16, copper 0.3 - 0.35, lithium 0.04 - 0.06, zinc 0.2 - 0.3, cetyltrimethylammonium bromide 0.06 - 0.1, graphene oxide 3 - 5, zirconium hydride 5 - 8, hexachloroethane 0.85 - 1, calcareous shale 0.4 - 0.6, sodium alginate 0.24 - 0.3, calcium silicide 0.2 - 0.4, silicon dioxide 2.3 - 2.4, etc.; although a complex material formula is adopted and the casting process is improved to improve the comprehensive performance of the aluminum alloy, the yield strength of the material is still only 231 MPa and the tensile strength is only 258 MPa. The working teeth of the gear made of such an aluminum alloy have lower impact resistance than forged steel, and the wear resistance after surface oxidation treatment still cannot be compared with alloy steel. However, the existing gear processing technology is complex and the composite materials are not firmly combined, so it needs to be improved. Summary of the Invention

[0004] The object of the present invention is to provide a hard tooth surface composite gear and its processing method. By means of an efficient processing technology, a gear body is prepared based on a high-strength and high-hardness material, and then, by using an electroplating process, a tooth surface is deposited on the outer surface of the working surface of the gear body. Not only is the combination of composite materials firmer, but the production efficiency is high, the processing is convenient, the thermal deformation and subsequent precision grinding process are omitted, and at the same time, the processing technology has better economy.

[0005] The above technical object of the present invention is achieved through the following technical solutions: A hard tooth surface composite gear includes a gear body and a tooth surface. The working surface of the gear body has a gear portion. The gear body is made of a metal material with a certain strength and hardness. The tooth surface is made of a metal material with a higher strength and hardness and has better wear resistance than the gear body. The gear body has good plastic properties, and the tooth surface is deposited on the outer surface of the working surface of the gear body by an electroplating process to form a composite gear.

[0006] Further, the thickness of the tooth surface is 10 microns - 20 microns.

[0007] Further, the material of the tooth surface is electroplated chromium or electroplated copper.

[0008] Further, the material of the gear body is structural steel or aluminum alloy.

[0009] Further, the contour curve of the gear body is obtained by offsetting the gear theoretical contour curve equidistantly.

[0010] Further, the offset amount of the equidistant offset is the coating thickness at the pitch circle of the gear.

[0011] Further, the contour curve of the gear body is obtained by subtracting the coating thickness values at each position from the gear theoretical contour curve, and the coating thickness is the tooth surface thickness.

[0012] A processing method for a hard tooth surface composite gear is characterized in that it includes the following steps: S1: Determine the contour curve of the gear body: Determine the contour curve of the gear body by subtracting the tooth surface thickness values at each position from the gear theoretical contour curve or determine the contour curve of the gear body by equidistant offset of the gear theoretical contour curve; S2: Process the gear body: If a gear body with an equal cross-section needs to be obtained, first use an extrusion process to obtain a bar-shaped profile with an equal cross-section. The cross-sectional contour curve of the bar-shaped profile is the same as the contour curve of the gear body, and then cut the bar-shaped profile into single-piece gear bodies; if a gear body with a non-equal cross-section needs to be obtained, first slice to obtain a single gear body blank, and then obtain the gear body through a cold heading process or an extrusion process S3: Prepare the composite gear: Deposit a tooth surface on the outer surface of the working surface of the gear body by an electroplating process to form a composite gear.

[0013] Furthermore, the thickness of the tooth surface is 10 microns to 20 microns.

[0014] Furthermore, the material of the tooth surface is electroplated chromium or electroplated copper.

[0015] Furthermore, the material of the gear body is structural steel or aluminum alloy.

[0016] In summary, the present invention has the following beneficial effects: 1. The present invention can adopt production processes such as electroplating, extrusion, and cold heading. Compared with gears produced by machining, it has the advantages of no chip generation, no tool wear, high production efficiency, and low cost.

[0017] 2. The present invention adopts high-efficiency processes such as extrusion and cold heading for the body material. Compared with the prior art that plastically deforms harder tooth surface materials, it has the advantages of easier processing, longer service life of equipment and molds, higher productivity, and lower comprehensive cost.

[0018] 3. The present invention uses the electroplating process to deposit wear-resistant metal on the tooth surface onto the gear body. Compared with the prior art that heat-treats structural steel or alloy steel to enhance the hardness and strength of the tooth surface, it has the advantages of being more convenient, no thermal deformation, and no subsequent grinding and finishing.

[0019] 4. The present invention uses the electroplating process to deposit wear-resistant metal on the tooth surface onto the gear body. Compared with the method of coating gears by PVD, it has the advantages of good economy and simple auxiliary tooling for shielding non-coated parts.

[0020] 5. The present invention can use lightweight materials such as aluminum alloy as the gear body, which has the advantage of light weight compared with steel gears. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those skilled in the art, other drawings can also be obtained based on these drawings.

[0022] Figure 1 is a schematic structural diagram of the composite gear of the present invention; Figure 2 is a schematic diagram of the gear body of the body; Figure 3 is a schematic diagram of the tooth surface of the tooth surface; Figure 4 is a schematic diagram of the comparison of the contour curves of the tooth part; In the figure, 1 is the tooth surface; 2 is the gear body; 3 is the actual contour curve of the gear; 4 is the contour curve of the gear body; 5 is the actual contour curve of one side of the gear; 6 is the symmetry line of the tooth; 7 is the theoretical contour curve of the gear. Detailed implementation mode

[0023] The present invention will be further described below with reference to the accompanying drawings.

[0024] Embodiment 1 In this embodiment, for gears with low precision requirements, the influence of the gear structure on the electroplated layer is ignored, and it is approximated that the coating is of equal thickness. Taking a spur cylindrical external gear as an example, Figure 1 is a schematic structural diagram of the present invention as an external gear. The tooth surface 1 is deposited on the outside of the gear body 2, and the gear body 2 is processed with structural elements such as shaft holes according to requirements.

[0025] As Figure 1 shown, a hard tooth surface composite gear includes a tooth surface 1 and a gear body 2. The gear body 2 is a metal material with good plasticity and certain strength and hardness. The gear body 2 is suitable for plastic deformation processing technology. The gear body 2 has a contour curve similar to that of a gear. The tooth surface 1 is a layer of metal with high strength and hardness on the circumferential surface of the gear. The tooth surface 1 is deposited on the gear body 2 through an electroplating process.

[0026] The main purpose of designing the hard tooth surface composite gear in this way is to enable the hard tooth surface composite gear to adopt a manufacturing process with high production efficiency, simplify the manufacturing process, reduce the investment in production equipment, etc., so that the hard tooth surface composite gear has the advantages of low production cost and good economy. At the same time, different materials are used for the tooth surface and the matrix. On the premise of meeting their respective usage requirements, the comprehensive cost of the materials can also be reduced, further improving the economy of the hard tooth surface composite gear.

[0027] During specific implementation, preferably, first manufacture the gear body 2 as shown in Figure 1 , Figure 2 shown, and then deposit the tooth surface 1 on the gear body 2 through an electroplating process.

[0028] The gear body 2 is mainly obtained in two steps. First, an equal-section bar profile is obtained by an extrusion process, and then the bar profile is cut into single-piece bodies. The cross-sectional contour curve of the bar profile is the same as the contour curve of the gear body 2. Preferably, the material of the gear body 2 is aluminum alloy.

[0029] Preferably, the tooth surface 1 is obtained by electroplating chromium.

[0030] For gears with low precision requirements, the influence of the gear structure on the electroplated layer is ignored. It is approximated that the electroplated layer is of equal thickness. The contour curve of the gear body can be simply obtained by equidistant offset based on the theoretical contour curve of the gear. The offset amount of this equidistant offset is generally the thickness of the electroplated layer at the pitch circle of the gear, that is, the thickness of the tooth surface 1 at the pitch circle. The contour curve of the gear body 2 is obtained by equidistant offset from the theoretical contour curve of the gear.

[0031] Taking the contour curve of the tooth part of an involute standard spur cylindrical gear as an example for illustration, as Figure 4 shown, Figure 4 On the right side of the symmetry line 6 of the tooth, there are the theoretical contour curve 7 of the gear and the contour curve 4 of the gear body 2. For the sake of clear comparison, the actual contour curve 3 of the gear is not drawn on the right side. On the left side of the symmetry line 6 of the tooth, there are the theoretical contour curve 7 of the gear, the contour curve 4 of the gear body 1, and the actual contour curve 5 of the single-sided gear. The theoretical contour curve 7 of the gear is only for design use and does not appear in the actual gear. In the ideal state, the actual contour curve 3 of the gear appears at the position of the theoretical contour curve 7 of the gear. In this example, the influence of the gear structure on the electroplated layer, that is, the influence on the tooth surface 1, is ignored. The contour curve 4 of the gear body 2 is simply obtained by equidistant offset based on the theoretical contour curve 7 of the gear. In actual production, an unequal-thickness tooth surface 1 is added on the basis of the contour curve 4 of the gear body 2 to obtain the actual contour curve 3 of the gear. The actual contour curve 3 of the gear deviates from the theoretical contour curve 7 of the gear, resulting in an error. Since this error is relatively small, it is acceptable in some occasions with low precision requirements.

[0032] Embodiment 2 This embodiment is for scenarios with high precision requirements. The contour curve of the gear body 2 is not simply obtained by equidistant offset based on the theoretical contour curve of the gear. The contour curve of the gear body 2 is obtained by subtracting the thickness value of the tooth surface 1 at each position from the theoretical contour curve of the gear. The thickness values of the tooth surface 1 at each position are affected by the size and structural shape changes of the gear and need to be measured and adjusted in actual production.

[0033] After determining the contour curve of the gear body 2, the gear body 2 can be machined according to the contour curve of the gear body 2, and then the tooth surface 1 is deposited on the gear body 2 through the electroplating process. Its principle and process are the same as those of Embodiment 1. The difference between it and Embodiment 1 is that the contour curve of the gear body 2 is not obtained by equidistant offset based on the theoretical contour curve of the gear, but the contour curve of the gear body 2 is calculated according to the actual thickness of the electroplated layer, that is, according to the actual thickness of the tooth surface 1.

[0034] Embodiment 3 This embodiment is primarily targeted at duplex gears, helical gears, herringbone gears, and other applications requiring gear bodies with non-uniform cross-sections. The gear body 2 is obtained by first slicing bar stock into individual body blanks, then cold heading or extrusion. The remaining principles are the same as in Examples 1 and 2.

[0035] Example 4 The gear body 2 is made of structural steel, which generally has a low carbon content and is easy to be plastically deformed. Generally speaking, structural steel has better comprehensive performance than aluminum alloy, and aluminum alloy is easier to plastically form.

[0036] Example 5 The tooth surface 1 is obtained by electroplating copper, and copper is more firmly bonded to some substrates.

[0037] The above description is only a preferred embodiment of the present invention. Therefore, any equivalent changes or modifications made according to the structure, characteristics and principles described in the scope of the patent application of the present invention are included in the scope of the patent application of the present invention.

Claims

1. A hard tooth surface composite gear, comprising a gear body (2) and a tooth surface (1), wherein the working surface of the gear body (2) has a gear portion, and is characterized in that: The gear body (2) is made of a metal material with certain strength and hardness. The gear body (2) has good plastic properties. The tooth surface (1) is made of a metal material with higher strength and hardness, and the wear resistance of the tooth surface (1) is better than that of the gear body (2). The tooth surface (1) is deposited on the outer surface of the working surface of the gear body (2) by electroplating process to form a composite gear.

2. The hard tooth surface composite gear according to claim 1, characterized in that: The thickness of the tooth surface (1) is 10 microns - 20 microns.

3. A hard tooth surface composite gear according to claim 1, characterized in that: The material of the tooth surface (1) is electroplated chromium or electroplated copper.

4. A hard tooth surface composite gear according to claim 1, characterized in that: The material of the gear body (2) is structural steel or aluminum alloy.

5. The hard tooth surface composite gear according to claim 1, characterized in that: The contour curve of the gear body (2) is obtained by equidistant offset from the gear theoretical contour curve.

6. The hard tooth surface composite gear according to claim 5, wherein: The offset amount of the equidistant offset is the coating thickness at the pitch circle of the gear.

7. A processing method for a hard tooth surface composite gear, characterized in that: It includes the following steps: S1: Determine the contour curve of the gear body (2): The contour curve of the gear body (2) is determined by subtracting the thickness value of the tooth surface (1) at each position from the gear theoretical contour curve, or the contour curve of the gear body (2) is determined by equidistant offset of the gear theoretical contour curve; S2: Machine the gear body (2): If a gear body (2) with an equal cross-section is required, first obtain a bar profile with an equal cross-section by extrusion process. The cross-sectional contour curve of the bar profile is the same as the contour curve of the gear body (2), and then the bar profile is cut into single-piece gear bodies (2); If a gear body (2) with a non-equal cross-section is required, first slice to obtain a blank of a single gear body (2), and then obtain the gear body (2) by cold heading process or extrusion process; S3: Prepare the composite gear: Deposit a layer of tooth surface (1) on the outer surface of the working surface of the gear body (2) by electroplating process to form a composite gear.

8. The processing method of a hard tooth surface composite gear according to claim 7, characterized in that: In step S3, the thickness of the tooth surface (1) is 10 microns - 20 microns.

9. The processing method of a hard tooth surface composite gear according to claim 7, characterized in that: In step S3, the material of the tooth surface (1) is electroplated chromium or electroplated copper.

10. A processing method for a hard tooth surface composite gear according to claim 7, characterized in that: In step S2, the material of the gear body (2) is structural steel or aluminum alloy.

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