Method for machining plastic-metal duplex planetary gears

Abstract

The present invention relates to a method for processing plastic and metal double planetary gears. First, the metal gear part is processed. The plastic part is pre-machined by turning and milling to create an inner hole and pin hole that are interference fit with the metal gear. After press fitting, the gear part of the plastic part is processed by using a gear hobbing machine. This method does not require mold opening, has a high degree of freedom, avoids mold development costs, greatly reduces development costs, and shortens the development cycle. It is very suitable for situations where product parameters are frequently changed during the new product R&D and verification stage, and is suitable for small-batch production of single pieces in the early stage.

Description

Technical Field

[0001] This invention relates to a method for processing plastic and metal double planetary gears, which mainly utilizes a centrally mounted bicycle planetary transmission component. Background Technology

[0002] With the rapid development of plastics as a basic industrial material in the industrial field, their strength, toughness, meshing noise reduction, and manufacturing processes have improved. More and more product structural components are using plastics to replace metal materials. Plastic gears have advantages such as self-lubrication, low inertia, low noise, and corrosion resistance, and in some scenarios, they offer superior performance compared to metal gears. Their applications are becoming increasingly widespread in consumer goods sectors such as micro-motors, electronic products, automotive parts, home appliances, office supplies, toys, and handicrafts. Due to market demand and innovative gear design concepts, some mechanical transmission mechanisms now feature double gears combining metal and plastic. The conventional processing strategy involves machining the metal gear portion and then injection molding the plastic gear portion using a mold. However, in the early testing phase of new product development, gear parameters need to be adjusted multiple times during verification. Conventional processing methods require mold repair or even remanufacturing after parameter adjustments, which significantly increases production costs and processing time. Injection molding is not suitable for single-piece or small-batch production. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a processing method for plastic and metal double planetary gears that does not require mold opening and has a high degree of freedom. This method can cope with the situation of frequent changes in product parameters during the new product development and verification stage, shorten the processing cycle and reduce production costs.

[0004] The processing method of the plastic and metal double planetary gear of the present invention is as follows:

[0005] S1: Select pre-machined metal gears, plastic parts (excluding teeth) with other dimensions already machined, and metal pins;

[0006] S2: Press fitting of plastic parts and metal gears, pressing the metal gear into the inner hole of the plastic part, while ensuring that the pin hole of the plastic part is aligned with the pin hole of the metal gear.

[0007] S3: Metal pin press-fitting. Press a metal pin into the pin hole to prevent the metal pin from tilting during the press-fitting process. The metal pin must not protrude after the press-fitting is completed.

[0008] S4: After press-fitting, the teeth of the plastic parts are machined on a gear hobbing machine.

[0009] The plastic part of the present invention is pre-machined with an inner hole that is interference-fitted with the metal gear.

[0010] The plastic part of the present invention is pre-machined with a plastic part pin hole, which is interference-fitted with the metal gear pin hole.

[0011] The plastic parts described in this invention are made of rod stock.

[0012] This invention patent mainly utilizes a mid-mounted bicycle planetary transmission mechanism, which typically employs a double planetary structure composed of plastic PEEK gears and metal planetary gears. If the metal gears are manufactured first and then the PEEK gears are injection molded, the mold cost is extremely high. Furthermore, the product parameters are not fixed in the early stages of development, and the gear parameters need to be adjusted multiple times during the verification process. Conventional processing methods require mold repair or even remanufacturing after parameter adjustments, which greatly increases production costs and processing time, making it unsuitable for single-piece, small-batch production. This invention first completes the machining of the metal gear portion. The plastic part is pre-machined using turning and milling to create the inner hole and pin hole for interference fit with the metal gear. After press-fitting, the gear portion of the plastic part is machined using a gear hobbing machine. This method eliminates the need for mold opening, offers high flexibility, avoids mold development costs, significantly reduces development expenses, and shortens the development cycle. It is ideal for situations where product parameters frequently change during the new product development and verification phase, and is suitable for early-stage single-piece, small-batch production. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the pressing process in an embodiment of the present invention.

[0014] Figure 2 This is a schematic diagram of the finished product according to an embodiment of the present invention.

[0015] In the diagram: 1. Metal gear; 2. Plastic part; 3. Metal pin; 4. Inner hole; 5. Pin hole for plastic part; 6. Pin hole for metal gear. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to device photographs and through embodiments. The following embodiments are explanations of the present invention, but the present invention is not limited to the following embodiments.

[0017] Example:

[0018] See Figure 1-2 The processing method of the plastic and metal double planetary gears in this embodiment is as follows:

[0019] S1: Select the machined metal gear 1, the plastic part 2 with all dimensions except the teeth already machined, and the metal pin 3;

[0020] S2: The plastic part 2 and the metal gear 1 are press-fitted together. The metal gear 1 is pressed into the inner hole 4 of the plastic part 2, while ensuring that the pin hole 5 of the plastic part is aligned with the pin hole 6 of the metal gear.

[0021] S3: Press-fit metal pin 3. Press the metal pin 3 into the pin hole to prevent the metal pin 3 from tilting during the pressing process. After pressing, the metal pin 3 must not protrude.

[0022] S4: After press fitting, the two teeth of the plastic part are machined on the gear hobbing machine.

[0023] In this embodiment, the plastic part 2 is pre-machined with an inner hole 4 that is interference-fitted with the metal gear 1.

[0024] In this embodiment, the plastic part is pre-machined with a plastic part pin hole 5, which is interference-fitted with the metal gear pin hole 6.

[0025] In this embodiment, plastic part 2 is made of rod material.

[0026] In this embodiment, the metal gear 1 is processed first. The plastic part 2 is pre-machined by turning and milling to create an inner hole and pin hole that are interference fit with the metal gear 1. After press fitting, the gear of the plastic part 2 is processed by using a gear hobbing machine. This method does not require mold opening, has a high degree of freedom, avoids the cost of mold development, greatly reduces development costs, and shortens the development cycle. It is very suitable for situations where product parameters are frequently changed during the new product development and verification stage, and is suitable for small-batch production of single pieces in the early stage.

[0027] Furthermore, it should be noted that any equivalent or simple changes made to the structure, features, and principles based on the concept of this invention are included within the scope of protection of this invention.

Claims

1. A method for processing a plastic and metal double planetary gear, characterized in that: S1: Select pre-machined metal gears, plastic parts (excluding teeth) with other dimensions already machined, and metal pins; S2: Press fitting of plastic parts and metal gears, pressing the metal gear into the inner hole of the plastic part, while ensuring that the pin hole of the plastic part is aligned with the pin hole of the metal gear. S3: Metal pin press-fitting. Press a metal pin into the pin hole to prevent the metal pin from tilting during the press-fitting process. The metal pin must not protrude after the press-fitting is completed. S4: After press-fitting, the teeth of the plastic parts are machined on a gear hobbing machine.

2. The method for processing plastic and metal double planetary gears according to claim 1, characterized in that: The plastic part is pre-machined with an inner hole that is interference-fitted with the metal gear.

3. The method of claim 1, wherein: The plastic part is pre-machined with a plastic pin hole, which is interference-fitted with the metal gear pin hole.

4. The method of claim 1, wherein: The plastic parts are made of rod stock.

Images