Considering the current processing problem of difficult drilling on arc surfaces, a tooling device based on arc surface drilling of brake shoe parts on drum brakes was designed. The tooling equipment was used to drill on ordinary radial arm drilling. treatment. This method is not only inexpensive and quick to process, but also can guarantee the processing accuracy, so it is a better choice. Provide similar parts processing ideas for the development of some small and medium-sized enterprises.
Preface
Drilling is one of the most common processes in the machinery industry. Some mechanical components often need to be drilled on arcuate surfaces. Drilling on arcuate surfaces is generally used for connection and installation between components. holes The requirements for technical parameters are relatively high. When drilling on a curved surface, due to uneven cutting forces, the center of the hole is likely to drift, causing large position errors and making it difficult to ensure accuracy.[1，2]。
This article takes the arc surface drilling process of the drum brake shoe produced by a machinery manufacturing enterprise as an example to design a drilling device on the arc surface to complete the mass production of parts on a ordinary radial drilling machine and solve the problem The company does not have the current situation of CNC multi-axis equipment and also solves the practical technical problem of difficult drilling on arc surfaces.
Parts processing technology and difficulty analysis
Drum brakes are widely used in various types of mining vehicles, and their main component, the brake shoe, is a key manufacturing component. The brake shoe parts are frame arch parts and the material is cast steel. As shown in Figure 1, the 18 holes of the part are distributed across the arcuate surface of the brake shoe. The technical difficulty lies in the processing of holes on the arc surface, and the position tolerance of each hole is strict.
Figure 1 Brake shoe hole machining dimensions
There are three processing technology solutions generally used to process such parts:[3]: Firstly, tracing processing, the specific process flow is tracing (marking the hole position) → proofing and punching → drilling. However, because the drilling position of the workpiece is an arc surface, it is difficult to guarantee the accuracy of the hole processing position, and the quality of the workpiece is difficult to guarantee. The second is to use advanced processing equipment – multi-axis CNC machine tools. This method is simple and easy to use. The equipment requirements of production enterprises are high, and only enterprises with multi-axis CNC equipment can process such parts, which limits the development of some small and medium-sized enterprises. The third is to make homemade tooling accessories, process innovation, and use simple tooling accessories to process on ordinary radial drilling machines. This method is not only inexpensive and quick to process, but also can guarantee the processing accuracy, so it is a better choice.
Tooling and assembly design
Based on the analysis of brake shoe parts processing technology and the current situation of the enterprise, a brake shoe arc surface drilling device is designed. As shown in Figure 2, the parts are fixed on the clamp body, and the clamp body and. indexing The device is fixedly connected and the indexing device is fixed on the shaft. Bearings are installed at both ends of the shaft. They are connected to the side plates of the tooling via end covers. steering wheel for rotation. Rotate the pliers body by turning the handle.
Figure 2 Device for drilling the arc surface of the brake shoes
1—Bottom plate 2, 9—Side plate 3—Outer cover 4—Screw 5—Bearing
6—Indexing Device 7—Clamping Body 8—Drill 10—Inner End Cover
11—handle 12—shaft
The clamp body is shown in Figure 3. The shoe is positioned with two processed holes, one side and the bottom surface, and is clamped with threaded positioning pins to complete the positioning and clamping of workpieces.
Figure 3 Pinch the concrete
1—locating plate 2, 5—nut 3, 4—locating pin
According to the size requirements of the hole on the arc surface of the shoe part, the indexing device is designed, as shown in Figure 4. The indexing device includes a support block, a fixed pin is fixed on the support block, a foot lever is placed on the fixed pin, and a foot lever is placed on the foot lever. A locating pin is fixed, and the foot lever is connected to the support block via a spring. The index plate fixedly connected to the workpiece support frame is made into partial teeth. The tooth angle size is consistent with the hole distribution angle on the arc surface of the brake shoe part. When the foot lever is depressed, positioning. the pin (with the pedal fixed together) and the index plate, and the index plate can be moved by turning the handwheel. Move to the next tooth, then release the foot lever. The foot lever will automatically rebound under the action of the spring. The teeth on the end of the locating pin mesh with the teeth on the index plate to complete the indexing attachment. plate. Start Process a row of 3 holes on the arc surface at this angle, and so on until all holes are processed. In this way, the parts can be clamped in one go and a total of 18 holes distributed over 6 rows can be processed.
Figure 4 Indexing device
1—Index plate 2—Spring 3—Pedal lever 4—Location pin
5—fixing pin 6—support block
Conclusion
The tooling fixture designed in this article for drilling holes on the shoe arch surface has been verified by production to have the characteristics of reasonable structure, simple operation and smooth operation . The processed parts meet the size requirements of the drawing. At the same time, the tooling is easy to maintain, promotes mass production and has good economic benefits. They provide similar parts processing ideas for the development of some small and medium-sized businesses.
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