Fixture design for turning thin walled pipe sleeve parts
Fixture design of machine tool is an important part of process equipment design. In the whole machining process, apart from clamping and fixing the processed parts, the fixture also requires to ensure the position accuracy of the processed parts and improve the processing productivity. This paper mainly expounds the fixture design scheme of turning thin-walled sleeve parts, changes the traditional design method, and improves the production efficiency of this kind of parts.
Thin walled sleeve parts are widely used in practical production, and they are also difficult to machine parts. Due to their own structural characteristics, the parts are prone to deformation and vibration under the action of cutting force and clamping force in the process of cutting, which affects the surface processing quality, dimensional accuracy and shape accuracy of parts. In order to solve the problem of machining this kind of parts, the fan-shaped soft claw is used to clamp the outer circle of the workpiece to increase the clamping contact area; the process rib is added to reduce the deformation caused by the clamping force; and the nut is clamped axially. These methods are only suitable for single piece or small batch production. For mass production, these devices are far from meeting the production requirements, and even the clamping force is insufficient, causing the rotation of the workpiece, or the clamping force is too large, causing the deformation of the workpiece, affecting the production efficiency and greatly increasing the production cost. If a set of economical and applicable special fixture is designed to process such parts, it is possible to The production efficiency and economic benefit are improved, the processing quality of parts is guaranteed, and the labor intensity of workers is reduced.
Analysis of structure and process of parts
Figure.1 thin walled pipe sleeve
The part belongs to the thin-walled step ring, which is forged and made of 45 steel. It is normalized before rough machining. The part is composed of 11 > 50mm, 11 > 56mm outer circle, and 11 > 44mm inner hole. The two outer circles have requirements for coaxiality of inner hole, the accuracy is LL > 0.02mm, the surface roughness of two outer circles and inner hole is ral. 6, and the outer circle with 11 > 50mm has roundness requirement, and the accuracy is 0.02mm. According to the surface roughness, geometric accuracy and shape accuracy of the parts, the parts in the In the process of machining, both clamping force and cutting force have an impact on the machining quality of parts. The key problem is to prevent the parts from deforming when machining the inner holes of parts. In order to ensure the processing quality of parts and meet the requirements of mass production of parts, we decided to design a set of special fixture to ensure the processing requirements of parts and improve the utilization rate of fixtures.
Structure and working principle of fixture
Fig.2 structure of fixture
As shown in Fig.2, clamp the specific left end surface and install the pressing plate 6, In order to prevent the relative rotation of the replaceable sleeve due to the force exerted on the cylindrical surface of the replaceable sleeve, the groove is milled on the cylindrical surface of the replaceable sleeve, which is fixed circumferentially with screws. The outer circle of the workpiece 10 is matched with the inner hole of the replaceable sleeve. The left end surface of the workpiece is pressed axially with the pressing plate 6 to make the right end face of the workpiece 10 and the replaceable sleeve Under the action of axial force, the left end face of the replaceable sleeve is also closely connected with the clamp, and the cutting can be carried out after pressing. After the parts are processed, loosen the nut 8. In order to facilitate the disassembly of the workpiece, the copper rod or rubber rod is used to pass through the specific slot of the clamp, and the left end face of the workpiece is knocked, and the workpiece is easy to take out. Using copper rod or rubber rod to knock and disassemble the workpiece does not affect the deformation of the workpiece, so the efficiency of the operator is greatly improved. It has been proved by practice that this kind of fixture can easily guarantee the machining quality of the parts, improve the production efficiency and greatly reduce the production cost of the enterprise.
Key points of fixture design and use
(1) In order to ensure the machining accuracy of the parts, the matching accuracy between the outer circle of the replaceable sleeve 2 and the hole of the fixture body is required to be higher. The fitting accuracy of the outer circle of the workpiece 10 and the replaceable pipe sleeve is lower than that of the outer circle of the replaceable pipe sleeve 2 and the inner hole of the clamp 1, and the clearance fit (H7/H6) is adopted.
(2) In the long-term use of the fixture, the matching accuracy of the replaceable pipe sleeve and the parts is reduced, and the fit clearance between the two parts is too large, which can not guarantee the coaxiality requirements of the inner hole and the outer circle of the parts. In order to ensure the processing quality of parts, the replaceable pipe sleeve 2 can be replaced, and the disassembly method of replaceable sleeve 2 is the same as that of Part 10. In this way, the reuse rate of the fixture is improved, the production cost is reduced and the service life of the fixture is prolonged.
(3) The fixture can not only process the thin-walled parts shown in Fig. 1, but also the parts shown in Fig. 3, FIG. 4 and Fig. 5, as well as other parts with similar structure, with a wide processing range.
Conclusion
The fixture is suitable for batch production of thin-walled pipe sleeve parts. The machining accuracy of the parts meets the requirements of the drawing. The processing quality is stable and the operation is convenient. The strength of the workers is reduced. The design and use of the fixture have a certain reference for the processing of thin-walled pipe sleeve parts.
Source: China Pipe Sleeves Manufacturer – Yaang Pipe Industry (www.epowermetals.com)
(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)
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