CNC milling machine processing special parts fixture (Figure)

The workpieces processed by CNC milling machines are generally complicated, and some fixtures are often used, which is beneficial to improve machining efficiency and ensure machining accuracy. When I actually processed and processed a part of an electronic scale, I encountered the problem of chamfering the front and back sides with curved symmetrical parts. For this type of part, I designed a set of fixtures. When the workpiece is clamped by the clamp for machining, the clamping and positioning time of the workpiece can be effectively reduced, the machining efficiency and the machining accuracy are improved, and the value is more obvious when the workpiece batch is large. The following will be specifically explained for your reference.

Problem raised

When the CNC milling machine processes the lifting lug parts (as shown in Figure 1), the chamfering angle is required to be 2mm×45°. The other processes of the workpiece have been completed. The two large faces have been processed well. The two holes have been boring and finished, and the outer arc allowance is 2 ~3mm. On the CNC milling machine, it is required to process the surrounding arc and chamfer. The arc edge can be processed in one time, but the chamfer needs to be completed by the positive and negative clamping. In the processing, the outer arc is machined with a full thickness of a milling cutter with a diameter of 40 mm, and the layer is not stratified for efficiency. The specific processing process: workpiece alignment → machining outer arc → chamfering → turning face clamping → performing reverse chamfering. The key point is that the chamfering is uniform on both the front and the back. There are several problems in the process:

figure 1

(1) The workpiece is inconvenient when it is being aligned. It can be seen from Fig. 1 that the workpiece can only be positioned and clamped with the center hole, and it is time consuming and troublesome to level the center connection of the two holes, not to mention mass production.

(2) Even if the workpiece is found, there will be problems in the machining, and the outer arc is well controlled, but the chamfering on both sides is not guaranteed. It is often qualified for frontal processing. When the reverse is processed, the arc on the opposite side will be cut off and cut.

(3) This workpiece is basically processed in batches every month, ranging from 50 to 100 pieces per batch.

In summary, it is necessary to design and fabricate a simple fixture in the actual machining process, which enables the workpiece to be easily, quickly and accurately positioned and clamped to ensure the accuracy of arc and chamfering during machining, and the fixture strives The structure is simple, convenient to manufacture, and has certain versatility for long-term use.

2. Problem analysis

For the workpieces required for such machining, first of all, how to accurately position and clamp, it is the key. The workpiece is positioned and clamped by two holes, and generally one column and one pin are used. Therefore, we first used the fixture shown in Figure 2 to clamp and machine the workpiece.

figure 2

1. Backing plate 2. Cylindrical positioning pin 3. Open platen 4. Nut 5. Cut edge positioning pin 6. T-shaped block

The backing plate 1 supports the workpiece, leaving a space for the cutter for machining the outer arc, and the two holes are processed by the boring machine to ensure the pitch of the hole is the standard pitch of the workpiece. The cylindrical positioning pin 2 and the chamfered positioning pin 5 are used for positioning the workpiece; the open platen 3 can quickly load and unload the workpiece to improve efficiency; and the T-shaped block 6 fixes the jig to the table.

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