Design and application of the most popular multipa

2022-08-22
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Abstract: in view of the shortcomings of V-shaped block clamping device, a new multi piece milling arc clamping fixture is designed

key words: V-block clamping device; Arc surface clamping device; Positioning block; 1 time fixture

1 introduction

when milling flat tenons and straight grooves on milling machines, most fixtures use V-block clamping devices, but for some parts with special shape and size, as shown in Figure 1, if V-block clamping is used, it will bring difficulties to milling processing

Figure 1 part drawing

it is known from Figure 1 that when clamping and milling the two sides of the part with V-shaped block, the clamping is positioned with 10 excircles. Because its length is too short, it is only 5mm. Although it can be clamped, it is far away from the center of the clamping point, and the clamping force is not enough. The workpiece is easy to fly by the milling cutter during milling. If the clamping force is increased, it is easy to clamp the clamping surface into a triangle and scrap it. If the excircle processing surface of 18 is clamped into the V-shaped block for processing, the end face of the workpiece cannot be positioned, resulting in processing errors

for this reason, we have designed a multi piece milling fixture clamped by an arc surface. As shown in Figure 2. It not only meets the requirements of workpiece clamping and positioning, but also simplifies the manufacturing process of the fixture. The use of this fixture not only reduces the scrap rate, but also greatly improves the productivity

Figure 2 multi piece milling fixture

1 Special plug 2 Cheese head screw 3 Special positioning block 4 Positioning block 5 Clip details 6 Clamping block

7 Clamping screw 8 Directional key 9 Countersunk screw 10 Left and right cover plates 11 Cylindrical pin

2 structure and technical requirements of multi piece milling fixture

2.1 the structure of multi piece milling fixture is shown in Figure 2. It is composed of special plug 1, positioning block 3, 4, clamp 5, clamp block 6, clamp screw 7 and directional key 8. The fixture orientation key 8 is installed on the worktable of X62W milling machine, and the a side is parallel to the worktable. After installation, tighten the clamping screw 7

2.2 technical requirements for multi piece milling fixture

(1) ensure that each positioning block is in a straight line

(2) ensure that all positioning blocks can move flexibly in the slot

(3) 18h/j56 transition fit is selected between the central hole of the positioning block and the outer circle 18 of the part

(4) the central hole of each positioning block is processed as a whole and needs to be followed along the central hole, which has practical application value. The central longitudinal plastic is an organic synthetic polymer material nbsp; Can carbon dioxide also become plastic? Cut to the right

2.3 positioning and clamping method of multi piece milling fixture

position a group of parts to be processed in the central hole between the positioning blocks. Since the positioning blocks can move freely in the groove, tighten the clamping screws after positioning, so that the positioning blocks are squeezed, so as to achieve the purpose of clamping

2.4 selection of milling cutter

machining of end face, side and symmetrical plane can be carried out on multiple milling fixtures. After the machining surface is determined, different types of cutters can be selected according to the corresponding plane. Figure 2 shows milling two symmetrical planes on X62W milling machine with combined milling cutter

3 conclusion

multi piece milling fixture has the following characteristics:

(1) it can process a group of parts, significantly improving productivity

(2) the three-point clamping mode of V-shaped block is replaced by arc surface clamping, which ensures the product quality and reduces the scrap rate

(3) milling with large feed rate can be carried out, and the workpiece is as stable as "Taishan". The position accuracy during machining is guaranteed

(4) in actual production, if the number of positioning blocks of multiple milling fixtures is increased, its productivity can be further improved

(5) the fixture manufacturing process is simple and the actual operation is convenient

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