Positioning and tool withdrawal tooling of the hot

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Positioning and tooling for fine boring

our factory mass produces sd-709 car air conditioning compressor cylinder block (Figure 1). Its material is acd10 (high strength aluminum alloy). The processing technology is to bore f22+0.05 central hole after rough and fine turning on both ends, and take this hole and one end face as the benchmark. Rough and fine boring cylinder holes. During rough boring, ensure that 7-f29.3+0.05+0.02 holes are bored round, and leave appropriate allowance for fine boring. The following describes the positioning and tool withdrawal tooling for fine boring 7-f29.3+0.05+0.02 holes

Figure 1

1 positioning during fine boring of cylinder hole

because the cylinder hole has strict shape and position tolerance requirements, the cantilever single edge high-speed fine boring process is adopted. Seven holes are fine bored on the special boring machine, and then completed with a special rotary fixture. The tool bar is equipped with two small boring tool heads for coarse and fine boring, and the sliding table makes feeding movement. The fine boring rotary fixture (Figure 2) is installed on the sliding table, and the cylinder block is clamped on the support block of the rotary fixture, Position with the center hole that has been processed to the finished size f22.5+0.05 and the cylinder hole f28.8+0.1 after rough boring. In fine boring, the self hole is generally used for positioning, and the virtual pin positioning method is adopted, that is, the positioning pin is used to fix the center line of the hole to be machined, and the positioning pin is removed after the workpiece is pressed to the fixed position, so that the boring bar can pass through. In the machining of sd-709 compressor cylinder block, using the mechanism of virtual pin positioning for reference, the boring bar and sliding tool sleeve are used to directly locate the hole to be machined, which reduces the coaxiality error between the positioning pin and the boring bar. In order to ensure that the diameter of the distribution circle of the seven cylinder holes is f74, the distance between the sample to be ground in the boring bar and the center of the friction paper to the bottom surface of the fixture is set to be B, and the distance between the rotation center of the rotary fixture (i.e. the centerline of the workpiece center hole) and the bottom surface of the fixture is a, which ensures that the mathematical relationship is a-b=1/2 74, that is, the diameter of the distribution circle of f74 is guaranteed. Specific clamping steps: install the cylinder block on the f22.5+0.03 mandrel, stick the support block tightly with the K surface, install a sliding tool setting sleeve matching it appropriately on the boring bar that has been finely ground on the excircle, its inner hole is coaxial with the outer cone, and use the taper part to face the hole to be machined (to avoid the boring head, insert a key slot on the inner hole of the sliding sleeve, and the taper is to improve the alignment and is not affected by the size of the hole to be machined). There shall be no gap in the circumferential direction. Then press the flange boss of the cylinder block with two sets of hook shaped pressing plates to press the cylinder block on the dividing plate. With the help of spring and indexing handle, the indexing device rotates the end cam to turn the rotary motion into axial movement and complete the bolt and pin pulling action. Use the locking handle to lift and lock the indexing plate. When one hole is machined, repeat indexing and locking in turn until the seven cylinder holes are machined

1. F22.5 mandrel 2 Support block 3 Indexing disc 4 Face cam 5 Index handle 6 Index pin

7 Locking handle 8 Clip details 9 Hook shaped pressing plate 10 Slide the tool sleeve 11 Boring bar

Figure 2

2 tool withdrawal after fine boring of cylinder hole

because the allowance radius direction of fine boring is only 0.25mm, the cutting allowance of the first boring head is 0.19mm, the cutting allowance of the second boring head is 0.06mm, and the unilateral allowance of honing is only 0.01 ~ 0.02mm, and the boring grain must be pressed during honing, so the cylinder hole is not allowed to have tool withdrawal grain. For this reason, the mechanism of horizontal tool withdrawal is used for reference, and the characteristics of rotary fixture are used to better solve this difficulty. The working principle of tool withdrawal is as follows: as shown in Figure 3, after the cylinder block is positioned and clamped, the slide table quickly retreats to its original position, and the sliding tool setting sleeve is removed. However, even some materials and additives that are already used in the market are not within the scope of national authorization. After the slide table is fast forwarded to work forward, the finish boring is completed at the end, and then the boring head and slide table stop, After the boring head stops stably, manually rotate the boring head to the tangent direction of the rotary circle f74 of the indexing disc. Loosen the locking handle, exit the indexing pin, and rotate the indexing disc slightly along the tangent direction of the boring head, so that the machined hole moves from the position of the thin solid line in the original figure to the position of the double dotted line. The cylinder wall is close to the side bus of the boring bar (this side bus is in the opposite direction of the boring head). At this time, any damage to the boring head and the product is not what the manufacturer and customers want to see. The tool tip is the farthest from the cylinder wall, thus avoiding the phenomenon of tool withdrawal and grooving. At this time, press the fast back button, the boring bar will not rotate, and the slide table will quickly back. After the slide table returns to its original position, turn the dividing disc to the next hole to be processed, bolt, lock, and then process the next hole, completing the processing of 7 cylinder holes in turn

Figure 3

3 processing effect and precautions:

the roundness and cylindricity error of the cylinder hole after processing are less than 0.01mm, and the position and circumferential graduation of the seven holes are controlled within ± 5 '

the cylinder hole processed by this positioning tool withdrawal method is to see what the materials it inspects are, there is no tool withdrawal pattern, and it can meet mass production, and there are no special requirements for workers' production skills and tool setting operations

before fine boring, the allowance and indexing error left in the rough boring process should be controlled within the allowable range. (end)

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