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Gear pump housing requires two holes for high precision machining. In the medium and small batch production, the general use of general-purpose machine tools and special tooling to processing, this processing method is difficult to achieve accuracy requirements. Our factory internship factory production of this part, from the processing methods, cutting tools, fixtures continue to improve, a better solution to this problem, the processing quality is stable and reliable.
1 pump hole accuracy requirements and processing methods
Figure 1 is a schematic diagram of the process of machining two holes in the gear pump body. As can be seen from Fig. 1, the aperture 12.5 is at level 7, and the two apertures have different ultimate sizes. The large aperture R18.41 is close to level 8, and the coaxiality, perpendicularity and position tolerances are required, especially the position tolerances are very small. Therefore, the hole is difficult to process.
Figure 1 pump hole machining process diagram
After repeated tests and improvements, the following processing methods are adopted: the two holes are machined on both end faces after the 4-φ9 hole machining process, and the accuracy of a pair of angle holes in 4-φ9 is increased to φ9H8 for positioning. Then three holes are machined with R18.41 and φ12.5. The first process: In the lathe with rotary chuck car indexing R18.41 hole to R18.31 +0.065 + 0.035 (R18.41 with casting bottom hole), drill φ12.5 hole to φ11.5, and then boring to φ12 .4 ± 0.01. The second process: the design of special composite reamers, lathe (due to drilling spindle rotation accuracy is low, can not use drilling) at the same time reaming R18.41 and φ12.5 coaxial hole. Big hole hinge to R18.41 + 0.055 + 0.025, two small holes hinge to φ12.5S7 size. The tool is mounted on the spindle (remove the chuck) and the rear end of the tool is provided with guide bearings on the clamp. Fixture mounted on the carriage (remove the knife holder), with a straight line indexing fixture. The third process: Drilling machine with a floating reamer to one of the small holes hinge φ12.5F7 size requirements.
2 fixture design
Since the second process of hole machining is the key process, only the fixture design of this process is introduced here.
(1) fixture program and structure: Select the pump body G surface and two φ9 diagonal hole for the positioning of the fixture with two pins on one side positioning. Linear indexing form. Clamp the part with two hook clamps. Figure 2 shows the structure of the fixture (Note: the figure shows only the key dimensions and the main part number). Clamp body 1 is an angle iron, with screws, tapered pins mounted on the carriage. Moving indexing block 2 and clamp body 1 through the dovetail guide rail, and with the bolt 3 lock. The indexing block 2 is provided with a cylindrical pin 4 and a chamfered pin 9 by which the part is positioned on the indexing block 2 and is pressed by the two hook- Seat 6 is used to support the rear end of the tool. With hand-drawn cylindrical indexing on the agency. For the convenience of operation, the workpiece is installed on the right side of the fixture, and the fixture body is provided with holes on the indexing block for the tool to enter the workpiece processing. In order to prevent the chips from entering the joining surfaces of the members 1 and 2, the chip holder 10 is fitted in the hole of the clip body 1.
Figure 2 fixture structure
1. Clamp body 2. Move indexing block 3. Lock nut 4. Cylindrical locating pin 5,12. Bushing 6. Support seat 7. Cylindrical pin 8. Screw
9. Cutting edge positioning pin 10. Anti-chip sets 11. Riding pin 13. Seal block 14. Hook-shaped platen 15. Indexing agencies on the institutions
(2) Fixture operation: Put the work piece into the two locating pins, tighten the hook-shaped platen nut and move the carriage longitudinally to insert the pin of the fixed mechanism 15 into the pin hole of the first hole. After machining the first hole, loosen the two lock nuts 3, pull out the cylinder pin of the alignment mechanism 15, move the index block 2 so that the cylinder pin of the alignment mechanism 15 is inserted into the second hole Pin hole, and tighten the nut 3, the processing of the second hole.
(3) fixture installation requirements: manufacturing, the indexing agencies for the cylinder pin and bushing 12 with the preparation, with the gap of not more than 0.01mm. Installation, to ensure that the fixture center line K and spindle lathe coaxiality, coaxial tolerance of 0.015mm. P positioning and positioning of the lathe spindle axis perpendicular to the tolerance of 0.02mm. When the fixture is installed and adjusted, the horizontal feed must be locked, and the vertical feed should be set as dead stop iron. (4) Fixture features: The principle of reference coincidence, positioning error is small, higher indexing accuracy. Tool support at both ends, beating small, high precision machining hole size. Clamping reliable, easy to operate. The long-term use of proof, can fully guarantee the processing accuracy requirements, the downside is the process of observation is not convenient.
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Water Based Adhesives
Water based adhesives are supplied as pre-mixed solutions, or are formulated as dry powders, which producers and distributors must then mix with water in order to obtain its adhesive properties. These properties are obtained when water is either lost from the glue line by evaporation or is absorbed by the substrate. Because of this, it is important to use at least one permeable substrate when applying water-based adhesives.
Because the polymers in water based adhesives are water soluble, the bonds that are formed between surfaces are more susceptible to moisture and water, although some kinds, like plant and casein glues, are made with a base material that is insoluble at room temperature. Although this has improved the resistance of such adhesives to the effects of water and moisture, water based solution adhesives are still perishable, and therefore contain a shorter storage life.
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