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With rapid development of die manufacturing industry in China, die spotting machine has been recognized and utilized by more and more domestic customers. However, as a kind of rising facilities, die spotting machine has not satisfied related national standard. Here I would like to discuss how to choose die spotting machine after combining with my working experience of many years.
I. Classification of Die Spotting Machines |
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1.According to movement direction of the main cylinder
Vertical type (up-and-down movements of the main cylinder)
Horizontal type (horizontal movements of the main cylinder)
2.According to pressurizing and clamping method
Press-plate type
Magnetic disk type
II. Dynamic Analysis and Technical Requirements of Die Spotting Machine
| 1. Vertical type: |
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Active force of the main cylinder: F (total tonnage)
Shearing stress of the frame base changes into r (i.e. deflection)
Cross-sectional area of frame base, working bench and die base along B-B is A.
Therefore frame and working bench will deform, which causes comparatively weak impression effects in the middle part during repair and maintenance of die (gradually decrease from external part to internal part).
Besides, upper and lower surfaces of dies are not absolutely parallel, and upper and lower working benches cannot be absolutely parallel due to up-and-down movements of the sliding table. Perform floating connection between cylinder and sliding bench, which are positioned through fractal surface and own positioning precision. Therefore, the following are required:
1) high of flatness of working bench;
2) large repeatability of working bench.
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| 2. Horizontal Type |
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Active force of cylinder: F (total tonnage)
Length of Green column: L
According to the above calculation: walls will roll backwardly under pressure, therefore the die-repair precision is smaller than that of vertical type. The method to calculate the rolling amount is as follows. Equip a dial indicator in the upper part of the wall. Make the dial indicator head contact with the wall, pressurize it and then the differential value is the rolling amount.
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III. Comparison of Advantages and Disadvantages of Vertical-type and Horizontal-type Die Spotting Machines
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Vertical-type |
Horizontal-type |
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Advantages: convenient operations and large fitting precision |
Advantages: small floor area and small cost |
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Disadvantages: large floor area and large cost |
Disadvantages: inconvenient operation and small fitting precision |
IV. Advantages and Disadvantages of Pressure-plate Type and Disk Type
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Pressure-plateType |
Disk Type |
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Advantages: small deformation of working bench and large flatness |
Advantages: convenient spotting and direct fitting of A and B plates |
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Disadvantages: inconvenient installation and spotting, and indirect fitting of A and B plates |
Disadvantages: easy deformation of working bench (low carbon steel) |
V. Inspection Method of Die Spotting Machine
1. Test of Repeatability
a. No inspection is necessary as long as upper working bench locking cylinder can be inserted, and the clearance between copper sleeve and axle shall not be too large.
b. Test method of repeatability of lower working bench: place a working bench in the rear part of the lower working bench and fix two dial indicators on it. Record the pressure values of the dial indicators as m. Make reciprocating movements of lower working bench, and record the movement values as m1, m2, and m3, with the difference between the largest value and smallest value as repeatability ≤0.05mm.
2. Test of Flatness of Upper and Lower Working Benches
Place Φ50 round bars of the same height (or blocks of the same height) under the working bench, to make the main cylinder decrease to the round bars of the same height. Apply pressure <10kg/cm2 , and measure the clearance with plug gauge (0 for three bars, while the remaining as the flatness of the upper and lower working benches), and change positions of the round bars of the same height.
3. Test Method of Demagnetizing Effects
a. After magnetizing of the magnetic disk, spray iron dust on the surface (on many points), and check if the iron dust is in the shape of magnetic force line after demagnetizing. 。
b. Carry out demagnetizing after magnetizing, place a small piece of iron plate on two polarities respectively, and fetch them slightly to see if there is any suction force.
VI. As for large-sized hydraulic facilities, the hydraulic impacts are quite large, generally are 8-15 times of the system pressure. Therefore, adopt vibration absorption facilities. The method to test the effects is as follows. Make the main cylinder descend or ascend rapidly, and to see if there is impact in case of sudden power cut. (The larger the sounds are, the larger the impact forces are.) |
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