1 Theoretically, the set of manipulator fc of the hi spindle is novel, and the culvert improvement design is AUrightsreserved. 0 The structure of the bed is improved based on the design of a general-purpose machine tool, although its design concept is rigorous, the design is clever, compared to the original The C620 lathe has been greatly improved. It is a typical machine tool in the lathe model, and its working structure principle is included in the textbook. However, it has been found in many years of use that the spindle opening and closing and braking mechanism of the machine tool still have shortcomings. This article will present the author's views and improve design measures on this issue.
1 The original CA6140 lathe spindle start and stop and brake operating mechanism principle The opening and closing mechanism of the CA6140 lathe is implemented by a two-way friction clutch. In order to save time, it is necessary to install the brake 11. The structural principle is detailed.
1. Double gear 2 gear 3. Sheep angle swing block 4 sliding sleeve 5. Lever 6 brake belt 7. Handle 8 joystick 9, 11. Crank 10 pull rod 12. Shaft 13. Tooth fan 14. Rack shaft 15 Fork 16. Pull rod spindle start and stop and brake control mechanism spindle start and stop and brake operating mechanism share a set of operating system, all controlled by the handle 7, when the handle 7 is in the up and down position, via the joystick 8, crank 9 (11), the pull rod 10, the shaft 12, the transmission of the toothed fan 13 causes the lower contact of the lever 5 to fall in the groove in the right or left concave cylindrical surface of the rack shaft 14, the brake band 6 is relaxed, the machine tool The spindle is in a forward or reverse motion state.
When the handle 7 is pulled to the middle position, the rack shaft 14 is moved to the intermediate position, at which time the two sides of the two-way friction clutch are not engaged, so that the shaft I is idling, the spindle movement is cut off, and at the same time the rack shaft 14 is on the left and the right. The peak in the middle of the groove will cause the lever 5 to rotate counterclockwise, thereby tightening the brake band 6, and the brake wheel of the drive shaft W is quickly stopped, so that the spindle of the lathe stops.
2 The actual use problems of the spindle start and stop and brake operating mechanism are ingeniously designed. The use of a joystick 7 for opening and closing and braking is interlocked with each other, which is easy to learn and easy to remember. However, after many years of operation and practice, it still has two shortcomings: () Inconvenient parking shifting shifting. In actual operation, it is usually necessary to perform a shifting shift operation after the spindle is stopped. At this time, the operator must use one hand to hang the gear, and the other hand can rotate the chuck of the main shaft to make the sliding gear in the changing mechanism engage and shift. At this time, since the main shaft is braked by the transmission shaft W, the main shaft in the same transmission chain cannot be rotated, thus making the shifting shift difficult.
Therefore, in actual operation, in order to shift gears, the operator has to loosen the brake band 6. However, in doing so, it causes difficulty to the brake of the main shaft, so the operator takes the reverse brake, causes the main shaft to enter the instantaneous reversal, causes the main shaft to enter and decelerate quickly, and then moves the handle 7 to the intermediate stop position to stop the main shaft. This reverse brake has little effect on the processing of small loads, but if the workpiece is machined under high load and high speed, the back brake hazard is obvious, and the impact generated by one reversal will damage the drive chain. The gears, even the danger of large workpieces flying out due to the inability of the clamps; and the high-speed reverse brakes, can cause high noise that impairs the health of the operator.
(2) The brake force adjustment of the brake is inconvenient, resulting in unreliable spindle brake. When the operator adjusts the braking force of the brake band 6 to exceed the actual required braking force, the pulling handle 7 is very laborious, and even the spindle cannot stably stay at the desired position. After the spindle is stopped, the spindle will automatically resume its original motion once the operator's hand leaves the spindle 7. This phenomenon occurs mainly because the adjustment of the brake band 6 is too short, causing the contact stress on the lower concave contact of the lever 5 and the two concave cylindrical grooves on the rack shaft 14 to be too large, and the lower portion of the lever 5 is touched. It is difficult for the head to climb on the peak between the two concave cylindrical grooves, and the convex peak and the lower contact are in point contact, and the contact stress between them is slightly offset, and the axial direction component is generated. After the hand leaves the handle 7, it will overcome the positioning pressure of the ball set by the original operating system (not shown), and push the rack shaft 14 to slide it back into the original concave cylindrical groove, so the spindle It automatically restores the original movement. This is a hidden danger that is highly prone to catastrophic accidents. Therefore, the spindle start and stop and brake operating mechanism are necessary for improved design.
3 Improve the design How to make the lathe spindle stop accurately, and then easily shift after parking. Of course, the good solution is to change the original machine structure as little as possible, and to ensure stable and reliable operation requirements. The author has carried out the following single-plate electromagnetic brake. It can be seen that the excitation coil, the yoke and the housing of the electromagnetic brake are mounted on the outer wall of the headstock, and the armature is sucked back by the electromagnetic field force to be pressed against the brake pad, thereby making the shaft W It stops quickly, so the spindle also stops. The amount of braking force is related to the size of the electromagnet and the amount of current required.
(see) designing the parking position of the cam at the appropriate position, attaching the cam to the joystick 8, mounting the corresponding travel switch SQ on the lathe bed and pressing the vertex of the cam to the parking position of the SQ travel switch and pressing the ball into the bead After the intermediate pits of the rack shaft 14 are aligned, they are fastened with screws.
(4) Improve the original main motor control circuit (see). Improve the original control circuit (a) to (). The working principle is as follows: when the SQ contact of the travel switch is depressed by the cam vertex, the current in the figure immediately causes the delay-opening relay KT to be charged, and thus the electromagnet YB is also energized, so the braking task is executed; if KT The delay time set by the relay has arrived. The delay-disconnecting relay KT will automatically cut off the current of its normally closed contact, and the electromagnet YB will be powered off immediately. In this way, the drive shaft W is in a free stop state, and the main shaft is also in a free stop state. At this time, the main shaft can be easily pulled to perform shift change without using the reverse brake. CA6140 lathe main motor control When the main shaft is changed from the forward rotation to the circuit, the comparison chart is reversed, or the reverse rotation enters the forward rotation. The operation is still convenient. The middle brake only passes the instantaneous brake, and the SQ is only turned on instantaneously, and immediately enters the cutting work. . The instantaneous energization of the YB electromagnet, which also has a certain buffering effect on the spindle changing direction of operation, thus protecting the components of the spindle and the drive chain.
4 Conclusion This improved design can fully meet the requirements of the spindle parking shift, eliminating the hidden danger caused by the reverse brake. The braking force does not need to be adjusted by the operator, but the design and on-site assembly adjustment, so the operation will More convenient and safer to use.
The modified workload is small, only need to add electromagnet, cam stroke switch, modify the main motor control circuit, and also eliminate the brake band device, the cost is not much.
Since the brake electromagnet and the cam travel switch are mounted on the surface of the machine tool casing, the debugging work is convenient, the electrical components are not easily damaged by the oil, and the replacement is easy.
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