Description of Design Problems of High Speed Spindle System of Tufting Machine
The problem of high speed of traditional spindle system
The schematic diagram of the main shaft system of the traditional tufting machine is shown in Figure 1, which is divided into two parts: the tufting needle mechanism and the looping hook mechanism. The working principle is that the main shaft transmits the power to the needle slave shaft through the eccentric crank rocker mechanism ABCD. The rocker-slider mechanism DEFG, then drives the tufting needle at the end of the slider to make a reciprocating linear motion, and the crank-rocker mechanism AHIJ drives the hook to reciprocate from the loop-forming hook on the shaft, and the needle hook cooperates with each other to complete the loop-forming motion. Form loops on the base fabric.
Configuration design requirements of high-speed spindle system
Through the analysis of the function and layout of the carpet tufting machine, the configuration design requirements of the high-speed spindle system are obtained as follows:
(1) It has the power transmission function between long-distance parallel shafts. The research object of this paper is a tuft with a width of 4 m For the main shaft system of the tufting machine, this width cannot be achieved by a single set of tufting needle mechanisms. Generally, two sets of mechanisms are used to drive each meter width. At the same time, the design of the needle hook must meet the timing relationship, so the designed mechanism must be parallel to the shaft at a long distance. It can transmit the power from the main shaft to the needle slave shaft and the hook slave shaft, and then transmit it to the needle beam and the hook beam through the actuator to complete the tufting movement.
(2) It can convert the movement mode. The input movement of the motor is The rotation around the axis of the main shaft, while the tufting needle and the looping hook need to realize the reciprocating linear motion and reciprocating swing perpendicular to the axis, so the mechanism must be able to convert the movement mode, and at the same time, it must meet the positional relationship between the input and the output.
(3) The vector sum of inertial force and inertial moment can be made to approach zero. The length-diameter ratio of the main shaft of the carpet tufting machine is 150, which belongs to the slender shaft. The traditional multi-link structure makes the main shaft force transmission as an offset structure. The inertial load is concentrated at the hinge between the link mechanism and the main shaft, and distributed on both sides of the main shaft, and the direction and size change constantly. vibration.
High-speed Design Method of Spindle System
From Section 1, it can be seen that the main factor affecting the high speed of the spindle system is the inertial load that changes in the direction and size of the spindle with time, so the high speed should be realized from the following four aspects.
(1) Add a symmetrical mechanism. From the structure of the mechanism Considering the type design, the inertial force and inertia moment generated by the mechanism in high-speed operation can be reduced by adding a reverse symmetrical mechanism or making the adjacent mechanism move in the opposite direction.
(2) Increase the balance weight. Start with the center of mass Si of the mechanism. , increase the balance weight, reduce the distance ri from the center of mass to each rotation center, and reduce the variation of the total center of mass of the actuator during high-speed operation. This method can reduce the inertia of the mechanism without significantly increasing the total mass of the mechanism
(3) Change the load transmission. The use of synchronous belt drive, chain drive and other flexible parts for load transmission can greatly reduce the load transmitted to the main shaft compared with rigid transmission, and at the same time make the load on the main shaft evenly distributed, which can prevent The load is concentrated, which can achieve the goal of reducing vibration while running at high speed.
(4) Lightweight structure. Start with reducing the mass mi and moment of inertia Jsi of each component, and reduce the inertial load. When the structure and strength allow, reduce the weight of the components. size, punch holes in the mass concentration or use new materials with lower density such as aluminum alloy, titanium alloy, etc.
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