A piston rod and cross connection structure improvement

A piston rod and cross connection structure improvement - 2019 12 - 04 Xu Yuelan ( Wuxi compressor co. , LTD. , jiangsu wuxi 214145) 1 introduction process with reciprocating piston compressor is a kind of important equipment, widely used in various industries in the cross is the crank connecting rod mechanism will drive rotary motion into reciprocating linear motion of the important parts. There are many kinds of crosshead and piston rod connecting method. Threaded connection, coupling connection, flange connection and wedge connection. Figure 1 is one of the threaded connection structure, its characteristic is crosshead and piston rod, relying on threaded connections, with the hydraulic nut fastening. This method has simple structure, the check point gap between piston and cylinder can be adjusted through the piston rod and cross connection thread. But because of the crosshead is fit closely with hydraulic nut, the elastic deformation of the piston rod in this interval will have a very small, even to give a lot of pre-tightening force when installation, easy to loose while under impact load. And piston in adjusting the check point gap need to rotate piston parts connected, with large size and weight of the piston is very inconvenient. The improved 2 2 structure. 1 flange connection structure and type of screw thread connection structure is most of the large reciprocating piston compressor, the piston rod and cross connection to adopt hydraulic tensile way to tighten the coupling nut. Hydraulic stretching way to tighten the nut, and mainly relies on the hydraulic connection stud to produce a certain amount of elastic deformation after loading, produce gap between the two fittings, through the rotation of the nut, eliminate the gap. When this clearance after eliminating the elastic deformation of stud still exists, to form the necessary preloaded. For reciprocating piston compressor load of a certain impact, if under the impact load produced by the elastic deformation is greater than the deformation produced by installing a preloaded, loose nut is easy to occur. As shown in figure 1 structure due to the elastic deformation is too small, only 0. 02 ~ 0. 5 mm or so, the structure of the unit was presented in this paper have occurred several times nut loose fault. Aiming at the shortcomings of the above structure, the structure of another, flange connection structure as shown in figure 2. The characteristics of this structure is added an elastic band on the piston rod, the hydraulic tensile nut to the piston rod and the matching of the connecting flange surface between steps. When installation will first connecting flange and hydraulic tensile nut on the piston rod, then use the method of hydraulic tensile tighten the three parts together, because of the piston rod set on the elastic deformation range, therefore, tighten elastic deformation, have the right to ensure that the three parts will not loosen under impact load. Connecting flange and crosshead also use hydraulic tensioning method to tighten, such requirements of pre-tightening force can be ensured and the operation is relatively simple. Considering the medium and large unit of piston rod for adjustment and check point gap, this structure is set up an adjusting ring and a set of adjustable gap, adjusting ring and adjustable gap as shown in figure 3, 4. By adjustment in order 3 in figure 2 adjustment ring and sequence 4 screws to complete together, finally by sequence 5 lead wire will adjust screw locking. The gap between piston check point can be through a set of different thickness of the gap to adjust, adjustable gap slices dissection structure. On-demand inserted into the appropriate thickness of the gap can adjust piston check point gap, no longer need to turn the piston, to be the center of the piston rod and the check point gap adjustment, hydraulic way to tighten the connection stud and coupling nut. In the symmetrical balance type compressor, sometimes because of both sides of the piston weight difference, on both sides of the reciprocating weight and balance, at this point can be connected by changing the size and thickness of flange cylindrical. Above is flange connection structure is superior to screwed connection from several aspects. 2. 2 the improvement of existing flange connection structure for structure in figure 2, the piston rod of governing structure has some deficiencies. First technology of adjusting ring is poorer, concrete structure as shown in the figure 3. Its shape tolerance is very difficult to do, need a certain equipment to complete. To process the characteristics of piston compressor, single small batch, this is undoubtedly increase the cost; Second in to adjust the end, with the lead wire lock adjusting screw pose a safety hazard, and at the same time also not beautiful. Due to the piston rod and crosshead are all moving parts, for a long period of time to fix a lead wire around a circle on the parts is unsafe, and once the piston rod and crosshead also to need to readjust in inconvenient. Therefore our flange connection structure of figure 2, in the piston rod to do the appropriate adjustment improvement, as shown in the figure 5. This set up a set of tools to adjust the structure, also will adjust the structure of the coil is improved. In figure 5 sequence 4 adjusting ring as shown in figure 6. Manufacturability of the adjusting ring is clearly figure 3 is improved. To tweak the tool by the clamp, adjusting screws and the clamp ring ( See figure 7) 。 Two semicircle clamp ring fixed in the cross head, set up two blocks in the horizontal and vertical directions for clamp, clamp pressure on the adjusting ring 4, through adjusting screw, adjustment ring 4 can promote the movement of the horizontal and vertical direction, so as to adjust the center of the piston rod, easy to operate. Center of the piston rod after adjusted, this set of tools can be removed. 3 conclusion the improved structure has the following advantages: ( 1) Easy installation; （ 2) High reliability; （ 3) Good manufacturability. For medium and large piston compressor, the piston rod and the connecting flange of cross structure instead of screw-type structure is a kind of inevitable. For the structure of the flange connection, the piston rod of the proposed a modified again, hope can help to everybody. Source: the compressor technology in 2015 the first A01 period