1 Introduction Non-grashof planar four-bar mechanism [1], which can not be rotated around the entire two poles, can realize complex motion requirements with simple structure, and is widely used in non-equal motion of automated machinery such as transportation and assembly. In the mechanism [2]. In this paper, based on the problem of the linkage trajectory of the Non-grashof mechanism, a natural equation method based on the characteristic analysis of the connecting rod curve is proposed [3]. Monte Carlo theory is used to determine the integrated independent peak field of the curve creation mechanism. The comprehensive evaluation index of the organization, the comprehensive linkage curve creation mechanism. In order to make this method widely used in the linkage trajectory synthesis, the non-grashof mechanism linkage curve database is established by using the random function generation method, and the number of revolutions, the number of nodes, the maximum point of curvature, and the variation of the curve of the connecting rod curve The curve is automatically classified according to the number of points, etc. [4]. Due to the unstable motion of the Non-grashof mechanism near the extreme position of the motion, the poor transmission performance, etc. [4], it is necessary to apply the stability of the mechanism to the mechanism. the study.
2Non-grashof mechanism and its parameters are represented by a4, a5, a6 and a7, the angular displacement of each member is represented by 5, 6 and 7, respectively, and the position of any point on the connecting rod is represented by a8 and a. The parameters of the selected mechanism are as follows [1]: a47000mm, a53600mm, a64600mma75200mm, a85500mm, a5519 calculate the angular displacement of the member according to the given parameters, and the upper and lower limits of the angular displacement change of the original A2B2 and the follower C2D2 are respectively 5l4745. , 5u312557l27694, 7u8306, that is, the swing angle of the original moving member is 526510, the swing angle of the follower is 719388.
3 ultimate position of the mechanism and the transmission angle 31 mechanism limit position of the swing angle plane four-bar mechanism ABCD, when the mechanism's original mover AB and the link BC are collinear, the angular displacement of the rocker CD at the two extreme positions is respectively 3l And 3u, then the following formula holds [1] cos3la20 a23-(a2-a1)22a0a3(1)cos3ua20 a23-(a2 a1)22a0a3(2) The swing angle of the joystick is represented by 3, and 3u3l 3 is (cos3u) -cos3lcos3)2(1-cos23l)sin23(3) Substituting equations (1) and (2) into equation (3) to obtain the relationship between the swing angle of the follower and the size parameter of the mechanism [4] (a2) 2-2pa2 q0(4) where p{a20 a23-3a21-(a20 a23 a21)cos3}/(1-cos3)q{a20 a23-a21-2a20a23sin23}/(1-cos3)32 transmission angle condition plane four shots The transmission angle of the mechanism is 2-3-, the angular displacement of the crank is 1 or 0 (the crank is collinear with the frame), and the transmission angle has a minimum value. The minimum value can be obtained by the following formula [1]: cos0a2 A23-(a0 a1)22a3a2(5)cosa2 a23-(a0-a1)22a3a2(6)4 drive the crank-rocker mechanism design of the Non-grashof mechanism. Since the two connecting rods of the Non-grashof mechanism are rockers, When the body is exercising, In this paper, the gear link combination mechanism is used as the drive mechanism of the Non-grashof mechanism. The linkage mechanism of the combined mechanism is a crank rocker mechanism, and the gear ratio of the gear mechanism is 13. Referring to the value of the swing angle 3 of the original moving member of the Non-grashof mechanism, the rocker swing angle of the crank rocker mechanism can be determined 18836 Thus, the values ​​of the crank-rocker mechanism and the upper and lower limits of the angular displacement of the follower are respectively [1]: a0100mm, a125mm, a29762mm, a33590mm3l3310, 3u12147 or 3l23854, 3u32691013331, k42205 motion limit position through mechanism design When the crank of the crank-rocker mechanism that drives the Non-grashof mechanism is moved to the extreme position, the Non-grashof mechanism is also at the end position. In order for the Non-grashof mechanism to smoothly pass the extreme position, it is necessary to be Non- in these positions. The follower of the grashof mechanism provides additional motion, which is accomplished by a train of incomplete gears that are coupled to the follower and that are driven by a crank rocker mechanism.
Analysis of design conditions of 51 incomplete gear mechanism The drive mechanism designed in the previous section shows that the Non-grashof mechanism is coupled with a gear mechanism with a gear ratio of 1#3 to form a watt-type flat six-bar mechanism, which is a single degree of freedom system. .
Therefore, the design condition of the pair of incomplete gears of the motion limit position passing mechanism is that the angular velocity ratio of the gear is equal to the value of d7/d1 of the position.
It is calculated that the ratio of the differential coefficient d7/d1 of the non-grashof mechanism in the vicinity of the two extreme positions 11567 (34745) and 119446 (331255) of the original member is 060 and 080, and two sets of Complete gear mechanism [1].
52 The limit position of the movement is the link gear combination mechanism designed by the working principle of the mechanism. When the angular displacement 1 of the original member A1B1 is 1566, 7566, 11566, 19446, 28566, and 33566, respectively, six motion states of the combined mechanism are formed.
A2B2C2D2 is the Non-grashof organization. The driving mechanism is composed of a crank rocker mechanism A1B1C1D1 and gear mechanisms I1 and I2; the motion limit position is composed of a gear train G1G2H1H2H3 composed of incomplete gears. The rocker C1D1 in the drive mechanism is disposed coaxially with the gear I1. In the vicinity of one of the motion limit positions 11566 of the crank rocker mechanism A1B1, the incomplete gear G1 and the gear G2 coaxially coupled with the lever A1B1 are in the meshing position (the meshing point on the base circle of the gear G1), which is the follower C2D2 provides auxiliary motion. Similarly, in the vicinity of the other motion limit position 119446 of A1B1, when the mark on the base circle of the gear H1 is in the meshing position, the gears H2, H3 are engaged to provide the auxiliary motion of the follower C2D2.
The angular displacement analysis of the 6-link gear combination mechanism is shown by the 1-3 curve and the 5-7 curve for the input-output angular displacement relationship of the two sets of basic linkage crank-rocker mechanism and the Non-grashof mechanism in the combined mechanism, respectively. Curve 1 represents the 1-3 angular displacement relationship, and curve 2 represents the 5-7 angular displacement relationship (5-7 curve translates 180 along the horizontal axis).
Input-output angular displacement relationship (1-7 curve) of a system consisting of a Non-grashof mechanism, a crank-rocker mechanism, and a gear mechanism with a gear ratio of 13.
1.1-3 angular displacement relationship 2.
5-7 angular displacement relationship 7 Conclusion The modulus of the gear is m15mm. The experimental model of the combination mechanism of the Non-grashof mechanism is made. The gear and linkage mechanism on the left is the system drive mechanism, and the four-bar mechanism in the middle is the Non-grashof mechanism. It is the movement limit position through the mechanism. The experimental results show that the system has good passability at the extreme positions in each motion cycle. It is indicated that the design method of this paper is effective for solving the problem of motion instability of the Non-grashof mechanism at the extreme position of motion. In the future, we will conduct in-depth and meticulous research on the dynamic performance of the Non-grashof mechanism in combination with problems such as dynamic performance and accuracy error.
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