OBRABOTKAMETALLOV Vol. 23 No. 3 2021 MATERIAL SCIENCE EQUIPMENT. INSTRUMENTS 6 1 4 The resultant is determined by: 2 2 G XG YG = + . (43) Consider the last Assur group for our mechanism. It is a second-class second-type group (Fig. 10). The length of the link GF, the x coordinate of the guide along which the slider F moves (in this case, it is zero) are needed to determine the trajectory of the point F. The length of the projection of the GF link on the OX axis is equal to the diff erence between the coordinates of the G point and the guide for the slider. Fig. 10. The second-class second-type Assur group Based on Fig. 10, the value of T is determined by: T XF XG = - . (44) From the GFT triangle, according to the Pythagorean theorem, we defi ne: 2 2 YF GF T = - . (45) Then the total motion of the point F is determined: ( )o YF EG YF = + . (46) Results and discussion The analysis revealed that the heddle fi xing mechanism can be placed outside the heddle frame. As a result, the values of the axial distance O2O3 were reduced by 100 mm. Due to the fact that the heddle shaft stroke is a known value obtained as a result of calculations of the shed geometry [1] (point G in Fig. 2), the methodology of synthesizing the mechanism [9, 29, 35, 36, 45–49] for moving the heddle suggests starting it from the last Assur group. The motion of the fourth heddle shaft equal to 75 mm is accepted as a known parameter [1, 9, 10, 29, 35, 36, 45–49]. The synthesis condition for this group is the equality of chords E′E = F′F relative to the horizontal axis. The angles of rotation of these levers are also equal and amount to μ1 = 15.15°. They were given previously and defi ned by formula (1). Further synthesis was carried out for the fourth second-class fi rst-type Assur group. Signifi cantly, the main condition for synthesis is the equalization of arcs (chords) E′E = D′D, EE0 = DD0 and arm lengths O4E = O3D. Further synthesis of the mechanism consisted of determining the swing angle of the lever with rollers, which is calculated by the formula (10). The swing angle of this lever depends, among other things, on the dimension of the arm O3D. The dimensions of this lever were taken within the range of 138.5–143.5 mm. By interpolating the values of angle β, we determined that β = 22.926°, corresponding to a chord length of 28 mm. We then calculated the length of the arm O3D of the lever O3DC to be 143.5 mm. When tackling the loom for manufacturing a variety of fabrics, up to ten heddles may be used, and their movement is determined by their position within the machine. Therefore, the dimension of one of the levers in the kinematic scheme, which allows the adjustment of the heddles’ stroke, was chosen as a variable parameter. In our case, it was the DO3 lever. Using the analytical dependences (11) and (12), it is possible to calculate the length of the DO3 lever and the value of the heddles’ stroke.
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