Power driving method for sliding table of forming machine

Abstract

The invention discloses a forming machine sliding table power driving method which comprises the steps that an eccentric crankshaft is adopted, the eccentric crankshaft serves as a driving shaft, and a toggle type connecting rod mechanism composed of a push rod, a connecting rod and a rocker is arranged on the eccentric crankshaft to push a sliding table to do linear reciprocating motion, so that the sliding table runs to a front dead point and enters a speed stable state. The toggle type connecting rod mechanism is adopted to drive the sliding table to do reciprocating linear motion, and compared with an original crank sliding block mechanism to drive the sliding table to move, the toggle mechanism has the advantages that the motion law of the toggle mechanism is more ideal, the quick-return characteristic is better, the return stroke time is about 1 / 2 of the forward stroke time, the speed fluctuation near a front dead point is small, and the speed fluctuation is small; the dwell time of the front dead point area is longer, and the impact stability is good; 2, the toggle type mechanism is more compact in structure, and larger sliding table stroke design parameters can be provided in the same design space;

Description

Technical Field

[0001] The invention relates to a forming machine production technology, in particular to a forming machine slide table power driving method. Background Art

[0002] In the prior art, the slide components of the forming machine are basically driven by a crank slider mechanism, which can meet the slide operation requirements of most working conditions. However, when upsetting thin parts or upsetting thin flange surfaces, the slide is required to have a smaller running acceleration when it runs to the front dead point to prevent the workpiece from rebounding due to force. However, the existing crank slider mechanism drives the slide, and when the slide runs to the front dead point, it is an acceleration process, and the workpiece is prone to rebound due to force. The existing equipment cannot meet the requirements of this working condition. Summary of the invention

[0003] The purpose of the present invention is to solve the deficiencies of the above-mentioned technology and to provide a method for driving a slide table of a forming machine which has good impact stability and can prevent the workpiece from rebounding due to force.

[0004] In order to achieve the above-mentioned purpose, the present invention provides a forming machine slide power driving method, including the use of an eccentric crankshaft, which is characterized in that the eccentric crankshaft is used as the driving shaft, and the slide is pushed to perform linear reciprocating motion by arranging a toggle-type connecting rod mechanism composed of a push rod, a connecting rod and a rocker on the eccentric crankshaft, so that the slide runs to the front dead point and enters a stable speed state; the toggle-type connecting rod mechanism composed of the push rod, the connecting rod and the rocker is that the other end of the push rod fixed on the eccentric crankshaft is axially fixed to the connecting rod and the rocker respectively through the toggle pin shaft, and the other end of the connecting rod is connected to the slide through the connecting rod shaft; the other end of the rocker is connected to the fixed point shaft.

[0005] Assume that the connecting rod shaft is point A O4, the fixed point shaft is point B O2, and the eccentric crankshaft is point C O1; during operation, due to the eccentricity R, the slide makes reciprocating motion along the AB straight line under the action of the connecting rod to complete the entire slide driving function. During the driving operation, when point A runs to the front dead point, the slide speed is stable and the acceleration basically tends to zero.

[0006] The present invention provides a method for driving a slide table of a forming machine, which uses a toggle-type connecting rod mechanism to drive the slide table to perform reciprocating linear motion. Compared with the motion of the slide table driven by the original crank slider mechanism, it can be found that: 1. The motion law of the toggle mechanism is more ideal, the quick return characteristic is better, the speed fluctuation near the front dead point is small, the dwell time in the front dead point area is longer, the impact stability is good, and the workpiece can be prevented from rebounding under force. 2. The structure of the toggle mechanism is more compact, and more slide stroke design parameters can be provided within the same design space. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1It is a schematic diagram of the travel position state of the slide table running to the front dead point and the rear dead point in an embodiment of the present invention;

[0008] Figure 2 It is a working principle diagram of the present invention;

[0009] Figure 3 Schematic diagram of the relationship between slide travel and angle. DETAILED DESCRIPTION

[0010] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0011] Example 1.

[0012] like Figure 1 , Figure 2 As shown, the present embodiment provides a method for driving a slide of a forming machine, comprising adopting an eccentric crankshaft as a driving shaft, and arranging a toggle-type connecting rod mechanism composed of a push rod L3, a connecting rod L2 and a rocker arm L1 on the eccentric crankshaft to push the slide to perform linear reciprocating motion, so that the slide runs to the front dead point and enters a stable speed state; the toggle-type connecting rod mechanism composed of the push rod L3, the connecting rod L2 and the rocker arm L1 is to axially fix the other end of the push rod L3 fixed on the eccentric crankshaft to the connecting rod L2 and the rocker arm L1 respectively through an toggle pin, and the other end of the connecting rod is connected to the slide through a connecting rod shaft; the other end of the rocker arm is connected to the fixed point shaft.

[0013] In this embodiment, the connecting rod shaft is assumed to be point A O4, the fixed point shaft is assumed to be point B O2, and the eccentric crankshaft is assumed to be point C O1; during operation, due to the eccentric distance R, the slide makes reciprocating motion along the straight line AB under the action of the connecting rod L2, completing the entire slide driving function. During the driving operation, when point A runs to the front dead point, the slide speed is stable and the acceleration basically tends to zero.

[0014] The working process of this embodiment is analyzed as follows:

[0015] like Figure 2 As shown, crank radius R; push rod L3, connecting rod L2, rocker arm L1, slide stroke S, connecting rod length L0. The position of the slide stated below refers to the point where the slide is connected to the connecting rod shaft, which is set as the slide hinge coordinate O4.

[0016] 1. Establish the coordinate system and the coordinates of each hinge point:

[0017] (1) Coordinate system

[0018] X-axis: The direction of the slide moving forward to the dead point is the positive direction,

[0019] Y axis: passes through the fulcrum of the crankshaft, is perpendicular to the X axis, and is positive upwards

[0020] Point O: The intersection of two coordinate axes.

[0021] (2) Key point coordinates

[0022] Crankshaft center coordinates: O0 (0, H0); fixed point.

[0023] Rocker fulcrum coordinates: O2 (-L1, 0) or (-L0, 0); fixed point.

[0024] The coordinates of the hinge point between the crankshaft and the push rod are: O1(x1, y1), and the angle between it and the negative direction of the y-axis is θ:.

[0025] The coordinates of the common hinge point of the push rod, connecting rod and rocker arm are: O3 (x3, y3), the moving point, which moves within a certain range in the rod system.

[0026] Slide hinge coordinates: O4 (x4, 0)

[0027] (3) Movement and direction

[0028] The starting position of the slide is at the front dead center. The slide moves backward from the front dead center to the rear dead center, and moves forward from the rear dead center to the front dead center.

[0029] The crankshaft rotates clockwise, and the starting position of the movement meets the requirements of the slide movement, that is, the starting position is at the lowest point, and clockwise rotation is positive rotation.

[0030] Here, the time taken by the crankshaft to drive the rocker and slide forward and backward through the push rod is different. Under the previous conditions, when the crankshaft drives the rocker and slide clockwise from the bottom dead center (the slide is at the front dead center) to the highest point (top dead center), the rocker and slide are at the dead center position (rear dead center), and then the crankshaft returns from the top dead center to the bottom dead center, and the slide returns from the rear dead center to the front dead center, moving a whole stroke; at the top dead center position of the crankshaft, its rotation angle is not 180°. In fact, the crankshaft rotation angle of the backward stroke is less than 180°, while the rotation angle of the forward stroke is greater than 180°. In terms of average speed, it is a fast-reverse-slow-forward working mode, while the instantaneous speed changes in a complex manner.

[0031] 2. Special situation analysis (limit position of rocker and slide)

[0032] 1. The working range of the joystick

[0033] (1) Minimum angle between the joystick and the X-axis

[0034] When the slide moves to the front dead center, the rocker L1 and the connecting rod L2 are in a straight line:

[0035] H0=L3-R

[0036] L0=L1

[0037] The angle between the joystick and the X axis:

[0038] αmin=0° (1)

[0039] (2) Angle between the rocker fulcrum, crankshaft fulcrum and X-axis

[0040] 1)Minimum angle

[0041] The angle formed at the initial position is the smallest, at this time:

[0042]

[0043] or

[0044] or

[0045] 2)Maximum angle

[0046] The angle is largest when the crankshaft and push rod are in a straight line

[0047]

[0048] (3) Maximum angle between the joystick and the X-axis

[0049] By analytical calculation, the relationship is

[0050]

[0051] From the triangular relationship

[0052] α max =γ max -γ min (7)

[0053] 2. The range of motion of the slide

[0054] (1) Front dead center coordinates

[0055] S max =L2 (8)

[0056] (2) Movement of the slide

[0057]

[0058] (3) Slide travel

[0059] ΔS=S max -S min (10)

[0060] 3. Angle of the putter

[0061] (1) In the starting position,

[0062] At the starting position, the push rod coincides with the y-axis position, at this time:

[0063] δ=0° (11)

[0064] (2) At the end position

[0065] When the push rod reaches the highest point, it is the final position. The horizontal displacement at this time is the angle between x3 and the positive direction of the y-axis:

[0066]

[0067] Given structure data

[0068] L0=L1=400mm L3=350mm H0=250mm L2=425mm

[0069] Substituting in, we get:

[0070] γ min =32.00538°

[0071] γ max =61.51041°

[0072] α max =29.50503°

[0073] δ max =7.035406°

[0074] S max =425mm

[0075] S min =324.7131mm

[0076] ΔS=S max -S min =100.28

[0077] 4. Summary

[0078] (1) At the starting position, the connecting rod L2 and the rocker L1 are in a straight line, the slide is at the front dead center position (x coordinate is 425), and the angle α of the rocker relative to the x-axis is The angle β of the connecting rod relative to the x-axis is also

[0079] (2) When the crankshaft rotates half a turn, the angle of the rocker arm at the highest position is: 29.50503, driving the slide to move backward from the front dead center to the final (rear dead center) position, the x coordinate is 325 (calculated value is 324.7mm), and the overall stroke is 100 (calculated value is 100.3mm).

[0080] (3) This is the working range of the rocker and the slide. Both the rocker and the slide are passive parts, driven by the crankshaft. Only the crankshaft, the active part, moves at a constant speed, while other parts move at variable speeds. The movement law is affected by the composition and position of the rod system. Therefore, within this range, the movement speeds of both the rocker and the slide are changing, and the change law needs further analysis.

[0081] (4) The swing angle of the push rod is not large within the entire range of motion, and the entire range is within 7.035406°

[0082] 3. Movement laws of components driven by the crankshaft

[0083] 1. Movement of the crankshaft

[0084] According to the definition of the crankshaft arrangement position and movement direction, the clockwise rotation angle of the crankshaft relative to the negative y-axis direction is θ, and the coordinate relationship of the hinge point O1 is:

[0085] x1=x0-R sinθ=-R sinθ (13)

[0086] y1=y0-Rcosθ=-H0-R cosθ (14)

[0087] and

[0088]

[0089] From the perspective of numerical analysis, given the crankshaft angle θ, the values ​​of x1 and y1 can be obtained.

[0090] 2. Movement of hinge point O3

[0091] The hinge point O3 is connected to the crankshaft by a push rod, and its motion trajectory follows the swing of the rocker. Its constraint is given by the distance between O1 and O3 (push rod length).

[0092] Relative to the joystick:

[0093] x3=x2+L1cosα=-L0+L1cosα (16)

[0094] y3=y2+L1sinα=L1sinα (17)

[0095] At the same time, the movement is generated by the constraint of the push rod, and the relationship is that the distance between the two points is the length of the rod, that is:

[0096]

[0097] Rod lengths L1 and L3 are constants. If the relationship between x3 and y3 relative to x1 and y1 is determined, the rotation relationship of the crankshaft can be converted into the swing position relationship of the rocker arm, thereby determining the coordinate value of the rocker arm relative to the crankshaft rotation.

[0098] 3. Movement of the slide hinge point O4

[0099] In the triangle relationship formed by the rocker and connecting rod and the X-axis:

[0100]

[0101] or

[0102]

[0103] y4=0

[0104] 4. Numerical calculation of the motion law of the crankshaft and its connection point

[0105] Numerical calculation is to substitute all the calculated data and calculate the results respectively: start from the crankshaft rotation, give the angle, common angle and special angle value respectively: the value of θ is Separation The special point angle is This is the angle of the rear dead point, and also the transition angle between backward and forward.

[0106] The coordinates of O1 (x1, y1) are calculated respectively, and then (x3, y3) and (x4, y4) are calculated, until the stroke s is calculated. Thus, the relationship data between the crankshaft angle and the slider stroke is obtained.

[0107] 5. Analysis of the motion relationship between the slider and the crankshaft angle

[0108] like Figure 3 The figure shows the change process of the slide in one cycle, and the data corresponds to the following table 1.

[0109] Table 1 Slider stroke calculation table

[0110]

[0111]

[0112] From the calculation data, we can see that the law of slide motion is:

[0113] 1. At the beginning and end, the crankshaft rotates more than 40 degrees, and the slide moves less than 1mm, almost no movement; the crankshaft rotates more than 70 degrees, and the slide travels less than 10mm, which is less than 1 / 10 of the total travel. The movement in this stage is very slow.

[0114] 2. The crankshaft continues to rotate 50°, that is, a total of 120°, which is about 1 / 2 stroke.

[0115] 3. After the crankshaft rotates 1 / 3 of a circle, the stroke is 1 / 2; after rotating another 1 / 3 of a circle, it quickly retreats and quickly advances, first completing the rapid retreat of 1 / 2 of the stroke, then the rapid forward of 1 / 2 of the stroke; after rotating another 1 / 3 of a circle, it returns to the origin from the 1 / 2 stroke.

[0116] 4. The slide moves back to the final position (rear dead center), the crankshaft rotates 173°, and moves forward to the front dead center, the crankshaft rotates 187°. The average speed of moving back is slightly faster, and the average speed of moving forward is slightly slower.

[0117] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for driving a slide of a forming machine, comprising adopting an eccentric crankshaft, characterized in that the eccentric crankshaft is used as a driving shaft, and a toggle-type connecting rod mechanism composed of a push rod, a connecting rod and a rocker is arranged on the eccentric crankshaft to push the slide to perform linear reciprocating motion, so that the slide runs to the front dead point and enters a speed stable state; the toggle-type connecting rod mechanism composed of the push rod, the connecting rod and the rocker is that the other end of the push rod fixed on the eccentric crankshaft is axially fixed to the connecting rod and the rocker respectively through a toggle pin, and the other end of the connecting rod is connected to the slide through a connecting rod shaft; the other end of the rocker is connected to the fixed point shaft.

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