Servo double-crank transmission mechanism and optimization method

Abstract

The invention relates to the technical field of press machines, in particular to a servo double-crank transmission mechanism and an optimization method. Comprising a servo motor, the servo motor is installed on a press machine body, a high-speed shaft supporting sleeve is further arranged on the press machine, one end of a rotor shaft of the servo motor penetrates through the high-speed shaft supporting sleeve to be connected with a main driving gear shaft in a locking mode, the other end of the rotor shaft of the servo motor is connected with a brake in a locking mode, and the brake is installed on the servo motor. A servo motor is connected with a low-speed large gear through a main driving gear shaft, a rocker arm fixing shaft and a connecting rod fixing shaft are arranged on the low-speed large gear, the connecting rod fixing shaft is connected with a driving connecting rod, the other end of the connecting rod drives a rocker arm to swing through the rocker arm fixing shaft, and the other end of the rocker arm drives a crankshaft to rotate. The crankshaft and the low-speed bull gear are installed in the crankshaft eccentric sleeve, and one end of the crankshaft penetrates through the low-speed bull gear to be connected with one end of the rocker arm.

Description

Technical Field

[0001] The invention relates to the technical field of presses, and in particular to a servo double crank transmission mechanism and an optimization method. Background Art

[0002] At present, common servo presses generally use two drive forms:

[0003] The rotation of the servo motor directly drives the slider to perform stamping operations through the reduction mechanism and the crank slider mechanism; this type of servo press inherits all the characteristics of an ordinary crank press. If the servo motor runs at a constant speed, the slider motion curve is still a sine curve like an ordinary crank press. The required motion curve can be obtained by changing the speed of the servo motor. However, this type of drive does not use a mechanical force amplification mechanism, and the torque of the servo motor is configured according to the nominal force stroke range, resulting in the selection of an overly large servo motor, which increases manufacturing costs.

[0004] The rotation of the servo motor is transmitted through the reduction mechanism and the toggle transmission mechanism, so that the crank movement that originally rotates around the fixed axis is converted through the connecting rod and the upper and lower toggle rods to drive the slider to move up and down linearly; this toggle mechanism significantly increases the force effect and better solves the problem of excessive torque of the servo motor. However, there are also problems such as complex toggle transmission mechanism, large total clearance of connection parts and high maintenance cost.

[0005] In summary, the above-mentioned servo press has the disadvantages of too large or high cost of servo motor, complex structure and high maintenance cost. Based on the above-mentioned problems, it is urgent to improve the connection mechanism between the servo motor and the slider to simplify the connection mechanism and achieve cost reduction and efficiency improvement. Summary of the invention

[0006] The problem to be solved by the present invention is to provide a simplified connection mechanism to optimize the transmission effect between the servo motor and the slider.

[0007] In view of the deficiencies in the prior art, the technical solution adopted by the present invention to solve the technical problems is: a servo double crank transmission mechanism, including a servo motor, a main drive gear shaft, a high-speed shaft support sleeve, a brake, a low-speed gear, a rocker arm, a connecting rod, a rocker arm fixed shaft, a connecting rod fixed shaft, a crankshaft eccentric sleeve, a crankshaft, and a crankshaft front support. The servo motor is installed on the press body, and the press is also provided with a high-speed shaft support sleeve. One end of the rotor shaft of the servo motor passes through the high-speed shaft support sleeve and is locked and connected to the main drive gear shaft, and the other end of the rotor shaft of the servo motor is locked and connected to the brake, and the brake is installed on the servo motor; the servo motor is connected to the low-speed gear through the main drive gear shaft, and the low-speed gear is provided with a rocker arm fixed shaft and a connecting rod fixed shaft, the connecting rod fixed shaft is connected to the driving connecting rod, the other end of the connecting rod drives the rocker arm to swing through the rocker arm fixed shaft, and the other end of the rocker arm drives the crankshaft to rotate; the crankshaft and the low-speed gear are installed in the crankshaft eccentric sleeve, and one end of the crankshaft passes through the low-speed gear and is connected to one end of the rocker arm.

[0008] Preferably, the servo motor has the characteristics of low speed and high torque, with a peak speed of ≤500 rpm and a peak torque of ≥12,000 Nm.

[0009] Preferably, the cooling method of the servo motor is natural cooling, forced air cooling, or forced liquid cooling.

[0010] Preferably, the rotor shaft of the servo motor and the main drive gear shaft are locked by a locking sleeve, a spline or a flat key.

[0011] Preferably, the brake is in the form of a pneumatic friction structure or an electromagnetic friction structure.

[0012] A method for optimizing a servo double crank transmission mechanism comprises the following steps:

[0013] Step 1: Determine the parameter variables. The double crank transmission mechanism consists of four rods, which are the low-speed gear, connecting rod, rocker arm and crankshaft eccentric sleeve. The lengths of the low-speed gear, connecting rod, rocker arm and crankshaft eccentric sleeve are L1, L2, L3 and L4 respectively. The offset angle between the rocker arm and the crankshaft is β.

[0014] X=(L1, L2, L3, L4, β);

[0015] Step 2: Determine the optimization target, taking the minimum nominal pressure torque M acting on the low-speed large gear g And the minimum speed fluctuation Δv of the slider in a given area at the nominal pressure stroke is taken as the optimization target, that is, minf(X)=αM g +(1-α)Δv, where α is the weighting coefficient, and its value range is [0, 1];

[0016] Step 3: Determine the conditions for the establishment of the double crank transmission mechanism. Taking the crankshaft eccentric sleeve as the shortest rod, the conditions for the establishment of the double crank transmission mechanism are: the sum of the longest rod and the shortest rod is less than or equal to the sum of the other two rods.

[0017] L4+L3≤L1+L2

[0018] L4+L2≤L1+L3

[0019] L4+L1≤L2+L3

[0020] L4≤L1

[0021] L4≤L2

[0022] L4≤L3

[0024] Step 4: Parameter variable value range. The allowed value range of each parameter variable is:

[0025] Lower limit:

[0026] Upper limit:

[0027] Optimized mechanism parameter solution: Use the optimization algorithm to obtain minf(X) under the constraints to achieve the optimization of the double crank transmission mechanism.

[0028] The beneficial effects of the present invention are as follows:

[0029] 1. The main transmission mechanism is composed of servo drive and double crank transmission. Compared with the traditional toggle transmission structure, it has a simple and compact structure and good assembly processability;

[0030] 2. The double crank transmission mechanism and the crank slider transmission mechanism are independent of each other. Compared with the traditional toggle transmission structure, it is easier to adjust the die height and slider stroke of the press;

[0031] 3. The double crank transmission mechanism has better low-speed characteristics near the bottom dead center, and has a more obvious force-increasing effect compared to the motor directly driving the slider;

[0032] 4. The two large gears drive in opposite directions, and the rod system is arranged symmetrically. The centrifugal forces acting on the crank and the rod system can offset each other, and the stress state on the fuselage guide rail can be greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a side view of the mechanism of the present invention;

[0034] Figure 2 It is an axonometric diagram of the mechanism of the present invention;

[0035] Figure 3It is a principle diagram of a double crank transmission mechanism involved in the present invention;

[0036] Figure 4 The present invention relates to a slider displacement curve diagram;

[0037] Figure 5 It is a slider speed curve diagram involved in the present invention;

[0038] Explanation of the accompanying drawings: 1. servo motor; 2. main drive gear shaft; 3. high-speed shaft support sleeve; 4. brake; 5. low-speed large gear; 6. rocker arm; 7. connecting rod; 8. rocker arm fixed shaft; 9. connecting rod fixed shaft; 10. crankshaft eccentric sleeve; 11. crankshaft; 12. crankshaft front support. DETAILED DESCRIPTION

[0039] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments of the present invention are provided for the purpose of illustration and description, and are not intended to be exhaustive or to limit the present invention to the disclosed forms. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are selected and described in order to better illustrate the principles and practical applications of the present invention, and to enable those of ordinary skill in the art to understand the present invention and thereby design various embodiments with various modifications suitable for specific uses.

[0040] The present invention provides a servo double crank transmission mechanism, which is used to drive a slide block to move up and down on a press, and includes a servo motor 1, a main driving gear shaft 2, a high-speed shaft support sleeve 3, a brake 4, a low-speed gear 5, a rocker arm 6, a connecting rod 7, a rocker arm fixed shaft 8, a connecting rod fixed shaft 9, a crankshaft eccentric sleeve 10, a crankshaft 11, and a crankshaft front support 12; the servo motor 1 drives the low-speed gear 5 through the main driving gear shaft 2, thereby realizing a first-stage reduction. The low-speed gear 5 drives the connecting rod 7 through the connecting rod fixed shaft 9, and the other end of the connecting rod 7 drives the rocker arm 6 to swing through the rocker arm fixed shaft 8; the crankshaft 11 drives the press slide block to move up and down, the crankshaft 11 and the low-speed gear 5 are installed in the crankshaft eccentric sleeve 10, one end of the crankshaft 11 passes through the low-speed gear 5 and is connected to one end of the rocker arm 6, and the rocker arm 6 drives the crankshaft 11 to rotate. The main drive gear shaft 2 is locked with the rotor shaft of the servo motor 1 to form a whole. The servo motor 1 and the high-speed shaft support sleeve 3 are both installed on the press body (not shown). One end of the rotor shaft of the servo motor 1 passes through the high-speed shaft support sleeve 3 and is locked with the main drive gear shaft 2. The other end of the rotor shaft of the servo motor 1 is locked with the rotating disk inside the brake 4. The brake 4 body is fixedly installed on the servo motor 1 to achieve the press stop braking and emergency braking during operation. The rocker arm 6, the connecting rod 7, the rocker arm fixed shaft 8, the connecting rod fixed shaft 9, and the crankshaft eccentric sleeve 10 form a mechanism to drive the crankshaft 11 to move. The mechanism is not limited to one group, and multiple servo motors 1 can be designed to form a parallel drive mechanism according to the actual press tonnage. The servo motor 1 is not limited to one, and multiple servo motors 1 can be designed to form a parallel drive mechanism according to the actual press tonnage. The servo motor 1 has the characteristics of low speed (peak speed ≤ 500 rpm) and high torque (peak torque ≥ 12000 Nm). The cooling method of the servo motor 1 includes but is not limited to natural cooling, forced air cooling, forced liquid (water, oil) cooling, etc. The locking method of the rotor shaft of the servo motor 1 and the main drive gear shaft 2 includes but is not limited to the structures of expansion sleeve, spline, flat key, etc. The form of the brake 4 includes but is not limited to the structures of pneumatic friction type, electromagnetic friction type, etc.

[0041] Figure 3The figure shows the principle diagram of the double crank transmission mechanism of the present invention. It adds a set of double crank transmission mechanism ABCD on the basis of the original crank-connecting rod mechanism DEF, wherein AD is the frame (crankshaft eccentric sleeve 10), AB is the driving crank (low-speed gear 5), CD is the driven crank (rocker arm 6), and the driven crank CD (rocker arm 6) is coaxial with the crank DE (crankshaft 11) in the crank-connecting rod transmission mechanism DEF, and the offset angle is β. Therefore, the uniform motion of the driving crank AB (low-speed gear 5) can be converted into the variable speed motion of the driven crank CD (rocker arm 6) through the double crank transmission mechanism, and then the slider is driven to reciprocate up and down through the original crank-connecting rod transmission mechanism DEF. Since the double crank transmission mechanism is composed of two sets of independent transmission mechanisms, it is only necessary to optimize the double crank transmission mechanism ABCD to achieve the purpose of optimizing the entire transmission mechanism.

[0042] A method for optimizing a servo double crank transmission mechanism comprises the following steps:

[0043] Step 1: Determine parameter variables and establish an optimization design model: The double crank transmission mechanism consists of four rods. The lengths of the rods L1 (low-speed gear 5), L2 (connecting rod 7), L3 (rocker arm 6), L4 (crankshaft eccentric sleeve 10) and the offset angle β between the driven crank CD (rocker arm 6) and the crank DE (crankshaft 11) are used as independent variables for the optimization design, that is,

[0044] X = (L1, L2, L3, L4, β)

[0045] X is the individual code of the genetic algorithm, L1, L2, L3, L4, and β are the parameter variables of the genetic algorithm, and this optimization method uses the genetic algorithm for encoding;

[0046] Step 2: Determine the optimization target, taking the minimum nominal pressure torque M acting on the active crank (low-speed gear 5) g And the minimum speed fluctuation Δv of the slider in a given area at the nominal pressure stroke is taken as the optimization target, that is, minf(X)=αM g +(1-α)Δv, where α is the weighting coefficient and its value range is [0, 1].

[0047] Step 3: Determine the conditions for the establishment of the double crank transmission mechanism. With the frame AD (crankshaft eccentric sleeve 10) as the shortest rod, the conditions for the establishment of the double crank transmission mechanism are: the sum of the longest rod and the shortest rod is less than or equal to the sum of the other two rods, that is,

[0048] L4+L3≤L1+L2

[0049] L4+L2≤L1+L3

[0050] L4+L1≤L2+L3

[0051] L4≤L1

[0052] L4≤L2

[0053] L4≤L3

[0054] Step 4: Parameter variable value range. The allowed value range of each parameter variable is:

[0055] Lower limit:

[0056] Upper limit:

[0057] Solving the optimized mechanism parameters: Using the optimization algorithm, minf(X) is obtained under the constraints to achieve the optimization of the double crank transmission mechanism.

[0058] When in use, the servo motor 1 drives the main drive gear shaft 2 to rotate, and the main drive gear shaft 2 drives the low-speed large gear 5; the low-speed large gear 5 drives the connecting rod 7, the connecting rod 7 drives the rocker arm 6, the movement of the rocker arm 6 causes the crankshaft 11 to move, and the crankshaft 11 drives the press slide to move; the main transmission mechanism of the present invention, which is superimposed with servo drive + double crank transmission, has a simple and compact structure and good assembly processability compared to the traditional toggle transmission structure. Two groups of the present invention's mechanisms can be selected according to process requirements, in which the two low-speed large gears 5 mesh and move in opposite directions. Figure 4 The figure shows the displacement curve of the slider after the double crank transmission mechanism is optimized. Figure 5 The figure shows the slider speed curve after the double crank transmission mechanism is optimized. As can be seen from the figure, the slider displacement curve is relatively gentle near the bottom dead center, and has a more obvious quick return characteristic. By driving the crankshaft movement through the double crank mechanism to achieve slider movement control, the working characteristics near the bottom dead center of the press can be effectively improved, with a good force-increasing effect, solving the problem of selecting too large a servo motor. At the same time, compared with the traditional toggle transmission structure, the double crank transmission structure has a simple and compact structure, good assembly processability, and lower maintenance cost.

Claims

1. A servo double crank transmission mechanism, characterized in that: The invention comprises a servo motor (1), a main drive gear shaft (2), a high-speed shaft support sleeve (3), a brake (4), a low-speed large gear (5), a rocker arm (6), a connecting rod (7), a rocker arm fixed shaft (8), a connecting rod fixed shaft (9), a crankshaft eccentric sleeve (10), a crankshaft (11), and a crankshaft front support (12). The servo motor (1) is installed on a press machine body, and the press machine is also provided with a high-speed shaft support sleeve (3). One end of the rotor shaft of the servo motor (1) passes through the high-speed shaft support sleeve (3) and is locked and connected to the main drive gear shaft (2). The other end of the rotor shaft of the servo motor (1) is locked and connected to the brake (4). The brake (4) is mounted on a servo motor (1); the servo motor (1) is connected to a low-speed gear (5) via a main drive gear shaft (2); a rocker arm fixing shaft (8) and a connecting rod fixing shaft (9) are provided on the low-speed gear (5); the connecting rod fixing shaft (9) is connected to a driving connecting rod (7); the other end of the connecting rod (7) drives a rocker arm (6) to swing via the rocker arm fixing shaft (8); the other end of the rocker arm (6) drives a crankshaft (11) to rotate; the crankshaft (11) and the low-speed gear (5) are mounted in a crankshaft eccentric sleeve (10); one end of the crankshaft (11) passes through the low-speed gear (5) and is connected to one end of the rocker arm (6).

2. The servo double crank transmission mechanism according to claim 1, characterized in that: The servo motor (1) has the characteristics of low speed and high torque, with a peak speed of ≤500 rpm and a peak torque of ≥12000 Nm.

3. The servo double crank transmission mechanism according to claim 2, characterized in that: The cooling method of the servo motor (1) is natural cooling, forced air cooling or forced liquid cooling.

4. The servo double crank transmission mechanism according to claim 3, characterized in that: The rotor shaft of the servo motor (1) and the main driving gear shaft (2) are locked in a manner of a locking sleeve, a spline or a flat key.

5. The servo double crank transmission mechanism according to claim 4, characterized in that: The brake (4) is in the form of a pneumatic friction structure or an electromagnetic friction structure.

6. A method for optimizing a servo double crank transmission mechanism, characterized in that: The following steps are included: Step 1: Determine the parameter variables. The double crank transmission mechanism is composed of four rods, which are a low-speed gear (5), a connecting rod (7), a rocker arm (6) and a crankshaft eccentric sleeve (10). The lengths of the low-speed gear (5), the connecting rod (7), the rocker arm (6) and the crankshaft eccentric sleeve (10) are L1, L2, L3 and L4 respectively. The offset angle between the rocker arm (6) and the crankshaft (11) is β. X=(L1, L2, L3, L4, β); Step 2: Determine the optimization target, taking the minimum nominal pressure torque M acting on the low-speed gear (5) g And the minimum speed fluctuation Δv of the slider in a given area at the nominal pressure stroke is taken as the optimization target, that is, minf(X)=αM g +(1-α)Δv, where α is the weighting coefficient, and its value range is [0, 1]; Step 3: Determine the conditions for the establishment of the double crank transmission mechanism. With the crankshaft eccentric sleeve (10) as the shortest rod, the conditions for the establishment of the double crank transmission mechanism are: the sum of the longest rod and the shortest rod is less than or equal to the sum of the other two rods. L4+L3≤L1+L2 L4+L2≤L1+L3 L4+L1≤L2+L3 L4≤L1 L4≤L2 L4≤L3 Step 4: Parameter variable value range. The allowed value range of each parameter variable is: Lower limit: Upper limit: Solving the optimized mechanism parameters: Using the optimization algorithm, minf(X) is obtained under the constraints to achieve the optimization of the double crank transmission mechanism.

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