Servo double-crank transmission mechanism and optimization method

Abstract

The present application relates to the technical field of press machine, in particular to a kind of servo double-crank transmission mechanism and optimization method.It includes servo motor, servo motor is installed on the press machine body, high-speed shaft support sleeve is also provided on the press machine, the rotor shaft one end of servo motor passes through high-speed shaft support sleeve and is locked with main drive gear shaft connection, the rotor shaft other end of servo motor is locked with brake, and brake is installed on servo motor;Servo motor is connected with low-speed gear through main drive gear shaft, low-speed gear is equipped with rocker arm fixed shaft, connecting rod fixed shaft, connecting rod fixed shaft connects drive connecting rod, the other end of connecting rod is driven to swing by rocker arm fixed shaft, the other end of rocker arm drives crankshaft rotation;Crankshaft and low-speed gear are installed in the eccentric sleeve of crankshaft and the one end of crankshaft passes through low-speed gear and is connected with the one end of rocker arm.

Description

Technical Field

[0001] This invention relates to the field of press technology, specifically to a servo double crank transmission mechanism and its optimization method. Background Technology

[0002] Currently, common servo presses generally use two types of drive mechanisms:

[0003] The rotation of the servo motor directly drives the slide to perform the stamping operation via a reduction gear and a crank-slider mechanism; this type of servo press inherits all the characteristics of a conventional crank press. If the servo motor runs at a constant speed, the slide motion curve is the same as that of a conventional crank press, still a sine curve. The desired motion curve can be obtained by changing the speed of the servo motor. However, this drive method does not employ a mechanical force amplification mechanism, and the torque of the servo motor is configured according to the nominal force stroke range, resulting in an oversized servo motor and increased manufacturing costs.

[0004] The rotation of the servo motor, through a reduction mechanism and an elbow transmission mechanism, transforms the crank motion that originally rotated around a fixed axis into a linear motion of the slider through a connecting rod and upper and lower elbows. This elbow mechanism significantly increases the force and effectively solves the problem of excessive torque in the servo motor. However, it also has the problems of complex elbow transmission mechanism, large total clearance at connection parts, and high maintenance costs.

[0005] In summary, the aforementioned servo presses suffer from drawbacks such as excessively large or costly servo motors, complex structures, and high maintenance costs. Based on these issues, it is imperative to improve the connection mechanism between the servo motor and the slider to simplify the connection 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] To address the shortcomings of existing technologies, the technical solution adopted by this invention is as follows: a servo double crank transmission mechanism, comprising a servo motor, a main drive gear shaft, a high-speed shaft support sleeve, a brake, a low-speed large gear, a rocker arm, a connecting rod, a rocker arm fixing shaft, a connecting rod fixing shaft, a crankshaft eccentric sleeve, a crankshaft, and a crankshaft front support. The servo motor is mounted on the press body, and the press also has a high-speed shaft support sleeve. One end of the servo motor's rotor shaft passes through the high-speed shaft support sleeve and is locked to the main drive gear shaft. The other end of the servo motor's rotor shaft is locked to the brake, which is mounted on the servo motor. The servo motor is connected to the low-speed large gear through the main drive gear shaft. The low-speed large gear has a rocker arm fixing shaft and a connecting rod fixing shaft. The connecting rod fixing shaft is connected to a drive connecting rod. The other end of the connecting rod drives the rocker arm to swing through the rocker arm fixing shaft, and the other end of the rocker arm drives the crankshaft to rotate. The crankshaft and the low-speed large gear are mounted inside the crankshaft eccentric sleeve, and one end of the crankshaft passes through the low-speed large 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 ≤500 rpm and a peak torque ≥12000 Nm.

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

[0010] Preferably, the rotor shaft of the servo motor is locked to the main drive gear shaft by means of a shrink sleeve, spline, or flat key.

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

[0012] An optimization method for a servo double crank drive mechanism includes the following steps:

[0013] Step 1: Determine the parameter variables. The double-crank transmission mechanism consists of four links: a low-speed gear, a connecting rod, a rocker arm, and a crankshaft eccentric sleeve. The lengths of the links 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 objective, using the minimum nominal pressure torque M acting on the low-speed large gear. g The optimization objective is to minimize the velocity fluctuation Δv of the slider within a given region at the nominal pressure stroke, i.e., minf(X) = αM. g +(1-α)Δv, where α is a weighting coefficient with a value range of [0, 1];

[0016] Step 3: Determining the conditions for the establishment of a double-crank transmission mechanism. Taking the crankshaft eccentric sleeve as the shortest link, the condition for the establishment of a double-crank transmission mechanism is: the sum of the longest link and the shortest link is less than or equal to the sum of the other two links.

[0017] L4 + L3 ≤ L1 + L2

[0018] L4 + L2 ≤ L1 + L3

[0019] L4 + L1 ≤ L2 + L3

[0020] L4≤L1

[0021] L4≤L2

[0022] L4≤L3;

[0023] Step 4: Range of values ​​for parameter variables. The allowed range of values ​​for each parameter variable is as follows:

[0024] Lower limit:

[0025] Maximum:

[0026] Solution of optimized mechanism parameters: Using an optimization algorithm, the minf(X) under the constraints is obtained, thus achieving the optimization of the double-crank transmission mechanism.

[0027] The beneficial effects of this invention are as follows:

[0028] 1. The main transmission mechanism adopts a combination of servo drive and double crank drive, which is simple and compact in structure and has good assembly processability compared with the traditional toggle type transmission structure.

[0029] 2. The double crank transmission mechanism and the crank-slider transmission mechanism are independent of each other, which makes it easier to adjust the mold mounting height and slide stroke of the press compared with the traditional toggle type transmission structure;

[0030] 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 with the motor directly driving the slider.

[0031] 4. The two large gears drive in opposite directions and the linkage is arranged symmetrically. The centrifugal forces acting on the crank and linkage can cancel each other out, which can greatly improve the stress state on the machine body guide rail. Attached Figure Description

[0032] Figure 1 This is a side view of the mechanism of the present invention;

[0033] Figure 2 This is an isometric view of the mechanism of this invention;

[0034] Figure 3This is a schematic diagram of the double crank transmission mechanism involved in this invention;

[0035] Figure 4 This invention relates to a slider displacement curve diagram;

[0036] Figure 5 This invention relates to a slider speed curve;

[0037] Explanation of reference numerals in the attached diagram: 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 fixing shaft; 9. Connecting rod fixing shaft; 10. Crankshaft eccentric sleeve; 11. Crankshaft; 12. Crankshaft front support. Detailed Implementation

[0038] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and design various embodiments with various modifications suitable for a particular purpose.

[0039] This invention provides a servo double crank transmission mechanism for driving the slide block up and down on a press. It includes 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 fixing shaft 8, a connecting rod fixing shaft 9, a crankshaft eccentric sleeve 10, a crankshaft 11, and a crankshaft front support 12. The servo motor 1 drives the low-speed large gear 5 through the main drive gear shaft 2, thereby achieving a single-stage reduction. The low-speed large gear 5 drives the connecting rod 7 through the connecting rod fixing shaft 9, and the other end of the connecting rod 7 drives the rocker arm 6 to swing through the rocker arm fixing shaft 8. The crankshaft 11 drives the press slide block to move up and down. The crankshaft 11 and the low-speed large gear 5 are installed inside the crankshaft eccentric sleeve 10. One end of the crankshaft 11 passes through the low-speed large gear 5 and connects to one end of the rocker arm 6, which drives the crankshaft 11 to rotate. The main drive gear shaft 2 and the rotor shaft of the servo motor 1 are locked together as a whole. The servo motor 1 and the high-speed shaft support sleeve 3 are both mounted 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 to the main drive gear shaft 2. The other end of the rotor shaft of the servo motor 1 is locked to the rotating disc inside the brake 4. The brake 4 body is fixedly mounted on the servo motor 1 to achieve press stop braking and emergency braking during operation. The rocker arm 6, connecting rod 7, rocker arm fixed shaft 8, connecting rod fixed shaft 9, and crankshaft eccentric sleeve 10 form a mechanism that drives the crankshaft 11. This mechanism is not limited to one set; multiple units can be designed to form a parallel drive mechanism according to the actual press tonnage. The servo motor 1 is not limited to one unit; multiple servo motors 1 can be designed to form a parallel drive mechanism according to the actual press tonnage. The servo motor 1 is characterized by low speed (peak speed ≤ 500 rpm) and high torque (peak torque ≥ 12000 Nm). The cooling methods for servo motor 1 include, but are not limited to, natural cooling, forced air cooling, and forced liquid (water, oil) cooling. The locking methods between the rotor shaft of servo motor 1 and the main drive gear shaft 2 include, but are not limited to, structures such as expansion sleeves, splines, and flat keys. The brake 4 includes, but is not limited to, pneumatic friction type and electromagnetic friction type structures.

[0040] Figure 3The diagram shows the principle of the double-crank transmission mechanism of this invention. It adds a double-crank transmission mechanism ABCD to the original crank-connecting rod mechanism DEF. AD is the frame (crankshaft eccentric sleeve 10), AB is the driving crank (low-speed large gear 5), and CD is the driven crank (rocker arm 6). The driven crank CD (rocker arm 6) is coaxial with the crank DE (crankshaft 11) in the crank-connecting rod transmission mechanism DEF, with an offset angle of β. Therefore, the uniform motion of the driving crank AB (low-speed large 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 independent transmission mechanisms, only the double-crank transmission mechanism ABCD needs to be optimized to achieve the optimization of the entire transmission mechanism.

[0041] An optimization method for a servo double crank transmission mechanism includes the following steps:

[0042] Step 1: Determine the parameter variables and establish the optimization design model: The double-crank transmission mechanism consists of four links. The lengths of each link—L1 (low-speed large 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 crank DE (crankshaft 11)—are taken as independent variables for the optimization design.

[0043] X = (L1, L2, L3, L4, β)

[0044] X is the individual code of the genetic algorithm, and L1, L2, L3, L4, and β are the parameter variables of the genetic algorithm. This optimization method uses the genetic algorithm for encoding.

[0045] Step 2: Determine the optimization target, using the minimum nominal pressure torque M acting on the driving crank (low-speed large gear 5) as the target. g The optimization objective is to minimize the velocity fluctuation Δv of the slider within a given region at the nominal pressure stroke, i.e., minf(X) = αM. g +(1-α)Δv, where α is the weighting coefficient, and its value ranges from [0, 1].

[0046] Step 3: Determining the conditions for the establishment of the double-crank transmission mechanism. Taking frame AD (crankshaft eccentric sleeve 10) as the shortest link, the condition for the establishment of the double-crank transmission mechanism is: the sum of the longest link and the shortest link is less than or equal to the sum of the other two links, that is...

[0047] L4 + L3 ≤ L1 + L2

[0048] L4 + L2 ≤ L1 + L3

[0049] L4 + L1 ≤ L2 + L3

[0050] L4≤L1

[0051] L4≤L2

[0052] L4≤L3

[0053] Step 4: Range of values ​​for parameter variables. The allowed range of values ​​for each parameter variable is as follows:

[0054] Lower limit:

[0055] Maximum:

[0056] Solution of optimized mechanism parameters: Using an optimization algorithm, the minf(X) under the constraints is obtained, thereby optimizing the double crank transmission mechanism.

[0057] 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 rocker arm 6 moves to make the crankshaft 11 move, and the crankshaft 11 drives the press slide to move; compared with the traditional toggle-type transmission structure, the main transmission mechanism of this invention, which combines servo drive and double crank transmission, is simple and compact in structure and has good assembly processability. Two sets of the mechanism of this invention 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 slider displacement curve after optimization of the double crank transmission mechanism. Figure 5 The figure shows the slider speed curve after optimization of the double-crank drive mechanism. As can be seen from the figure, the slider displacement curve exhibits a relatively flat speed near the bottom dead center, with a noticeable quick-return characteristic. Driving the crankshaft through the double-crank mechanism to control the slider motion effectively improves the working characteristics of the press near the bottom dead center, providing a better force amplification effect and solving the problem of selecting an oversized servo motor. Furthermore, compared to the traditional toggle-type drive structure, the double-crank drive structure is simpler and more compact, has better assembly processability, and lower maintenance costs.

Claims

1. An optimization method for a servo double crank transmission mechanism, comprising a servo double crank transmission mechanism, including 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 fixing shaft (8), a connecting rod fixing shaft (9), a crankshaft eccentric sleeve (10), a crankshaft (11), and a crankshaft front support (12). The servo motor (1) is mounted on the press body, and the press 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 to the main drive gear shaft (2). The rotor of the servo motor (1) rotates... The other end of the sub-shaft is locked to the brake (4), which is mounted on the servo motor (1). The servo motor (1) is connected to the low-speed large gear (5) through the main drive gear shaft (2). The low-speed large gear (5) is provided with a rocker arm fixing shaft (8) and a connecting rod fixing shaft (9). The connecting rod fixing shaft (9) is connected to the drive connecting rod (7). The other end of the connecting rod (7) drives the rocker arm (6) to swing through the rocker arm fixing shaft (8). The other end of the rocker arm (6) drives the crankshaft (11) to rotate. The crankshaft (11) and the low-speed large gear (5) are installed in the crankshaft eccentric sleeve (10), and one end of the crankshaft (11) passes through the low-speed large gear (5) and is connected to one end of the rocker arm (6). The servo motor (1) has the characteristics of low speed and high torque, with a peak speed ≤500 rpm and a peak torque ≥12000 Nm; The servo motor (1) is cooled by natural cooling, forced air cooling, or forced liquid cooling. The rotor shaft of the servo motor (1) is locked to the main drive gear shaft (2) by a shrink sleeve, spline, or flat key. The brake (4) is in the form of a pneumatic friction structure or an electromagnetic friction structure; Its features are: Includes the following steps, Step 1: Determine the parameter variables. The double crank transmission mechanism consists of four links: a low-speed gear (5), a connecting rod (7), a rocker arm (6), and a crankshaft eccentric sleeve (10). The lengths of each link are as follows: The offset angle between the rocker arm (6) and the crankshaft (11) is , ； Step 2: Determine the optimization target, which is the minimum nominal pressure torque acting on the low-speed large gear (5). and the minimum speed fluctuation of the slider within a given range at the nominal pressure stroke. As the optimization target, i.e. In the formula, These are weighting coefficients, and their values ​​range from [value range missing]. ; Step 3: Determining the conditions for the establishment of the double crank transmission mechanism. Taking the crankshaft eccentric sleeve (10) as the shortest link, the conditions for the establishment of the double crank transmission mechanism are: the sum of the longest link and the shortest link is less than or equal to the sum of the other two links. ； Step 4: Range of values ​​for parameter variables. The allowed range of values ​​for each parameter variable is as follows: Lower limit: ; Maximum: ; Optimized mechanism parameter solution: Using optimization algorithms, the optimal mechanism parameters are obtained under the constraints. This achieves the optimization of the double crank transmission mechanism.

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