CN102126301A - Triangular toggle-rod working mechanism of servo mechanical press and optimized design method thereof - Google Patents

Abstract

The invention relates to a triangular toggle working mechanism of a servo mechanical press and an optimization design method thereof. Including crank AB, connecting rod BCE, upper toggle CD, lower toggle EF, and a slider constructed by point F, where the upper toggle CD and lower toggle EF are not equal in length, and the upper toggle CD is shorter than the lower toggle Rod EF, point D and point F are on the vertical line, and the triangle connecting rod BCE constructed by point B, point C and point E. Because the present invention adopts the structure of changing the symmetrical toggle lever into an asymmetrical toggle lever and changing the linear connecting rod into a triangular connecting rod, it can ensure that the fuselage mechanism is compact, the stroke of the slider is sufficient, and the slider moves downward monotonously. With a higher boost ratio, the required driving torque at the crank can be greatly reduced, thereby reducing the capacity and cost of the servo motor. The invention is simple and convenient to use, and the designed triangular toggle working mechanism of the servo mechanical press is reasonable in structure, convenient and practical.

Description

Triangular toggle working mechanism of servo mechanical press and its optimal design method

technical field

The invention relates to a triangular toggle working mechanism of a servo mechanical press and an optimization design method thereof, belonging to an innovative design in the field of mechanical transmission.

Background technique

Ordinary mechanical presses are generally driven by ordinary AC asynchronous motors, and large flywheels are used for energy storage; while servo mechanical presses use AC servo motors instead of AC asynchronous motors, and cancel the flywheel, which not only simplifies the transmission chain, but also improves the automation and intelligence of the equipment. It can also save energy and reduce noise significantly, which is of great significance to energy saving and emission reduction in the manufacturing industry. Since the servo mechanical press has no flywheel, the working pressure is mainly generated by the instantaneous torque of the motor, so the capacity of the driving motor is much larger than that of the ordinary press. The use of large-capacity servo motors leads to high equipment costs, which has become a major obstacle to the promotion and application of servo mechanical presses.

By improving the working mechanism and increasing the force ratio of the working mechanism, the driving torque of the motor can be reduced, which plays a decisive role in reducing the capacity of the motor, reducing the cost of the servo mechanical press, and promoting the engineering application of this technology. The working mechanism of a traditional mechanical press generally adopts a crank connecting rod, a symmetrical toggle or a multi-link structure. The crank connecting rod has the advantage of simple structure, but the nominal pressure stroke is small and the booster ratio is small, so it can only be applied to small servo mechanical presses, such as a press disclosed in Chinese Patent No. ZL200320118186.8; although the symmetrical toggle There is a rapid return of the free stroke and the approximate stop characteristic of the working stroke, but the booster ratio is still not large enough, such as the mechanism disclosed in the Chinese patent No. ZL 200720054117.3 and ZL 200820082737.2; and the multi-link mechanism can improve the motion characteristics of the slider in the working stroke , there are still disadvantages such as the boost ratio is not optimal and the structure is complex, such as the mechanism disclosed in Chinese Patent No. ZL 200820030514.1.

Contents of the invention

The purpose of the present invention is to consider the above-mentioned problems and provide a motor with a relatively high booster ratio, which can greatly reduce the required driving torque at the crank under the condition of ensuring a compact fuselage mechanism, sufficient slider stroke, and monotonous downward movement of the slider. , And then reduce the capacity of the servo motor and the cost of the triangular toggle mechanism of the servo mechanical press.

Another object of the present invention is to provide a simple and convenient optimal design method for the triangular toggle working mechanism of the servo mechanical press.

The technical scheme of the present invention is: the triangular toggle working mechanism of the servo mechanical press of the present invention includes the crank AB constructed by points A and B, the connecting rod BCE constructed by points B, C and E, and the connecting rod BCE constructed by points C and The upper toggle link CD built at point D, the lower toggle link EF built at points E and F, the slider built at point F, the rotation joint between the crankshaft and the fuselage at point A, and the crankshaft and triangle at point B The revolving joint between the connecting rods, the revolving joint between the triangular connecting rod and the upper toggle is established at point C, the revolving joint between the upper toggle and the fuselage is established at point D, and the triangular toggle and the lower toggle are established at point E The rotary joint between the toggle link, the rotary joint between the lower toggle link and the slider is established at point F, and the moving joint is established between the slider and the fuselage, which is characterized by the difference between the upper toggle link CD and the lower toggle link EF long, and the upper toggle CD is shorter than the lower toggle EF, point D and point F are on a vertical line, and the connecting rod constructed by point B, point C and point E is a triangular connecting rod BCE.

The side CE of the above-mentioned triangular connecting rod BCE is the shortest side, and the included angle ∠CBE does not exceed 30°.

The positional relationship between the crankshaft center of the crankshaft AB and the fixed hinge point of the upper toggle is represented by vector l ₁ ; when the slider is at the upper limit position, AB, DC, and FE intersect at one point; when the slider is at the lower limit position, points C and E Not necessarily on the DF line.

The optimal design method of the triangular toggle working mechanism of the servo mechanical press of the present invention comprises the following steps:

1) Construct a parametric mechanism model

To build a parametric mechanism model, it is necessary to determine the minimum structural parameters that can describe the triangular toggle mechanism, and use two closed vector loops composed of vector l ₁ , l ₂ , l ₃ , l ₄ , l ₅ , l ₆ to describe the mechanism scale, a set of minimum structural parameters of the triangular toggle mechanism includes: the distance l ₁ from the fixed hinge point of the upper toggle to the center of the crankshaft, the length l ₂ of the crank, the length l ₃ of the upper side of the triangular connecting rod, the length l ₄ of the lower side of the triangular connecting rod, the lower elbow Rod length l ₆ , and the azimuth angle φ 11 from the fixed hinge point of the upper toggle to the crankshaft center vector l ₁ , the azimuth angle φ ₂₁ of the crank vector l ₂ , the azimuth angle φ ₃₁ of the upper side vector l ₃ of the triangular connecting rod, and the azimuth φ ₃₁ of the triangular connecting rod The angle γ between the upper and lower side vectors and the azimuth angle φ ₆₁ of the lower toggle vector, where the coordinate system adopts a right-handed Cartesian coordinate system, the origin of the coordinates is established on the center of the crankshaft, all azimuths start from the positive direction of the X axis, and The counterclockwise rotation direction is positive;

2) Establish a parametric virtual prototype model

The establishment of parametric virtual prototype model includes: parametric geometric modeling, constraint modeling and application of force and drive,

Geometric modeling: establish 10 design variables DV1, DV2, ..., DV10, respectively corresponding to 10 structural parameters l ₁ , l ₂ , l ₃ , l ₄ , l ₆ , φ ₁₁ , φ ₂₁ , φ ₃₁ , γ and φ ₆₁ ; the X and Y axis coordinates of key points A, B, C, D, E and F are represented by design variables, and the coordinates of 5 key points can be determined given a set of initial values of design variables value; after determining the cross-sectional size values of each geometric component, the crank AB can be constructed from points A and B, the triangular connecting rod BCE can be constructed from points B, C and E, and the upper toggle CD can be constructed from points C and D , the lower toggle EF is constructed from points E and F, and the slider is constructed from point F;

Constraint modeling: establish the rotation joint between the crankshaft and the fuselage at point A, establish the rotation joint between the crankshaft and the triangular connecting rod at point B, and establish the rotating joint between the triangular connecting rod and the upper toggle at point C, Establish the rotation joint between the upper toggle link and the fuselage at point D, establish the rotation joint between the triangular toggle link and the lower toggle link at point E, and establish the rotation joint between the lower toggle link and the slider at point F. Establish a moving pair between the slider and the fuselage, and set the friction coefficient of each moving pair and the radius of the rotating pair pin;

Application of force and driving: Apply a single force on the slider to simulate the time-varying stamping load, and the stamping load curve can be established by using the STEP, IF or AKIMA function; apply the driving torque on the rotary joint between the crankshaft and the fuselage, The rotational speed can be a constant value, determined according to the punching frequency, and the rotational speed can also be a driving function that changes with time. The direction of rotation is generally counterclockwise, and it is bidirectional in the swing work and free work modes, which is given by the drive function;

3) Analyze the sensitivity of each structural parameter

In order to reduce the complexity of the optimization model, the number of design variables participating in the optimization calculation should be reduced as much as possible, so it is necessary to conduct sensitivity analysis on all structural parameters and analyze the importance of each parameter; by performing design research, analyze the sensitivity of structural parameters to the target, Specifically include:

Create the target object: the booster ratio is the ratio between the load of the slider and the driving torque of the crank. During design, it is required that the load of the slider is not greater than the nominal pressure within the nominal pressure stroke, so it can be assumed that the slider is within the entire nominal pressure stroke If the load is a constant value equal to the nominal pressure, the problem of maximizing the boost ratio can be transformed into the problem of minimizing the crank driving torque, that is, the target object is set as the crank driving torque;

Structural parameter assignment: Given the initial value of the structural parameters, specify the value range of each structural parameter.

After analyzing the sensitivity of the structural parameters one by one, select the structural parameters with higher sensitivity as design variables for optimization;

4) Establish optimization model and solve

(1) Determine the design variables and objective function:

The above 10 structural parameters can be expressed in vector form as

In order to reduce the dimension of the optimization problem, according to the results of the sensitivity analysis of structural parameters, the result parameters with greater sensitivity can be selected as design variables;

According to the dynamic analysis model, the drive torque of the crank is related to the mass of the rods, the position of the center of mass, the moment of inertia, the load of the slider, the radius of the pin shaft of the rotating pair, the coefficient of friction and the above 10 structural parameters; when the material of the rod, the given load and After the pin radius, the crank driving torque is only related to the above 10 structural parameters, and the crank driving torque is obtained by the internal solver through the Newton-Raphson numerical calculation method. Here, the crank driving function can be expressed as an implicit function:

The objective function of the crank drive torque minimization optimization problem can be described as

(2) Determine the constraints:

The overall structural constraints of the fuselage:

Horizontal:

portrait:

为横向限制尺寸，

为纵向限制尺寸；in,

is the lateral limit size,

is the vertical constraint size;

Toggle Angle Constraint:

Upper toggle:

Lower Toggle:

和

 为与设计变量 相关的约束函数，

为上肘杆最大限制摆角，为下肘杆最大限制摆角；in,

and

for and design variable The associated constraint function,

is the maximum limit swing angle of the upper toggle, is the maximum limit swing angle of the lower toggle;

Slider Travel Constraints:

 为与设计变量

 相关的约束函数,和

分别表示滑块最大行程的上、小限值，可以取相等值；in,

for and design variable

related constraint functions, and

Respectively represent the upper and lower limits of the maximum stroke of the slider, and can take the same value;

The downward direction of the slider is invariant:

 为与设计变量

 相关的约束函数；in,

for and design variable

related constraint functions;

(3) Optimization calculation: define the objective function as the crank driving torque, define the objective as minimizing the objective function, add design variables and constraints, select the generalized reduced gradient method as the optimization algorithm, set the convergence error limit, the maximum number of iterations and the differential method By default, optimization calculations are started.

Because the present invention adopts the structure of changing the symmetrical toggle lever into an asymmetrical toggle lever and changing the linear connecting rod into a triangular connecting rod, it can ensure that the fuselage mechanism is compact, the stroke of the slider is sufficient, and the slider moves downward monotonously. , has a higher booster ratio, which can greatly reduce the required driving torque at the crank, thereby reducing the capacity and cost of the servo motor. The triangular toggle working mechanism of the servo mechanical press of the present invention is reasonable in design, convenient and practical, and the optimal design method of the triangular toggle working mechanism of the servo mechanical press of the present invention is simple and convenient.

Description of drawings

Fig. 1 is the structural model of triangular toggle mechanism of the present invention

Fig. 2 is a schematic diagram of the motion characteristics of the slide block after the optimization design of the present invention;

Fig. 3 is a schematic diagram of crank driving torque before and after optimization of the present invention;

Fig. 4 is a schematic diagram of the booster ratio of the mechanism before and after the optimization of the present invention;

Fig. 5 is a schematic diagram of the allowable load of the slider before and after the optimization of the present invention.

Detailed ways

In order to better understand the technical solutions of the present invention, a further detailed description will be made below in conjunction with the accompanying drawings and embodiments.

Step 1: Construct the structural model of the triangular toggle mechanism

As shown in Figure 1, change the equal-length upper and lower toggles of the symmetrical toggle mechanism to unequal-length toggles CD and EF, and the upper toggle CD is shorter than the lower toggle EF, and points D and F are on a vertical line Above; change the linear connecting rod of the symmetrical toggle mechanism to a triangular connecting rod BCE, and the CE side is the shortest side, and the included angle ∠CBE does not exceed 30°; the crank radius of the crankshaft is AB, and the hinge point between the crankshaft center and the upper toggle is fixed The positional relationship of the slider is expressed by vector l ₁ ; when the slider is at the upper limit position, AB, DC, and FE intersect at one point; when the slider is at the lower limit position, points C and E are not necessarily on the DF line.

Step 2: Build a parametric institutional model

To build a parametric mechanism model, it is necessary to determine the minimum structural parameters that can describe the triangular toggle mechanism. This invention uses two closed vector loops composed of vectors l ₁ , l ₂ , l ₃ , l ₄ , l ₅ , and l ₆ to describe The scale of the institution is shown in Figure 1. A minimum set of structural parameters describing the triangular toggle mechanism includes: the distance l ₁ from the fixed hinge point of the upper toggle to the center of the crankshaft, the length l ₂ of the crank, the length l ₃ of the upper side of the triangular link, the length l ₄ of the lower side of the triangular link, and the lower toggle Length l ₆ , and the azimuth angle φ 11 from the fixed hinge point of the upper toggle to the crankshaft center vector l ₁ , the azimuth angle φ _{21 of} the crank vector l ₂ , the azimuth angle φ ₃₁ of the upper side vector l ₃ of the triangular connecting rod, the upper and lower sides of the triangular connecting rod The side vector angle γ , the azimuth angle φ ₆₁ of the lower toggle vector. Among them, the coordinate system adopts the right-handed Cartesian coordinate system, and the origin of the coordinates is established on the center of the crankshaft. All azimuths start from the positive direction of the X-axis, and take the counterclockwise rotation direction as positive.

Step 3: Establish a parametric virtual prototype model

In the virtual prototype design software ADAMS, the establishment of parametric virtual prototype model includes: parametric geometric modeling, constraint modeling and the application of force and drive.

Geometric modeling: establish 10 design variables DV1, DV2, ..., DV10, respectively corresponding to 10 structural parameters l ₁ , l ₂ , l ₃ , l ₄ , l ₆ , φ ₁₁ , φ ₂₁ , φ ₃₁ , γ and φ ₆₁ ; the X and Y axis coordinates of key points A, B, C, D, E and F are represented by design variables, and the relationship between parameterized coordinate values and design variables is shown in Figure 2. Given a The coordinate values of the five key points can be determined by setting the initial values of the design variables; after determining the cross-sectional dimension values of each geometric component, the crank AB can be constructed from points A and B, and the triangle can be constructed from points B, C and E. The connecting rod BCE constructs the upper toggle CD from points C and D, constructs the lower toggle link EF from points E and F, and constructs the slider from point F.

Constraint modeling: establish the rotation joint between the crankshaft and the fuselage at point A, establish the rotation joint between the crankshaft and the triangular connecting rod at point B, and establish the rotating joint between the triangular connecting rod and the upper toggle at point C, Establish the rotation joint between the upper toggle link and the fuselage at point D, establish the rotation joint between the triangular toggle link and the lower toggle link at point E, and establish the rotation joint between the lower toggle link and the slider at point F. A moving pair is established between the slider and the fuselage, and the coefficient of friction of each moving pair and the radius of the pin axis of the rotating pair are set.

Application of force and driving: Apply a single force on the slider to simulate the time-varying stamping load, and the stamping load curve can be established by using the STEP, IF or AKIMA function; apply the driving torque on the rotary joint between the crankshaft and the fuselage, The speed can be constant, determined according to the punching frequency, and the speed can also be a driving function that changes with time. The direction of rotation is generally single counterclockwise, and it is bidirectional in swing work and free work mode, which is given by the drive function.

Step 4: Analyze the sensitivity of each structural parameter

In order to reduce the complexity of the optimization model, the number of design variables participating in the optimization calculation should be reduced as much as possible, so it is necessary to conduct sensitivity analysis on all structural parameters and analyze the importance of each parameter. In the virtual prototyping software ADAMS, the sensitivity of structural parameters to the target can be analyzed by performing Design Study, including:

Create the target object: the booster ratio is the ratio between the load of the slider and the driving torque of the crank. During design, it is required that the load of the slider is not greater than the nominal pressure within the nominal pressure stroke, so it can be assumed that the slider is within the entire nominal pressure stroke If the load is a constant value equal to the nominal pressure, the problem of maximizing the boost ratio can be transformed into the problem of minimizing the crank driving torque, that is, the target object is set as the crank driving torque.

Structural parameter assignment: Given the initial value of the structural parameters, specify the value range of each structural parameter.

After analyzing the sensitivity of the structural parameters one by one, the parameters with higher sensitivity are selected as design variables for optimization.

Step 5: Establish an optimization model and solve it

(1) Determine the design variables and objective function:

The above 10 structural parameters can be expressed in vector form as

In order to reduce the dimension of the optimization problem, according to the results of the sensitivity analysis of structural parameters, the result parameters with greater sensitivity can be selected as design variables.

According to the dynamic analysis model, the drive torque of the crank is related to the mass of the rods, the position of the center of mass, the moment of inertia, the load of the slider, the radius of the rotating pin shaft, the coefficient of friction and the above 10 structural parameters. When the rod material, given load and pin radius are determined, the crank driving torque is only related to the above 10 structural parameters. In ADAMS, the crank driving torque is obtained by the internal solver through the Newton-Raphson numerical calculation method. Here, the crank driving function can be expressed as an implicit function:

The objective function of the crank drive torque minimization optimization problem can be described as

(2) Determine the constraints:

The overall structural constraints of the fuselage:

Horizontal:

portrait:

为横向限制尺寸，

为纵向限制尺寸。in,

is the lateral limit size,

Limit the size for portrait orientation.

Toggle Angle Constraint:

Upper toggle:

Lower Toggle:

和

 为与设计变量

 相关的约束函数，

为上肘杆最大限制摆角，

为下肘杆最大限制摆角。in,

and

for and design variable

The associated constraint function,

is the maximum limit swing angle of the upper toggle,

It is the maximum limit swing angle of the lower toggle.

Slider Travel Constraints:

 为与设计变量

 相关的约束函数,

和分别表示滑块最大行程的上、小限值，可以取相等值。in,

for and design variable

related constraint functions,

and Respectively represent the upper and lower limits of the maximum stroke of the slider, and can take equal values.

The downward direction of the slider is invariant:

 为与设计变量

 相关的约束函数。in,

for and design variable

related constraint functions.

(3) Optimization calculation: In ADAMS, define the objective function as the crank driving torque, define the objective as minimizing the objective function, add design variables and constraints, select the generalized reduced gradient method as the optimization algorithm, set the convergence error limit, and the maximum iteration The number of times and the difference method are the default values, and the optimization calculation is started.

Example:

For the optimal design of the triangular toggle working mechanism of a servo mechanical press, the main design performance indicators are: the working stroke of the slider is 200mm, the nominal pressure Pg is 1600kN, and the nominal pressure point is 6mm. Other main design requirements include: the horizontal limit dimension Lh is 600mm, the longitudinal limit dimension Lv is 320mm, the maximum swing angle of the upper and lower toggles does not exceed 50°, and the maximum torque of the servo motor does not exceed 1500Nm.

According to the first, second and third steps of the implementation steps, given the initial values of 10 structural parameters (as shown in Table 1), the parametric virtual prototype model was established, and the parameter sensitivity analysis was carried out according to the fourth step. According to the analysis results (such as As shown in Table 1), the design variables determined for optimization are DV1, DV2, DV3, DV4, DV6, DV7, DV8, and DV9. According to the fifth step and the main performance indicators and design requirements, an optimization model is established and solved. The results of the optimized design are shown in Tables 2 and 3. Table 3 shows the structural parameter values before and after optimization. Figure 2 shows the motion characteristics of the slider after the optimized design. Figure 3 shows the driving torque of the crank before and after optimization. , Figure 4 shows the boost ratio of the mechanism before and after optimization, and Figure 5 shows the allowable load of the working mechanism before and after optimization. It can be seen that on the premise of meeting the design performance index and design requirements, at the nominal pressure stroke of 6mm, the boost ratio increases from 85/m to 123/m, an increase of 45%, and the crank driving torque decreases from 18743Nm before optimization to 13010Nm. The drop reached 30%.

Table 1 Coordinates of key points represented by design variables

design point X coordinate Y coordinate A 0 0 B DV_2 *COS(DV_7) DV_2 *SIN(DV_7) C DV_2 *COS(DV_7) + DV_3*COS(DV_8) DV_2 * SIN(DV_7) + DV_3 * SIN(DV_8) D. DV_1 *COS(DV_6) DV_1 *SIN(DV_6) E. DV_2 *COS(DV_7) + DV_4 *COS(DV_8 + DV_9) DV_2 * SIN(DV_7) + DV_4 * SIN(DV_8 + DV_9) f DV_1 *COS(DV_6) DV_2 * SIN(DV_7) + DV_4 * SIN(DV_8 + DV_9) + DV_5 * SIN(DV_10)

Table 2 Initial values of structural parameters and parameter sensitivities at the initial values

Table 3 Structural parameter values before and after optimization

Claims (4)

1. A cam toggle lever working mechanism of servo mechanical press comprises a crank AB constructed by a point A and a point B, a connecting rod BCE constructed by the point B, the point C and the point E, an upper toggle lever CD constructed by the point C and the point D, a lower toggle lever EF constructed by the point E and the point F, a slide block constructed by the point F, a rotating pair between a crankshaft and a machine body is established by the point A, a rotating pair between the crankshaft and a triangular connecting rod is established by the point B, a rotating pair between the triangular connecting rod and the upper toggle lever is established by the point C, a rotating pair between the upper toggle lever and the machine body is established by the point D, a rotating pair between the triangular toggle lever and the lower toggle lever is established by the point E, a rotating pair between the lower toggle lever and the slide block is established by the point F, a moving pair is established between the slide block and the machine body, and is characterized in that the upper toggle lever CD is not equal to the lower toggle lever EF, the upper toggle lever CD is shorter than the lower toggle lever EF, the point D and the point F are on, And the connecting rods constructed by the points C and E are triangular connecting rods BCE.

2. The triangular toggle working mechanism of the servo mechanical press as claimed in claim 1, wherein the CE side of the BCE of the triangular link is the shortest side, and the included angle ≈ CBE is not more than 30 °.

3. The triangular toggle operating mechanism of a servo-mechanical press as claimed in claim 1, wherein the positional relationship between the crank center of the crankshaft AB and the fixed hinge point of the upper toggle link is represented by a vectorl ₁Represents; when the slider is at the upper limit position, AB, DC and FE are intersected at one point, and when the slider is at the lower limit position, C point and E point are not necessarily positioned on the DF line.

4. A method for optimizing the design of the triangular toggle rod operating mechanism of the servo mechanical press according to claim 1, which is characterized by comprising the following steps:

1) constructing parameterized mechanism models

Constructing parameterized mechanism model by determining minimum structural parameters capable of describing triangular toggle mechanism and adopting vectorl ₁、l ₂、l ₃、l ₄、l ₅、l ₆Two closed vector rings are formed to describe the dimension of the mechanism, and a set of minimum structural parameters of the triangular toggle link mechanism comprises: distance l from fixed hinged point of upper toggle rod to center of crankshaft₁Length of crank l₂Length l of upper side of triangular connecting rod₃Lower side length l of triangular connecting rod₄Lower toggle length l₆And upper toggle lever fixed hinge point to crankshaft center vectorl ₁Azimuth angle ofφ ₁₁Crank vectorl ₂Azimuth angle ofφ ₂₁Triangle, triangleConnecting rod upper edge vectorl ₃Azimuth angle ofφ ₃₁Upper and lower edge vector included angle of triangular connecting rodγAzimuth angle of lower toggle lever vectorφ ₆₁The coordinate system adopts a right-handed Cartesian coordinate system, the origin of coordinates is established on the center of a crankshaft, all azimuth angles start from the positive direction of the X axis, and the counterclockwise rotation direction is taken as the positive direction;

2) establishing parameterized virtual prototype model

The establishment of the parameterized virtual prototype model comprises the following steps: parametric geometric modeling, constraint modeling and application of forces and drives,

geometric modeling: establishing 10 design variables DV1, DV2, … and DV10 respectively corresponding to 10 structural parameters l in the parameterized mechanism model₁、l₂、l₃、l₄、l₆，φ ₁₁、φ ₂₁、φ ₃₁、γAndφ ₆₁(ii) a The X-axis coordinates and the Y-axis coordinates of the key points A, B, C, D, E and F are expressed by design variables, and the coordinate values of 5 key points can be determined by giving a group of initial values of the design variables; after the section size values of all geometric components are determined, a crank AB can be respectively constructed from a point A and a point B, a triangular connecting rod BCE can be constructed from the point B, the point C and the point E, an upper toggle rod CD can be constructed from the point C and the point D, a lower toggle rod EF can be constructed from the point E and the point F, and a sliding block can be constructed from the point F;

constraint modeling: establishing a rotating pair between a crankshaft and a machine body at a point A, establishing a rotating pair between the crankshaft and a triangular connecting rod at a point B, establishing a rotating pair between the triangular connecting rod and an upper toggle rod at a point C, establishing a rotating pair between the upper toggle rod and the machine body at a point D, establishing a rotating pair between the triangular toggle rod and a lower toggle rod at a point E, establishing a rotating pair between the lower toggle rod and a sliding block at a point F, establishing a moving pair between the sliding block and the machine body, and setting the friction coefficient of each moving pair and the pin shaft radius of the rotating pair;

application of force and drive: applying a single force simulating the stamping load and changing along with time on the sliding block, and establishing a stamping load curve by adopting a STEP, IF or AKIMA function; the driving torque is applied to a rotating pair between a crankshaft and a machine body, the rotating speed can be a constant value and is determined according to stamping frequency, the rotating speed can also be a driving function which changes along with time, the rotating direction is generally anticlockwise, the rotating direction is bidirectional in a swinging working mode and a free working mode, and the driving function is given;

3) sensitivity of analysis of each structural parameter

In order to reduce the complexity of the optimization model, the number of design variables participating in optimization calculation should be reduced as much as possible, and then all structural parameters need to be subjected to sensitivity analysis, and the importance of each parameter is analyzed; analyzing the sensitivity of the structural parameters to the target by performing a design study, including:

creating a target object: the force increasing ratio is the ratio between the slide block load and the crank driving torque, and the slide block load is required to be not more than the nominal pressure in the nominal pressure stroke during design, so that the problem of force increasing ratio maximization can be converted into the problem of crank driving torque minimization on the premise that the slide block load is a constant value equal to the nominal pressure in the whole nominal pressure stroke, namely, the target object is set as the crank driving torque;

structural parameter assignment: giving an initial value of the structural parameter, and specifying a value range of each structural parameter;

analyzing the sensitivity of the structural parameters one by one, and selecting the structural parameters with higher sensitivity as design variables for optimization;

4) establishing optimization model and solving

(1) Determining design variables and an objective function:

the above 10 structural parameters can be expressed in a vector form as

In order to reduce the dimensionality of the optimization problem, a result parameter with higher sensitivity can be selected as a design variable according to the result of the sensitivity analysis of the structural parameter;

according to a dynamics analytic model, the crank driving torque is related to the mass of each rod, the position of a mass center, the rotational inertia, the slider load, the shaft radius of a rotating pair pin, the friction coefficient and the 10 structural parameters; after determining the rod material, the given load and the pin radius, the crank driving torque is only related to the 10 structural parameters, the crank driving torque is obtained by an internal solver through a Newton-Raphson numerical calculation method, and here, a crank driving function can be expressed as an implicit function:

the objective function of the crank drive torque minimization optimization problem can be described as

(2) Determining a constraint condition:

the overall structure of the fuselage is restricted:

transverse:

longitudinal direction:

wherein,

in order to limit the dimensions in the lateral direction,

is a longitudinal limit size;

and (3) toggle rod swing angle constraint:

an upper toggle rod:

a lower toggle link:

wherein,

and

to and design variablesThe associated constraint function(s) is (are),

the swing angle is limited to the maximum extent by the upper toggle rod,

the swing angle is limited to the maximum extent for the lower toggle rod;

and (3) restricting the stroke of the sliding block:

wherein,

to and design variables

The associated constraint function(s) is (are),

and

respectively representing the upper limit value and the lower limit value of the maximum stroke of the slide block, and taking the same value;

the down direction of the slide block is invariable restrained:

wherein,

to and design variables

A related constraint function;

(3) and (3) optimizing and calculating: defining an objective function as crank driving torque, defining an objective as minimizing the objective function, adding design variables and constraint conditions, selecting a generalized simple gradient method as an optimization algorithm, setting a convergence error limit, a maximum iteration number and a difference mode as default values, and starting optimization calculation.

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