Method for controlling a central cylinder of a six-axis horizontal machining center

Abstract

The present application relates to a kind of six-axis horizontal machining center mid-position function oil cylinder control method, comprising the following steps: step 1, initialization oil cylinder piston rod position, the position of piston rod is moved to right limit position, constructs the movement path initial solution of first piston, and as current global optimal solution;Step 2, traverse piston rod movement path, calculate the movement distance of first piston when piston rod moves each time;Step 3, traverse piston rod movement path, generate the movement path current solution of first piston, and calculate the objective function value of the movement path current solution of first piston;Step 4, compare the movement path current solution of first piston with current global optimal solution;Step 5, repeat step 2-4 until meeting termination condition, finally return the global optimal solution recorded;The present application quickly solves and obtains optimal first piston movement path, makes first piston movement distance shortest, greatly reduces the wear of first piston, prolongs the service life of oil cylinder.

Description

Technical Field

[0001] This invention relates to the field of hydraulic cylinder control technology, and in particular to a method for controlling the center functional hydraulic cylinder of a six-axis horizontal machining center. Background Technology

[0002] A hydraulic cylinder, also known as a hydraulic actuator, is a hydraulic actuator that converts hydraulic energy into mechanical energy, primarily used to achieve linear reciprocating motion or oscillating motion. Conventional hydraulic cylinders only have two extreme positions, left and right. When system pressure is released, the cylinder piston is in a free state, resulting in low stopping accuracy of the actuator, a jarring sensation during startup, and poor starting smoothness. Therefore, a hydraulic cylinder with a neutral position function has been developed, such as... Figure 1 As shown.

[0003] The hydraulic cylinder with a neutral position function includes a cylinder body, a first piston, and a second piston.

[0004] The cylinder body has a first piston receiving cavity and a second piston receiving cavity that are interconnected. The cylinder body includes a cylinder barrel, a left end cap, and a right end cap. A stepped through hole is axially opened in the middle of the cylinder barrel. The stepped through hole includes a first through hole section for forming the first piston receiving cavity and a second through hole section for forming the second piston receiving cavity. The left end cap and the right end cap are respectively installed at both ends of the cylinder barrel. The left end cap covers the second through hole section, and the inner end face of the left end cap forms a left limit position limiting surface. The right end cap covers the first through hole section, and the inner end face of the right end cap forms a right limit position limiting surface. The inner diameter of the second through hole section is smaller than the inner diameter of the first through hole section. The first through hole section and the second through hole section fit together to form an intermediate position limiting step surface.

[0005] The first piston is movably disposed within the first piston receiving cavity, and the outer wall of the first piston is sealed and connected to the inner wall of the first through-hole section. The second piston is movably disposed within the second piston receiving cavity, and the outer wall of the second piston is sealed and connected to the inner wall of the second through-hole section. The first piston and the second piston divide the interior of the cylinder into a first oil chamber, a second oil chamber, and a third oil chamber. The first oil chamber is located on the side of the first piston away from the second piston, the second oil chamber is located between the first piston and the second piston, and the third oil chamber is located on the side of the second piston away from the first piston. The cylinder has three oil inlets, namely a first oil inlet communicating with the first oil chamber, a second oil inlet communicating with the second oil chamber, and a third oil inlet communicating with the third oil chamber. An intermediate push rod is provided between the first piston and the second piston. One end of the intermediate push rod is fixed to the first piston, and the other end extends into the cavity of the second piston. A piston rod is provided on the side of the second piston away from the first piston. One end of the piston rod is fixed to the second piston, and the other end extends out of the cylinder body through the perforation of the front end cover. The stroke of the first piston is less than the axial length of the intermediate push rod, and the sum of the stroke of the first piston and the axial length of the intermediate push rod is less than the stroke of the second piston.

[0006] This type of hydraulic cylinder with a center position function is usually used in complex working conditions. The movement stroke of the cylinder piston rod is complex and varied. Due to the separate design of the first and second pistons, the piston rod needs to cooperate with the first piston when switching between the left extreme position, the middle position and the right extreme position. How to optimize the movement path of the first piston according to the required movement path of the piston rod, minimize the movement distance of the first piston and reduce the wear of the first piston is the difficulty of the automatic control of this hydraulic cylinder.

[0007] Therefore, this invention proposes a method for controlling the center-position functional hydraulic cylinder of a six-axis horizontal machining center to solve the above problems. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a control method for the center functional cylinder of a six-axis horizontal machining center, which can quickly solve for the optimal first piston movement path, so as to minimize the movement distance of the first piston, reduce the wear of the first piston to the greatest extent, and extend the service life of the cylinder.

[0009] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: a control method for a center-position hydraulic cylinder in a six-axis horizontal machining center. The hydraulic cylinder with a center-position function includes a cylinder body, a first piston, and a second piston. The cylinder body has a first piston receiving cavity and a second piston receiving cavity that are interconnected. A middle position limiting step surface is formed between the first piston receiving cavity and the second piston receiving cavity. The side of the first piston receiving cavity away from the second piston receiving cavity has a right limit position limiting surface, and the side of the second piston receiving cavity away from the first piston receiving cavity has a left limit position limiting surface. The first piston and the second piston are respectively movably disposed in the first piston receiving cavity and the second piston receiving cavity, and the cylinder body is divided into three oil chambers with oil inlets. The side of the first piston near the second piston has a middle push rod, and the side of the second piston away from the first piston has a piston rod. The stroke of the first piston is less than the axial length of the middle push rod, and the sum of the stroke of the first piston and the axial length of the middle push rod is less than the stroke of the second piston. The innovation is that the control method includes the following steps:

[0010] Step 1: Initialize the position of the hydraulic cylinder piston rod by moving the piston rod to its rightmost extreme position d. 00 Construct an initial solution S0 for the movement path of the first piston, and use S0 as the current global optimal solution S. * ;

[0011] Step 2: For the required movement path V={N01, N02.....N0} of the piston rod nThe process iterates through the piston rod's movement path. If the constraints are satisfied, the stopping position of the first piston is selected according to the constraints for each movement of the piston rod. If the constraints are not satisfied, the stopping position of the first piston is randomly selected. The distance the first piston moves is then calculated for each movement of the piston rod. The calculation formula is as follows:

[0012] ;

[0013] in, This indicates the stopping position of the first piston when the piston rod stops moving for the i-th time. This indicates the stopping position of the first piston when the piston rod stops moving for the (i-1)th time;

[0014] Step 3: Traverse the piston rod's movement path, generate the current solution S for the first piston's movement path, and calculate the objective function value of the current solution S for the first piston's movement path. The calculation formula is:

[0015] ;

[0016] Step 4: Compare the current solution S of the first piston's movement path with the current global optimal solution S. * Compare the solutions; if the current solution S is better than the current global best solution S... * ,Right now < If so, then update S*;

[0017] Step 5: Repeat steps 2-4 until the termination condition is met, and finally return the recorded global optimal solution S*.

[0018] Furthermore, the control method includes the following definitions:

[0019] Cluster N1={d} at the stop position of the first piston movement 10 ,d 11}, where when the first piston abuts against the right limit position limiting surface, the first piston is at position d. 10 When the first piston abuts against the intermediate position limiting step surface, the first piston is in position d. 11 ;

[0020] The cluster N2={d} at the stop position of the second piston movement 20 ,d 21 ,d 22}, where when the first piston is against the right limit position limiting surface and the second piston is against the end of the intermediate push rod, the second piston is at position d. 20 When the first piston is against the middle position limiting step surface and the second piston is against the end of the middle push rod, the second piston is in position d. 21When the second piston abuts against the left limit position limiting surface, the second piston is at position d. 22 ;

[0021] Piston rod movement stop position cluster N0={d 00 ,d 01 ,d 02}, where d 00 ,d 01 ,d 02 Corresponding to the right extreme position, the middle position, and the left extreme position respectively, the movement path V of the piston rod moving n times is V = {N01, N02, ..., N0...} n The stopping position N0 of the piston rod after the i-th movement. i ={N1 i N2 i}, N0 i ∈N0, i∈N, N={1,2,.......,n}, n is the total number of piston rod movements, N1 i ∈N1, N2 i N2 represents the position where the second piston stops moving when the piston rod stops moving for the i-th time. i ∈N2.

[0022] Furthermore, when constructing the initial solution S0 of the first piston's movement path in step 1, the piston rod movement path V={N01, N02.....N0} is traversed. n If the constraints are satisfied, the stopping position of the first piston is selected according to the constraints for each movement of the piston rod. If the constraints are not satisfied, the stopping position of the first piston is randomly selected. After the piston rod movement path is traversed, an initial solution S0 = {N11, N12, ..., N1} of the first piston movement path is formed, which has n stopping positions of the first piston. n}

[0023] Furthermore, the constraints include:

[0024] The piston rod stops at position N0 during its i-th movement. i The following constraints exist:

[0025] Constraint 1: If N0 i =d 00 Then N2 i =d 20 And N1 i =d 10 ;

[0026] Constraint 2: If N0 i =d 01 Then N2 i =d 21And N1 i =d 11 ;

[0027] Constraint 3: If N0 i =d 02 Then N2 i =d 22 ;

[0028] The following constraints exist during the movement of the piston rod:

[0029] Constraint 4: If N0 i-1 =d 00 N0 i =d 02 And N0 i+1 =d 00 When, then N1 i =d 10 ;

[0030] Constraint 5: If N0 i-1 =d 00 N0 i =d 02 And N0 i+1 =d 01 When, then N1 i =d 11 ;

[0031] Constraint 6: If N0 i-1 =d 01 N0 i =d 02 And N0 i+1 =d 00 When, then N1 i =d 10 ;

[0032] Constraint 7: If N0 i-1 =d 01 N0 i =d 02 And N0 i+1 =d 01 When, then N1 i =d 11 ;

[0033] Constraint 8: If N1 i =N1 i-1 Then the distance L that the first piston moves in the i-th iteration is... i It is 0.

[0034] Furthermore, the termination condition for step 5 is that the total calculation time reaches a preset time limit or the number of traversals reaches a preset number limit.

[0035] The advantages of this invention are:

[0036] (1) The control method of the present invention uses a combination of constraint conditions and random selection to solve the total distance of the first piston movement as the objective function value according to the required movement path of the piston rod. By comparing the objective function value of the current solution with the objective function value of the current global best solution, the solution with the smaller objective function value is selected to update the current global best solution, thereby quickly obtaining the optimal movement path of the first piston with the shortest movement distance, minimizing the wear of the first piston and extending the service life of the oil cylinder.

[0037] (2) The control method of the present invention not only sets the constraint of the piston rod movement stop position according to the characteristics of the oil cylinder, but also constrains the movement timing and movement process of the first piston, so as to improve the response speed of the piston rod and reduce the interference of the first piston movement on the piston rod movement, thereby improving the control accuracy of the oil cylinder piston rod. Attached Figure Description

[0038] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0039] Figure 1 This is a schematic diagram of the hydraulic cylinder with a center position function according to the present invention.

[0040] Figure 2 This is a flowchart of the hydraulic cylinder control method for the center position of a six-axis horizontal machining center according to the present invention. Detailed Implementation

[0041] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0042] Hydraulic cylinders with intermediate position function, such as Figure 1 As shown, it includes a cylinder block, a first piston 21, and a second piston 22.

[0043] The cylinder body has a first piston receiving cavity and a second piston receiving cavity that are interconnected. In this embodiment, the cylinder body includes a cylinder barrel 11, a left end cap 12, and a right end cap 13. A stepped through hole is axially opened in the middle of the cylinder barrel 11. The stepped through hole includes a first through hole section 51 for forming the first piston receiving cavity and a second through hole section 52 for forming the second piston receiving cavity. The left end cap 12 and the right end cap 13 are respectively installed at both ends of the cylinder barrel 11. The left end cap 12 covers the second through hole section 52, and the inner end face of the left end cap 12 forms a left limit position limiting surface 43. The right end cap 13 covers the first through hole section 51, and the inner end face of the right end cap 13 forms a right limit position limiting surface 41. The inner diameter of the second through hole section 52 is smaller than the inner diameter of the first through hole section 51. The first through hole section 51 and the second through hole section 52 cooperate to form an intermediate position limiting step surface 42.

[0044] The first piston 21 is movably disposed within the first piston receiving cavity, and the outer wall of the first piston 21 is sealed and connected to the inner wall of the first through hole section 51. The second piston 22 is movably disposed within the second piston receiving cavity, and the outer wall of the second piston 22 is sealed and connected to the inner wall of the second through hole section 52. The first piston 21 and the second piston 22 divide the interior of the cylinder into a first oil chamber, a second oil chamber, and a third oil chamber. The first oil chamber is located on the side of the first piston 21 away from the second piston 22, the second oil chamber is located between the first piston 21 and the second piston 22, and the third oil chamber is located on the side of the second piston 22 away from the first piston 21. The cylinder has three oil inlets: a first oil inlet 31 communicating with the first oil chamber, a second oil inlet 32 ​​communicating with the second oil chamber, and a third oil inlet 33 communicating with the third oil chamber.

[0045] An intermediate push rod 23 is provided between the first piston 21 and the second piston 22. One end of the intermediate push rod 23 is fixed to the first piston 21, and the other end extends into the cavity of the second piston. A piston rod 24 is provided on the side of the second piston 22 away from the first piston 21. One end of the piston rod 24 is fixed to the second piston 22, and the other end extends out of the cylinder body through the perforation of the front end cover 12. The stroke of the first piston 21 is less than the axial length of the intermediate push rod 23, and the sum of the stroke of the first piston 21 and the axial length of the intermediate push rod 23 is less than the stroke of the second piston 22.

[0046] The hydraulic cylinder uses two independent pistons located in different chambers within the cylinder body, and three oil inlets to control the pressure in the three chambers, thereby controlling the smooth movement of the two pistons.

[0047] When the third oil inlet 33 is pressurized to enter oil, the first oil inlet 31 and the second oil inlet 32 ​​are not pressurized. Under the action of pressure, the second piston 22 drives the piston rod 24 to move to the right, and pushes the first piston 21 to move to the right through the intermediate push rod 23. When the first piston 21 touches the right limit position limiting surface 41, the cylinder piston rod 24 reaches the right limit position and stops.

[0048] When oil is pressurized through the first oil inlet 31 and the third oil inlet 33, and the second oil inlet 32 ​​has no pressure, and the pressure of the third oil inlet 33 is less than the pressure of the first oil inlet 31, the first piston 21 moves to the left under the pressure, and pushes the piston rod 24 to the left through the intermediate push rod 23 and the second piston 22. When the first piston 21 abuts against the intermediate position limiting step surface 42, the piston rod 24 moves to the intermediate position and stops.

[0049] When oil is pressurized through the second oil inlet 32 ​​and depressurized through the third oil inlet 33, the second piston 22, under pressure, drives the piston rod 24 to move to the left. When the second piston 22 abuts against the left limit position limiting surface 43, the piston rod 24 moves to the left limit position. During this process, the first piston 21 can selectively remain against the intermediate position limiting step surface 42 (where the pressure from the first oil inlet 31 is greater than that from the second oil inlet), or move to the right and abut against the right limit position limiting surface 41 (where there is no pressure from the first oil inlet 31). The position selection of the first piston 21 not only affects the response speed of the piston rod's next movement, but also, if the first piston position is not properly selected, it will cause the movement stroke to become muddy, accelerating the wear of the first piston and affecting the service life of the hydraulic cylinder.

[0050] The hydraulic cylinder control method for the center position of the six-axis horizontal machining center provided in this embodiment aims to quickly solve for the optimal first piston movement path, so as to minimize the movement distance of the first piston, reduce the wear of the first piston to the greatest extent, and extend the service life of the hydraulic cylinder.

[0051] Example

[0052] Define the cluster N1={d} where the first piston stops moving. 10 ,d 11 When the first piston 21 abuts against the right limit position limiting surface 41, the first piston is in position d. 10 When the first piston 21 abuts against the intermediate position limiting step surface 42, the first piston is in position d. 11 .

[0053] The cluster N2={d} at the stop position of the second piston movement 20 ,d 21 ,d 22 When the first piston 21 is against the right limit position limiting surface 41 and the second piston 22 is against the end of the intermediate push rod, the second piston is in position d. 20 When the first piston 21 abuts against the intermediate position limiting step surface 42 and the second piston 22 abuts against the end of the intermediate push rod, the second piston is in position d. 21 When the second piston 22 abuts against the left limit position limiting surface 43, the second piston is in position d. 22 .

[0054] Piston rod movement stop position cluster N0={d 00 ,d 01 ,d 02}, where d 00 ,d 01 ,d 02 Corresponding to the right extreme position, the middle position, and the left extreme position respectively, the movement path V of the piston rod moving n times is V = {N01, N02, ..., N0...} n The stopping position N0 of the piston rod after the i-th movement. i ={N1 i N2 i}, N0 i Let N ∈ N0, i ∈ N, N = {1, 2, ..., n}, where n is the total number of piston rod movements. i N1 represents the first piston stop position corresponding to the i-th piston rod stopping movement. i ∈N1, N2 i N2 represents the position where the second piston stops moving when the piston rod stops moving for the i-th time. i ∈N2.

[0055] The piston rod stops at position N0 during its i-th movement. i The following constraints exist:

[0056] Constraint 1: If N0 i =d 00 Then N2 i =d 20 And N1 i =d 10 ;

[0057] Constraint 2: If N0 i =d 01 Then N2 i =d 21 And N1 i =d 11 ;

[0058] Constraint 3: If N0 i =d 02 Then N2 i =d 22 ;

[0059] The following constraints exist during the movement of the piston rod:

[0060] Constraint 4: If N0 i-1 =d 00 N0 i =d 02 And N0 i+1 =d00 When, then N1 i =d 10 This indicates the position d of the first piston when the piston rod moves in the sequence of right extreme position, left extreme position, and right extreme position. 10 Keep it fixed in place;

[0061] Constraint 5: If N0 i-1 =d 00 N0 i =d 02 And N0 i+1 =d 01 When, then N1 i =d 11 This indicates that when the piston rod moves in the sequence of right extreme position, left extreme position, and intermediate position, during the process of the piston rod moving from the right extreme position to the left extreme position, the first piston moves from position d... 10 Move to position d 11 Then keep it fixed in place;

[0062] Constraint 6: If N0 i-1 =d 01 N0 i =d 02 And N0 i+1 =d 00 When, then N1 i =d 10 This indicates that when the piston rod moves in the sequence of middle position, left extreme position, and right extreme position, during the process of the piston rod moving from the middle position to the left extreme position, the first piston moves from position d... 11 Move to position d 10 Then keep it fixed in place;

[0063] Constraint 7: If N0 i-1 =d 01 N0 i =d 02 And N0 i+1 =d 01 When, then N1 i =d 11 This indicates the position d of the first piston when the piston rod moves in the sequence of middle position, left extreme position, and middle position. 11 Keep it fixed in place;

[0064] Constraint 8: If N1 i =N1 i-1 Then the distance L that the first piston moves in the i-th iteration is... i A value of 0 indicates that when the first piston stops at the same position in two consecutive movements, the first piston does not make any additional movement and simply keeps its position fixed.

[0065] The six-axis horizontal machining center center-position functional hydraulic cylinder control method provided in this embodiment is as follows: Figure 2 As shown, it includes the following steps:

[0066] Step 1: Initialize the position of the hydraulic cylinder piston rod by moving the piston rod to its rightmost extreme position d. 00 Construct an initial solution S0 for the movement path of the first piston, and use S0 as the current global optimal solution S. * ;

[0067] When constructing the initial solution S0 of the first piston's movement path, the piston rod movement path V = {N01, N02, ..., N0} is traversed. n If the constraints are satisfied, the stopping position of the first piston is selected according to the constraints for each movement of the piston rod. If the constraints are not satisfied, the stopping position of the first piston is randomly selected. After the piston rod movement path is traversed, an initial solution S0 = {N11, N12, ..., N1} of the first piston movement path is formed, which has n stopping positions of the first piston. n}

[0068] Step 2: For the required movement path V={N01, N02.....N0} of the piston rod n The process iterates through the piston rod's movement path. If the constraints are satisfied, the stopping position of the first piston is selected according to the constraints for each movement of the piston rod. If the constraints are not satisfied, the stopping position of the first piston is randomly selected. The distance the first piston moves is then calculated for each movement of the piston rod. The calculation formula is as follows:

[0069] ;

[0070] Step 3: Traverse the piston rod's movement path, generate the current solution S for the first piston's movement path, and calculate the objective function value of the current solution S for the first piston's movement path. The calculation formula is:

[0071] ;

[0072] Step 4: Compare the current solution S of the first piston's movement path with the current global optimal solution S. * Compare the solutions; if the current solution S is better than the current global best solution S... * ,Right now < If so, then update S*;

[0073] Step 5: Repeat steps 2-4 until the termination condition is met, i.e., the total computation time reaches the preset time limit or the number of traversals reaches the preset number of times limit, and finally return the recorded global best solution S*.

[0074] The control method in this embodiment, based on the required movement path of the piston rod, uses a combination of constraints and random selection to solve for the total movement distance of the first piston as the objective function value. By comparing the objective function value of the current solution with the objective function value of the current global best solution, the solution with the smaller objective function value is selected to update the current global best solution, thereby obtaining the optimal movement path of the first piston with the shortest movement distance, minimizing the wear of the first piston and extending the service life of the hydraulic cylinder.

[0075] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for controlling a center-position hydraulic cylinder in a six-axis horizontal machining center, the hydraulic cylinder with a center-position function comprising a cylinder body, a first piston, and a second piston, wherein the cylinder body has a first piston receiving cavity and a second piston receiving cavity that are interconnected, a middle position limiting step surface is formed between the first piston receiving cavity and the second piston receiving cavity, a right limit position limiting surface is provided on the side of the first piston receiving cavity away from the second piston receiving cavity, and a left limit position limiting surface is provided on the side of the second piston receiving cavity away from the first piston receiving cavity, the first piston and the second piston are respectively movably disposed within the first piston receiving cavity and the second piston receiving cavity, and the cylinder body is divided into three oil chambers with oil inlets, a middle push rod is provided on the side of the first piston near the second piston, and a piston rod is provided on the side of the second piston away from the first piston, the stroke of the first piston is less than the axial length of the middle push rod, and the sum of the stroke of the first piston and the axial length of the middle push rod is less than the stroke of the second piston, characterized in that: The control method includes the following steps: Step 1: Initialize the position of the hydraulic cylinder piston rod by moving the piston rod to its rightmost extreme position d. 00 Construct an initial solution S0 for the movement path of the first piston, and use S0 as the current global optimal solution S. * ; Step 2: For the required movement path V={N01, N02.....N0} of the piston rod n The process iterates through the piston rod's movement path. If the constraints are satisfied, the stopping position of the first piston is selected according to the constraints for each movement of the piston rod. If the constraints are not satisfied, the stopping position of the first piston is randomly selected. The distance the first piston moves is then calculated for each movement of the piston rod. The calculation formula is as follows: ； in, This indicates the stopping position of the first piston when the piston rod stops moving for the i-th time. This indicates the stopping position of the first piston when the piston rod stops moving for the (i-1)th time; Step 3: Traverse the piston rod's movement path, generate the current solution S for the first piston's movement path, and calculate the objective function value of the current solution S for the first piston's movement path. The calculation formula is: ； Step 4: Compare the current solution S of the first piston's movement path with the current global optimal solution S. * Compare the solutions; if the current solution S is better than the current global best solution S... * ,Right now < If so, then update S*; Step 5: Repeat steps 2-4 until the termination condition is met, and finally return the recorded global optimal solution S*.

2. The method for controlling the center-position functional hydraulic cylinder of a six-axis horizontal machining center according to claim 1, characterized in that: The control method includes the following definitions: Cluster N1={d} at the stop position of the first piston movement 10 ,d 11 }, where when the first piston abuts against the right limit position limiting surface, the first piston is at position d. 10 When the first piston abuts against the intermediate position limiting step surface, the first piston is in position d. 11 ; The cluster N2={d} at the stop position of the second piston movement 20 ,d 21 ,d 22 }, where when the first piston is against the right limit position limiting surface and the second piston is against the end of the intermediate push rod, the second piston is at position d. 20 When the first piston is against the middle position limiting step surface and the second piston is against the end of the middle push rod, the second piston is in position d. 21 When the second piston abuts against the left limit position limiting surface, the second piston is at position d. 22 ; Piston rod movement stop position cluster N0={d 00 ,d 01 ,d 02 }, where d 00 ,d 01 ,d 02 Corresponding to the right extreme position, the middle position, and the left extreme position respectively, the movement path V of the piston rod moving n times is V = {N01, N02, ..., N0...} n The stopping position N0 of the piston rod after the i-th movement. i ={N1 i N2 i }, N0 i ∈N0, i∈N, N={1,2,.......,n}, n is the total number of piston rod movements, N1 i ∈N1, N2 i N2 represents the position where the second piston stops moving when the piston rod stops moving for the i-th time. i ∈N2.

3. The method for controlling the center-position functional hydraulic cylinder of a six-axis horizontal machining center according to claim 2, characterized in that: In step 1, when constructing the initial solution S0 of the first piston's movement path, the piston rod movement path V = {N01, N02, ..., N0} is traversed. n If the constraints are satisfied, the stopping position of the first piston is selected according to the constraints for each movement of the piston rod. If the constraints are not satisfied, the stopping position of the first piston is randomly selected. After the piston rod movement path is traversed, an initial solution S0 = {N11, N12, ..., N1} of the first piston movement path is formed, which has n stopping positions of the first piston. n } 4. The method for controlling the center-position functional hydraulic cylinder of a six-axis horizontal machining center according to claim 3, characterized in that: The constraints include: The piston rod stops at position N0 during its i-th movement. i The following constraints exist: Constraint 1: If N0 i =d 00 Then N2 i =d 20 And N1 i =d 10 ; Constraint 2: If N0 i =d 01 Then N2 i =d 21 And N1 i =d 11 ; Constraint 3: If N0 i =d 02 Then N2 i =d 22 ; The following constraints exist during the movement of the piston rod: Constraint 4: If N0 i-1 =d 00 N0 i =d 02 And N0 i+1 =d 00 When, then N1 i =d 10 ; Constraint 5: If N0 i-1 =d 00 N0 i =d 02 And N0 i+1 =d 01 When, then N1 i =d 11 ; Constraint 6: If N0 i-1 =d 01 N0 i =d 02 And N0 i+1 =d 00 When, then N1 i =d 10 ; Constraint 7: If N0 i-1 =d 01 N0 i =d 02 And N0 i+1 =d 01 When, then N1 i =d 11 ; Constraint 8: If N1 i =N1 i-1 Then the distance L that the first piston moves in the i-th iteration is... i It is 0.

5. The method for controlling the center-position functional hydraulic cylinder of a six-axis horizontal machining center according to claim 4, characterized in that: The constraints include: the termination condition of step 5 is that the total calculation time reaches a preset time limit or the number of traversals reaches a preset number limit.

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