Post-processing method of five-axis double-swing-angle machine tool based on C axis

Abstract

The invention discloses a post-processing method of a five-axis double-swing-angle machine tool based on a C axis, which comprises the following steps of: determining a conversion matrix from a tool coordinate system to a workpiece coordinate system according to positions and vector directions of a tool and a workpiece corresponding to a machine tool form; according to the coordinate transformation matrix, constructing a kinematics model of the machine tool in the corresponding form; according to the kinematic model, the movement distance of each movement axis of the machine tool under the condition that the RTCP compensation exists or not is solved; the swing angle of the fifth shaft is determined according to the included angle between the cutter swing length vector in the cutter location file and the corresponding projection; according to the value of the swing angle of the fifth shaft, the rotation angle of the C shaft is calculated; and according to the rotation angles of the fifth axis and the C axis, the fifth axis swing direction of the first cutter contact in the machining track is obtained through calculation in combination with a kinematic model. According to the technical scheme, the problem that the stroke of the C shaft is too large due to the fact that the fifth shaft of an existing machine tool only swings in a single direction is solved, the machining efficiency of the machine tool is improved, and the service life of the swing angle milling head is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of machine tool control, and in particular to a post-processing method of a five-axis double-swing angle machine tool based on a C-axis. Background Art

[0002] Five-axis machine tools have advantages such as high degrees of freedom and high precision, and have obvious advantages in processing curved parts. Therefore, five-axis machine tools are widely used in aerospace, mold, navigation, automobile and other industrial fields. However, compared with traditional three-axis machine tools, five-axis machine tools have two more degrees of rotational freedom, which also increases the complexity of the machine tool structure and the difficulty of analysis of post-processing calculations of machine tool processing.

[0003] Five-axis machine tools with different kinematic chains require post-processors that match different functional requirements. Traditional five-axis double-swing angle machine tools are XYZAC or XYZBC motion forms, with two rotation axes A (B), C and three linear axes X, Y, and Z. In recent years, major research institutes have conducted a lot of research on the post-processing solution of five-axis machine tools. At present, the development of post-processors based on kinematic analysis has become mature. However, all current post-processing solution methods are based on the constructed machine tool kinematic model, which is only a linear or nonlinear set of equations. The solution results do not take into account the actual working conditions of the machine tool itself, and sometimes there are the following disadvantages:

[0004] First of all, the calculated value of the fifth axis of the machine tool is often a positive number. Taking the XYZBC motion form as an example, if the value of the fifth axis (B axis) of the machine tool is a positive number, the swing head will only swing in one direction during the processing, thus affecting its service life.

[0005] In addition, since the B-axis only swings in one direction, the C-axis will rotate at a large angle during processing, causing excessive stroke, which will affect processing efficiency and the service life of the swing milling head. Summary of the invention

[0006] In view of the above problems, the present invention provides a post-processing method for a five-axis double-swing angle machine tool based on the C-axis. By constructing a kinematic model for the tool and workpiece of the machine tool, calculating the swing angles of the fifth axis and the C-axis, and further calculating the machining trajectory, the problem of the large C-axis stroke caused by the fifth axis of the machine tool swinging only in a single direction caused by the existing machine tool post-processing calculation is solved. The machining efficiency of the machine tool can be improved, and the service life of the swing angle milling head can be extended.

[0007] To achieve the above object, the present invention provides a post-processing method for a five-axis double-swing machine tool based on a C-axis, comprising:

[0008] According to the position and vector direction of the tool and workpiece corresponding to the machine tool form, determine the conversion matrix from the tool coordinate system to the workpiece coordinate system;

[0009] Construct the kinematic model of the corresponding machine tool according to the coordinate transformation matrix;

[0010] The moving distance of each moving axis of the machine tool is obtained by solving the kinematic model without RTCP compensation and with RTCP compensation;

[0011] Determine the swing angle of the fifth axis according to the angle between the vector of the tool swing length in the tool location file and the corresponding projection;

[0012] According to the value of the fifth axis swing angle, calculate the rotation angle of the C axis;

[0013] According to the rotation angle of the fifth axis and the C axis, the fifth axis swing direction of the first tool contact point in the machining trajectory is calculated in combination with the kinematic model.

[0014] In the above technical solution, preferably, the conversion matrix from the tool coordinate system to the workpiece coordinate system is determined according to the positions and vector directions of the tool and the workpiece corresponding to the machine tool form, and the specific process includes:

[0015] Setting (P x , P y , P z , U x , U y , U z ) is the position and vector direction of the tool location file CLS;

[0016] According to the transformation relationship between adjacent coordinate systems, the transformation matrix from tool coordinate system to workpiece coordinate system is determined as:

[0017] [u w 0] T = w T t [u t 0] T

[0018] [p w 0] T = w T t [p t 0] T

[0019] Among them, u w 、u t 、p w 、p t They are the initial vector direction of the workpiece, the initial vector direction of the tool, the initial position coordinates of the workpiece, and the initial position coordinates of the tool;w T t is the coordinate transformation matrix from the tool end to the workpiece end.

[0020] In the above technical solution, preferably, the kinematic model of the corresponding machine tool is constructed according to the coordinate transformation matrix, and the specific process includes:

[0021] Multiply the coordinate transformation matrices to obtain the kinematic model of the five-axis linkage machine tool:

[0022]

[0023] Wherein, LT is the tool swing length, which is the distance from the fifth axis rotation center to the tool tip point, LBC is the Z-direction distance from the fifth axis rotation center to the C axis rotation center, α is the swing angle of the fifth axis, β is the swing angle of the C axis, L x L is the linear distance that the X axis of the machine tool moves. y is the linear distance that the Y axis of the machine tool moves, L z It is the linear distance that the Z axis of the machine tool moves.

[0024] In the above technical solution, preferably, the kinematic model is used to solve the moving distance of each motion axis of the machine tool without RTCP compensation and with RTCP compensation, and the specific process includes:

[0025] The kinematic model is solved simultaneously, and the solutions of each motion axis of the machine tool without RTCP compensation are obtained as follows:

[0026]

[0027] In the case of RTCP compensation, since the CNC system inside the machine tool has compensated the X, Y, and Z axes, the solution for each axis of the machine tool is:

[0028]

[0029] Among them, if the α value is a positive number, the swing angle of the fifth axis of the machine tool is positive.

[0030] In the above technical solution, preferably, the swing angle of the fifth axis is determined according to the angle between the vector of the tool swing length in the tool location file and the corresponding projection, and the specific process includes:

[0031] Set the projection of the tool position file vector of the workpiece in the XY direction of the machine tool as LW, and set the vector of the tool swing length as (U xLT , U yLT , U zLT );

[0032] In the initial state of the machine tool, the fifth axis is swung α°, then the tool swing length vector (UxLT , U yLT , U zLT ) is (LTsinα, 0, LTcosα), and the fifth axis is swung -α°, then the tool swing length vector (U xLT , U yLT , U zLT ) is (-LTsinα, 0, LTcosα);

[0033] Set U xLT The angle between LW and the beam is λ, and the calculation method of λ is:

[0034] When U x The value is positive, U xLT When the value is positive, U xLT The angle λ between LW is

[0035] When U x The value is positive, U xLT When the value is negative, U xLT The angle λ between LW is

[0036] When U x The value is negative, U xLT When the value is positive, U xLT The angle λ between LW is

[0037] When U x The value is negative, U xLT When the value is negative, U xLT The angle λ between LW is

[0038] Among them, U x The swing direction of the fifth axis is determined by obtaining the tool position vector file and judging the swing direction of the fifth axis according to the size of λ.

[0039] In the above technical solution, preferably, the calculation of the rotation angle of the C-axis according to the value of the swing angle of the fifth axis includes:

[0040] When U x The value is positive, U y When the value is positive and α is negative,

[0041] When U x The value is positive, U y When the value is positive, α is positive.

[0042] When U x The value is positive, U yWhen the value is negative, α is negative.

[0043] When U x The value is positive, U y When the value is negative and α is positive,

[0044] When U x The value is negative, U y When the value is positive and α is negative,

[0045] When U x The value is negative, U y When the value is positive, α is positive.

[0046] In the above technical solution, preferably, the fifth axis swing direction of the first tool contact point in the machining trajectory is calculated based on the rotation angle of the fifth axis and the C axis in combination with the kinematic model, and the specific process includes:

[0047] According to the swing angle α of the fifth axis and the swing angle β of the C axis, the moving distance of each axis of the machine tool is calculated in combination with the kinematic model:

[0048]

[0049] Among them, after the fifth-axis swing direction of the first tool contact point is determined, the tool contact points of the subsequent processing trajectory are all consistent with the fifth-axis swing direction of the first tool contact point.

[0050] Compared with the prior art, the beneficial effects of the present invention are as follows: by constructing a kinematic model for the tool and workpiece of the machine tool, calculating the swing angles of the fifth axis and the C axis, and further calculating the processing trajectory, the problem of the large C-axis stroke caused by the fifth axis of the machine tool swinging only in a single direction caused by the prior art post-processing calculation of the machine tool is solved, the processing efficiency of the machine tool is improved, and the service life of the swing angle milling head is extended. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 A schematic flow chart of a post-processing method for a C-axis based five-axis double-swing machine tool disclosed in an embodiment of the present invention. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0054] like Figure 1 As shown, a post-processing method of a five-axis double-swing machine tool based on a C-axis provided by the present invention includes:

[0055] According to the position and vector direction of the tool and workpiece corresponding to the machine tool form, determine the conversion matrix from the tool coordinate system to the workpiece coordinate system;

[0056] Construct the kinematic model of the corresponding machine tool according to the coordinate transformation matrix;

[0057] The moving distance of each moving axis of the machine tool with and without RTCP compensation is obtained by solving the kinematic model;

[0058] Determine the swing angle of the fifth axis according to the angle between the vector of the tool swing length in the tool location file and the corresponding projection;

[0059] According to the value of the fifth axis swing angle, calculate the rotation angle of the C axis;

[0060] According to the rotation angle of the fifth axis and the C axis, the fifth axis swing direction of the first tool contact point in the machining trajectory is calculated in combination with the kinematic model.

[0061] In this implementation, a kinematic model is constructed for the tool and workpiece of the machine tool, the swing angles of the fifth axis and the C axis are calculated, and the processing trajectory is further calculated. This solves the problem of a large C-axis stroke caused by the fifth axis of the machine tool swinging in only a single direction caused by the existing machine tool post-processing calculation, thereby improving the machine tool processing efficiency and extending the service life of the swing angle milling head.

[0062] Specifically, a five-axis double-swing angle machine tool includes an XYZAC or XYZBC motion form. This embodiment takes an XYZBC form machine tool as an example to specifically illustrate the post-processing method of a five-axis machine tool.

[0063] In the above implementation, preferably, according to the position and vector direction of the tool and the workpiece corresponding to the machine tool form, the conversion matrix from the tool coordinate system to the workpiece coordinate system is determined, and the specific process includes:

[0064] Setting (Px , P y , P z , U x , U y , U z ) is the position and vector direction of the tool location file CLS;

[0065] According to the transformation relationship between adjacent coordinate systems, the transformation matrix from tool coordinate system to workpiece coordinate system is determined as:

[0066] [u w 0] T = w T t [u t 0] T

[0067] [p w 0] T = w T t [p t 0] T

[0068] Among them, u w 、u t 、p w 、p t They are the initial vector direction of the workpiece, the initial vector direction of the tool, the initial position coordinates of the workpiece, and the initial position coordinates of the tool; w T t is the coordinate transformation matrix from the tool end to the workpiece end.

[0069] In the above implementation, preferably, the kinematic model of the corresponding machine tool is constructed according to the coordinate transformation matrix, and the specific process includes:

[0070] Multiply the coordinate transformation matrices to obtain the kinematic model of the five-axis linkage machine tool:

[0071]

[0072] Among them, LT is the tool swing length, which is the distance from the fifth axis rotation center to the tool tip point, LBC is the Z-direction distance from the fifth axis rotation center to the C axis rotation center, α is the swing angle of the fifth axis, β is the swing angle of the C axis, L x L is the linear distance that the X axis of the machine tool moves. y is the linear distance that the Y axis of the machine tool moves, L z It is the linear distance that the Z axis of the machine tool moves.

[0073] In the above implementation, preferably, the moving distance of each moving axis of the machine tool without RTCP compensation and with RTCP compensation is obtained according to the kinematic model, and the specific process includes:

[0074] The kinematic model is solved simultaneously, and the solutions of each motion axis of the machine tool without RTCP compensation are obtained as follows:

[0075]

[0076] In the case of RTCP compensation, since the CNC system inside the machine tool has compensated the X, Y, and Z axes, the solution for each axis of the machine tool is:

[0077]

[0078] Among them, the value of α is the inverse cosine function. According to the properties of the function, its domain is [-1, 1] and its range is [0, π]. Since α is the swing angle of the B-axis, the α value calculated by the inverse function is positive. When reflected on the machine tool, the swing angle of the B-axis is positive. In other words, if the solution is simply based on the kinematic model, the swing angle of the B-axis cannot be negative.

[0079] In combination with the above-mentioned embodiments, preferably, the present invention adopts the angle between the vector of the tool swing length in the tool position file and the corresponding projection to determine the swing angle of the fifth axis, and the specific process includes:

[0080] Set the projection of the tool position file vector of the workpiece in the XY direction of the machine tool as LW, and set the vector of the tool swing length as (U xLT , U yLT , U zLT ), when calculating the tool pendulum length vector during implementation, the pendulum length LT needs to be set to 1;

[0081] In the initial state of the machine tool, the fifth axis is swung α°, then the tool swing length vector (U xLT , U yLT , U zLT ) is (LTsinα, 0, LTcosα), and the fifth axis swings -α°, then the tool swing length vector (U xLT , U yLT , U zLT ) is (-LTsinα, 0, LTcosα);

[0082] Set U xLT The angle between LW and the beam is λ, and the calculation method of λ is:

[0083] When U x The value is positive, U xLT When the value is positive, U xLT The angle λ between LW is

[0084] When U x The value is positive, U xLT When the value is negative, U xLT The angle λ between LW is

[0085] When U x The value is negative, U xLT When the value is positive, U xLT The angle λ between LW is

[0086] When U x The value is negative, U xLT When the value is negative, U xLT The angle λ between LW is

[0087] Among them, U x Obtained from the tool position vector file, the swing direction of the fifth axis is determined according to the size of λ. The basis for determining whether the B-axis swings in the positive or negative direction is the size of the λ angle. The absolute value of the λ angle is determined when the B-axis swings α° and -α° respectively. The smaller absolute value of the λ angle is taken as the swing angle of the B-axis.

[0088] In the above implementation, preferably, the rotation angle of the C-axis is calculated according to the value of the swing angle of the fifth axis, and the specific process includes:

[0089] When U x The value is positive, U y When the value is positive and α is negative,

[0090] When U x The value is positive, U y When the value is positive, α is positive.

[0091] When U x The value is positive, U y When the value is negative, α is negative.

[0092] When U x The value is positive, U y When the value is negative and α is positive,

[0093] When U x The value is negative, U y When the value is positive and α is negative,

[0094] When U xThe value is negative, U y When the value is positive, α is positive.

[0095] When U x The value is negative, U y When the value is negative, α is negative.

[0096] When U x The value is negative, U y When the value is negative and α is positive,

[0097] In the above implementation, preferably, according to the rotation angle of the fifth axis and the C axis, the fifth axis swing direction of the first tool contact point in the machining trajectory is calculated in combination with the kinematic model, and the specific process includes:

[0098] According to the swing angle α of the fifth axis and the swing angle β of the C axis, the moving distance of each axis of the machine tool is calculated in combination with the kinematic model:

[0099]

[0100] It should be noted that when all the tool contact points in a tool path are calculated, if there are both positive and negative values ​​of α, it will cause a large range of swings in the B axis during the processing, which may cause global interference in the processing, thereby damaging the workpiece or machine tool. Therefore, after the swing direction of the fifth axis (B axis) of the first tool contact point is determined, the tool contact points of the subsequent processing trajectory are all consistent with the B axis swing direction of the first tool contact point.

[0101] According to the post-processing method of the C-axis-based five-axis double-swing machine tool disclosed in the above embodiment, during the implementation process, taking the XYZBC form machine tool as an example, the CLS file of a certain tool contact point is (-20.8999, -34.1056, 15.0000, -0.4940321, -0.8061871, 0.3255682), where U x , U y , U z They are -0.4940321, -0.8061871, and 0.3255682 respectively. According to the above calculation method, the value of the B axis is -71.036, and the value of the C axis is 58.484. If the B axis takes a positive value of 71.036 according to the traditional algorithm, the value calculated for the C axis is -121.516. It can be seen that the C axis travel will be shortened by using the method proposed by the present invention.

[0102] In addition, the post-processing solution of the XYZAC form machine tool is similar to the calculation method of the above XYZBC. During the implementation process, the calculation is performed according to the following formula:

[0103]

[0104] Where γ is the swing angle of the machine tool A axis.

[0105] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A post-processing method for a five-axis double-swing machine tool based on a C-axis, characterized in that: include: According to the position and vector direction of the tool and workpiece corresponding to the machine tool form, determine the conversion matrix from the tool coordinate system to the workpiece coordinate system; Construct the kinematic model of the corresponding machine tool according to the coordinate transformation matrix; The moving distance of each moving axis of the machine tool is obtained by solving the kinematic model without RTCP compensation and with RTCP compensation; Determine the swing angle of the fifth axis according to the angle between the vector of the tool swing length in the tool location file and the corresponding projection; According to the value of the fifth axis swing angle, calculate the rotation angle of the C axis; According to the rotation angle of the fifth axis and the C axis, the fifth axis swing direction of the first tool contact point in the machining trajectory is calculated in combination with the kinematic model.

2. The post-processing method of the C-axis based five-axis double-swing machine tool according to claim 1, characterized in that: The process of determining the conversion matrix from the tool coordinate system to the workpiece coordinate system according to the position and vector direction of the tool and the workpiece corresponding to the machine tool form includes: Setting (P x , P y , P z , U x , U y , U z ) is the position and vector direction of the tool location file CLS; According to the transformation relationship between adjacent coordinate systems, the transformation matrix from tool coordinate system to workpiece coordinate system is determined as: [u w 0] T = w T t [u t 0] T [p w 0] T = w T t [p t 0] T Among them, u w 、u t 、p w 、p t They are the initial vector direction of the workpiece, the initial vector direction of the tool, the initial position coordinates of the workpiece, and the initial position coordinates of the tool; w T t is the coordinate transformation matrix from the tool end to the workpiece end.

3. The post-processing method of the C-axis based five-axis double-swing machine tool according to claim 2, characterized in that: The kinematic model of the corresponding machine tool is constructed according to the coordinate transformation matrix, and the specific process includes: Multiply the coordinate transformation matrices to obtain the kinematic model of the five-axis linkage machine tool: Wherein, LT is the tool swing length, which is the distance from the fifth axis rotation center to the tool tip point, LBC is the Z-direction distance from the fifth axis rotation center to the C axis rotation center, α is the swing angle of the fifth axis, β is the swing angle of the C axis, L x L is the linear distance that the X axis of the machine tool moves. y is the linear distance that the Y axis of the machine tool moves, L z It is the linear distance that the Z axis of the machine tool moves.

4. The post-processing method of the C-axis based five-axis double-swing machine tool according to claim 3, characterized in that: The kinematic model is solved to obtain the moving distance of each moving axis of the machine tool without RTCP compensation and with RTCP compensation, and the specific process includes: The kinematic model is solved simultaneously, and the solutions of each motion axis of the machine tool without RTCP compensation are obtained as follows: In the case of RTCP compensation, since the CNC system inside the machine tool has compensated the X, Y, and Z axes, the solution for each axis of the machine tool is: Among them, if the α value is a positive number, the swing angle of the fifth axis of the machine tool is positive.

5. The post-processing method of the C-axis based five-axis double-swing machine tool according to claim 4, characterized in that: The swing angle of the fifth axis is determined according to the angle between the vector of the tool swing length in the tool location file and the corresponding projection, and the specific process includes: Set the projection of the tool position file vector of the workpiece in the XY direction of the machine tool as LW, and set the vector of the tool swing length as (U xLT , U yLT , U zLT ); In the initial state of the machine tool, the fifth axis is swung α°, then the tool swing length vector (U xLT , U yLT , U zLT ) is (LTsinα, 0, LTcosα), and the fifth axis is swung -α°, then the tool swing length vector (U xLT , U yLT , U zLT ) is (-LTsinα, 0, LTcosα); Set U xLT The angle between LW and the beam is λ, and the calculation method of λ is: When U x The value is positive, U xLT When the value is positive, U xLT The angle λ between LW is When U x The value is positive, U xLT When the value is negative, U xLT The angle λ between LW is When U x The value is negative, U xLT When the value is positive, U xLT The angle λ between LW is When U x The value is negative, U xLT When the value is negative, U xLT The angle λ between LW is Among them, U x The swing direction of the fifth axis is determined by obtaining the tool position vector file and judging the swing direction of the fifth axis according to the size of λ.

6. The post-processing method of the C-axis based five-axis double-swing machine tool according to claim 5, characterized in that: The specific process of calculating the rotation angle of the C axis according to the value of the swing angle of the fifth axis includes: When U x The value is positive, U y When the value is positive and α is negative, When U x The value is positive, U y When the value is positive, α is positive. When U x The value is positive, U y When the value is negative, α is negative. When U x The value is positive, U y When the value is negative and α is positive, When U x The value is negative, U y When the value is positive and α is negative, When U x The value is negative, U y When the value is positive, α is positive. When U x The value is negative, U y When the value is negative, α is negative. When U x The value is negative, U y When the value is negative and α is positive, 7. The post-processing method of the C-axis based five-axis double-swing machine tool according to claim 6, characterized in that: The fifth axis swing direction of the first tool contact point in the machining trajectory is calculated based on the rotation angle of the fifth axis and the C axis in combination with the kinematic model. The specific process includes: According to the swing angle α of the fifth axis and the swing angle β of the C axis, the moving distance of each axis of the machine tool is calculated in combination with the kinematic model: Among them, after the fifth-axis swing direction of the first tool contact point is determined, the tool contact points of the subsequent processing trajectory are all consistent with the fifth-axis swing direction of the first tool contact point.

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