1. A five-axis machining tool position feed speed control method is characterized by comprising the following steps:

s1, receiving a feed quantity command, and calculating the speed of each motion axis of the five-axis machine tool under the feed quantity command according to a preset feed distribution mode;

s2, when the speed of one or more moving axes is larger than the corresponding speed threshold value, correcting the speed of each moving axis of the five-axis machine tool into the ratio of the stroke of each moving axis to the correction time, wherein the correction time is the maximum value of the ratio of the stroke of each moving axis to the corresponding speed threshold value;

and S3, carrying out coordinate transformation on the speed of each motion axis of the five-axis machine tool to obtain the feed speed of the tool position under a workpiece coordinate system, and controlling the tool according to the feed speed of the tool position.

2. The five-axis machining tool position feed speed control method of claim 1, wherein S1 is preceded by: sampling and obtaining speed samples of all movement axes of the five-axis machine tool under different feed amount instruction samples, and fitting based on the feed amount instruction samples and the speed samples of all movement axes of the five-axis machine tool to obtain the preset feed distribution mode.

3. The five-axis machining tool position feed speed control method according to claim 1 or 2, characterized in that the preset feed distribution mode is as follows:

wherein, V_ΛThe speed of the lambda motion axis of the five-axis machine tool under the feed amount instruction is F, the lambda motion axis is the feed amount instruction₁And Λ₂The positions of lambda motion axes of the front and rear five-axis machine tools for executing the feed quantity command are lambda₁And λ₂The positions of the lambda motion axis of the five-axis machine tool before and after the feed quantity instruction is executed are respectively.

4. The five-axis machining tool position feed speed control method according to claim 1, wherein the speeds of the motion axes of the five-axis machine tool after being corrected in the step S2 are as follows:

wherein, V_ΛFor correcting speed of inverted V-axis of motion of five-axis machine tool, S_ΛThe stroke of the lambda motion axis of the five-axis machine tool, t is the correction time, S_X、S_Y、S_Z、S_AAnd S_CStroke, V, of axes of motion of five-axis machine tool X, Y, Z, A and C, respectively_XMAX、V_YMAX、V_ZMAX、V_AMAXAnd V_CMAXThe speed thresholds for five-axis machine tool X, Y, Z, A and the C motion axis, respectively.

5. The five-axis machining tool position feed speed control method of claim 1, wherein S3 is preceded by: transforming the coordinates of the tool location points under the machine tool coordinate system to a workpiece coordinate system to obtain the position relation between the positions of all the movement axes under the machine tool coordinate system and the tool location points under the workpiece coordinate system; the position relation is derived to obtain the conversion relation between the speed of each motion axis in the machine tool coordinate system and the speed of the tool location point in the workpiece coordinate system;

and in the step S3, calculating the speed of the cutter position point under the workpiece coordinate system according to the transformation relation, and calculating the feed speed of the cutter position according to the speed of the cutter position point.

6. The five-axis machining tool position feed speed control method according to claim 5, characterized in that the positional relationship is:

wherein X, Y, Z, A and C are the positions of the tool location point under the machine coordinate system on the X, Y, Z, A axis and the C axis respectively, x, y and z are the positions of the tool location point under the workpiece coordinate system on the x, y and z axes respectively, i, j and k are the postures of the tool location point under the workpiece coordinate system on the x, y and z axes respectively, (T)_X,T_Y,T_Z) As position coordinates of the workpiece coordinate system relative to the tool zero point coordinate system, D_YFor five-axis machine toolsDeviation of the A-axis and the C-axis in the Y-direction, D_ZThe deviation of the axis A and the axis C of the five-axis machine tool in the Z direction is shown, H is the vertical distance between the upper surface of the workbench and the end surface of the main shaft, and L is the vertical distance between the tool nose point and the end surface of the main shaft.

7. The five-axis machining tool position feed speed control method according to claim 6, characterized in that the transformation relation is:

wherein, V_x、V_yAnd V_zThe velocity, V, of the tool location point in the x, y and z axes, respectively, under the workpiece coordinate system_X、V_Y、V_Z、V_AAnd V_CRespectively the moving axis speeds of the tool location point under the machine tool coordinate system on X, Y, Z, A and C axes, M is a coordinate system speed mapping matrix, R_XIs a first mapping parameter, R_X＝X+M_X，R_YIs a second mapping parameter, R_Y＝Y+D_Y+M_Y，R_ZAs a third mapping parameter, R_Z＝Z+H-D_Z+M_Z，M_X、M_YAnd M_ZThe position of the tool in X, Y and the Z axis in the zero coordinate system of the tool, respectively.

8. The five-axis machining tool position feed speed control method according to any one of claims 5 to 7, characterized in that the tool position feed speed is as follows:

wherein f is the tool position feed speed, V_x、V_yAnd V_zThe tool position in the x, y and z axes of the workpiece coordinate system.

9. A five-axis machining tool position feed speed control system is characterized by comprising:

the receiving and distributing module is used for receiving a feed quantity instruction and calculating the speed of each motion axis of the five-axis machine tool under the feed quantity instruction according to a preset feed distributing mode;

the correction module is used for correcting the speed of each motion axis of the five-axis machine tool into the ratio of the stroke of each motion axis to the correction time when the speed of one or more motion axes is greater than the corresponding speed threshold, and the correction time is the maximum value of the ratio of the stroke of each motion axis to the corresponding speed threshold;

and the transformation and control module is used for carrying out coordinate transformation on the speed of each motion axis of the five-axis machine tool to obtain the feed speed of the tool position under a workpiece coordinate system and controlling the cutter according to the feed speed of the tool position.

Background

With the continuous penetration of information technology into the processing field, the application of Distributed digital Control (DNC) is becoming widespread, and its main function is to establish communication with Numerical Control devices such as machine tools for data interaction. Compared with the traditional processing mode, the DNC does not need an external sensor, data acquisition is more convenient, and the DNC is an important assistance force for realizing intelligent integration of processing. The five-axis numerical control machining technology is widely applied to machining of complex surface parts in the fields of aerospace and the like, and how to improve the quality and efficiency of five-axis numerical control machining is a main research problem of numerous scholars and production personnel. The optimization of the feeding speed is a processing technology optimization mode which has the most direct processing influence, the most intuitive optimization effect and the most research.

The feed speed given in the process planning stage refers to the speed of the tool relative to the workpiece along the tool path and is described by the workpiece coordinate system, and the numerical control code feed speed command F in the actual machining stage is described by the machine tool coordinate system. In the traditional three-axis machining process, only translation exists between a cutter and a workpiece; in the five-axis machining process, the movement of the rotating shaft enables the workpiece coordinate system and the machine tool coordinate system to rotate relatively, so that the feeding speed of the cutter relative to the workpiece in actual machining is inconsistent with the feeding speed given in the process planning stage, namely the feeding speed of the cutter at the cutter point on the surface of the workpiece is different from the expected feeding speed set in the cutter path planning process. In the existing five-axis machining process, the feeding speed of a cutter relative to a workpiece is usually controlled directly based on a feeding speed instruction, and the control mode is not suitable for five-axis machining, so that the quality and the efficiency of five-axis machining are greatly limited.

Disclosure of Invention

Aiming at the defects and improvement requirements of the prior art, the invention provides a five-axis machining cutter position feeding speed control method and system, and aims to solve the problems of low machining quality and low efficiency caused by directly controlling the feeding speed of a cutter based on a feeding speed instruction in the five-axis machining process.

To achieve the above object, according to an aspect of the present invention, there is provided a five-axis machining tool position feed speed control method, including: s1, receiving a feed quantity command, and calculating the speed of each motion axis of the five-axis machine tool under the feed quantity command according to a preset feed distribution mode; s2, when the speed of one or more moving axes is larger than the corresponding speed threshold value, correcting the speed of each moving axis of the five-axis machine tool into the ratio of the stroke of each moving axis to the correction time, wherein the correction time is the maximum value of the ratio of the stroke of each moving axis to the corresponding speed threshold value; and S3, carrying out coordinate transformation on the speed of each motion axis of the five-axis machine tool to obtain the feed speed of the tool position under a workpiece coordinate system, and controlling the tool according to the feed speed of the tool position.

Further, S1 is preceded by: sampling and obtaining speed samples of all movement axes of the five-axis machine tool under different feed amount instruction samples, and fitting based on the feed amount instruction samples and the speed samples of all movement axes of the five-axis machine tool to obtain the preset feed distribution mode.

Furthermore, the preset feeding distribution mode is as follows:

wherein, V_ΛThe speed of the lambda motion axis of the five-axis machine tool under the feed amount instruction is F, the lambda motion axis is the feed amount instruction₁And Λ₂The positions of lambda motion axes of the front and rear five-axis machine tools for executing the feed quantity command are lambda₁And λ₂The positions of the lambda motion axis of the five-axis machine tool before and after the feed quantity instruction is executed are respectively.

Further, the speed of each motion axis of the five-axis machine tool after being corrected in S2 is as follows:

wherein, V_ΛFor correcting speed of inverted V-axis of motion of five-axis machine tool, S_ΛThe stroke of the lambda motion axis of the five-axis machine tool, t is the correction time, S_X、S_Y、S_Z、S_AAnd S_CStroke, V, of axes of motion of five-axis machine tool X, Y, Z, A and C, respectively_XMAX、V_YMAX、V_ZMAX、V_AMAXAnd V_CMAXThe speed thresholds for five-axis machine tool X, Y, Z, A and the C motion axis, respectively.

Further, S3 is preceded by: transforming the coordinates of the tool location points under the machine tool coordinate system to a workpiece coordinate system to obtain the position relation between the positions of all the movement axes under the machine tool coordinate system and the tool location points under the workpiece coordinate system; the position relation is derived to obtain the conversion relation between the speed of each motion axis in the machine tool coordinate system and the speed of the tool location point in the workpiece coordinate system; and in the step S3, calculating the speed of the cutter position point under the workpiece coordinate system according to the transformation relation, and calculating the feed speed of the cutter position according to the speed of the cutter position point.

Further, the position relationship is:

wherein X, Y, Z, A and C are the positions of the tool location point under the machine coordinate system on the X, Y, Z, A axis and the C axis respectively, x, y and z are the positions of the tool location point under the workpiece coordinate system on the x, y and z axes respectively, i, j and k are the postures of the tool location point under the workpiece coordinate system on the x, y and z axes respectively, (T)_X,T_Y,T_Z) As position coordinates of the workpiece coordinate system relative to the tool zero point coordinate system, D_YDeviation of A-axis and C-axis of five-axis machine tool in Y-direction, D_ZThe deviation of the axis A and the axis C of the five-axis machine tool in the Z direction is shown, H is the vertical distance between the upper surface of the workbench and the end surface of the main shaft, and L is the vertical distance between the tool nose point and the end surface of the main shaft.

Further, the transformation relation is:

wherein, V_x、V_yAnd V_zThe velocity, V, of the tool location point in the x, y and z axes, respectively, under the workpiece coordinate system_X、V_Y、V_Z、V_AAnd V_CRespectively the moving axis speeds of the tool location point under the machine tool coordinate system on X, Y, Z, A and C axes, M is a coordinate system speed mapping matrix, R_XIs a first mapping parameter, R_X＝X+M_X，R_YIs a second mapping parameter, R_Y＝Y+D_Y+M_Y，R_ZAs a third mapping parameter, R_Z＝Z+H-D_Z+M_Z，M_X、M_YAnd M_ZThe position of the tool in X, Y and the Z axis in the zero coordinate system of the tool, respectively.

Further, the tool position feeding speed is as follows:

wherein f is the tool position feed speed, V_x、V_yAnd V_zThe tool position in the x, y and z axes of the workpiece coordinate system.

According to another aspect of the invention, a five-axis machining tool position feed speed control system is provided, comprising: the receiving and distributing module is used for receiving a feed quantity instruction and calculating the speed of each motion axis of the five-axis machine tool under the feed quantity instruction according to a preset feed distributing mode; the correction module is used for correcting the speed of each motion axis of the five-axis machine tool into the ratio of the stroke of each motion axis to the correction time when the speed of one or more motion axes is greater than the corresponding speed threshold, and the correction time is the maximum value of the ratio of the stroke of each motion axis to the corresponding speed threshold; and the transformation and control module is used for carrying out coordinate transformation on the speed of each motion axis of the five-axis machine tool to obtain the feed speed of the tool position under a workpiece coordinate system and controlling the cutter according to the feed speed of the tool position.

Generally, by the above technical solution conceived by the present invention, the following beneficial effects can be obtained: the method comprises the steps of analyzing and setting a distribution mode of a numerical control system for a feeding speed in advance, for example, acquiring a large number of actual movement speeds of various movement axes in the numerical control system and a feeding amount instruction F in advance, analyzing and fitting to obtain a corresponding relation between the actual movement speeds and the feeding amount instruction F, so that the feeding distribution mode is preset for the numerical control system, and in the actual five-axis machining process, when any numerical control code is executed, the speed of the F instruction in the code distributed to each movement axis can be calculated according to the preset feeding distribution mode, the three-axis feeding speed of a cutter relative to a workpiece is further converted and obtained, the cutter is controlled to cut and machine the workpiece based on the three-axis feeding speed, and the problems of low machining quality and low efficiency caused by the fact that the five-axis machining directly controls the feeding speed of the cutter based on the feeding speed instruction are solved; in addition, each motion axis is constrained by the physical performance and has speed limit, the speed of each motion axis is corrected based on the speed limit, the numerical control system is prevented from being damaged due to overhigh speed of one or more motion axes, the safety of five-axis numerical control machining is improved, and the service life of the five-axis machining device is prolonged.

Drawings

FIG. 1 is a flow chart of a five-axis machining tool position feed speed control method according to an embodiment of the invention;

FIG. 2 is a diagram of a self-developed DNC software interface provided by an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a five-axis numerical control machine tool provided by the embodiment of the invention;

fig. 4 is a block diagram of a five-axis machining tool position feed speed control system according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

In the present application, the terms "first," "second," and the like (if any) in the description and the drawings are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.

Fig. 1 is a flowchart of a five-axis machining tool position feed speed control method according to an embodiment of the present invention. Referring to fig. 1, the method for controlling the feed speed of the five-axis machining tool position according to the present embodiment will be described in detail with reference to fig. 2 to 3, and the method includes operations S1 to S3.

And operation S1, receiving the feed quantity command, and calculating the speed of each motion axis of the five-axis machine tool under the feed quantity command according to the preset feed distribution mode.

According to an embodiment of the present invention, before performing operation S1, the method further includes: sampling to obtain speed samples of all movement axes of the five-axis machine tool under different feed amount instruction samples, and fitting to obtain a preset feed distribution mode based on a plurality of groups of feed amount instruction samples obtained by sampling and the speed samples of all movement axes of the five-axis machine tool. Wherein the feed amount command is an F command. It will be appreciated that the preset feed distribution pattern may vary from one numerical control system to another.

Specifically, for example, self-developed DNC software is used to collect speed samples of each motion axis of the five-axis machine tool under each feed command sample during actual machining. The DNC software is developed based on Remotools development components in Heidenhain, communication is established with the numerical control system based on TCP/IP and LSV-2 protocols, corresponding data of the numerical control system can be collected by calling sdk provided in the development components, and a software interface is shown in figure 2.

The motion axes of the axis machine tool include three axes of X, Y and Z axes, and two of an a axis rotating around the X axis, a B axis rotating around the Y axis, and a C axis rotating around the Z axis, wherein the Z axis is parallel to the main axis. In the present embodiment, the movement axes of the five-axis machine tool include an X axis, a Y axis, a Z axis, an a axis, and a C axis, for example, as shown in fig. 3.

In an embodiment of the numerical control system of the present invention (for example, a mckelan UCP 800Duro type five-axis numerical control machine tool embedded with a hidehan TINC530M numerical control system), the preset feed distribution manner obtained by fitting is:

wherein, V_ΛThe speed of the lambda motion axis of the five-axis machine tool under the feed quantity command F, wherein F is the feed quantity command, and lambda₁And Λ₂The positions of the V-axis motion axis of the five-axis machine tool lambda before and after the feed quantity command F is executed are respectively₁And λ₂The positions of the lambda motion axis of the five-axis machine tool before and after the feed quantity command F is executed are respectively. For other numerical control systems, the preset feeding distribution mode of the other numerical control systems obtained by fitting may be different from the preset feeding distribution mode, and the control object in the embodiment of the present invention is not limited to the numerical control system.

When the numerical control system receives a feed quantity instruction F, directly calculating the speed V distributed to each motion axis of the five-axis machine tool under the feed quantity instruction F based on a preset feed distribution mode of the numerical control system_X、V_Y、V_Z、V_AAnd V_C。

In operation S2, when the speed of one or more motional axes is greater than the corresponding speed threshold, the speed of each motional axis of the five-axis machine tool is corrected to a ratio of the stroke of each motional axis to a correction time, which is the maximum value of the ratio of the stroke of each motional axis to the corresponding speed threshold, respectively.

The speed threshold in this embodiment is the maximum speed V that can be tolerated or attained by the respective axis of motion Lambda_ΛMAX. When V is obtained in operation S1_XGreater than V_XMAXOr V_YGreater than V_YMAXOr V_ZGreater than V_ZMAXOr V_AGreater than V_AMAXOr V_CGreater than V_CMAXWhen any one or more of the five-axis machine tool is satisfied, the speed V of each motion axis of the five-axis machine tool is adjusted_X、V_Y、V_Z、V_AAnd V_CCorrected to the following values, respectively:

wherein, V_ΛFor correcting speed of inverted V-axis of motion of five-axis machine tool, S_ΛThe stroke of a lambda motion axis of the five-axis machine tool, t is correction time, S_X、S_Y、S_Z、S_AAnd S_CStroke, V, of axes of motion of five-axis machine tool X, Y, Z, A and C, respectively_XMAX、V_YMAX、V_ZMAX、V_AMAXAnd V_CMAXThe speed thresholds for five-axis machine tool X, Y, Z, A and the C motion axis, respectively. The feeding speed F' of the numerical control system obtained by synthesis after correction in actual execution is as follows:

wherein, V in the above formula_ΛThe speed of the motion axis of the five-axis machine tool is corrected.

And operation S3, performing coordinate transformation on the speed of each motion axis of the five-axis machine tool to obtain the feed speed of the tool position under the workpiece coordinate system, and controlling the tool according to the feed speed of the tool position.

According to an embodiment of the present invention, operation S3' and operation S3 "are further included before performing operation S3.

In operation S3', the coordinates of the tool location point in the machine coordinate system are transformed into the workpiece coordinate system, and the position relationship between the position of each motion axis in the machine coordinate system and the tool location point in the workpiece coordinate system is obtained.

In this embodiment, a coordinate transformation process in operation S3 will be described by taking a five-axis machine tool as an a-C double-turntable five-axis numerical control machine tool as an example. Three coordinate systems are involved in the kinematic analysis process: the cutter zero coordinate system { T }, locate at the center of end surface of main axis, fixedly connect with lathe; the workpiece coordinate system { W }, fixedly connect with work piece, it is the reference coordinate system while generating the knife way; and the transition coordinate system { H }, which is positioned at the center of the workbench, has unchanged relative position with the workpiece coordinate system. The coordinate system positions and associated code numbers are depicted in fig. 3. The kinematic analysis can obtain the position and posture transformation relation of a point under a zero coordinate system { T } of the cutter under a workpiece coordinate system { W } after five-axis motion:

solving the above formula to obtain the position relation of the position (x, y, z) and the attitude (i, j, k) corresponding to five-axis motion under the workpiece coordinate system:

wherein X, Y, Z, A and C are the positions of the tool location point under the machine coordinate system on the X, Y, Z, A axis and the C axis respectively, x, y and z are the positions of the tool location point under the workpiece coordinate system on the x, y and z axes respectively, i, j and k are the postures of the tool location point under the workpiece coordinate system on the x, y and z axes respectively, (T)_X,T_Y,T_Z) As position coordinates of the workpiece coordinate system relative to the tool zero point coordinate system, D_YDeviation of A-axis and C-axis of five-axis machine tool in Y-direction, D_ZThe deviation of the A axis and the C axis of the five-axis machine tool in the Z direction is shown, and H is the upper surface of the workbench andand L is the vertical distance between the tool nose point and the end surface of the main shaft.

In operation S3 ″, the positional relationship is derived to obtain a transformation relationship between the velocity of each motion axis in the machine coordinate system and the velocity of the tool position in the workpiece coordinate system.

Assuming that the position of the tool setting point under the tool zero point coordinate system { T } is (M)_X,M_Y,M_Z) And respectively deriving T from two sides of the position relation to obtain the conversion relation between the machine tool motion axis speed under the cutter zero coordinate system { T } and the cutter position three-axis motion speed under the workpiece coordinate system { W } as follows:

wherein, V_x、V_yAnd V_zThe velocity, V, of the tool location point in the x, y and z axes, respectively, under the workpiece coordinate system_X、V_Y、V_Z、V_AAnd V_CRespectively the moving axis speeds of the tool location point under the machine tool coordinate system on X, Y, Z, A and C axes, M is a coordinate system speed mapping matrix, R_XIs a first mapping parameter, R_X＝X+M_X，R_YIs a second mapping parameter, R_Y＝Y+D_Y+M_Y，R_ZAs a third mapping parameter, R_Z＝Z+H-D_Z+M_Z。

In combination with the above feed distribution method, V can be obtained_x、V_yAnd V_zThe relation between the numerical control code feeding amount instruction F is as follows:

wherein M is_(i,j)Represents the ith row and jth column element, Λ, of the coordinate system velocity mapping matrix M₁And Λ₂The positions of lambda motion axes of the front and rear five-axis machine tools for executing the feed quantity command are lambda₁And λ₂The positions of the lambda motion axis of the five-axis machine tool before and after the feed quantity instruction is executed are respectively.

Three-axis velocity V according to the tool position_x、V_yAnd V_zThe tool position feed speed f can be obtained as follows:

therefore, the relationship between the cutter feeding speed F and the numerical control code feeding amount command F is as follows:

p_x＝M_(1,1)I_X+M_(1,2)I_Y+M_(1,3)I_Z+M_(1,4)I_A+M_(1,5)I_C

p_y＝M_(2,1)I_X+M_(2,2)I_Y+M_(2,3)I_Z+M_(2,4)I_A+M_(2,5)I_C

p_z＝M_(3,1)I_X+M_(3,2)I_Y+M_(3,3)I_Z+M_(3,4)I_A+M_(3,5)I_C

furthermore, a numerical control code feed amount command F is set, a cutter is controlled to cut and process a workpiece at a cutter position feed speed F, and the workpiece is positioned on a workbench and is controlled by the motion of the A, C rotating shaft. Therefore, in the five-axis machining process, when any numerical control code is executed, the speed of the F command in the code distributed to each motion axis can be calculated, so that the feeding speed of the cutter relative to a workpiece is obtained through coordinate transformation, and the problems of low machining quality and low efficiency caused by the fact that the five-axis machining directly controls the feeding speed of the cutter based on the feeding speed command are solved.

Fig. 4 is a block diagram of a five-axis machining tool position feed speed control system according to an embodiment of the present invention. Referring to FIG. 4, the five-axis machining tool position feed speed control system 400 includes a receiving and dispensing module 410, a modification module 420, and a transformation and control module 430.

The receiving and distributing module 410, for example, executes operation S1, and is configured to receive the feed amount command and calculate the speed of each motion axis of the five-axis machine tool under the feed amount command according to the preset feed distribution manner.

The correction module 420 performs, for example, operation S2 for correcting the speed of each moving axis of the five-axis machine tool to a ratio of the travel of each moving axis to a correction time that is the maximum of the ratio of the travel of each moving axis to the corresponding speed threshold, respectively, when the speed of one or more moving axes is greater than the corresponding speed threshold.

The transformation and control module 430 performs operation S3, for example, to coordinate the speeds of the motion axes of the five-axis machine tool, obtain the tool position feeding speed in the workpiece coordinate system, and control the tool according to the tool position feeding speed.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.