JP6435655B2 - Condition determination method used for thermal displacement estimation device of machine tool - Google Patents

Description

  The present invention relates to a condition determination method used in a thermal displacement estimation device for a machine tool.

Patent Document 1 describes that a structural model of a machine tool is divided into a plurality of blocks, and a structural analysis is performed with each block temperature being a uniform value, thereby estimating a thermal displacement amount of the structural body model. ing. That is, the temperatures at the nodes included in the same block have the same value. And the thermal displacement vector of each node is represented by {δ} = [K] ⁻¹ [F] {T}. Here, {δ} is a thermal displacement vector of each node, [K] is a stiffness matrix of the structure model, [F] is a force coefficient matrix of each node, and {T} is each block. It is a temperature vector. In addition, all the vectors used in this specification mean column vectors.

  The number of elements of the temperature vector {T} of each block depends on the number of blocks, and is significantly smaller than the number of nodes. Therefore, the calculation amount of the thermal displacement vector {δ} at each node is greatly reduced. Therefore, the calculation speed of the thermal displacement vector {δ} at each node can be increased. As a result, real-time thermal displacement correction can be performed while performing the calculation in real time during machining.

International Publication No. 2012/157687

  Here, each block temperature is acquired by a temperature sensor arranged in the block. In the above calculation, the temperatures at the nodes included in the same block are actually different temperatures, but are set to a uniform value for speeding up the calculation. That is, the structural analysis is performed with a node at which the temperature sensor is disposed and a node remote from the temperature sensor as a uniform temperature. Therefore, the difference between the actual temperature and the temperature used for the structural analysis becomes large at the node far from the temperature sensor. The greater the temperature deviation, the greater the deviation between the actual thermal displacement amount and the estimated thermal displacement amount.

  By disposing a large number of temperature sensors and increasing the number of blocks to be divided, temperature deviation within the same block is reduced. As a result, a highly accurate thermal displacement amount can be estimated. However, the higher the number of temperature sensors, the higher the cost.

  An object of this invention is to provide the condition determination method used for the thermal displacement amount estimation apparatus of a machine tool which can estimate a thermal displacement amount with high precision, reducing the number of blocks to divide | segment.

According to a first aspect of the present invention, there is provided a condition determining method used in a thermal displacement estimation apparatus for a machine tool, wherein at least one temperature distribution of the structure model is obtained by performing a thermal analysis of the structure model of the machine tool. A first thermal displacement at at least some nodes of the structure model by performing a structure analysis of the structure model based on a thermal analysis step of performing and a temperature distribution of the structure model acquired by the thermal analysis A first structural analysis step for obtaining a quantity, and when the structure model is divided into a plurality of blocks, each block temperature is a uniform value, and when each block temperature is a combination pattern, the structure A second structural analysis method for obtaining a second thermal displacement amount of each pattern at at least some nodes of the structural model by performing a structural analysis of the body model. When, as is as the difference between the second thermal displacement amount of each pattern and the first thermal displacement amount in the corresponding node is less optimal, optimal for determining the optimum combination pattern of block temperature of said each from the respective patterns In the pattern determination step, and when one temperature detection position is provided in one block, a node corresponding to the block temperature in the optimum combination pattern is selected from the temperature distribution obtained by the thermal analysis. position, and a temperature detection position determining step of determining as the temperature detection position in the structure of the machine tool.

  The first thermal displacement amount is approximately equal to the actual thermal displacement amount of the structure because the structure model is analyzed based on the temperature distribution of the structure model obtained by the thermal analysis. On the other hand, when the structural body model is divided into a plurality of blocks, the second thermal displacement amount is a value that deviates from the actual thermal displacement amount of the structural body in order to make each block temperature a uniform value.

In the optimum pattern determination step, the optimum combination pattern of the block temperatures is determined as being optimal as the difference between the first thermal displacement amount and the second thermal displacement amount is smaller . That is, the combination pattern of the block temperature as the difference becomes smaller is the optimum combination pattern. After the optimum combination pattern of block temperatures is determined, the temperature detection position corresponding to the optimum combination pattern is determined. In determining the temperature detection position, a temperature distribution by thermal analysis is used. Therefore, it is possible to estimate the amount of thermal displacement with high accuracy by arranging the temperature sensor at the obtained temperature detection position.

(Claim 2) In addition, the second structure analysis process, a block temperature of said each a pattern of a plurality of combinations, and, in the case where the block boundary position and pattern of a plurality of positions, the structure of the structure model By performing each analysis, the second thermal displacement amount of each pattern at at least some of the nodes of the structure model is obtained, and the optimum pattern determining step includes the first thermal displacement amount at the corresponding nodes and the respective thermal displacement amounts. The optimum position pattern of the block boundary position and the optimum combination pattern of the respective block temperatures may be determined as the smaller the difference from the second thermal displacement amount of the pattern, the more optimal .

In the optimum pattern determining step, the optimum position pattern of the block boundary position and the optimum combination pattern of the block temperature are determined such that the difference between the first thermal displacement amount and the second thermal displacement amount is reduced . That is, the combination pattern of the block boundary position and the block temperature that makes the difference small is the optimum pattern. After the optimum combination pattern of block temperatures is determined, the temperature detection position corresponding to the optimum combination pattern is determined. In determining the temperature detection position, a temperature distribution by thermal analysis is used. Therefore, by arranging the temperature sensor at the obtained temperature detection position and setting the block boundary position to be divided in the structural analysis as the optimum position pattern, it is possible to estimate the thermal displacement amount with high accuracy.

( Claim 3 ) Further, the respective block temperatures in the second structural analysis step are conditioned on being in a range between a minimum value and a maximum value in the respective blocks in the temperature distribution. May be. The temperature detected by the temperature sensor arranged in the block is a temperature selected from the temperatures in the block in the temperature distribution obtained by the thermal analysis. Therefore, by giving the above conditions, the calculation load required for the second structure analysis is reduced.

( Claim 4 ) Further, the thermal analysis step acquires a plurality of temperature distributions in a plurality of states, respectively, and the first structure analysis step performs a structural analysis of the structure model based on the plurality of temperature distributions. By performing the first thermal displacement amount in each temperature distribution, the second structure analysis step acquires the second thermal displacement amount of each pattern in the first state, and in the other state The second thermal displacement amount of each pattern is acquired based on the corresponding temperature of each node in the plurality of temperature distributions, and the optimum pattern determination step includes the first thermal displacement amount in each state and the second thermal displacement amount of each pattern. The optimum combination pattern of the respective block temperatures in the plurality of states may be determined based on the difference from the thermal displacement amount.

  The temperature distribution of the structure of the machine tool varies depending on the time zone, and varies depending on the season and installation environment. Therefore, by determining an optimal combination pattern of block temperatures in consideration of a plurality of temperature distributions, it is possible to estimate the amount of thermal displacement with high accuracy even if the environment changes.

( Claim 5 ) Further, the thermal analysis step acquires a plurality of temperature distributions in a plurality of states, respectively, and the first structure analysis step performs a structural analysis of the structure model based on the plurality of temperature distributions. By performing the first thermal displacement amount in each temperature distribution, the second structure analysis step acquires the second thermal displacement amount of each pattern in the first state, and in the other state The second thermal displacement amount of each pattern is acquired based on the corresponding temperature of each node in the plurality of temperature distributions, and the optimum pattern determination step includes the first thermal displacement amount in each state and the second thermal displacement amount of each pattern. The optimum position pattern of the block boundary position in the first state may be determined based on the difference from the thermal displacement amount.
By determining the optimum position pattern of the block boundary position in consideration of a plurality of temperature distributions, it is possible to estimate the amount of thermal displacement with high accuracy even if the environment changes.

( Claim 6 ) In addition, the first structure analysis step and the second structure analysis step include the first thermal displacement amount and the second structure at only some of the plurality of nodes included in the structure model. You may make it acquire the amount of thermal displacement. Since the displacement amounts are compared for only some of the nodes, the calculation load in the optimum pattern determination step is reduced.

( Claim 7 ) Further, the machine tool is provided with at least three moving axes in orthogonal directions, and the first structural analysis step and the second structural analysis step include the first thermal displacement amount only on one moving axis. And the second thermal displacement amount respectively, and the optimum pattern determination step is performed based on a difference between the first thermal displacement amount and the second thermal displacement amount of each pattern only on the one moving axis. The optimum pattern to be determined may be determined.

  The degree of influence on the machining accuracy is different for the movement axes in the three orthogonal directions. Therefore, by determining only the optimum pattern in consideration of only the movement axis that has a great influence on the machining accuracy, it is possible to obtain a high effect on the machining accuracy while keeping the calculation load low.

It is a figure which shows the machine structure of the machine tool of this embodiment. It is a block diagram which shows the structure of the non-structure of the machine tool of this embodiment. It is a perspective view which shows the structure model of a column. It is a figure which shows a block and a block boundary position in the structure model of a column. It is a flowchart of the determination method of the conditions (temperature detection position) by the condition determination apparatus in 1st embodiment. It is the 1st thermal displacement amount acquired in S2 of FIG. It is a block temperature table produced | generated by S3 of FIG. It is a block temperature pattern produced | generated by S4 of FIG. It is the 2nd thermal displacement amount of each pattern acquired in S5 of FIG. It is a figure of the column which shows the temperature detection position determined in S7 of FIG. It is the 1st thermal displacement amount acquired in 2nd embodiment. It is the 2nd thermal displacement amount of each pattern acquired in a second embodiment. It is a flowchart of the determination method of the conditions (temperature detection position) by the condition determination apparatus in 3rd embodiment. It is the 1st thermal displacement amount acquired in S12 of FIG. It is a block temperature table produced | generated in S13 of FIG. It is a morning block temperature pattern produced | generated in S14 of FIG. It is a daytime block temperature pattern produced | generated in S14 of FIG. It is the evening block temperature pattern produced | generated in S14 of FIG. It is the second thermal displacement amount of each morning pattern generated in S15 of FIG. It is the second thermal displacement amount of each daytime pattern generated in S15 of FIG. It is the 2nd thermal displacement amount of each pattern of evening produced | generated in S15 of FIG. It is a figure which shows the block boundary position in the structure model of the column determined in 4th embodiment. It is a flowchart of the determination method of the conditions (block boundary position) by the condition determination apparatus in 4th embodiment. It is a flowchart of the determination method of the conditions (temperature detection position and block boundary position) by the condition determination apparatus in 5th embodiment.

<First embodiment>
(1. Machine configuration of machine tool)
A horizontal machining center as an example of the machine tool 10 will be described with reference to FIG. The machine tool 10 is a machine tool having three rectilinear axes (X, Y, Z axes) orthogonal to each other (corresponding to the “movement axis” of the present invention) and a vertical rotation axis (B axis) as movement axes. is there. The machine tool 10 to which the present invention is applied is not limited to the machine tool 10 described below.

  As shown in FIG. 1, the machine body of the machine tool 10 includes a bed 11, a column 12, a saddle 13, a main shaft 14, a slide table 15, and a turntable 16 as structures. The bed 11 has a substantially rectangular shape and is arranged on the floor. A column 12 is provided on the bed 11 so as to be movable in the X-axis direction (the front-rear direction in FIG. 1). A saddle 13 is provided on the side surface of the column 12 so as to be movable in the Y-axis direction (up and down direction in FIG. 1). The saddle 13 is provided with a main shaft 14 so as to be rotatable about an axis parallel to the Z-axis direction. A rotary tool 19 is attached to the tip of the main shaft 14. A slide table 15 is provided on the bed 11 so as to be movable in the Z-axis direction. A turntable 16 is provided on the slide table 15 so as to be rotatable around the Y axis (B axis). A workpiece W is fixed to the turntable 16 via a jig.

(2. Outline of non-structure structure of machine tool)
As illustrated in FIG. 2, the machine tool 10 includes a thermal displacement estimation device 20, a thermal displacement correction device 30, and a control device 40 as non-structural bodies in addition to the structures 11 to 16 described above. The condition determination method of the present invention determines the condition of the thermal displacement amount estimation device 20.

  The control device 40 controls an actuator (not shown) for driving the structures 12 to 16 as the moving body to process the workpiece W with the rotary tool 19. In detail, the control apparatus 40 controls each actuator based on the position command value with respect to the structures 12-16 which move.

  The thermal displacement estimation device 20 analyzes the structure model in real time based on the detected temperatures T1 to T4 detected by each of the plurality of temperature sensors 21a to 21d arranged at predetermined positions of the structures 11 to 16. By performing the above, the amount of thermal displacement at a predetermined position of each of the structures 11 to 16 is estimated.

  For example, the thermal displacement estimation device 20 performs the structural analysis of the structure model of the column 12 based on the detected temperatures T1 to T4 by the plurality of temperature sensors 21a to 21d (shown in FIG. 1) arranged in the column 12. Thus, the amount of thermal displacement at a plurality of positions on the sliding surface (left side surface in FIG. 1) of the column 12 that contributes to the machining point thermal displacement with the saddle 13 is estimated. The plurality of temperature sensors 21 a to 21 d are not limited to the column 12 and may be arranged at predetermined positions of the structures 11 to 16 of the machine tool 10. Details of the thermal displacement estimation device 20 will be described later.

  The thermal displacement correction device 30 is a structure as a moving body in order to eliminate a shift in the relative position between the workpiece W and the rotary tool 19 caused by the thermal displacement of each structure 11 to 16 of the machine tool 10. Correction for position command values of 12 to 16 is performed.

  Specifically, as shown in FIG. 2, the thermal displacement correction device 30 includes a correction value calculation unit 31 and a correction unit 32. The correction value calculation unit 31 calculates the correction value of the position command value for the structures 12 to 16 as the moving body in real time based on the thermal displacement amount obtained by the thermal displacement amount estimation device 20. The correction unit 32 corrects the position command value by the control device 40 based on the correction value obtained by the correction value calculation unit 31.

(3. Basic explanation of structural analysis)
Next, the basics of the structural analysis by the structural analysis unit 23 (shown in FIG. 2) of the thermal displacement estimation device 20 will be described. With reference to FIG. 3 for the basics of the structural analysis when estimating the amount of thermal displacement of the column 12 by taking as an example the case of performing the thermal displacement correction accompanying the thermal displacement of the column 12 which is one of the structures of the machine tool 10. To explain. The structural analysis by the structural analysis unit 23 can be similarly applied to other structures such as the bed 11 in addition to the column 12.

  The structural analysis unit 23 performs structural analysis by a finite element method using the structure model. In FIG. 3, a thick line L1 is a shape line of the column 12, and a thin line L2 is a boundary line segment of the element S in the structural analysis by the finite element method. The end points of each thin line L2 are nodes Po1, Po2, Po3,. In FIG. 3, each element S is a tetrahedral primary element. Each element S is not limited to a tetrahedral primary element, and a tetrahedral secondary element, a hexahedral primary element, a hexahedral secondary element, or the like can be applied.

  That is, the structural analysis unit 23 performs real-time structural analysis on the structure model of the column 12 by the finite element method based on each element S of FIG. 3, and the structure model of the column 12 that contributes to the machining point thermal displacement. The amount of thermal displacement at some nodes Po1, Po2 and Po3 is estimated. Here, the temperature of all nodes is necessary as an analysis condition in the structural analysis by the finite element method for the structure model of the column 12.

(4. Description of block of structural analysis and block temperature)
When the structure analysis unit 23 performs the structure analysis using the temperatures of all the nodes of the structure model as the temperatures at the corresponding positions of the actual structures 11 to 16, it requires a very large number of calculations and requires a long time calculation. It takes time.

  Therefore, the structure analysis unit 23 divides the structure model into a plurality of blocks, and performs the structure analysis assuming that the block temperatures of the plurality of blocks are uniform values. Therefore, the temperature of each node used for the structural analysis by the structural analysis unit 23 is a value different from the temperature of each part of the actual structural bodies 11 to 16, but the structural analysis unit 23 can have a uniform block temperature. The amount of calculation of the structural analysis by 23 is greatly reduced, and high-speed calculation is possible.

  A plurality of blocks B1 to B4 obtained by dividing the structure model of the column 12 will be described with reference to FIG. As shown in FIG. 4, the structure model of the column 12 is divided by a Y-direction block boundary Ly and a Z-direction block boundary Lz. That is, the structure model of the column 12 is divided into a plurality of blocks B1 to B4. Actually, the structure model of the column 12 is divided into a plurality of blocks also in the X-axis direction. However, in FIG. 4, it is assumed that the structure model is divided only in the YZ plane.

  Each temperature sensor 21a-21d is arrange | positioned inside each of several block B1-B4. That is, the number of blocks B1 to B4 matches the number of temperature sensors 21a to 21d. Each of the block temperatures T1 to T4 of the plurality of blocks B1 to B4 is a uniform value, and is a detection temperature T1 to T4 detected by each of the plurality of temperature sensors 21a to 21d. Therefore, the temperatures of the nodes included in each of the blocks B1 to B4 are the corresponding block temperatures T1 to T4. For example, the temperatures of all nodes included in the block B1 are detected temperatures T1 by the temperature sensor 21a disposed inside the block B1.

  Here, the detected temperatures T1 to T4 by the temperature sensors 21a to 21d have different values depending on the positions where the temperature sensors 21a to 21d are arranged. Accordingly, the block temperatures T1 to T4 used for the structural analysis have different values depending on the positions of the temperature sensors 21a to 21d. The block temperatures T1 to T4 affect the analysis accuracy. Therefore, the position of the temperature sensors 21a to 21d that can estimate the thermal displacement amount with high accuracy is determined by the condition determination method described below.

(5. Detailed description of the thermal displacement estimation device 20)
Next, a thermal displacement amount estimation method by the thermal displacement amount estimation device 20 will be described with reference to FIGS. As shown in FIG. 2, the thermal displacement estimation device 20 includes temperature sensors 21 a to 21 d, a block temperature acquisition unit 22, and a structure analysis unit 23.

  As shown in FIG. 1, the temperature sensors 21 a to 21 d are arranged inside the column 12. As shown in FIG. 4, each temperature sensor 21a-21d is arrange | positioned inside the block B1-B4. The block temperature acquisition unit 22 acquires the block temperatures T1 to T4 as the detected temperatures of the corresponding temperature sensors 21a to 21d.

  The structure analysis unit 23 performs the structure analysis of the structure model of the column 12 based on the block temperatures T1 to T4 in each of the plurality of blocks B1 to B4. In the present embodiment, the structural analysis unit 23 performs a structural analysis by the finite element method on the structural body model of the column 12, and among the sliding surfaces of the saddle 13 in the column 12, the heat of predetermined nodes Po 1, Po 2, Po 3. Estimate the amount of displacement. As conditions for the structural analysis, material constants, temperatures at each node, structural constraints, spring elements in the support structure, and the like are required. Here, among the conditions of the structural analysis, only the temperature at each node changes, and other conditions are known. And the block temperature T1-T4 acquired by the block temperature acquisition part 22 is used for the temperature information in each node.

The structural analysis by the structural analysis unit 23 is expressed by a matrix arithmetic expression such as Expression (1). The number of computations of equation (1) is N _part1 × 2 × N _block times. Here, in the following formulas, the number of rows and columns or the number of elements is used.

Here, {[delta] _part1} is a node Po1, Po2, Po3 thermal displacement amount vector of (number of elements N _part1). [P1 _part1] is node Po1, Po2, Po3 coefficient related to the matrix (the number of rows N _part1, the number of columns N _block) is. {T _block } is a temperature vector (number of elements N _block ) of each of the blocks B1 to B4. That is, {T _block } corresponds to the block temperature T1 to T4 displayed as a column vector.

That is, the structural analysis unit 23 uses the coefficient matrix [P1 _part1 ] stored in advance and the block temperatures T1 to T4 acquired by the block temperature acquisition unit 22, and the thermal displacement of the nodes Po1, Po2, Po3 according to the equation (1). Get quantity.

(6. Method for deriving structural analysis formula)
Hereinafter, a method for deriving the matrix arithmetic expression (formula (1)) used for the structural analysis by the structural analysis unit 23 will be described. The stiffness equation of the structure model is expressed by equation (2). {F} is an external force vector (number of elements N _all ) at each node. [K] is a stiffness matrix (number of rows N _all , number of columns N _all ), which is a known value obtained from the material constant of the column 12 and the shape of the column 12. {Δ _all } is a displacement vector (number of elements N _all ) of each node. all means the number of all nodes. All vectors used in the specification mean column vectors.

Further, the relational expression of the nodal force according to the temperature of the nodal point is expressed by the formula (3). [F] is a nodal force coefficient matrix (number of rows N _all , number of columns N _all ), which is a known value obtained from the material constant of the column 12 and the shape of the column 12. {T _all } is a temperature vector (number of elements N _all ) at each node.

Since the left sides of Expressions (2) and (3) are common, the thermal displacement vector {δ _all } at each node is expressed as Expression (4). That is, the thermal displacement vector {δ _all } at each node in Equation (4) corresponds to the thermal displacement at each node. Here, for ease of later explanation, the multiplication matrix of the inverse matrix of the stiffness matrix [K] and the nodal force coefficient matrix [F] is expressed as [P] as shown in Equation (5).

In order to calculate the thermal displacement vector {δ _all } of all the nodes, that is, the thermal displacement amount of all the nodes based on the equation (5), a very large number of calculation times are required and a long calculation time is required. Cost. However, in the present embodiment, the temperatures of the nodes in each of the blocks B1 to B4 obtained by dividing the structure model of the column 12 into a plurality are uniform values. That is, the type of temperature is the same as the total number of blocks B1 to B4. Then, the above-described equation (5) is expressed as equation (6) as follows.

The number of calculations in equation (6) can be significantly reduced compared to the number of calculations in equation (5) described above, but it can be further reduced by doing the following. The thermal displacement vector {δ _all } indicates the thermal displacement at all nodes of the structure model of the column 12. However, in order to perform correction by the thermal displacement correction device 30, the amount of thermal displacement of the entire column 12 is not necessary, and only a portion of the column 12 where the saddle 13 slides is sufficient. Therefore, the equation (6) thermal displacement amount vector {[delta] _all} in, some of the nodes of column 12 Po1, Po2, the thermal displacement amount vectors {[delta] _part1} in Po3, thermal displacement at the nodes of the other sites When divided into vectors {δ _part2 }, the following equation (7) is obtained.

Of the formula (7), when to extract only thermal displacement vector {[delta] _part1} at the nodes Po1, Po2, Po3 of the structure model of the column 12 can be expressed as the above-mentioned equation (1).

(7. Condition determination method)
The condition determination method of this embodiment determines the position where the temperature sensors 21a to 21d are arranged, that is, the position where the block temperatures T1 to T4 are detected. The condition determination method will be described with reference to FIGS. Here, the condition determination method is performed by a condition determination apparatus configured by a computer. That is, the following processing is processing by the condition determining device.

  As shown in FIG. 5, the condition determining device performs thermal analysis on the structure model of the column 12 (S <b> 1: thermal analysis step in FIG. 5). The thermal analysis is performed based on a structure model, a heat transfer condition of the structure, an externally applied heat condition applied to the structure, a constraint condition, and the like. The heat transfer condition depends on the material of the structure, for example. The externally applied heat condition is, for example, the environmental temperature of the structure, heat received from an external structure (for example, the main shaft 14). The constraint condition is a condition in which thermal displacement is restricted.

  The condition determining device acquires the temperature distribution of the structure model of the column 12 by thermal analysis. In the present embodiment, the condition determining device acquires the temperature distribution of the structure model when, for example, an average environmental temperature change in one day is used as a condition. Note that the case where the condition determining device acquires a plurality of temperature distributions will be described in another embodiment.

Subsequently, the condition determination device performs a first structure analysis of the structure model based on the temperature distribution of the structure model of the column 12 acquired by the thermal analysis (S2 in FIG. 5: first structure analysis step). As a result, the condition determining device, as shown in FIG. 6, the first thermal displacement amounts δ _{No1, Z1} , δ at at least some of the nodes Po1, Po2, Po3 (shown in FIGS. 3 and 4) of the structure model. _{Get No1, Z2} and _{δNo1, Z3} .

In the present embodiment, the first thermal displacement amounts _{ΔNo1, Z1} , _{ΔNo1, Z2} , and _{ΔNo1, Z3} acquired by the condition determining device acquire only the thermal displacement amount in the Z-axis direction. The suffix No. 1 corresponds to the first thermal displacement amount, and the suffixes Z1, Z2, and Z3 correspond to the nodes Po1, Po2, and Po3. The first thermal displacement amounts δ _{No1, Z1} , δ _{No1, Z2} , δ _{No1, Z3} coincide with the actual thermal displacement amounts of the nodes Po1, Po2, Po3 of the column 12 under the conditions used in the thermal analysis.

  The condition determining device performs the following processing in parallel with the first thermal analysis step. The condition determining device generates a block temperature table related to the blocks B1 to B4 as shown in FIG. 7 based on the temperature distribution of the structure model of the column 12 obtained by thermal analysis (S3 in FIG. 5: block temperature). Table generation step).

As shown in FIG. 7, the block temperature table shows the minimum values Ta _B1,1 , Ta _B2,1 , Ta _B3,1 , Ta _B4,1 to the maximum value Ta _B1,1 for each of the blocks B1 to B4 _{. n1} , Ta _{B2, n2} , Ta _{B3, n3} , Ta _{B4, n4} are arranged in this order. The node temperature subscripts B1 to B4 correspond to the blocks B1 to B4, and the subscripts n1, n2, n3, and n4 correspond to the number of types of node temperatures in each of the blocks B1 to B4. That is, n1, n2, n3, and n4 are numbers equal to or less than the number of nodes in each of the blocks B1 to B4.

Subsequently, the condition determining device generates a block temperature pattern C when each block temperature is a plurality of combination patterns based on the block temperature table (S4 in FIG. 5: block temperature pattern generating step). As shown in FIG. 8, each of the block temperature patterns C1 to _Cj includes the block temperatures Ta _{B1,1 to} Ta _{B1, n1} , Ta _{B2,1 to} Ta _{B2, n2} , and Ta _B3,1 of the blocks B1 to B4. -TaB3 _{, n3} , _TaB4,1 -TaB4 _{, n4} are included. For example, the pattern C1 is a pattern including Ta _B1,1 , Ta _B2,1 , Ta _B3,1 and Ta _B4,1 . That is, the number of patterns C is “n1 × n2 × n3 × n4”.

Subsequently, the condition determining apparatus performs the second structure analysis of the structure model of the column 12 for each of the block temperature patterns C (S5 in FIG. 5: second structure analysis step). As a result, the condition determining apparatus, as shown in FIG. 9, the second thermal displacement amount δ _{No2, Z1, C1} at at least some nodes Po1, Po2, Po3 (shown in FIGS. 3 and 4) of the structure model. _{~δ No2, Z1, Cj, δ} No2, Z2, C1 ~δ No2, Z2, Cj, δ No2, Z3, C1 ~δ No2, Z3, acquires _Cj.

In the present embodiment, the second thermal displacement amounts δ _{No2, Z1, C1 to} δ _{No2, Z1, Cj} , δ _{No2, Z2, C1 to} δ _{No2, Z2, Cj} , δ _{No2, Z3,} acquired by the condition determining device _{. C1 to} δ _{No2, Z3, and Cj} shall acquire only the amount of thermal displacement in the Z-axis direction. Subscript No2 corresponds to the second thermal displacement amount, subscripts Z1, Z2, and Z3 correspond to nodes Po1, Po2, and Po3, and subscripts C1 to Cj correspond to block temperature pattern C. .

Here, the second structural analysis in the condition determining apparatus is a structural analysis performed by the structural analysis unit 23 according to the equation (1). Since the number of blocks is four and the number of nodes is three, the coefficient matrix [P1 _part1 ] in Expression (1) is expressed as Expression (8).

Then, the second thermal displacement amounts δ _{No2, Z1, C1} , δ _{No2, Z2, C1} , and δ _{No2, Z3,} C1 in the pattern C1 are expressed as in Expression (9). Further, the second thermal displacement amounts δ _{No2, Z1, Cj} , δ _{No2, Z2, Cj} , and δ _{No2, Z3,} Cj in the pattern Cj are expressed as in Expression (10).

Subsequently, the condition determining device determines the first thermal displacement amounts δ _{No1, Z1} , δ _{No1, Z2} , δ _{No1, Z3} and the second thermal displacement amounts δ _{No2, Z1} of the respective patterns C at the corresponding nodes Po1, Po2, Po3. _{, C1 to} δ _{No2, Z1, Cj} , δ _{No2, Z2, C1 to} δ _{No2, Z2, Cj} , δ _{No2, Z3, C1 to} δ _{No2, Z3, Cj} Is determined (S6 in FIG. 5: optimal pattern determination step). That is, the condition determining device selects one pattern from the patterns C1 to Cj.

The optimum combination pattern of each block temperature is a combination pattern that minimizes the evaluation function Φ1 shown in Expression (11). That is, the second thermal displacement amounts δ _{No2, Z1, C1 to} δ _{No2, Z1, Cj} , δ _{No2, Z2, C1 to} δ _{No2, Z2, Cj} , δ _{No2, Z3, C1} to each of the patterns _C1 to _Cj When δ _{No 2, Z 3, and Cj} are respectively substituted into Expression (11), the pattern C that minimizes the evaluation function Φ1 is the optimum combination pattern. Here, in Expression (11), the subscript Z (m) corresponds to Z1, Z2, and Z3, and the subscript C corresponds to any one of the patterns C1 to Cj.

  Subsequently, based on the optimum combination pattern of each block temperature and the temperature distribution of the structure model obtained by the thermal analysis, the condition determining device determines the temperature detection position, that is, the temperature in the machine tool structure (column 12). The arrangement positions of the sensors 21a to 21d are determined (S7 in FIG. 5: temperature detection position determination step).

For example, when the pattern C2 is determined as the optimal combination pattern of the block temperatures in the optimal pattern determination step, the optimal block temperature of each of the blocks B1 to B4 is Ta _B1,2 , Ta _B2,1 , Ta _B3,1 and Ta _B4,1 .

The determination of the temperature detection position in block B1 will be described. The condition determining device extracts a node coincident with the optimum block temperature Ta _B1,2 from the temperature distribution in the block B1 obtained by the thermal analysis. The position of the extracted node is the temperature detection position, that is, the position where the temperature sensor 21a is arranged. The determination of the temperature detection position in the blocks B2 to B4 is the same.

  FIG. 10 shows a state in which the temperature sensors 21a (C2), 21b (C2), 21c (C2), and 21d (C2) are arranged at the positions of the nodes corresponding to the pattern C2. The temperature sensors 21a to 21d are arranged at the positions shown in FIG. 10, the block temperature acquisition unit 22 shown in FIG. 2 acquires the block temperatures T1 to T4, and the structural analysis unit 23 performs structural analysis based on the block temperatures T1 to T4. I do.

Here, the first thermal displacement amounts δ _{No1, Z1} , δ _{No1, Z2} , δ _{No1, Z3} are the first structure analysis of the structure model based on the temperature distribution of the structure model of the column 12 obtained by the thermal analysis. Therefore, the actual thermal displacement amount of the column 12 is substantially equal. On the other hand, the second thermal displacement δ _{No2, Z1, C1 to} δ _{No2, Z1, Cj} , δ _{No2, Z2, C1 to} δ _{No2, Z2, Cj} , δ _{No2, Z3, C1 to} δ _{No2, Z3, Cj} are When the structure model of the column 12 is divided into a plurality of blocks B1 to B4, the block temperatures Ta _{B1,1 to} Ta _{B1, n1} , Ta _{B2,1 to} Ta _{B2, n2} , Ta _{B3,1 to} Ta _{B3, Since n3} and Ta _{B4,1 to} Ta _{B4, n4} are set to uniform values, the values deviate from the actual thermal displacement of the structure.

However, in the optimum pattern determination process, the first thermal displacement amount δ _{No1, Z1} , δ _{No1, Z2} , δ _{No1, Z3} and the second thermal displacement amount δ _{No2, Z1, C1 to} δ _{No2, Z1, Cj} , δ _{No2 , Z2, C1 ~δ No2, Z2} , Cj, based on the difference between the _{δ No2, Z3, C1 ~δ No2} , Z3, Cj, optimal combination pattern of the block temperature is determined. First thermal displacement δ _{No1, Z1} , δ _{No1, Z2} , δ _{No1, Z3} and second thermal displacement δ _{No2, Z1, C1 to} δ _{No2, Z1, Cj} , δ _{No2, Z2, C1 to} δ _{No2, Z2 , Cj} , δ _{No2, Z3, C1 to} δ _{No2, Z3, Cj} , the smaller the difference, the more optimal. That is, the combination pattern of the block temperature that makes the difference small is the optimum combination pattern. After the optimum combination pattern of block temperatures is determined, the temperature detection position corresponding to the optimum combination pattern is determined. In determining the temperature detection position, a temperature distribution by thermal analysis is used. Therefore, by arranging the temperature sensors 21a (C2), 21b (C2), 21c (C2), and 21d (C2) at the obtained temperature detection positions, it is possible to estimate the amount of thermal displacement with high accuracy.

In addition, each block temperature Ta _{B1,1 to} Ta _{B1, n1} , Ta _{B2,1 to} Ta _{B2, n2} , Ta _{B3,1 to} Ta _{B3, n3} , Ta _{B4,1 to} Ta _{B4, For n4} , the block temperature table shown in FIG. 7 is used. That is, each block temperature Ta _{B1,1 to} Ta _{B1, n1} , Ta _{B2,1 to} Ta _{B2, n2} , Ta _{B3,1 to} Ta _{B3, n3} , Ta _{B4,1 to} Ta _{B4, n4} is determined by thermal analysis. The condition is that the temperature distribution is within the range between the minimum value and the maximum value in each of the blocks B1 to B4. The detected temperatures T1 to T4 by the temperature sensors 21a to 21d arranged in the blocks B1 to B4 are temperatures selected from the temperatures in the blocks B1 to B4 in the temperature distribution by the thermal analysis. Therefore, by giving the above conditions, the calculation load required for the second structure analysis is reduced.

  Further, the first structure analysis step and the second structure analysis step in the condition determining apparatus include the first thermal displacement amount at only some of the nodes Po1, Po2, Po3 among the plurality of nodes included in the structure model of the column 12. Obtain the second thermal displacement. Since the displacement amounts are compared for only some of the nodes Po1, Po2 and Po3, the calculation load in the optimum pattern determination step is reduced.

  Further, the machine tool is provided with a moving axis in three orthogonal directions. However, the structural analysis by the structural analysis unit 23, and the first structural analysis and the second structural analysis in the condition determining device are the thermal displacement amount, the first thermal displacement amount and the second thermal displacement only on one moving axis (Z axis). Get the displacement amount. A corresponding optimum pattern is determined based on the difference between the first thermal displacement amount on only one movement axis (Z-axis) and the second thermal displacement amount of each pattern.

  Here, the degree of influence on the machining accuracy differs in the movement axes in the three orthogonal axes. Therefore, by determining the optimum pattern in consideration of only the movement axis (Z axis) that has a great influence on the machining accuracy, it is possible to obtain a high effect on the machining accuracy while keeping the calculation load low.

<Second embodiment>
In the first embodiment, the condition determination device determines the temperature detection position based on the first thermal displacement amount and the second thermal displacement amount in the Z-axis direction. In the second embodiment, the condition determining device determines the temperature detection position based on the first thermal displacement amount and the second thermal displacement amount in the X, Y, and Z axis directions.

The condition determining apparatus performs the first structure analysis of the structure model based on the temperature distribution of the structure model of the column 12 acquired by the thermal analysis in S1 of FIG. 5 (S2 of FIG. 5: first structure analysis step). . As a result, the condition determining device, as shown in FIG. 11, has first thermal displacement amounts δ _{No1, X1} , δ _No1 at some nodes Po1, Po2, Po3 (shown in FIGS. 3 and 4) of the structure model. _{, X2} , δ _{No1, X3} , δ _{No1, Y1} , δ _{No1, Y2} , δ _{No1, Y3} , δ _{No1, Z1} , δ _{No1, Z2} , δ _{No1, Z3} .

  The subscripts X1, X2, and X3 correspond to the X-axis direction of the nodes Po1, Po2, and Po3. The subscripts Y1, Y2, and Y3 correspond to the Y-axis direction of the nodes Po1, Po2, and Po3. Subscripts Z1, Z2, and Z3 correspond to the Z-axis direction of nodes Po1, Po2, and Po3.

Then, the condition determination device performs the second structural analysis in S5 of FIG. 5 to obtain the second thermal displacement amount δ _No2 at some nodes Po1, Po2, Po3 of the structure model as shown in FIG. (S5 in FIG. 5: second structure analysis step).

The condition determining apparatus determines the difference between the first thermal displacement amount δ _No1 (shown in FIG. 11) at the corresponding nodes Po1, Po2, Po3 and the second thermal displacement amount δ _No2 (shown in FIG. 12) of each pattern C. Based on the above, the optimum combination pattern of each block temperature is determined (S6 in FIG. 5: optimum pattern determination step). That is, the condition determining apparatus selects one pattern from the patterns C1 to Cj shown in FIG.

The optimum combination pattern of each block temperature is a combination pattern that minimizes the evaluation function Φ2 shown in Expression (12). That is, when the second thermal displacement amount δ _No2 for each of the patterns C1 to Cj is substituted into the equation (12), the pattern C that minimizes the evaluation function Φ2 is the optimal combination pattern.

Subsequently, the condition determining device determines the temperature detection position in the structure (column 12) of the machine tool based on the optimum combination pattern of each block temperature and the temperature distribution of the structure model acquired by thermal analysis. (S7 in FIG. 5: temperature detection position determination step).
As in the present embodiment, by determining the temperature detection position in consideration of the X, Y, and Z axis directions, the calculation load increases, but a more accurate thermal displacement amount can be estimated.

<Third embodiment>
In the first embodiment, the temperature detection position is determined using the temperature distribution in a predetermined state (corresponding to a predetermined time state or an average state in a predetermined season). In the third embodiment, the temperature detection position is determined using temperature distributions in a plurality of states. Here, the plurality of states correspond to a state at a plurality of times in a day, a state at each predetermined time of a plurality of seasons, a state at a plurality of times for each of the plurality of seasons, and the like. In the following, three states of morning, noon and evening are considered.

  Processing of the condition determining device in the present embodiment will be described with reference to FIGS. 13 to 17C. As shown in FIG. 13, the condition determining device performs thermal analysis for each of the three states of morning, noon, and evening for the structure model of the column 12 (S <b> 11 in FIG. 13: thermal analysis step). That is, the externally applied heat condition applied to the structure varies depending on the time zone. Therefore, the condition determination device acquires the temperature distribution of the three states of the structure model of the column 12 by thermal analysis.

Subsequently, the condition determining apparatus performs a first structure analysis of the structure model based on each of the three temperature part distributions of the structure model of the column 12 acquired by the thermal analysis (S12 in FIG. 13: first Structural analysis process). As a result, as shown in FIG. 14, the condition determining apparatus performs at least some nodes Po1, Po2, Po3 (shown in FIGS. 3 and 4) of the structure model for each of the three states of morning, noon, and evening. ) First thermal displacement δ _{No1, Z1, D1} , δ _{No1, Z2, D1} , δ _{No1, Z3, D1} , δ _{No1, Z1, D2} , δ _{No1, Z2, D2} , δ _{No1, Z3, D2} , δ _{Get No1, Z1, D3} , _{δNo1, Z2, D3} , _{δNo1, Z3, D3} . Subscripts D1, D2, and D3 correspond to morning, noon, and evening.

  The condition determining device performs the following processing in parallel with the first thermal analysis step. Based on the temperature distribution of the structure model of the column 12 obtained by the thermal analysis, the condition determining apparatus performs blocks related to blocks B1 to B4 for each of the three states of morning, noon, and evening as shown in FIG. A temperature table is generated (S13 in FIG. 13: block temperature table generation step).

  Here, as shown in FIG. 15, the daytime and evening node temperatures in the block temperature table are generated as the temperatures at the daytime and evening nodes corresponding to the morning nodes when the morning node temperatures are used as a reference. . That is, in FIG. 15, the node temperatures described in the same row are the morning, noon, and evening temperatures at the same node.

As shown in the first column and the second column of the node temperature of the block B1 in FIG. 15, there are a plurality of nodes whose morning node temperatures are Ta _{B1,1, D1} . Evening temperatures may vary. In such a case, each is considered as a different type, and one of the morning node temperatures is Ta _{B1,1, D1, case1,} and the other morning node temperature is Ta _{B1,1, D1, case2} .

Subsequently, the condition determining device generates a block temperature pattern C when each block temperature is a plurality of combination patterns based on the block temperature table (S14 in FIG. 13: block temperature pattern generation step). That is, the block temperature patterns C1 _{D1 to} Cj _D1 related to the morning are as shown in FIG. 16A. The block temperature patterns related to daytime and evening are as shown in FIGS. 16B and 16C for C1 _{D2 to} Cj _D2 and C1 _{D3 to} Cj _D3 .

Here, the morning, noon, and evening block temperatures in the same pattern C are the temperatures of the same nodes in each block. For example, if the numbers following C are the same, it means that the temperature of block B1 in pattern C1 _D1 is the morning temperature of node X, and the temperature of block B1 in pattern C1 _D2 is The temperature is the daytime temperature of the node X, and the temperature of the block B1 in the pattern C1 _D3 is the evening temperature of the node X.

Subsequently, the condition determining device performs the second structural analysis of the structure model of the column 12 for each of the block temperature patterns C in each of the three states of morning, noon, and evening (S15 in FIG. 13: second). Structural analysis process). As a result, as shown in FIGS. 17A, 17B, and 17C, the condition determining apparatus performs the second thermal displacement amount at at least some nodes Po1, Po2, Po3 (shown in FIGS. 3 and 4) of the structure model. δ _No2 is acquired.

That is, the condition determination device acquires the second thermal displacement amount δ _No2 of each pattern C1 _{D1 to} Cj _D1 in the morning as the first state by the second structural analysis, and each day and evening in the other states. The second thermal displacement amounts δ _No2 of the patterns C1 _{D2 to} Cj _D2 and C1 _{D3 to} Cj _D3 are acquired based on the corresponding temperatures of the nodes in the temperature distribution of the three states.

Subsequently, the condition determining apparatus determines each of the first thermal displacement amount δ _{No1 at} the corresponding nodes Po1, Po2, Po3 and the second thermal displacement amount δ _{No2 of} each pattern C in the three states of morning, noon, and evening. Based on the difference, an optimal combination pattern of each block temperature is determined (S16 in FIG. 13: optimal pattern determination step). That is, the condition determining device selects one pattern from the patterns C1 to Cj. The optimum combination pattern of each block temperature is a combination pattern that minimizes the evaluation function Φ3 shown in Expression (13). Here, in Expression (13), the subscript D (q) corresponds to D1, D2, and D3.

For example, it is assumed that the optimum combination pattern is C2. That is, the optimum combination pattern of each block temperature in the morning is C2 _D1 shown in FIG. 16A. The optimum combination pattern of the respective block temperatures in the daytime is C2 _D2 shown in FIG. 16B. The optimum combination pattern of each block temperature in the evening is C2 _D3 shown in FIG. 16C.

  Subsequently, based on the optimum combination pattern of each block temperature and the temperature distribution of the structure model obtained by the thermal analysis, the condition determining device determines the temperature detection position, that is, the temperature in the machine tool structure (column 12). The arrangement positions of the sensors 21a to 21d are determined (S17 in FIG. 13: temperature detection position determination step). That is, the position of the node corresponding to each block temperature pattern C2 is the temperature detection position.

  As described above, the temperature distribution of the structure of the machine tool varies depending on the time zone, and varies depending on the season and the installation environment. Therefore, by determining an optimal combination pattern of block temperatures in consideration of a plurality of temperature distributions, it is possible to estimate the amount of thermal displacement with high accuracy even if the environment changes.

<Fourth embodiment>
In the above embodiment, based on the difference between the first thermal displacement amount δ _No1 based on the first structural analysis and the second thermal displacement amount δ _No2 based on the second structural analysis in a state where the boundary positions of the blocks B1 to B4 are fixed. The temperature detection positions of the blocks B1 to B4 were determined. In the present embodiment, the boundary positions of the blocks B1 to B4 are determined in a state where the temperature detection positions in the blocks B1 to B4 are fixed.

  For example, the case of column 12 will be described as an example. As shown in FIGS. 4 and 18, the plurality of blocks B1 to B4 in the structure model of the column 12 are partitioned by block boundaries Ly and Lz. The temperature detection positions, that is, the arrangement positions of the temperature sensors 21a to 21d are fixed positions as shown in FIGS. In this case, the positions of the block boundaries Ly and Lz can be the positions shown in FIG. 4 or the positions shown in FIG. In the present embodiment, the positions of the block boundaries Ly and Lz are determined.

Processing of the condition determining device in the present embodiment will be described with reference to FIG. The condition determining apparatus performs a thermal analysis (S21 in FIG. 19), and performs a first structural analysis to obtain a first thermal displacement amount δ _No1 (S22 in FIG. 19). Thermal analysis and first structural analysis are the same as in the first embodiment.

  The condition determination device performs the following processing in parallel with the first structural analysis. The condition determining device acquires temperatures at a plurality of predetermined positions set in advance based on the temperature distribution of the structure model of the column 12 acquired by thermal analysis (S23 in FIG. 19, block temperature acquisition step). The plurality of predetermined positions are positions where the temperature sensors 21a to 21d are arranged, and are predetermined positions.

Subsequently, the second thermal displacement amount δ _No2 is obtained by performing the second structural analysis for each of the plurality of patterns E in which the positions of the block boundaries Ly and Lz are changed (S24 in FIG. 19, the second structural analysis). Process). Here, the block boundary Ly in the Y-axis direction includes the Y-axis position of the temperature sensor located on the Y-axis minus side (the lower side in FIG. 18) of the two temperature sensors 21a and 21c, and the two temperature sensors 21b, It is changed between the Y axis position of the temperature sensor located on the Y axis plus side (upper side in FIG. 18) of 21d. The block boundary Lz in the Z-axis direction is the Z-axis position of the temperature sensor located on the Z-axis minus side (the right side in FIG. 18) of the two temperature sensors 21a and 21b, and the two temperature sensors 21c and 21d. It is changed between the Z axis position of the temperature sensor located on the Z axis plus side (left side in FIG. 18).

Therefore, in each of the position patterns E, the coefficient matrix [P1 _part1 ] in Expression (1) relating to the second structure analysis in the condition determining device is different. That is, Expression (1) in the second structure analysis is represented by Expression (14) in the case of the position pattern E1, and is represented by Expression (15) in the case of the position pattern Ek. Here, the coefficient matrices [P1 _part1 (E1)] and [P1 _part1 (Ek)] in the respective position patterns E1 and Ek are expressed by equations (16) and (17).

When Expressions (14) and (15) are developed, the second thermal displacement amounts δ _No2 of the nodes Po1, Po2 and Po3 in the position patterns E1 and Ek are expressed by Expressions (18) and (19).

Subsequently, the condition determining device determines the block boundary position based on the difference between the first thermal displacement amount δ _{No1 at} the corresponding nodes Po1, Po2, Po3 and the second thermal displacement amount δ _{No2 of} each position pattern E. An optimal position pattern is determined (S25 in FIG. 19: optimal pattern determination step). That is, the condition determining device selects one pattern from among the plurality of position patterns E.

The optimum position pattern of the block boundary position is a pattern that minimizes the evaluation function Φ4 shown in Expression (20). That is, the second thermal displacement amounts δ _{No2, Z1, E1 to} δ _{No2, Z1, Ej} , δ _{No2, Z2, E1 to} δ _{No2, Z2, Ek} , δ _{No2, Z3, E1} to each of the patterns _E1 to _Ek When δ _{No 2, Z 3, and Ek} are respectively substituted into Expression (20), the pattern E that minimizes the evaluation function Φ4 is the optimum position pattern. Here, in the equation (20), the subscript E corresponds to any of the patterns E1 to Ek.

From the above, for example, the positions of the block boundaries Ly and Lz shown in FIG. From equation (22), it can be said that the smaller the difference between the first thermal displacement amount δ _No1 and the second thermal displacement amount δ _No2 , the more optimal. That is, the block boundary position pattern E that makes the difference small is the optimum position pattern. Therefore, by dividing into the plurality of blocks B1 to B4 based on the determined positions of the block boundaries Ly and Lz, it is possible to estimate the thermal displacement amount with high accuracy.

  In the determination of the block temperature in the third embodiment, the determination of the optimum block temperature using a plurality of temperature distributions can be applied to the determination of the block boundary position in the present embodiment. In this case, even if the environment changes, a highly accurate thermal displacement amount is estimated.

<Fifth embodiment>
In the present embodiment, the boundary position between the blocks B1 to B4 is changed, and the difference between the second thermal displacement amount δ _No2 and the first thermal displacement amount δ _No1 of each pattern when the temperature detection position is changed. Based on the above, the optimal positions of the block boundaries Ly and Lz are determined, and the optimal temperature detection positions in the blocks B1 to B4 divided by the determined block boundaries Ly and Lz are determined.

Processing of the condition determining device in the present embodiment will be described with reference to FIG. The condition determining device performs a thermal analysis (S31 in FIG. 20), performs a first structural analysis, and obtains a first thermal displacement amount δ _No1 (S32 in FIG. 20). Thermal analysis and first structural analysis are the same as in the first embodiment.

  The condition determination device performs the following processing in parallel with the first structural analysis. The condition determining device generates a block temperature table for each pattern E of the block boundary position based on the temperature distribution of the structure model of the column 12 obtained by thermal analysis (S33 in FIG. 20: block temperature table generating step). . That is, the condition determining apparatus generates a block temperature table as shown in FIG. 7 for each position pattern E of the block boundaries Ly and Lz.

  Subsequently, based on the block temperature table, the condition determining device generates a block temperature pattern C when each block temperature is a plurality of combination patterns for each position pattern E (S34 in FIG. 20: block temperature pattern). Production process). That is, the condition determining apparatus generates a block temperature table as shown in FIG. 8 for each position pattern E of the block boundaries Ly and Lz.

  Subsequently, the condition determining apparatus performs the second structure analysis of the structure model of the column 12 for each of the block temperature patterns C for each position pattern E (S35 in FIG. 20: second structure analysis step).

Subsequently, the condition determining device determines the difference between the first thermal displacement amount δ _{No1 at} the corresponding nodes Po1, Po2, Po3 and the second thermal displacement amount δ _No2 of the temperature pattern C for each position pattern E, An optimum position pattern of the block boundary position is determined, and an optimum combination pattern of block temperatures in the determined optimum position pattern (S36 in FIG. 20: optimum pattern determination step).

The optimum pattern related to the block boundary position and the block temperature is a pattern that minimizes the evaluation function Φ5 shown in Expression (21). That is, when the second thermal displacement amount δ _No2 for each of the patterns E1 to Ek and for each of the patterns C1 to Cj is substituted into the equation (21), the pattern E and the pattern that minimizes the evaluation function Φ5 C is the optimum pattern.

  Subsequently, based on the optimum combination pattern of each block temperature and the temperature distribution of the structure model obtained by the thermal analysis, the condition determining device determines the temperature detection position, that is, the temperature in the machine tool structure (column 12). The arrangement positions of the sensors 21a to 21d are determined (S37 in FIG. 20: temperature detection position determination step).

  As described above, in the optimum pattern determination step, the block boundary position pattern and the block temperature combination pattern that reduce the difference between the first thermal displacement amount and the second thermal displacement amount are set as the optimum patterns. After the optimum combination pattern of block temperatures is determined, the temperature detection position corresponding to the optimum combination pattern is determined. In determining the temperature detection position, a temperature distribution based on thermal analysis is used. Therefore, by arranging the temperature sensor at the obtained temperature detection position and setting the block boundary position to be divided in the structural analysis as the optimum position pattern, it is possible to estimate the thermal displacement amount with high accuracy.

10: Machine tool, 11: Bed, 12: Column, 13: Saddle, 14: Spindle, 15: Slide table, 16: Turntable, 19: Rotary tool, 20: Thermal displacement estimation device, 21a-21d: Temperature sensor B1-B4: Block, Ly, Lz: Block boundary, Po1, Po2, Po3: Node

Claims (7)

A thermal analysis step of obtaining at least one temperature distribution of the structure model by performing a thermal analysis of the structure model of the machine tool;
A first thermal displacement amount is acquired at at least some nodes of the structure model by performing a structure analysis of the structure model based on a temperature distribution of the structure model acquired by the thermal analysis. Structural analysis process;
When the structure model is divided into a plurality of blocks, each block temperature is a uniform value, and when each of the block temperatures is a plurality of combinations of patterns, the structure model is subjected to a structural analysis. A second structural analysis step of obtaining a second thermal displacement amount of each pattern at at least some nodes of the structure model;
Optimal pattern determination that determines the optimum combination pattern of each block temperature from each pattern, assuming that the smaller the difference between the first thermal displacement amount at the corresponding node and the second thermal displacement amount of each pattern, the more optimal Process,
In the case where one block has one temperature detection position, the position of the node corresponding to the block temperature in the optimum combination pattern is selected from the temperature distribution obtained by the thermal analysis. a temperature detecting position determination step of determining, as the temperature detection position in a structure of the machine,
The condition determination method used for the thermal displacement amount estimation apparatus of a machine tool provided with. In the second structural analysis step, when each block temperature is a pattern of a plurality of combinations, and the block boundary position is a pattern of a plurality of positions, by performing a structural analysis of the structure model, Obtaining a second thermal displacement amount of each pattern at at least some nodes of the structure model;
The optimum pattern determining step is assumed to be optimal as the difference between the first thermal displacement amount at the corresponding node and the second thermal displacement amount of each pattern is smaller, and the optimum position pattern of the block boundary position and the respective Determine the optimal combination of block temperatures,
The condition determination method used for the thermal displacement amount estimation apparatus of the machine tool according to claim 1. Each said block temperature in said 2nd structure analysis process is on the condition that it is in the range of the minimum value and the maximum value in each said block among said temperature distribution, The condition of Claim 1 or 2 A condition determination method used in a thermal displacement estimation device for a machine tool. The thermal analysis step acquires a plurality of temperature distributions in a plurality of states,
The first structural analysis step acquires the first thermal displacement amount in each temperature distribution by performing a structural analysis of the structure model based on the plurality of temperature distributions,
The second structural analysis step acquires the second thermal displacement amount of each pattern in the first state, and the second thermal displacement amount of each pattern in another state corresponds to each node in the plurality of temperature distributions. Get based on temperature,
The optimum pattern determining step determines an optimum combination pattern of the respective block temperatures in the plurality of states based on a difference between the first thermal displacement amount in each state and the second thermal displacement amount of each pattern. To
The condition determination method used for the thermal displacement estimation apparatus of the machine tool as described in any one of Claims 1-3. The thermal analysis step acquires a plurality of temperature distributions in a plurality of states,
The first structural analysis step acquires the first thermal displacement amount in each temperature distribution by performing a structural analysis of the structure model based on the plurality of temperature distributions,
The second structural analysis step acquires the second thermal displacement amount of each pattern in the first state, and the second thermal displacement amount of each pattern in another state corresponds to each node in the plurality of temperature distributions. Get based on temperature,
The optimum pattern determining step determines an optimum position pattern of the block boundary position in the first state based on a difference between the first thermal displacement amount in each state and the second thermal displacement amount of each pattern. ,
The condition determination method used for the thermal displacement amount estimation apparatus of the machine tool according to claim 2 . The first structural analysis step and the second structural analysis step acquire the first thermal displacement amount and the second thermal displacement amount at only some of the nodes included in the structure model, The condition determination method used for the thermal displacement amount estimation apparatus of the machine tool as described in any one of Claims 1-5 . The machine tool includes at least three orthogonal axes of movement,
The first structural analysis step and the second structural analysis step acquire the first thermal displacement amount and the second thermal displacement amount in only one moving axis, respectively.
The optimum pattern determination step determines a corresponding optimum pattern based on a difference between the first thermal displacement amount and the second thermal displacement amount of each pattern only on the one movement axis.
The condition determination method used for the thermal displacement estimation apparatus of the machine tool as described in any one of Claims 1-6 .

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