JP2023138881A - Contact dynamic stiffness calculation system and processing system - Google Patents

Abstract

To provide a contact dynamic stiffness calculation system that is capable of calculating contact dynamic stiffness with high accuracy by taking into account contact states between a workpiece and workpiece support members.SOLUTION: A contact dynamic stiffness calculation system 130 acquires basic information related to a workpiece W containing information of a processing position I on the workpiece W supported by workpiece support members 34, 41. Further, the contact dynamic stiffness calculation system 130 calculates a difference bending angle that is a difference between a workpiece bending angle and a support member bending angle at a contact part of the workpiece W and the workpiece support members 34, 41, at the time an initial state in which acting force is not applied by an abrasive wheel T to the workpiece W supported by the workpiece support members 34, 41, changes to an acting state in which the acting force is applied. In addition, a spring constant and an attenuation coefficient at the contact part of the workpiece W and the workpiece support members 34, 41 are calculated on the basis of, the basic information and the difference bending angle, in order to calculate contact dynamic stiffness.SELECTED DRAWING: Figure 6

Description

The present invention relates to a contact dynamic stiffness calculation system and a processing system.

Conventionally, various configurations have been proposed for estimating the machining result when a workpiece is machined with a tool such as a grinding wheel. For example, Patent Document 1 describes that when a workpiece is ground by a grinding wheel, the depth of grinding marks on the workpiece is estimated by taking into consideration the contact static rigidity between the workpiece and the grinding wheel. has been done. The contact static rigidity used here is not a value measured when the grinding wheel is stationary, but is calculated using the theoretical contact static rigidity during grinding. The contact static stiffness is represented by the spring constant K between the workpiece and the grinding wheel.

JP2015-208812A

In the configuration disclosed in Patent Document 1, the depth of grinding marks on the workpiece is estimated in consideration of the support rigidity of the grindstone and the workpiece support member that supports the workpiece. The support rigidity changes not only by the rigidity of the support member that supports the workpiece, but also by the state of contact between the workpiece and the workpiece support member. However, since the configuration disclosed in Patent Document 1 does not take into account the change in the contact state, an error occurs in the calculation result of the dynamic stiffness of the workpiece, and the estimation accuracy decreases. Therefore, in order to estimate the machining results of a workpiece with high accuracy, it is necessary to calculate the dynamic stiffness of the machining point on the workpiece with high accuracy, taking into account the contact state between the workpiece and the workpiece support member. It has been demanded.

The present invention has been made in view of such problems, and is a contact dynamic stiffness calculation system that can calculate contact dynamic stiffness with high accuracy by considering the contact state between a workpiece and a workpiece support member. This is what we are trying to provide.

One aspect of the present invention is a contact dynamic stiffness calculation system that calculates contact dynamic stiffness at a contact portion between a workpiece and a workpiece support member when processing the workpiece supported by the workpiece support member with a tool. ,
a basic information acquisition unit that acquires basic information about the workpiece including information on the machining position on the workpiece;
When the workpiece supported by the workpiece support member changes from an initial state in which no acting force is applied from the tool to an operating state in which an acting force is applied to the workpiece from the tool, the workpiece and the above-mentioned A differential bending angle for calculating a differential bending angle that is the difference between the workpiece bending angle that is the bending angle of the workpiece at the contact portion with the workpiece support member and the support member bending angle that is the bending angle of the workpiece support member. A calculation section,
The spring constant and damping coefficient at the contact portion between the workpiece and the workpiece support member are calculated based on the basic information acquired by the basic information acquisition unit and the differential bending angle calculated by the differential bending angle calculation unit. a contact dynamic stiffness calculation unit that calculates the contact dynamic stiffness of the workpiece based on the spring constant and the damping coefficient;
A contact dynamic stiffness calculation system is provided.

According to the above aspect, the contact dynamic stiffness calculation section calculates the contact portion between the workpiece and the workpiece support member based on the basic information including information on the machining position and the differential bending angle calculated by the differential bending angle calculation section. A spring constant and a damping coefficient are calculated, and a contact dynamic stiffness, which is a dynamic stiffness at the contact portion, is calculated based on the spring constant and damping coefficient. As a result, the contact dynamic rigidity is calculated by taking into account the deviation that occurs between the workpiece bending angle, which is the bending angle of the workpiece, and the support member bending angle, which is the bending angle of the workpiece support member. As a result, the contact dynamic stiffness can be calculated with high accuracy by taking into account the contact state between the workpiece and the workpiece support member.

As described above, according to the above aspect, it is possible to provide a contact dynamic stiffness calculation system that can calculate the contact dynamic stiffness with high accuracy by considering the contact state between the workpiece and the workpiece support member. can.

1 is a diagram showing a processing system in Embodiment 1. FIG. 1 is a functional block diagram of a machining estimation device including a contact dynamic stiffness calculation system in Embodiment 1. FIG. A schematic diagram showing the state of interference between a workpiece and a grinding wheel during grinding. FIG. 3 is a diagram showing the shape of a workpiece in a grinding simulation using a group of radial line segments, and shows a state in which the workpiece represented by radial line segments interferes with the outer circumferential line of a grinding wheel during grinding. FIG. 3 is a diagram showing the correspondence between machining positions and differential bending angles in the contact dynamic stiffness calculation system of Embodiment 1. (a) A sectional view showing an initial state of a workpiece supported on a workpiece support member, and (b) a sectional view showing a state in which an acting force from a grindstone is applied to the workpiece. FIG. 3 is a schematic diagram showing the workpiece side dynamic rigidity and tool side dynamic rigidity during grinding in Embodiment 1. FIG. 3 is a diagram showing a processing system according to a second embodiment. FIG. 2 is a functional block diagram of a dynamic stiffness determination unit including a contact dynamic stiffness calculation system in Embodiment 1. FIG. FIG. 7 is a diagram showing a processing system according to a third embodiment. FIG. 7 is a schematic diagram showing the workpiece side dynamic rigidity and tool side dynamic rigidity during cutting in Embodiment 3.

(Embodiment 1)
1. Configuration of Processing System 1 The processing system 1 in the first embodiment will be described with reference to FIG. 1. The machining system 1 is intended for a machining device that performs grinding. The processing system 1 includes a grinder 2 as a processing device and a processing section 3.

The grinding machine 2 rotates a workpiece W, rotates a grinding wheel T as a tool that is a rotating body, and rotates the grinding wheel T relative to the workpiece W in a direction intersecting the axis of the workpiece W. By approaching the workpiece W, the outer peripheral surface or inner peripheral surface of the workpiece W is ground. As the grinding machine 2, a table traverse type grinding machine, a grinding wheel head traverse type grinding machine, etc. can be applied. Further, the grinding machine 2 can be a cylindrical grinding machine, a cam grinding machine, or the like.

In this embodiment, as shown in FIG. 1, the workpiece W is, for example, a member formed in the shape of a shaft. However, the shape of the workpiece W is not limited to the axial shape, but can be any shape.

In this embodiment, the workpiece W is substantially rod-shaped and includes supported portions WR and WL located at both ends. However, the workpiece W shown in FIG. 1 is only an example, and the grinding machine 2 can grind workpieces having various shapes. In this embodiment, one of the supported parts WL is located on one end surface in the axial direction, and forms a center hole into which a spindle center 34 as a workpiece support member to be described later is inserted. The center hole constituting the supported portion WL has a conical shape along the tip shape of the main shaft center 34.

The other supported portion WR is located on the other end surface in the axial direction and forms a center hole into which a spindle center 34 as a workpiece support member to be described later is inserted. The center hole constituting the supported portion WR has a conical shape along the tip shape of the main shaft center 34. Then, in the workpiece W, the position where the grinding wheel T contacts becomes the processing position I.

The processing unit 3 includes a control device 3a that controls the grinding machine 2, and a machining estimation device 3b that estimates machining results. The control device 3a can control the grinding process by controlling the grinder 2. The machining estimation device 3b has a contact dynamic stiffness calculation system 130, which will be described later, and calculates the workpiece side dynamic stiffness (Cw, Kw) including the contact dynamic stiffness (Cwc, Kwc) calculated by the contact dynamic stiffness calculation system 130. ) is used to simulate the grinding process, thereby performing a process of estimating the machining result on the workpiece W.

The processing estimation device 3b can function as a simulation device independent of the grinding machine 2 and the control device 3a, or can function as a simulation device that operates in conjunction with the grinding machine 2 and the control device 3a. In the former case, the machining estimation device 3b can determine optimal grinding conditions without actually grinding the workpiece W, for example. In the latter case, the machining estimation device 3b operates in parallel with the grinding of the workpiece W by the grinding machine 2, for example, to correct the grinding conditions or to affect various controls. You can do it. Further, the machining estimation device 3b can also be a built-in system of the grinding machine 2 and the control device 3a.

2. Configuration of Grinding Machine 2 and Control Device 3a An example of the configuration of the grinding machine 2 and control device 3a will be described in detail with reference to FIG. 1. The grinding machine 2 is, for example, a table traverse type cylindrical grinding machine. That is, the grinding machine 2 is configured to move the workpiece W in the axial direction of the workpiece W, and move the grinding wheel T in a direction intersecting the axis of the workpiece W. Moreover, in this embodiment, the case where the grinding machine 2 grinds the cylindrical outer peripheral surface of the workpiece W with the grinding wheel T is given as an example.

The grinding machine 2 includes a bed 10, a table 20, a spindle device 30, a tailstock device 40, and a grindstone head 50. The spindle device 30 and tailstock device 40 provided on the table 20 function as workpiece support members that support the workpiece W. The grindstone head 50 functions as a tool support member that supports the grindstone T. That is, the grinding machine 2 grinds the workpiece W supported by the workpiece support member using the grinding wheel T supported by the tool support member. Note that the grinding machine 2 may further include a sizing device (not shown) that obtains the external dimensions of the workpiece W. Below, the components of the grinding machine 2 will be explained in detail.

The bed 10 is installed on an installation surface. The bed 10 is formed to have a long width (length in the Z-axis direction) on the front side in the X-axis direction (bottom side in FIG. 1), and a short width on the back side in the X-axis direction (top side in FIG. 1). has been done.

The bed 10 includes a Z-axis guide surface 11 extending in the Z-axis direction on the upper surface on the front side in the X-axis direction. Furthermore, the bed 10 is equipped with a Z-axis drive mechanism 12 that drives along the Z-axis guide surface 11. In the first embodiment, an example is given in which the Z-axis drive mechanism 12 includes a ball screw mechanism 12a and a Z-axis motor 12b. A ball screw mechanism 12a extends parallel to the Z-axis guide surface 11, and a Z-axis motor 12b drives the ball screw mechanism 12a.

In order to drive the Z-axis drive mechanism 12, a Z-axis drive circuit and a Z-axis detector 12c (not shown) are provided. The Z-axis drive circuit includes an amplifier circuit and drives the Z-axis motor 12b. In this embodiment, the Z-axis detector 12c is, for example, an angle detector such as an encoder, and detects the angle of the rotation axis of the Z-axis motor 12b. In addition, the Z-axis drive mechanism 12 can be replaced with the above-mentioned structure provided with the ball screw mechanism 12a, and can also apply a linear motor etc.

The bed 10 also includes a guide surface 13 extending in a direction intersecting the Z-axis direction on the upper surface of the back side in the X-axis direction. In this embodiment, the guide surface 13 is an X-axis guide surface extending in the X-axis direction perpendicular to the Z-axis. Furthermore, the bed 10 is equipped with an X-axis drive mechanism 14 that drives along the X-axis guide surface 13. In this embodiment, an example is given in which the X-axis drive mechanism 14 includes a ball screw mechanism 14a and an X-axis motor 14b. A ball screw mechanism 14a extends parallel to the X-axis guide surface 13, and an X-axis motor 14b drives the ball screw mechanism 14a.

In order to drive the X-axis drive mechanism 14, an X-axis drive circuit and an X-axis detector 14c (not shown) are provided. The X-axis drive circuit includes an amplifier circuit and drives the X-axis motor 14b. In the first embodiment, the X-axis detector 14c is, for example, an angle detector such as an encoder, and detects the rotation angle of the rotation axis of the X-axis motor 14b. In addition, the X-axis drive mechanism 14 can also be replaced with the configuration provided with the above-mentioned ball screw mechanism 14a, and a linear motor or the like can also be applied.

The table 20 is formed in an elongated shape and is supported by the Z-axis guide surface 11 of the bed 10 so as to be movable in the Z-axis direction (horizontal left-right direction). Further, the table 20 is fixed to a ball screw nut of the Z-axis ball screw mechanism 12a, and is moved in the Z-axis direction by the rotational drive of the Z-axis motor 12b.

The spindle device 30 supports the workpiece W and rotationally drives the workpiece W. The spindle device 30 is arranged at one end of the table 20 in the Z-axis direction. The spindle device 30 includes a spindle housing 31, a spindle 32, a spindle motor 33, a spindle center 34, a spindle detector 35, and a spindle drive circuit (not shown).

The spindle housing 31 is fixed on the table 20. The main shaft 32 is rotatably supported by the main shaft housing 31 via a bearing. The main shaft motor 33 rotates the main shaft 32 .

The spindle center 34 (corresponding to a support center) constitutes a workpiece support member that supports the end surface of the workpiece W at one end in the axial direction (the left end in FIG. 1). Specifically, the spindle center 34 is configured to perform machining with respect to a center hole (hereinafter also referred to as "center hole WR") on the spindle side that constitutes the supported portion WR formed on the end surface of one end in the axial direction of the workpiece W. The object W is supported while being pressed in the axial direction.

The spindle center 34 is fixed to the spindle 32 and rotatably provided with respect to the spindle housing 31. However, if the spindle device 30 is provided with a rotating member (not shown), such as a turning member, the spindle center 34 is fixed to the spindle housing 31 and is provided so as to be unrotatable relative to the spindle housing 31. Also good. Moreover, the spindle device 30 may be provided with a chuck that grips the workpiece W as a workpiece support member instead of the spindle center 34. Note that the chuck is rotationally driven by being connected to the main shaft 32.

The spindle detector 35 and the spindle drive circuit are provided to drive the spindle motor 33. In the first embodiment, the spindle detector 35 is, for example, an angle detector such as an encoder, and detects the rotation angle of the rotating shaft of the spindle motor 33. The spindle drive circuit includes an amplifier circuit and drives the spindle motor 33.

The tailstock device 40 supports the workpiece W together with the spindle device 30. The tailstock device 40 is arranged on the other end side of the table 20 in the Z-axis direction. The tailstock device 40 is provided so as to be movable on the table 20 in the Z-axis direction. The tailstock device 40 includes a tailstock center 41 and an adjustment mechanism 42. Note that when the grinding machine 2 grinds the inner circumferential surface of the workpiece W, the tailstock device 40 is not necessary.

The tailstock center 41 (corresponding to a support center) constitutes a workpiece support member that supports the end surface of the other axial end (the right end in FIG. 1) of the workpiece W. Specifically, the tailstock center 41 is connected to a center hole (hereinafter also referred to as "center hole WL") on the tailstock side that constitutes the supported part WL formed on the end surface of the other end in the axial direction of the workpiece W. , supports the workpiece W in a pressed state in the axial direction. The tailstock center 41 may be provided in a non-rotatable manner or may be provided in a rotatable manner.

Further, the tailstock center 41 may be positioned at a fixed position relative to the workpiece W, or may be provided so as to be movable relative to the workpiece W in the axial direction of the workpiece W. Also good. In the latter case, the tailstock center 41 may be configured to be able to adjust the pressing force applied to the workpiece W in the axial direction of the workpiece W. The pressing force can be controlled by means for adjusting spring force, means for adjusting fluid pressure, etc.

In the first embodiment, the tailstock device 40 includes an adjustment mechanism 42, and the adjustment mechanism 42 is configured, for example, by a spring, so that the tailstock center 41 exerts a pressing force. Here, in a state where the tailstock center 41 exerts a pressing force on the workpiece W, the spindle center 34 also exerts a pressing force on the workpiece W as a reaction. Specifically, the adjustment mechanism 42 allows the tailstock center 41 and the spindle center 34 to adjust the pressing force applied to the workpiece W in the axial direction of the workpiece W. That is, the adjustment mechanism 42 allows the tailstock center 41 and the spindle center 34 to adjust the supporting force of the workpiece W. Here, the pressing force against the workpiece W by the tailstock center 41 and the spindle center 34 can be adjusted by an actuator or by an operator.

The grinding wheel head 50 includes a grinding wheel T, and drives the grinding wheel T to rotate. In addition to the grinding wheel T, the grinding wheel head 50 includes a grinding wheel head main body 51, a grinding wheel shaft 52, a grinding wheel motor 53, and a grinding wheel drive circuit (not shown).

The grinding wheel T is formed into a disk shape. The grinding wheel T is used to grind the outer peripheral surface or the inner peripheral surface of the workpiece W. The grinding wheel T is configured by fixing a plurality of abrasive grains with a binder. As the abrasive grains, general abrasive grains made of ceramic materials such as alumina and silicon carbide, and superabrasive grains such as diamond and CBN are used.

Binders include vitrified (V), resinoid (B), rubber (R), silicate (S), shellac (E), metal (M), electrodeposition (P), magnesia cement (Mg), etc. . Furthermore, the grinding wheel T has a configuration with pores and a configuration without pores. Depending on the type of binder and the presence or absence of pores, the grinding wheel T may have a structure that can be elastically deformed or a structure that can hardly be elastically deformed. The elastic modulus of the elastically deformable grinding wheel T varies depending on the type of binder, the presence or absence of pores, the porosity, and the like.

The grindstone head main body 51 is formed, for example, in a rectangular shape in plan view, and is supported by the X-axis guide surface 13 of the bed 10 so as to be movable in the X-axis direction (horizontal front-rear direction). Further, the grindstone head main body 51 is fixed to a ball screw nut of the X-axis ball screw mechanism 14a, and is moved in the X-axis direction by the rotational drive of the X-axis motor 14b. The grindstone head main body 51 constitutes a tool support member that supports the grindstone wheel T.

The whetstone shaft 52 is rotatably supported by the whetstone head main body 51 via a bearing. A grinding wheel T is fixed to the tip of the grinding wheel shaft 52, and as the grinding wheel shaft 52 rotates, the grinding wheel T rotates. The grinding wheel motor 53 rotates the grinding wheel shaft 52 . As the bearing, a static pressure bearing, a rolling bearing, etc. are used.

The grinding wheel motor 53 transmits rotational driving force to the grinding wheel shaft 52 via a belt, for example. However, the grinding wheel motor 53 may be arranged coaxially with the grinding wheel shaft 52. Generally, the rotational speed of the grinding wheel T driven by the grinding wheel motor 53 is higher than the rotational speed of the workpiece W driven by the spindle motor 33. The grinding wheel drive circuit is provided to drive the grinding wheel motor 53. The grinding wheel drive circuit includes an amplifier circuit and drives the grinding wheel motor 53.

The control device 3a is a CNC (Computer Numerical Control) device and a PLC (Programmable Logic Controller) device that execute processing control. That is, the control device 3a controls the positions of the table 20 and the grindstone head 50 by driving the Z-axis drive mechanism 12 and the X-axis drive mechanism 14 as moving devices based on the grinding program. That is, the control device 3a controls the positions of the table 20, the grindstone head 50, etc., thereby causing the workpiece W and the grinding wheel T to approach and separate from each other relatively. Further, the control device 3a controls the spindle device 30 and the grindstone head 50. That is, the control device 3a controls the rotation of the main shaft 32 and the grinding wheel T.

Further, when the axial pressing force on the workpiece W by the tailstock center 41 and the spindle center 34 can be adjusted by an actuator, the control device 3a controls the axial pressing force by controlling the actuator. can be adjusted.

3. Configuration of Processing Estimation Device 3b The configuration of the processing estimation device 3b will be described with reference to FIG. 2. The machining estimation device 3b includes a command value acquisition section 101, an estimation section 102, a workpiece side dynamic stiffness table storage section 103, a tool side dynamic stiffness table storage section 104, a dynamic stiffness determination condition acquisition section 105, a dynamic stiffness determination section 106, and a correction section. It includes a quantity calculation section 107 and an output section 108.

The command value acquisition unit 101 acquires command values for controlling the grinding machine 2 during grinding. When the machining estimation device 3b is a simulation device independent of the grinding machine 2 and the control device 3a, the command value acquisition unit 101 inputs the grinding program and the configuration information of the grinding machine 2, A command value for controlling each part of 2 is generated by calculation. Further, when the machining estimation device 3b functions as a simulation device that operates in conjunction with the grinding process by the grinding machine 2 and the control device 3a, the command value acquisition unit 101 acquires the command value directly from the control device 3a. be able to.

The estimation unit 102 executes a grinding simulation using the command value acquired by the command value acquisition unit 101, thereby determining the state of the workpiece W or the grinding wheel T during the grinding process, the shape of the workpiece W, and the grinding wheel. At least one of the shape of T and the mechanical state of the grinding machine 2 is estimated.

The state of the workpiece W includes, for example, the vibration state and temperature state of the workpiece W. The condition of the grinding wheel T includes, for example, the vibration condition and temperature condition of the grinding wheel T, the grinding resistance generated in each part of the outer peripheral surface of the grinding wheel T, the sharpness of the grinding wheel T, and the condition of the abrasive grains forming the grinding wheel T. Including. The condition of the abrasive grains includes, for example, the average protrusion amount of the abrasive grains, the abrasive grain distribution, and the like. The shape of the workpiece W includes a shape in the middle of the grinding process and a shape in the final stage of the grinding process. The shape of the grinding wheel T includes a shape in the middle of the grinding process and a shape in the final stage of the grinding process. The mechanical state of the grinding machine 2 includes the vibration state, temperature state, etc. of the parts that make up the grinding machine 2.

In this embodiment, the estimation unit 102 estimates the shape of the workpiece W, the state of the workpiece W, and the mechanical state of the grinding machine 2 by performing a process in which the shape of the workpiece W changes sequentially through a grinding simulation. Let us take as an example the case of estimation. In this embodiment, the grinding process simulation is performed assuming that the grinding wheel T does not deform. In addition to the above-mentioned estimation target, the estimating unit 102 can also estimate the grinding resistance generated for each part of the outer circumferential surface of the grinding wheel T.

The estimation section 102 includes an interference amount calculation section 111, a grinding efficiency calculation section 112, a grinding characteristic determination section 113, and a grinding resistance calculation section 114.

The interference amount calculation unit 111 calculates the relative position of the workpiece W and the grinding wheel T, the shape of the outer peripheral surface of the workpiece W, and the outer circumference of the grinding wheel T, which are obtained using the command value acquired by the command value acquisition unit 101. The amount of interference between the workpiece W and the grinding wheel T is calculated based on the surface shape. The amount of interference corresponds to the amount of grinding in the radial direction of the workpiece W at each location in the circumferential direction of the workpiece W. In other words, the amount of interference is the amount of removal of the workpiece W ground by the grinding wheel T, specifically, the amount of removal of the workpiece W in the radial direction at each location in the circumferential direction of the workpiece W. As shown in FIG. 3, the amount of interference is the volume of the portion where the workpiece W and the grinding wheel T interfere (the shaded portion in FIG. 3: interference region).

The interference amount calculation unit 111 geometrically calculates the amount of interference by arithmetic processing. Here, the interference amount calculation unit 111 stores the outer peripheral surface shape of the workpiece W and the outer peripheral surface shape of the grinding wheel T. As shown on the right side of FIG. 4, the shape of the outer circumferential surface of the workpiece W is expressed by a plurality of radial line segments on polar coordinates with the rotation center Ow of the workpiece W as the origin. In other words, the interference amount calculation unit 111 calculates a plurality of points that connect the division points (white points in FIG. 4) on the outer peripheral surface of the workpiece W divided into equal angles (p) and the rotation center Ow (origin) of the workpiece W. The group of line segments is stored as the shape of the outer peripheral surface of the workpiece W. The dividing points indicated by white points in FIG. 4 are stored as the shape of the outer peripheral surface of the workpiece W before being removed by the grinding wheel T.

The interference amount calculation unit 111 calculates a line representing each line segment of the workpiece W and the shape of the outer circumferential surface of the grinding wheel T based on the relative position (distance between axes) between the workpiece W and the grinding wheel T and the outer circumferential surface shape of the grinding wheel T. Determine the intersection point (black point in Figure 4) with The interference amount calculation unit 111 stores the determined intersection point (black point in FIG. 4) as the shape of the outer peripheral surface of the workpiece W after the workpiece W has been removed by the grinding wheel T. In other words, the interference amount calculation unit 111 changes the stored outer peripheral surface shape of the workpiece W.

Then, the interference amount calculation unit 111 calculates the area of the triangle △Ow-a1-a2 formed by the origin Ow and adjacent points a1 and a2 among the points that define the outer peripheral surface shape of the workpiece W before removal, from the area of the triangle △Ow-a1-a2. The area of a triangle ΔOw-b1-b2 formed by points b1 and b2 (intersection with the grinding wheel T) and the origin Ow is subtracted. The area after the subtraction is calculated for all adjacent points that define the outer peripheral surface shape of the workpiece W.

Then, the interference amount calculation unit 111 integrates the areas after each subtraction, and multiplies the integrated total area by the thickness of the workpiece W to calculate the interference amount (removal amount). Note that in the above, the area of the portion to be removed was calculated by calculating the areas of two types of triangles and calculating the difference between the areas. Alternatively, the area of the removed portion may be calculated by directly calculating the rectangle a1-a2-b1-b2.

The grinding efficiency calculation section 112 shown in FIG. 2 calculates the grinding efficiency Z' based on the amount of interference calculated by the interference amount calculation section 111. The grinding efficiency Z' is calculated by calculating the amount of interference per unit time, that is, the volume of the workpiece W ground by the grinding wheel T in a unit time.

The grinding characteristic determining unit 113 determines the grinding characteristic kc based on the material of the workpiece W, the type of abrasive grains and binder of the grinding wheel T, the state of the outer peripheral surface of the grinding wheel T, and the like. The state of the outer circumferential surface of the grinding wheel T is expressed using, for example, an index representing the wear state of the abrasive grains of the grinding wheel T or the sharpness. Here, the grinding characteristic determination unit 113 stores the grinding characteristics in each state in advance through experiments, analysis, etc.

The grinding resistance calculation unit 114 calculates the grinding resistance Fn in the normal direction (X-axis direction) to the outer peripheral surface of the workpiece W based on the grinding efficiency Z' and the grinding characteristics kc. The grinding resistance Fn is obtained by multiplying the grinding efficiency Z' by the grinding characteristic kc (Fn=kc×Z').

The grinding characteristics kc have a substantially linear relationship such that the grinding resistance Fn in the normal direction (X-axis direction) increases as the grinding efficiency Z' increases. The relationship of the grinding characteristics kc changes, for example, when the grinding wheel T wears out. For example, when the grinding wheel T is worn out, the grinding resistance Fn in the normal direction changes to become larger with respect to the grinding efficiency Z'.

The workpiece side dynamic stiffness table storage unit 103 stores dynamic stiffness data Cw, Kw (hereinafter referred to as workpiece side dynamic stiffness data) regarding the workpiece W side when the workpiece W side and the grinding wheel T side are divided with the machining region as a boundary. (referred to as stiffness data). The workpiece side dynamic stiffness table storage section 103 includes a dynamic stiffness table storage section 103a relating to the workpiece W, a dynamic stiffness table storage section 103b relating to each device 20, 30, and 40 constituting the workpiece support member, and a dynamic stiffness table storage section 103b relating to the workpiece W and the workpiece. It includes a correspondence storage unit 103c for calculating the contact dynamic rigidity, which is the dynamic rigidity of the contact portion with the support member (spindle center 34, tailstock center 41).

The dynamic stiffness table storage unit 103a regarding the workpiece W stores dynamic stiffness data Cwa, Kwa of the workpiece W (hereinafter referred to as workpiece dynamic stiffness data). The workpiece dynamic stiffness data Cwa, Kwa can be obtained by, for example, known hammering or FEM analysis of the workpiece W. When there are multiple types of workpieces W to be ground, the dynamic stiffness table storage unit 103a stores workpiece dynamic rigidity data Cwa and Kwa for each of the multiple types of workpieces W.

The dynamic stiffness table storage unit 103b regarding each device 20, 30, 40 forming a workpiece support member stores dynamic stiffness data Cwb, Kwb (hereinafter referred to as support member movement) of each device 20, 30, 40 forming a workpiece support member. (referred to as stiffness data). The supporting member dynamic stiffness data Cwb and Kwb can be obtained by hammering, FEM analysis, etc. for each of the devices 20, 30, and 40 that constitute the workpiece supporting member.

When the grinding machine 2 is capable of changing the setup of each device 20, 30, 40 that configures multiple types of workpiece support members, the dynamic stiffness table storage unit 103b configures multiple types of workpiece support members. Support member dynamic stiffness data Cwb and Kwb for each device 20, 30, and 40 are stored. Further, when the support member dynamic stiffness data Cwb, Kwb changes depending on processing conditions, the dynamic stiffness table storage unit 103b stores the correspondence between the processing conditions and the support member dynamic stiffness data Cwb, Kwb. do.

The correspondence storage unit 103c is used to calculate dynamic stiffness data Cwc and Kwc (hereinafter referred to as contact dynamic stiffness data) at the contact portion between the workpiece W and the workpiece support member (spindle center 34, tailstock center 41). memorize the correspondence relationship. In the first embodiment, the correspondence storage unit 103c stores the correspondence between the processing position I shown in FIG. 5 and the differential bending angles ΔθL and ΔθR, which will be described later.

3-1. Correspondence between machining position I and differential bending angles ΔθL and ΔθR The correspondence between machining position I shown in FIG. This will be explained below.

First, the initial state shown in FIG. 6(a) is a state before any force is applied to the workpiece W from the grinding wheel T. When the workpiece W is ground by the grinding wheel T, the working force is applied from the grinding wheel T to the processing position I of the workpiece W, as shown in FIG. 6(b). It bends to escape to the opposite side of the grinding wheel T. Then, both ends of the workpiece W where the center holes WR and WL, which are the supported parts, are located change to be inclined with respect to the axis S0 of the workpiece W in the initial state. The amount of change in one center hole WR of the workpiece W with respect to the initial state can be expressed as an angle θWR between the axis S0 of the workpiece W in the initial state and the axis SWR at the end where the center hole WR is located. Similarly, the amount of change in the other center hole WL of the workpiece W with respect to the initial state can be expressed as the angle θWL between the axis S0 of the workpiece W in the initial state and the axis SWL at the end where the center hole WL is located. can.

Further, as shown in FIG. 6(b), when the workpiece W is ground by the grinding wheel T, as the workpiece W is bent, the spindle center 34 and the tailstock, which serve as workpiece support members, are The center 41 also bends. As a result, the spindle center 34 and the tailstock center 41 also change to be inclined with respect to the axis S0 of the workpiece W in the initial state. The amount of change in the tailstock center 41 from the initial state can be expressed as an angle θCR between the axis S0 of the workpiece W in the initial state and the axis SCR in the tailstock center 41 after the change. Similarly, the amount of change in the spindle center 34 from the initial state can be expressed as the angle θCL between the axis S0 of the workpiece W in the initial state and the axis SCL in the spindle center 34 after the change.

As shown in FIG. 6(b), there is a deviation between the amount of change θWR of the center hole WR of the workpiece W and the amount of change θCR of the tailstock center 41. The absolute value of the deviation of the amount of change is defined as the differential bending angle ΔθR. Similarly, there is a deviation between the amount of change θWL of the center hole WL of the workpiece W and the amount of change θCL of the spindle center 34. The absolute value of the deviation of the amount of change is defined as the differential bending angle ΔθL.

The differential bending angles ΔθR and ΔθL each change based on the processing position I. In this embodiment, the position where a pressure F of 1N is applied to the workpiece W is defined as a virtual machining position, and the virtual machining position is moved in the axial direction from the position of one center hole WR to the position of the other center hole WL. The actual measured values of the differential bending angles ΔθR and ΔθL were obtained, and the correspondence relationship between the processing position I and the differential bending angle Δθ shown in FIG. 5 was created. Then, as described above, the correspondence relationship is stored in the correspondence relationship storage section 103c. In addition, instead of creating the corresponding relationship by obtaining the actual measured values of the differential bending angles ΔθR and ΔθL, it is possible to theoretically calculate the relationship between the machining position I and the changes θWR, θWL, θCR, and θCL. Accordingly, a correspondence relationship between the processing position I and the differential bending angles ΔθR and ΔθL may be created.

The tool side dynamic stiffness table storage unit 104 shown in FIG. 2 stores dynamic stiffness data Ct, Kt (hereinafter referred to as tool (referred to as lateral dynamic stiffness data). That is, the tool side dynamic stiffness table storage section 104 stores tool side dynamic stiffness data Ct, Kt in the grindstone head 50 including the grinding wheel T. The tool side dynamic stiffness table storage unit 104 stores tool side dynamic stiffness data Ct, Kt for each type of grinding wheel T, for example.

In addition, if the grinding wheel T is supported by a hydrostatic bearing and the pressure of the hydrostatic bearing can be controlled, the tool side dynamic rigidity data Ct, Kt will change depending on the pressure of the hydrostatic bearing. The data may be Therefore, the tool-side dynamic stiffness table storage section 104 may store the damping coefficient Ct and the spring constant Kt according to the pressure of the hydrostatic bearing as the machining conditions. When the tool-side dynamic stiffness data Ct, Kt changes depending on machining conditions, etc., the tool-side dynamic stiffness table storage unit 104 stores the correspondence between the machining conditions, etc. and the tool-side dynamic stiffness data Ct, Kt. .

4. Acquisition of Dynamic Rigidity Determination Conditions As shown in FIG. 2, the dynamic rigidity determination condition acquisition unit 105 acquires dynamic rigidity determination conditions when performing grinding with the grinder 2. Specifically, the dynamic stiffness determination condition acquisition unit 105 acquires the dynamic stiffness determination condition at the time of estimation by the estimation unit 102 (when being processed). The dynamic stiffness determining condition acquired by the dynamic stiffness determining condition acquisition unit 105 is information used by the dynamic rigidity determining unit 106 to calculate each dynamic stiffness. The dynamic rigidity determining conditions to be acquired include, for example, the type of workpiece W, the type of workpiece support member, the type of grinding wheel T, the pressing force by the spindle center 34 and the tailstock center 41, and the like.

If the machining estimation device 3b is a simulation device independent of the grinding machine 2, the dynamic stiffness determination condition acquisition unit 105 determines the dynamic stiffness by inputting the mechanical configuration of the grinding machine 2 and the grinding program. Get the conditions for In addition, when the machining estimation device 3b functions as a simulation device that operates in conjunction with the grinding process by the grinding machine 2, the dynamic stiffness determination condition acquisition unit 105 acquires the mechanical configuration of the grinding machine 2 and the grinding process from the control device 3a. The conditions for determining the dynamic stiffness may be acquired by inputting a machining program, or information regarding the conditions may be acquired directly from the control device 3a of the grinding machine 2.

5. Configuration of Dynamic Rigidity Determination Unit 106 The dynamic rigidity determination unit 106 determines dynamic rigidity data that affects the grinding process. The dynamic stiffness determination unit 106 separately determines workpiece side dynamic stiffness data Cw, Kw and tool side dynamic stiffness data Ct, Kt shown in FIG. That is, the dynamic stiffness determination section 106 includes a workpiece side dynamic stiffness determination section 121 and a tool side dynamic rigidity determination section 125.

The workpiece side dynamic rigidity (Cw, Kw) and the tool side dynamic rigidity (Ct, Kt) will be explained with reference to FIG. 7. The workpiece side dynamic rigidity (Cw, Kw) is the dynamic rigidity of the workpiece W side including the workpiece W and relating to the table 20, the spindle device 30, and the device 40. On the other hand, the tool side dynamic rigidity (Ct, Kt) includes the grinding wheel T and is the dynamic rigidity related to the grinding wheel head 50. Each will be explained in detail below.

5-1. Workpiece side dynamic stiffness (Cw, Kw)
The workpiece side dynamic rigidity (Cw, Kw) is the dynamic rigidity exhibited when the workpiece W is supported by the spindle device 30 and the device 40 as workpiece support members constituting the grinding machine 2. The workpiece side dynamic stiffness (Cw, Kw) is defined by the damping coefficient Cw and the spring constant Kw. The damping coefficient Cw is a value representing the relationship between the relative speed of the workpiece W with respect to the reference position of the grinding machine 2 and the external force that the workpiece W receives. The spring constant Kw is a value representing the relationship between the relative position of the workpiece W with respect to the reference position of the grinding machine 2 and the external force that the workpiece W receives. Note that any dynamic stiffness may include a mass term Mw in addition to the damping coefficient and spring constant.

As shown in FIG. 7, the workpiece side dynamic rigidity (Cw, Kw) is calculated by the workpiece dynamic rigidity (Cwa, Kwa), the support member dynamic rigidity (Cwb, Kwb), the workpiece W and the workpiece support member ( The contact dynamic stiffness (Cwc, Kwc) between the spindle center 34 and the tailstock center 41) can be broken down into contact dynamic rigidity (Cwc, Kwc).

The workpiece-side dynamic rigidity determination unit 121 includes a workpiece dynamic rigidity calculation unit 122 , a support member dynamic rigidity calculation unit 123 , and a contact dynamic rigidity calculation unit 133 . The workpiece dynamic stiffness calculating section 122 selects a workpiece corresponding to the type of the workpiece W obtained by the dynamic stiffness determination condition obtaining section 105 from among the dynamic stiffness tables related to the workpiece W stored in the dynamic stiffness table storage section 103a. Calculate object stiffness data Cwa, Kwa. Further, the support member dynamic stiffness calculation section 123 selects the dynamic stiffness determination condition acquisition section 105 from among the dynamic stiffness tables stored in the dynamic stiffness table storage section 103b regarding each device 20, 30, 40 constituting the workpiece support member. Support member dynamic stiffness data Cwb and Kwb corresponding to the type of workpiece support member obtained in .

The contact dynamic rigidity (Cwc, Kwc) is the dynamic rigidity between the workpiece W and the workpiece support member (spindle center 34, tailstock center 41), and is the dynamic rigidity between the workpiece W and the workpiece support member (spindle center 34, tailstock center 41). , the dynamic rigidity exhibited by contact with the tailstock center 41). As described above, the contact dynamic stiffness (Cwc, Kwc) changes depending on the processing position I. The contact dynamic stiffness (Cwc, Kwc) is defined by the damping coefficient Cwc and the spring constant Kwc. The damping coefficient Cwc is a value representing the relationship between the relative speed of the workpiece W and the workpiece support member (spindle center 34, tailstock center 41) and the external force that the workpiece W receives. The spring constant Kwc is a value representing the relationship between the relative position of the workpiece W and the workpiece support member (spindle center 34, tailstock center 41) and the external force that the workpiece W receives. The contact dynamic stiffness (Cwc, Kwc) is calculated by the contact dynamic stiffness calculation system 130 shown in FIG.

5-1-1. Configuration of contact dynamic stiffness calculation system 130 The configuration of the contact dynamic stiffness calculation system 130 shown in FIG. 7 will be described. The contact dynamic stiffness calculation system 130 includes a basic information acquisition section 131, a differential bending angle calculation section 132, and a contact dynamic stiffness calculation section 133 included in the workpiece side dynamic stiffness determination section 121, and the workpiece side dynamic stiffness table storage section 103. It is configured by the included correspondence relationship storage unit 103c.

The basic information acquisition unit 131 acquires basic information regarding the workpiece W. The basic information includes at least position information of the processing position I on the workpiece W. Furthermore, the basic information may include the maximum support diameters dR and dL of the center hole WR and WL in the workpiece W shown in FIG. 6(a). Further, the basic information may include information regarding the shape of the workpiece W. In this embodiment, the basic information includes information regarding the maximum support diameters dR, dL, and the shape of the workpiece W, as well as the machining position I.

The differential bending angle calculation unit 132 shown in FIG. Differential bending angles ΔθR and ΔθL corresponding to the processing position I on the object W are calculated.

The contact dynamic stiffness calculation unit 133 calculates the contact dynamic stiffnesses Cwc and Kwc using the differential bending angles ΔθR and ΔθL. In this embodiment, the center hole sizes of the center holes WR and WL, which are the supported parts in the workpiece W acquired by the basic information acquisition unit 131, that is, the maximum support diameters dR and dL are used together with the differential bending angles ΔθR and ΔθL. Then, the contact dynamic stiffness Cwc and Kwc are calculated. The contact dynamic rigidity (Cwc, Kwc) is the contact dynamic rigidity (Cwcr, Kwcr) between one center hole WR of the workpiece W and the tailstock center 41, and the contact dynamic rigidity (Cwcr, Kwcr) between the other center hole WL of the workpiece W and the spindle center. 34 and the contact dynamic stiffness (Cwcl, Kwcl). The contact dynamic stiffness data Cwcr, Kwcr) and the contact dynamic stiffness data Cwcl, Kwcl can be defined as follows.

First, as shown in FIG. 6(b), when the differential bending angles ΔθR and ΔθL become large, the bending becomes large at the contact portion between the workpiece W and the workpiece support member (spindle center 34, tailstock center 41), and the difference When the bending angles ΔθR and ΔθL become smaller, the bending becomes smaller at the contact portion between the workpiece W and the workpiece support member (spindle center 34, tailstock center 41). Furthermore, as the maximum support diameters dR and dL increase, the center holes WR and WL become deeper, and the spindle center 34 and tailstock center 41 enter deeper into the center holes WR and WL. The contact portions of the center 34 and tailstock center 41) become larger. Conversely, when the maximum support diameters dR, dL become smaller, the center holes WR, WL become shallower, and the spindle center 34 and tailstock center 41 enter more shallowly into the center holes WR, WL. The contact area with the center 34 and tailstock center 41) becomes smaller. As a result, the spring constants Kwcr and Kwcl in contact dynamic stiffness are inversely proportional to the differential bending angles ΔθR and ΔθL, and proportional to the maximum support diameters dR and dL, respectively.

Therefore, the spring constants Kwcr and Kwcl in the contact dynamic stiffness can be defined according to the following relational expressions (Equations 1 and 2), respectively.
Kwcr=α/ΔθR・dR (Formula 1)
Kwcl=β/ΔθL・dL (Formula 2)
Note that α and β are coefficients, and are calculated from the predetermined differential bending angles ΔθR and ΔθL and the predetermined maximum support diameters dR and dL obtained by actual measurement in advance, and the measured spring constants Kwcr and Kwcl, and the above formula 1, The spring constants Kwcr and Kwcl calculated by Equation 2 can be set to match values.

On the other hand, since the damping coefficients Cwcr and Cwcl in contact dynamic stiffness are mainly caused by frictional damping, when focusing only on frictional damping, the differential bending angles ΔθR and ΔθL are proportional to the damping energy. Further, as the maximum support diameters dR, dL increase, the friction increases, and as the maximum support diameters dR, dL decrease, the friction decreases.

Therefore, the damping coefficients Cwcr and Cwcl in the contact dynamic stiffness can be defined as the following relational expressions (Equations 3 and 4), respectively.
Cwcr=γ・ΔθR・dR (Formula 3)
Cwcl=δ・ΔθL・dL (Formula 4)
Note that γ and δ are coefficients, and can be determined in the same manner as α and β.

As described above, the contact dynamic stiffness calculation unit 133 calculates the contact dynamic stiffness Cwc (Cwcr and Cwcl) and Kwc (Kwcr and Kwcl) from ΔθR, ΔθL, dR, and dL based on the relational expressions 1 to 4 above. It can be calculated.

5-2. Tool Side Dynamic Rigidity As shown in FIG. 7, the tool side dynamic rigidity (Ct, Kt) includes the grinding wheel T and is the dynamic stiffness related to the grinding wheel head 50. The tool side dynamic stiffness (Ct, Kt) is defined by the damping coefficient Ct and the spring constant Kt. The damping coefficient Ct is a value representing the relationship between the relative speed of the grinding wheel T with respect to the reference position on the grinding wheel head 50 and the external force that the grinding wheel T receives. The spring constant Kt is a value representing the relationship between the relative position of the grinding wheel T with respect to the reference position on the grinding wheel head 50 and the external force that the grinding wheel T receives. The tool side dynamic rigidity (Ct, Kt) is the dynamic rigidity (Cta, Kta) of the grinding wheel T and the dynamic rigidity (Ctb, Ktb) exerted when the grinding wheel T is supported by the grinding wheel head body 51. include. Note that any dynamic stiffness may include a mass term in addition to the damping coefficient and spring constant.

The tool-side dynamic stiffness (Ct, Kt) is determined by the tool-side dynamic stiffness determination unit 125 shown in FIG. It can be calculated based on the correspondence between the dynamic stiffness determination conditions and the tool side dynamic stiffness data Ct, Kt.

6. Correction amount calculation unit 107
The correction amount calculation unit 107 calculates the correction amount for the relative displacement of the grinding wheel T and the workpiece W in the X-axis direction due to the grinding resistance, based on each dynamic stiffness data determined by the dynamic stiffness determination unit 106. do. The amount of correction regarding displacement can be determined from each dynamic stiffness data and grinding resistance. That is, the correction amount regarding displacement can be calculated from the grinding resistance, the workpiece side dynamic rigidity data Cw, Kw, and the tool side dynamic rigidity data Ct, Kt.

However, in the present embodiment, the workpiece side dynamic stiffness data Cw, Kw includes workpiece dynamic stiffness data Cwa, Kwa, support member dynamic stiffness data Cwb, Kwb, and contact dynamic stiffness data Cwc, Kwc, respectively. That is, the correction amount regarding the displacement is calculated from the grinding resistance, the workpiece side dynamic rigidity data Cwa, Kwa, Cwb, Kwb, Cwc, Kwc, and the tool side dynamic rigidity data Ct, Kt.

The correction amount calculation unit 107 outputs the calculated correction amount to the estimation unit 102. As described above, the estimation unit 102 calculates the estimation based on the relative position of the workpiece W and the grinding wheel T, the outer peripheral surface shape of the workpiece W, and the outer peripheral surface shape of the grinding wheel T acquired by the command value acquisition unit 101. , estimate the estimation target. However, due to the grinding resistance, the relative position between the workpiece W and the grinding wheel T is different from the relative position based on the command value.

Therefore, when the estimation unit 102 estimates the estimation target, the correction amount calculation unit 107 calculates the relative position between the workpiece W and the grinding wheel T in addition to the relative position acquired by the command value acquisition unit 101. Use the relative position plus the correction amount. That is, the estimation unit 102 estimates the estimation target based on the relative position based on the command value and the correction amount calculated using each dynamic stiffness data.

In particular, in the first embodiment, the correction amount calculation unit 107 outputs the calculated correction amount to the interference amount calculation unit 111 of the estimation unit 102. As described above, the interference amount calculation unit 111 calculates the relative position between the workpiece W and the grinding wheel T, the outer peripheral surface shape of the workpiece W, and the outer peripheral surface shape of the grinding wheel T acquired by the command value acquisition unit 101. Based on this, the amount of interference between the workpiece W and the grinding wheel T is calculated. However, due to the grinding resistance, the relative position between the workpiece W and the grinding wheel T is different from the relative position based on the command value.

Therefore, in addition to the relative position acquired by the command value acquisition unit 101, the interference amount calculation unit 111 calculates the relative position between the workpiece W and the grinding wheel T used for calculating the interference amount by the correction amount calculation unit 107. The relative position with the corrected amount added is used. That is, the interference amount calculation unit 111 calculates the interference amount based on the relative position based on the command value and the correction amount calculated using each dynamic stiffness data.

Since the interference amount calculation section 111 calculates the amount of interference considering the correction amount, the grinding efficiency calculation section 112, the grinding characteristic determination section 113, and the grinding resistance calculation section 114 calculate the amount of interference obtained based on the amount of interference considering the correction amount. Grinding efficiency Z', grinding characteristics kc, and grinding resistance Fn are obtained.

The output unit 108 outputs the estimation target estimated by the estimation unit 102. In other words, the output unit 108 outputs the state of the workpiece W or grinding wheel T during grinding, the shape of the workpiece W, the shape of the grinding wheel T, and the mechanical state of the processing system 1 (corresponding to the mechanical state of the grinding machine 2). ). The output unit 108 may, for example, teach the estimation result to a teaching device (not shown). Further, the output unit 108 can also output the estimation result to the control device 3a of the grinding machine 2. In this case, the control device 3a can correct the grinding conditions, for example, using the estimation results. That is, the control device 3a can control the grinding process using the estimation result.

Further, the control device 3a can also control the adjustment mechanism 42 of the tailstock device 40 using the estimation result to adjust the pressing force by the spindle center 34 and the tailstock center 41. Further, when the grinding machine 2 includes a chuck, the control device 3a can also adjust the gripping force of the chuck using the estimation result. Note that the control device 3a can appropriately select a control target using the estimation result.

Furthermore, the control device 3a performs the various processes described above using the estimation results. In addition, the control device 3a can also control machining using various types of dynamic stiffness determined by the dynamic stiffness determination unit 106, regardless of the estimation results. For example, the control device 3a uses various types of dynamic stiffness determined by the dynamic stiffness determination unit 106, regardless of the estimation results, to adjust the pressing force by the spindle center 34 and the tailstock center 41, and adjust the gripping force of the chuck. You can also do things like:

7. Effects According to the present embodiment, the contact dynamic stiffness calculation unit 133 calculates the workpiece to Calculate the spring constant Kwc and damping coefficient Cwc at the contact part between W and the workpiece support member (spindle center 34, tailstock center 41), and calculate the dynamic rigidity at the contact part based on the spring constant Kwc and the damping coefficient Cwc. The contact dynamic stiffness (Kwc, Cwc) is calculated. As a result, the contact dynamic rigidity (Kwc, Cwc) is determined by the workpiece bending angles θWR, θWL, which are the bending angles of the workpiece W, and the support member, which is the bending angle of the workpiece support members (spindle center 34, tailstock center 41). It is calculated by taking into consideration the deviation that occurs between the bending angles θCR and θCL. As a result, the contact dynamic rigidity can be calculated with high accuracy by taking into consideration the contact state between the workpiece W and the workpiece support member (spindle center 34, tailstock center 41).

In addition, the first embodiment includes a correspondence storage section 103c in which the correspondence between the processing position I and the differential bending angles ΔθR and ΔθL is stored in advance. Then, the differential bending angle calculation unit 132 calculates the differential bending angles ΔθR and ΔθL based on the correspondence relationship stored in the correspondence storage unit 103c and the processing position I included in the basic information. Thereby, the differential bending angles ΔθR and ΔθL can be easily obtained based on the processing position I, and calculation processing can be performed at high speed.

Further, in the first embodiment, the basic information acquisition unit 131 is configured to obtain the maximum support of the center holes WR and WL, which are supported parts of the workpiece W by the workpiece support members (spindle center 34 and tailstock center 41). The diameters dR and dL are further acquired as the basic information. Then, in the contact dynamic stiffness calculation unit 133, the spring constants Kwcr, Kwcl and the damping coefficients Cwcr, Cwcl are calculated by at least the maximum support diameters dR, dL acquired by the basic information acquisition unit 131 and the difference calculated by the differential bending angle calculation unit 132. It is calculated based on the bending angles ΔθR and ΔθL. As a result, the contact state between the workpiece W and the workpiece support member (spindle center 34, tailstock center 41) can be considered more accurately, so that the dynamic rigidity can be calculated with higher accuracy.

Further, the machining system 1 in the first embodiment includes a contact dynamic rigidity calculation system 130, a machining device 2 that processes the workpiece W, a control device 3a that controls machining by the machining device 2, and a contact dynamic rigidity calculation system 130. The estimation unit 102 estimates the machining result of the workpiece W by the machining device 2 based on the workpiece side dynamic stiffness (Cw, Kw) including the contact dynamic rigidity (Cwc, Kwc) calculated by the above. Then, the control device 3a controls the machining by the machining device 2 based on the machining result estimated by the estimation unit 102. As a result, the workpiece W can be machined by reflecting the machining results estimated based on the workpiece side dynamic stiffness (Cw, Kw) including the contact dynamic stiffness (Cwc, Kwc). It can be molded into the desired shape with higher precision.

Further, in the processing system 1 according to the first embodiment, the tool in the processing device 2 is a grinding wheel T, and the processing device 2 is a grinder. Thereby, the workpiece W processed by the grinder can be formed into the desired shape with higher precision.

In addition, in the first embodiment, the workpiece side dynamic rigidity (Cw, Kw) is divided into the workpiece dynamic rigidity (Cwa, Kwa), the support member dynamic rigidity (Cwb, Kwb), and the contact dynamic rigidity (Cwc, Kwc). separated. By separating each dynamic stiffness data in this way, it becomes easy to determine each dynamic stiffness data. For example, even if the devices 20, 30, and 40 constituting the workpiece W and the workpiece support member are the same, when only the pressing force by the spindle center 34 and the tailstock center 41 is adjusted, the contact dynamic stiffness data Cwc , Kwc are changed. Therefore, calculation processing becomes easy. For example, in a case where estimation processing by the processing estimation device 3b and control of grinding processing by the control device 3a are performed simultaneously, highly accurate grinding processing can be realized by performing calculation processing at high speed.

As described above, according to the first embodiment, the contact dynamic rigidity (Cwc, Kwc) is determined by considering the contact state between the workpiece W and the workpiece support member (spindle center 34, tailstock center 41). It is possible to provide a contact dynamic stiffness calculation system 130 that can calculate with high accuracy.

(Embodiment 2)
In the first embodiment described above, the processing section 3 includes the control device 3a and the machining estimation device 3b as shown in FIG. 1, but in the second embodiment shown in FIG. The rigidity determination unit 106 is provided, but the processing estimation device 3b is not provided. As shown in FIG. 9, the configuration of the dynamic stiffness determining section 106 is the same as in the first embodiment. Note that the same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 9, in the second embodiment, the workpiece side dynamic stiffness (Cw, Kw) determined by the dynamic stiffness determination unit 106 is inputted to the control device 3a together with the command value. The workpiece side dynamic stiffness (Cw, Kw) includes the contact dynamic stiffness (Cwc, Kwc) calculated by the contact dynamic stiffness calculation system 130. The control device 3a controls the processing by the processing device 2 based on these.

That is, the processing system 1 of the second embodiment includes a contact dynamic stiffness calculation system 130, a processing device 2 that processes the workpiece W, and a control device 3a that controls processing by the processing device 2. Then, the control device 3a controls the processing by the processing device 2 based on the workpiece side dynamic stiffness (Cw, Kw) including the contact dynamic stiffness (Cwc, Kwc) calculated by the contact dynamic stiffness calculation system 130. As a result, processing by the processing device 2 can be controlled without using the estimation result by the estimation unit 102 of Embodiment 1, so calculation processing can be performed faster and highly accurate grinding can be achieved. .

(Embodiment 3)
A processing system 201 according to the third embodiment will be explained with reference to FIG. 10. The processing system 201 is intended for a processing system that performs cutting. The processing system 201 includes a lathe 202 as a processing device and a processing section 203.

The lathe 202 rotates the workpiece W and moves the cutting tool T2 relative to the workpiece W, thereby turning the workpiece W. The processing unit 203 includes a control device 203a that controls the lathe 202, and a processing estimation device 203b that estimates an estimation target related to processing. The control device 203a can control cutting by controlling the lathe 202. The machining estimation device 203b estimates the state of the workpiece W or cutting tool T2 during cutting with the lathe 202, the shape of the workpiece W, the shape of the cutting tool T2, and the mechanical state of the machining system 201 (the mechanical state of the lathe 202). ). The machining estimation device 203b performs the estimation process of the estimation target described above by inputting information used for cutting and performing a simulation.

The lathe 202 includes, for example, a bed 210, a spindle device 220, a tailstock device 230, and a tool stand 250. The main spindle device 220 and the tailstock device 230 function as workpiece supporting members. The spindle device 220 is fixed to the upper surface of the bed 210, supports one end WL of the workpiece W, and rotates the workpiece W. The spindle device 220 includes a spindle housing 221, a spindle 222, a spindle motor 223, a chuck 224, a spindle detector 225, and a spindle drive circuit (not shown).

The main shaft housing 221 is fixed on the bed 210. The main shaft 222 is rotatably supported by the main shaft housing 221 via a bearing. The main shaft motor 223 rotates the main shaft 222 . The chuck 224 is fixed to the main shaft 222 and grips one end of the workpiece W. The spindle detector 225 and the spindle drive circuit are provided to drive the spindle motor 223. In detail, the chuck 224 constitutes a workpiece support member, and one end of the workpiece W held by the chuck 224 constitutes a supported portion WL. The maximum support diameter dL of the supported portion WL corresponds to the diameter of the outer peripheral surface of the supported portion WL that the claws of the chuck 224 contact.

The tailstock device 230 is disposed on the bed 210 so as to face the main spindle device 220 in the Z-axis direction. The tailstock device 230 is provided on the bed 210 so as to be movable in the Z-axis direction. The tailstock device 230 includes a tailstock center 231 that supports the other end of the workpiece W. In addition, in detail, the tailstock center 231 enters into the center hole WR at the other end of the workpiece W and constitutes a workpiece support member that supports the workpiece W.

The tool stand 250 includes a Z-axis slide stand 251, an X-axis slide stand 252, a turret (swivel-type tool rest) 253, and a plurality of cutting tools T2. The Z-axis slide table 251 is supported movably in the Z-axis direction by the Z-axis guide surface 211 of the bed 210, and is moved in the Z-axis direction by a Z-axis drive mechanism 212 provided on the bed 210.

The X-axis slide base 252 is supported movably in the X-axis direction by an X-axis guide surface 251a on the Z-axis slide base 251, and is moved in the X-axis direction by an X-axis drive mechanism 251b provided on the Z-axis slide base 251. Move to. The turret 253 is provided on the X-axis slide base 252 so as to be rotatable around an axis parallel to the Z-axis direction. The plurality of cutting tools T2 are fixed to the outer peripheral surface of the turret 253. The plurality of cutting tools T2 can be different types of tools.

The control device 203a is a CNC (Computer Numerical Control) device and a PLC (Programmable Logic Controller) device that execute processing control. That is, the control device 203a controls the position of the cutting tool T2 by driving the Z-axis drive mechanism 212 and the X-axis drive mechanism 251b as moving devices based on the cutting program. That is, the control device 203a relatively moves the workpiece W and the cutting tool T2 by controlling the position of the cutting tool T2 and the like. Further, the control device 203a controls the rotation of the main shaft 222 and the turret 253.

The machining estimation device 203b of this embodiment has the same configuration as the machining estimation device 3b of Embodiment 1 shown in FIG. However, the grinding in the first embodiment is changed to cutting, and the grinding wheel T is changed to a cutting tool T2.

Next, in this embodiment, the workpiece side dynamic rigidity (Cw, Kw) and the tool side dynamic rigidity (Ct, Kt) will be described with reference to FIG. 11. The workpiece side dynamic rigidity (Cw, Kw) is the dynamic rigidity exhibited when the workpiece W is supported by the chuck 224 and the tailstock center 231, which are workpiece support members that constitute the lathe 202. The workpiece side dynamic stiffness (Cw, Kw) is defined by the damping coefficient Cw and the spring constant Kw. The damping coefficient Cw is a value representing the relationship between the relative speed of the workpiece W with respect to the reference positions of the spindle device 220 and the tailstock device 230 and the external force that the workpiece W receives. The spring constant Kw is a value representing the relationship between the relative position of the workpiece W with respect to the reference positions of the spindle device 220 and the tailstock device 230 and the external force that the workpiece W receives.

As in Embodiment 1, the workpiece side dynamic rigidity (Cw, Kw) is the workpiece dynamic rigidity (Cwa, Kwa), the support member dynamic rigidity (Cwb, Kwb), the workpiece W and the workpiece support. It can be broken down into contact dynamic rigidity (Cwc, Kwc) between the members (chuck 224, tailstock center 231).

The tool-side dynamic rigidity (Ct, Kt) is the dynamic rigidity regarding the tool stand 250, including the cutting tool T2. The tool side dynamic stiffness (Ct, Kt) is defined by the damping coefficient Ct and the spring constant Kt. The damping coefficient Ct is a value representing the relationship between the relative speed of the cutting tool T2 with respect to the reference position on the tool stand 250 and the external force that the cutting tool T2 receives. The spring constant Kt is a value representing the relationship between the relative position of the cutting tool T2 with respect to the reference position on the tool stand 250 and the external force that the cutting tool T2 receives.

The processing system 201 in the third embodiment has the same effects as the processing system 1 in the first embodiment.

(others)
In the first to third embodiments described above, the grinding process using the grinding machine 2 and the cutting process using the lathe 202 were explained by giving examples. In addition to these, cutting using a machining center is also applicable.

1, 201 Processing system 130 Contact dynamic stiffness calculation system 2 Grinding machine (processing equipment)
202 Lathe (processing equipment)
3a Control device 3b Machining estimation device 34 Spindle center (workpiece support member)
41, 231 Tailstock center (workpiece support member)
203a Control device 203b Machining estimation device 224 Chuck (workpiece support member)

Claims (6)

A contact dynamic rigidity calculation system that calculates contact dynamic rigidity at a contact portion between a workpiece and a workpiece support member when processing a workpiece supported by the workpiece support member with a tool, the system comprising:
a basic information acquisition unit that acquires basic information about the workpiece including information on the machining position on the workpiece;
When the workpiece supported by the workpiece support member changes from an initial state in which no acting force is applied from the tool to an operating state in which an acting force is applied to the workpiece from the tool, the workpiece and the above-mentioned A differential bending angle for calculating a differential bending angle that is the difference between the workpiece bending angle that is the bending angle of the workpiece at the contact portion with the workpiece support member and the support member bending angle that is the bending angle of the workpiece support member. A calculation section,
The spring constant and damping coefficient at the contact portion between the workpiece and the workpiece support member are calculated based on the basic information acquired by the basic information acquisition unit and the differential bending angle calculated by the differential bending angle calculation unit. a contact dynamic stiffness calculation unit that calculates the contact dynamic stiffness of the workpiece based on the spring constant and the damping coefficient;
Contact dynamic stiffness calculation system. a correspondence storage unit in which a correspondence between the processing position and the differential bending angle is stored in advance;
The contact according to claim 1, wherein the differential bending angle calculation unit calculates the differential bending angle based on the correspondence relationship stored in the correspondence storage unit and the processing position included in the basic information. Dynamic stiffness calculation system. The basic information acquisition unit further acquires, as the basic information, a maximum support diameter of a supported part of the workpiece supported by the workpiece support member;
The contact dynamic stiffness calculation section calculates the spring constant and the damping coefficient based on at least the maximum support diameter acquired by the basic information acquisition section and the differential bending angle calculated by the differential bending angle calculation section. The contact dynamic stiffness calculation system according to claim 1 or 2. A processing system comprising the contact dynamic stiffness calculation system according to any one of claims 1 to 3, a processing device that processes the workpiece, and a control device that controls processing by the processing device,
The control device is a machining system that controls machining by the machining device based on the dynamic rigidity of the workpiece including the contact dynamic rigidity calculated by the contact dynamic rigidity calculation system. Calculated by the contact dynamic stiffness calculation system according to any one of claims 1 to 3, a processing device that processes the workpiece, a control device that controls processing by the processing device, and the contact dynamic stiffness calculation system. and an estimator that estimates a machining result on the workpiece by the machining device based on the dynamic stiffness of the workpiece including the contact dynamic rigidity obtained,
The control device is a machining system that controls machining by the machining device based on the machining result estimated by the estimator. The processing system according to claim 4 or 5, wherein the tool is a grindstone and the processing device is a grinder.

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