JP2006062021A - Turret lathe including rotary tool turret - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain technical means for correcting a machining error due to thermal deformation of a machine with higher accuracy, in a lathe including a turret for mounting a rotary tool. <P>SOLUTION: A correction value is computed at every tool station of a rotary tool turret. The rotational history of the tool in the respective stations of the turret is individually detected to compute different correction values in every tool station or temperature sensors are installed at equal spaces in the circumferential direction of the turret to compute a correction value of each turret from the temperature distribution in the peripheral direction of the turret. In computing the correction value of each tool station, in addition to the rotational history of the tool station, at least the rotational history of the two or more tool stations adjacent to each other is weighted by the adjacent degree and the elapsed time to compute the correction values. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lathe provided with a turret on which a rotating tool can be mounted, and more particularly to a turret lathe characterized by a means for correcting a processing error due to thermal deformation of a machine.

  When machining a workpiece with a lathe, heat is generated in the bearing portion of the spindle that rotates at high speed and the workpiece machining portion. The heat generated in the spindle bearing is transmitted to the spindle and the headstock, and the heat generated in the workpiece machining part is transmitted to the bed and the tool rest via the cutting oil. Therefore, as the machine tool is operated, the machine temperature rises locally and as a whole, and thermal deformation of the machine itself due to this temperature rise appears as a workpiece machining error.

  Therefore, in order to correct the machining error due to thermal deformation of the machine and the workpiece, the temperature of each part of the machine, for example, the headstock and the tool post, is measured, and the relationship between the machine temperature and the machining error generated in the workpiece is measured in advance. From this measured value, a correction formula for machining error due to machine temperature is obtained and registered in the NC device, and the correction value is obtained by substituting the machine temperature for actual machining of the workpiece into the correction formula, and output from the NC device. The machining accuracy is improved by correcting the command value to be performed with the correction value and setting the position of the tool post.

Main heat sources in a lathe are a spindle bearing, a workpiece machining position, a hydraulic pump, and the like. In addition, since the bed is large in size, it is greatly deformed by heat and is greatly affected by room temperature. Therefore, in the conventional lathe, as shown in FIG. 6, temperature sensors s ₁ , s ₂ , s ₃ ... Are installed at important points such as a room temperature sensor s ₀ and a lathe bed 1, spindle head 2, tool post 3. The coefficients α ₀ , α ₁ , α ₂ , α ₃ ... Multiplied by the detected values t ₀ , t ₁ , t ₂ , t _3. Registered in the means 13, and based on the detected temperature when actually machining the workpiece,
δ = α ₀ t ₀ + α ₁ t ₁ + α ₂ t ₂ + α ₃ t ₃ +... + α _n t _n + β
Thus, a correction value (origin setting value) δ is obtained, and the command value of the machining program 15 is corrected with this correction value δ to set the position of the tool post 2. Here, n is the number of temperature sensors attached to the machine.

On the other hand, in a machining center or the like, a correction value is obtained from a rotation history of a spindle to correct a workpiece machining error. For example, as shown in FIG. 7, the correction term δ _s due to the spindle rotation is changed to δ _s = ε _m using the m + 1 spindle rotation speeds w _m , w _m−1 ... W ₀ immediately before detection at the sampling period d. w _m + ε _m-1 w _m-1 + ... + ε ₀ w ₀
It is to obtain and correct at. Here, ε _m , ε _m-1 ... Ε ₀ are correction coefficients obtained by test machining or the like, and m is the number of histories stored in the memory of the NC device. It shows that it is going.
JP 2003-285244 A

  The turret lathe turret can only be equipped with a turning tool such as a fixed drill that cuts the tool bit or the center hole (fixed tool turret) and a built-in tool drive shaft. There is a machine (rotating tool turret) that enables machining and the like, and a lathe having a fixed tool turret and a rotating tool turret in one machine is also used. Conventionally, machining errors are corrected for a lathe equipped with a rotating tool turret in the same manner as a lathe equipped with a fixed tool turret. In other words, regardless of what tool is attached to which tool station of the turret, the machining error is corrected with the correction value calculated with the same correction formula for all the tools attached to the tool station. .

  When the rotary tool mounted on the rotary tool turret is relatively small and the frequency of use is small, it is possible to correct the machining error by the conventional method as described above. However, when the tool to be installed becomes large and the frequency of use increases, there arises a problem that the processing error varies depending on the tool station used at the time of processing. With the conventional method, this variation can be corrected appropriately. There wasn't.

  This invention makes it a subject to obtain the technical means which can correct | amend the processing error by the thermal deformation of the machine in the lathe provided with the rotary tool turret with higher precision.

  According to the present invention, in a lathe equipped with a rotating tool turret, the above-described problem is solved by calculating a correction value for each tool station of the rotating tool turret. In order to calculate a different correction value for each tool station, it is necessary to detect the temperature distribution in the circumferential direction of the turret or to detect the heat generation amount for each tool mounting station. Therefore, in the present invention, a method for individually detecting the rotation history of the tool at each tool station of the turret and calculating a different correction value for each tool station, and installing temperature sensors at equal intervals in the circumferential direction of the turret. Thus, a method for calculating a correction value for each turret from the temperature distribution in the circumferential direction of the turret is proposed.

The turret lathe according to the invention of claim 1 of the present application includes a turret 4 provided with a plurality of tool stations T ₁ , T ₂ ... For mounting rotating tools, and temperature sensors s ₁ , s mounted at predetermined positions of the machine. ₂ and a calculation means 13 for calculating a correction value δ of a machining error based on the detected values t ₁ , t ₂ ... Of these temperature sensors, each tool station T of the turret ₁ , rotation history storage means 14 for storing the rotation history of the tool every T ₂ ..., And the calculation means uses the stored value of the rotation history storage means to determine the machining error for each tool station of the turret. The correction values δ ₁ , δ ₂ ... Are calculated.

The amount of thermal deformation of a certain tool station T _i is most greatly influenced by the rotation history of the tool station, and then affected by the rotation history of the adjacent tool stations T _i-1 and T _{i + 1.} It is influenced by the rotation history of the neighboring tool stations and is influenced most by the rotation history nearer in time, such as being influenced by the rotation history of the adjacent tool station. Therefore, in order to calculate the correction value of each tool station, in addition to the rotation history of the tool station, the rotation history of at least a plurality of adjacent tool stations is weighted by the degree of the adjacent and the elapsed time. Will be.

The turret lathe according to the invention of claim 2 of the present application includes a turret 4 having a plurality of tool stations T ₁ , T ₂ ... For mounting a rotating tool, and temperature sensors s ₁ and s mounted at predetermined positions of the machine. And a plurality of turrets mounted at equal intervals in the circumferential direction of the turret in a lathe including ₂ ... And a calculation means 13 for calculating a correction value of a machining error based on detection values of these temperature sensors Temperature sensors C ₁ , C ₂ ..., And the calculation means calculates machining error correction values δ ₁ , δ ₂ ... For each tool station of the turret using the detection value of the turret temperature sensor. It is characterized by doing.

In the case of the invention of claim 2, the correction value at each tool station of the rotary tool turret is multiplied by the detected values τ ₁ , τ ₂ ... Of the temperature sensors C ₁ , C _2. It is realizable by calculating | requiring coefficient (eta) ₁ , (eta) _2, ... for every tool station.

  According to the present invention, since the correction value of the machining error is calculated for each tool station of the rotary tool turret, the turret 4 is non-uniform due to the usage frequency of the plurality of rotary tools attached to the turret and the variation of the machining load. Even when thermal deformation occurs, there is no variation in error due to the tool station, and higher machining accuracy can be realized.

  In particular, the present invention is effective for a lathe (composite lathe) equipped with a large rotating tool turret capable of heavy-duty machining, and a composite lathe capable of machining workpieces of various shapes with high accuracy on the same machine. There is an effect that it can be provided.

1 to 3 are diagrams for explaining a first embodiment of the present invention and for explaining a method of using a rotation history. The calculation means 13 of the NC device 12 for controlling the lathe 10, as in the conventional device, the detection temperature t ₀ of the temperature sensor s _0, headstock 1, the tool rest 2, provided the machine of the key points, such as bed 3 Detection temperatures t ₁ , t ₂ , t ₃ ... Of the temperature sensors s ₁ , s ₂ , s ₃ .

The tool post 2 includes a rotating tool turret 4, and an indexing motor 5 for indexing the rotating tool turret and a tool driving motor 6 are provided. The indexing motor 5 is rotationally driven by a tool selection command from the machining program 15, and the tool driving motor 6 is rotationally driven by a tool rotation command from the machining program 15, so that the tool station T _i used for machining is used. The rotation speed w of the tool mounted on the tool station can be recognized by the NC device 12. Therefore, by providing a memory area for each tool station and storing the tool rotation speed for each predetermined sampling period in the memory area corresponding to the tool station used at that time, the rotation history for each tool station is stored in the NC device. Is stored in the memory 14. The stored rotation speed history is stored in the latest predetermined period by the procedure of adding new data and deleting the oldest data.

Assuming that the turret 4 is a turret of 12 stations as shown in FIG. 2, the rotation history of the tool at each tool station T _i (i = 1, 2,... 12) is the rotation history of the tool drive motor 6. 3 (a), the detected rotation speeds w _m , w _m−1 ... W ₀ for each sampling period d similar to those shown in FIG. 7 are calculated when they are detected. Are assigned to the tool turrets T ₁ , T _2, ... T ₁₂ . That is, if the rotation history of the tool drive motor 6 is as shown in FIG. 3A and the tool stations determined at each rotation are T ₁ , T ₃ , T _1. The rotation history of T ₁ is as shown in FIG. 3B, and the rotation history of the third station T ₃ is as shown in FIG.

Correction amount? T _i according to the rotary tool driven at a certain tool station _{T i (i = 1,2 ··· 12} ) the _{δT i = ε m w im +} ε m-1 w im-1 + ··· ε 0 w i0
If the coefficients ε _m , ε _m−1 ... Ε ₀ take the same value in all tool stations, for example, the correction amount δT ₁ of the first station T ₁ is determined by the tool station. Only the rotation history at the time of being operated, that is, only the rotation history in FIG. 3B is substituted into w _1m , w _1m-1 ... W ₁₀ (w _{1 at the} time when another tool station is selected is 0). Correction amount? T ₃ of the third station T ₃ is calculated similarly using a rotating history shown in FIG. 3 (c), the same applies to the other tool stations. As a matter of course, the correction amounts δT ₂ and δT ₁₂ of the tool stations T ₂ and T ₁₂ on which the fixed tool is mounted are zero.

Thermal deformation at a tool station T _i is affected not only by heat generation at the tool station but also by heat generation at the surrounding tool stations. Assuming that affected all tool stations, the correction amount [delta] _i when performing processing by using a tool of the tool station T _i is
δ _i = δ _a × E + γ _i1 δT ₁ + γ _i2 δT ₂ ... γ _i12 δT ₁₂ Here, δ _a is the same as the conventional formula δ _a = α ₀ t ₀ + α ₁ t ₁ + α ₂ t ₂ + α ₃ t ₃ ... Α _n t _n + β
Is the correction amount due to thermal deformation of the entire machine. However, the coefficients α ₀ , α ₁ , α ₂ ... Α _n are not necessarily the same as those in the past.

On the other hand, γ _i1 δT ₁ + γ _i2 δT ₂ +... + Γ _i12 δT ₁₂ is a correction term due to thermal deformation of the turret 4, and γ _ij (i, j = 1 to 12) is the rotation of the j-th station T _j . The history is a coefficient that affects the correction value of the i-th station T _{i, and} the values of γ _ij are all defined as different values (may be defined as γ _ij = γ _ji ). E in the equation is a weighting factor of the deformation of the entire machine with respect to the deformation of the turret.

The coefficients ε _m , ε _m−1 ... Ε ₀ , α ₀ , α ₁ , α ₂ ... Α _n and β, γ _ij (i, j = 1 to 12) and E defined as above. Is obtained from the measurement data of the error at the time of test machining or actual workpiece machining, and is registered in the calculation means 13 of the NC device, whereby a certain tool station T _i is determined using the above formula. The correction value δ _i at the time can be calculated as an individual value for each turret, so by correcting the origin setting value with the correction value, machining due to tool station differences that were impossible with the conventional method Variations in error can be corrected, and higher-precision machining can be realized.

  4 and 5 are explanatory views showing a second embodiment of the present invention. In the figure, the same reference numerals are used for the same members or values as those of the first embodiment. Only differences from the first embodiment will be described below.

In the second embodiment, temperature sensors C ₁ , C ₂ ... C _k (k is the number of temperature sensors mounted on the turret. Instead of the rotation history of the tool of the first embodiment, shown in the figure. 6), the temperature sensors C ₁ , C ₂ ... C ₆ are mounted on the back surface of the turret at the same interval in the circumferential direction, as shown in FIG. . Detection temperature tau _k of the temperature sensor _{C k (k = 1 ··· 6} ) is received by the wireless receiving apparatus 7 is sent to the interface 11, along with other temperature t _0, t ₁ ··· t _n Input to the arithmetic means 13.

The calculation means 13 calculates a correction value δ _i for each tool station T _i .
δ _i = δ _a × E + η _i1 τ ₁ + η _i2 τ ₂ + ... η _i6 τ ₆
However, δ _a = α ₀ t ₀ + α ₁ t ₁ + α ₂ t ₂ + α ₃ t ₃ ... Α _n t _n + β, i = 1-12
And the coefficients α ₀ , α ₁ ,..., Β and η ₁₁ , η ₁₂ ... Η _ik ..., And ₁₂₆ are registered, and based on these coefficients and the detected temperature. Thus, the correction value δ _i (i = 1 to 12) for each tool station is calculated. Here, δ _a indicates a correction amount due to deformation of the entire machine, and η _i1 τ ₁ + η _i2 τ ₂ +... Η _i6 τ ₆ indicates a correction amount for the tool station T _i due to deformation of the turret 4. The coefficient η _ik (i is the number of the tool station and k is the number of the turret temperature sensor) is obtained as a different value for each tool station (in consideration of the positional relationship between the tool station and the sensor). For example, in the example of Fig. 5, the positional relationship of the sensors C ₁ and C ₂ with respect to the tool station T ₁ and the sensors C ₂ and C with respect to the tool station T ₃ are defined. since ₃ positional relationship to be the same, when calculating the correction amount of the tool station T detected temperature tau ₁ of the sensor C _1, C ₂ for _1, coefficient of τ ₂ η _11, η ₁₂ each tool station T ₃ Sensor C _2, the correction factor taking into account the effect of the C ₃ eta _32, may be defined as equal to the eta _33.).

Α ₀ , α ₁ , α ₂ ... Α _n , β and η ₁₁ , η ₁₂ ... Η ₁₂₆ in the equation defined above are measured values of errors when testing or actual workpieces are machined. By calculating from the above and registering it in the calculation means 13, the correction value considering the thermal deformation of the turret 4 can be obtained for each tool station as in the first embodiment, and high machining accuracy is realized. It becomes possible to do.

Block diagram showing an example of the first embodiment Illustration showing the number of the tool station of the rotary tool turret Explanatory drawing showing distribution of rotation history to tool stations Block diagram showing an example of the second embodiment Diagram showing temperature sensor placed on turret Block diagram showing conventional means Diagram showing examples of spindle rotation history

Explanation of symbols

4 Turret
13 Calculation means
14 Rotation history storage means C ₁ , C ₂ ... Turret temperature sensors T ₁ , T ₂ ... Tool stations t ₁ , t ₂ ... Detection values s ₁ , s ₂ ... Temperature sensors δ Correction value

Claims (2)

A turret (4) provided with a plurality of tool stations (T ₁ , T ₂ )... For mounting a rotating tool, a temperature sensor (s ₁ , s ₂ ) mounted at a predetermined position of the machine, and these Each of the tool stations (T of the turret) in a lathe provided with a calculation means (13) for calculating a correction value (δ) of a machining error based on the detected values (t ₁ , t ₂ ). ₁ , T ₂ )... For each tool station of the turret using the stored value of the rotation history storage means. A turret lathe characterized by calculating a correction value (δ ₁ , δ ₂ ). A turret (4) provided with a plurality of tool stations (T ₁ , T ₂ )... For mounting a rotating tool, a temperature sensor (s ₁ , s ₂ ) mounted at a predetermined position of the machine, and these In a lathe equipped with a calculation means (13) for calculating a correction value of a machining error based on a detected value of the temperature sensor, a plurality of turret temperature sensors (C ₁₎ mounted at equal intervals in the circumferential direction of the turret. , C ₂ )... And the calculation means calculates a correction value (δ ₁ , δ ₂ )... Of machining error for each tool station of the turret using the detection value of the turret temperature sensor. A turret lathe characterized by this.

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