OPERATING STATE DISPLAY DEVICE AND OPERATING STATE DISPLAY METHOD FOR FEED AXIS IN MACHINE TOOL

Abstract

An operating state display device displays an operating state of a feed axis in a machine tool including the feed axis. The feed axis linearly moves a moving body via a ball screw with a servomotor. The operating state display device includes a passage number count unit, a use frequency calculation unit, and a display unit. The passage number count unit preliminarily divides an operating range of an axis operation of the feed axis into a predetermined number of sections and counts passage numbers of the moving body in the respective sections. The use frequency calculation unit calculates frequencies of use in respective classified types of the axis operation in each of the sections based on the counted passage numbers. The display unit displays the calculated frequencies of use in the respective classified types on a monitor in a predetermined aspect.

Claims

1. An operating state display device that displays an operating state of a feed axis in a machine tool including the feed axis, the feed axis linearly moving a moving body via a ball screw with a servomotor, the operating state display device comprising: a passage number count unit that preliminarily divides an operating range of an axis operation of the feed axis into a predetermined number of sections and counts passage numbers of the moving body in the respective sections; a use frequency calculation unit that calculates frequencies of use in respective classified types of the axis operation in each of the sections based on the counted passage numbers; and a display unit that displays the calculated frequencies of use in the respective classified types on a monitor in a predetermined aspect.

2. The operating state display device of the feed axis in the machine tool according to claim 1, further comprising a threshold calculation unit that calculates thresholds indicating biases of the frequencies of use of the respective sections, based on a length of life of the feed axis and a ratio of a section number whose type of the axis operation is a cutting feed type in a total section number in the operating range, wherein the display unit displays the calculated thresholds on the monitor together with the frequencies of use.

3. An operating state display method that displays an operating state of a feed axis on a monitor in a machine tool including the feed axis, the feed axis linearly moving a moving body via a ball screw with a servomotor, the operating state display method executing: preliminarily dividing an operating range of an axis operation of the feed axis into a predetermined number of sections and counting passage numbers of the moving body in the respective sections; calculating frequencies of use in respective classified types of the axis operation in each of the sections based on the counted passage numbers; and displaying the calculated frequencies of use in the respective classified types on the monitor.

4. The operating state display method of the feed axis in the machine tool according to claim 3, further executing calculating thresholds indicating biases of the frequencies of use of the respective sections, based on a length of life of the feed axis and a ratio of a section number whose type of the axis operation is a cutting feed type in a total section number in the operating range, wherein the displaying includes displaying the calculated thresholds on the monitor together with the frequencies of use.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 is a block diagram of a position control device and an operating state display device for a feed axis.

[0018] FIG. 2 is an explanatory diagram illustrating a dividing example of an operating range of the feed axis.

[0019] FIG. 3 is a flowchart of an operating state display method for the feed axis.

[0020] FIG. 4 is a graph illustrating a display example of an operating state of the feed axis.

[0021] FIG. 5 is a graph illustrating a display example of the operating state of the feed axis.

DETAILED DESCRIPTION

[0022] The following describes embodiments of the disclosure based on the drawings.

[0023] FIG. 1 is an exemplary block diagram of a position control device for a feed axis in a machine tool to which the disclosure is applied.

[0024] In this position control device, a position command from a numerical control device (NC device) 10 and a current position from a position detector 6 mounted on a servomotor 7 are input to an adder 1, and then, a calculated position deviation is input to a position controller 2. The position controller 2 generates a speed command value corresponding to a position error amount. A velocity controller 3 generates a torque command value corresponding to the speed command value and a speed detection value obtained by calculating the current position from the position detector 6 with a differentiator 5. A current controller 4 controls a current in the servomotor 7 based on the input torque command value. The position control device includes a ball screw 8 and a moving body 9 such as a table.

[0025] The NC device 10 includes a storage unit 11 and a monitor 12 in addition to a feed axis controller (not illustrated) that outputs a position command and input means. The storage unit 11 stores the current position detected at the position detector 6, a control current value of the servomotor 7, and information used in these processes. The monitor 12 displays an operating state.

[0026] The storage unit 11 divides an operating range of the feed axis into a plurality of sections (here, ten sections) as illustrated in FIG. 2, and stores dividing lines and ranges of the respective sections. The ranges of the respective sections are appropriately set in a range of about one tenth to one hundredth of a stroke amount corresponding to a machine size since dividing the operating range in the minimum unit of the feed axis position causes an enormous volume of data amount. Especially, when there is a range or the like through which the moving body 9 passes only in the ATC operation and the APC operation, it is not necessary to divide the operating range at equal intervals.

[0027] Furthermore, the NC device 10 includes a passage number count unit 13, a use frequency calculator 14, and a display unit 15. The passage number count unit 13 is passage number count means that counts and accumulates the number of times the moving body 9 passes through the divided section. The use frequency calculator 14 is use frequency calculation means that, based on the counted passage number and types of an axis operation (here, a cutting feed type and a fast-feed type for the ATC operation and the like), classifies and calculates frequencies of use of the respective sections according to the types of the axis operation. The display unit 15 is display means that creates a predetermined graph from the frequencies of use classified and calculated at the use frequency calculator 14 to display it on the monitor 12. That is, the NC device 10 functions also as an operating state display device for the feed axis.

[0028] A calculation method of the operating state of the feed axis in the operating state display device configured as described above will be described based on a flowchart in FIG. 3.

[0029] At S1, it is determined whether or not the moving body 9 has passed through a feed axis position X.sub.n (a dividing line set in FIG. 2) based on position information of the position detector 6. At S2, after the passage through the dividing line has been confirmed, it is determined whether or not a moving direction is a positive direction. At S3, in the case of the move in the positive direction, it is determined whether the axis operation of the feed axis is the cutting feed type or the fast-feed type. This determination is performed by, for example, comparing a feed velocity with a preliminarily set reference velocity.

[0030] Here, when the axis operation is the cutting feed type, the passage number is added to the classification of the cutting feed in a section (a feed axis range X.sub.n1 to X.sub.n) on a negative side of its dividing line at S4. On the other hand, when the axis operation is the fast-feed type, the passage number is added to the classification of the fast-feed in the section (the feed axis range X.sub.n1 to X.sub.n) on the negative side of its dividing line at S5.

[0031] On the other hand, in the case of the move in the negative direction in the determination at S2, it is determined whether the axis operation of the feed axis is the cutting feed type or the fast-feed type at S6.

[0032] Here, when the axis operation is the cutting feed type, the passage number is added to the classification of the cutting feed type in a section (a feed axis range X.sub.n to X.sub.n+1) on a positive side of its dividing line at S7. On the other hand, when the axis operation is the fast-feed type, the passage number is added to the classification of the fast-feed type in the section (the feed axis range X.sub.n to X.sub.n+1) on the positive side of its dividing line at S8. These S1 to S8 are a passage number count step.

[0033] Next, the frequencies of use of the respective sections are classified and calculated according to the types of the axis operation, based on the counted passage number for every classification of the axis operation at S9 (a use frequency calculation step). Such a frequency of use may be calculated as a parameter obtained by multiplying the frequency of use by a coefficient in consideration of a load in an axial direction or the feed velocity, in addition to direct display of the passage number. For example, when the load in the axial direction is considered, the load in the axial direction may be estimated from a load of the servomotor 7 so that the coefficient is calculated from a ratio of the load in the axial direction to an average load assumed in design. When the feed velocity is considered, a velocity of the feed velocity may correspond to the operation coefficient in the formula (1).

[0034] Then, after a display command to the monitor 12 is input at S10, a graph where the calculated frequencies of use are discriminated for every classification is created to be displayed on the monitor 12 at S11 (a display step). When the display command is not input, the process returns to S1, and then, the count of the passage number through the feed axis position and the calculation of the frequency of use are repeated.

[0035] FIG. 4 illustrates a display example on the monitor 12. Thus classifying the frequency of use in the cutting feed and the fast-feed types to display them for every section facilitates an examination to which position a workpiece should be moved in order to avoid a bias of an axis use position.

[0036] Thus, with the operating state display device and method for the feed axis in the above-described embodiment, the frequencies of use for the respective sections divided in the operating range of the feed axis are displayed according to the types of the axis operation, thus being possible to monitor the use position of the feed axis used in cutting to accurately understand the operating state of the feed axis. Accordingly, the advance preparation such as the change of the setup position is ensured to avoid acceleration of replacement of a component due to a malfunction by local abrasion, thus ensuring the maximum life of the machine.

[0037] Although the above-described embodiment is configured to display the frequency of use on the monitor after the input of the display command, the timing of the display is not limited to this timing. The frequency of use may be displayed on the monitor in real time without waiting the input, or the frequency of use may be periodically displayed based on when the passage number of the moving body reaches a setting value in a predetermined section, or when a total used period of the feed axis reaches a setting value.

[0038] For example, in a case of a machine tool including a plurality of feed axes such as an X-axis, a Y-axis, and a Z-axis, the frequency of use can be switchingly displayed for every feed axis, or the frequencies of use of all the feed axes can be simultaneously displayed on one screen.

[0039] Further, as illustrated in FIG. 5, thresholds can be displayed together. Here, a threshold for determining the end of its life and a threshold indicating the bias of the use position are illustrated. The threshold for determining the end of its life may use a value obtained by dividing the length of life calculated by the above-described formula (1) by section number in the operating range of the feed axis. The threshold indicating the bias of the use position may be calculated based on, for example, the following formula (2) (a threshold calculation step).

Threshold Indicating Bias of Use Position=Threshold for determining End of LifeSection Number Whose Ratio of Cutting Feed is Equal to or More than Certain Ratio/Total Section Number(2)

[0040] Thus, a guidance to uniformly use the feed axis can be performed by setting and displaying the threshold indicating the bias of the use position, corresponding to the section used for the cutting feed. The display of the threshold is not limited to the display of the two thresholds, and may be the display of the threshold indicating the bias of the use position alone.

[0041] Additionally, although the above-described embodiment configures the operating state display device for the feed axis in the NC device, the operating state display device for the feed axis may be disposed as another device different from the NC device or may be disposed as a separate device outside the machine tool. Further, the operating state of the feed axis can be displayed in units of a plurality of machine tools when one operating state display device is coupled to the plurality of machine tools by wire or wirelessly.

[0042] It is explicitly stated that all features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original disclosure as well as for the purpose of restricting the claimed invention independent of the composition of the features in the embodiments and/or the claims. It is explicitly stated that all value ranges or indications of groups of entities disclose every possible intermediate value or intermediate entity for the purpose of original disclosure as well as for the purpose of restricting the claimed invention, in particular as limits of value ranges.