Numerical control device, numerical control method, and numerical control program

Abstract

A numerical control device (10) controls a machine tool (1) to which a plurality of tools are detachably attached. The numerical control device (10) comprises at least one memory (30) and at least one processor (40). In the memory (30), identification information of a plurality of tool groups, in which a plurality of tools are classified on the basis of shape information relating to the shape of each tool and to each of which two or more tools belong, is stored, and also control information that is set for each tool and used to control the machine tool (1) is stored in association with the identification information of the tool group to which the corresponding tool belongs. The processor (40) acquires additional identification information added as identification information and additional control information added as control information, and compares the additional control information with control information of each tool belonging to the tool group having the same identification information as the additional identification information.

Description

Numerical control device, numerical control method, and numerical control program

[0001] The present disclosure relates to a numerical control device, a numerical control method, and a numerical control program.

[0002] There is a numerical control device for controlling a machine tool that determines the correctness of a newly input tool offset value based on the dimensions of a plurality of pre-registered tools and the tool offset values (see, for example, Patent Document 1).

[0003] Japanese Unexamined Patent Application Publication No. 2016-184293

[0004] The above numerical control device detects whether there is an error in the input by comparing the input tool offset value with the correlation between the dimensions of a plurality of pre-registered tools and the tool offset values. Therefore, a relatively large correlation is required between the dimensions of the plurality of tools and the tool offset values. However, in a machine tool dedicated to specific processing, etc., there is no correlation between the dimensions of the plurality of mounted tools and the tool offset values, and it may not be possible to determine the correctness of the input value by the method of the above device.

[0005] Therefore, even when the correlation between the dimensions of a plurality of tools and the tool offset values is small, it is desired to be able to determine whether there is an error in the tool offset value input by the operator.

[0006] One aspect of the present disclosure is a numerical control device for controlling a machine tool to which a plurality of tools are detachably mounted, comprising at least one memory and at least one processor, wherein the memory stores identification information for a plurality of tool groups to which at least two or more tools belong, each of which is a plurality of tool groups classified based on shape information relating to the shape of the respective tools, and stores control information used for controlling the machine tool set for each tool, associated with the identification information of the tool group to which the corresponding tool belongs, and the processor acquires additional identification information added as identification information and additional control information added as control information, and compares the control information of each tool belonging to the tool group having the same identification information as the additional identification information with the additional control information.

[0007] This is a schematic diagram showing a numerical control device according to one embodiment of the present disclosure and the configuration of a machine tool to which the numerical control device is applied. This is a schematic diagram showing the configuration of the tool magazine provided in the machine tool shown in Figure 1. This is a block diagram conceptually subdivided the configuration of the numerical control device shown in Figure 1 based on its function. This is a diagram for explaining the various types of information stored in the memory of the numerical control device shown in Figure 1. This is an example of a database stored in the memory shown in Figure 4. This is a flowchart explaining a numerical control method according to one embodiment of the present disclosure.

[0008] A numerical control device 10, a numerical control method, and a numerical control program according to one embodiment of this disclosure will be described below with reference to the drawings. The numerical control device 10 according to this embodiment is a device that numerically controls the operation of a machine tool 1 that performs predetermined processing on a workpiece W, as shown in Figure 1, for example.

[0009] First, let's describe the configuration of the machine tool 1. As shown in Figure 1, the machine tool 1 includes a bed 2, a table 3 on which the workpiece W is fixed, a spindle 4 that holds the tool T, a spindle head 5 that supports the spindle 4, and an ATC (automatic tool changer) 6.

[0010] Table 3 is positioned on the bed 2 and is supported so as to be movable in the horizontal direction by a feed motor (not shown) provided within the bed 2. The upper surface of table 3 is provided with optional fixing means (not shown) for securing the workpiece W. A column 7 is also provided behind table 3, extending vertically upward from the bed 2.

[0011] The spindle 4 has a chuck (not shown) that holds the tool T with its tip pointing downwards. The spindle 4 is attached to a spindle head 5 that is supported by a drive motor 8 so as to be movable vertically relative to the upper end of the column 7. In other words, the machine tool 1 performs predetermined machining on the workpiece W by moving the table 3 on which the workpiece W is set horizontally and moving the spindle 4 to which the tool T is attached vertically.

[0012] The ATC 6 includes, for example, a swivel-type tool magazine 6a and a tool changing section (not shown) that holds a tool T removed from the spindle 4 and a plurality of replacement tools T1 to Tn, as shown in Figures 1 and 2. In this case, the tools T, T1 to Tn are, for example, drills, end mills, milling cutters, etc., and each differs in at least one of the following: type, effective length, or diameter.

[0013] The tool magazine 6a is a device formed in the shape of a roughly circular box, and on its outer circumferential surface, there are a plurality of tool holding parts 6b for holding tools T, T1 to Tn, each arranged at equal intervals in the circumferential direction around the central axis A. The tool changer is a mechanism positioned between the tool magazine 6a and the spindle 4, and is a mechanism for automatically changing a tool T attached to the spindle 4 by known technology with one of the tools T1 to Tn stored in the tool magazine 6a.

[0014] As shown in Figure 3, the numerical control device 10 includes an input device 20, a memory 30 having a volatile storage medium such as RAM and a non-volatile storage medium such as ROM, HDD, or SSD, and at least one processor 40 such as a CPU. The numerical control device 10 in this embodiment also includes a display device 50.

[0015] The input device 20 is configured, for example, as a keyboard, touch panel, USB or other serial interface, or a combination thereof, and is a device that receives various information input from the operator. In other words, the input device 20 is a device that receives input of various programs and various setting values ​​for causing the machine tool 1 to process the workpiece W.

[0016] Memory 30 stores, for example, a system program 31 and an application program 32 that perform the basic functions of the numerical control device 10, as shown in Figure 4. Memory 30 also stores a machining program 33 that causes the machine tool 1 to perform a predetermined machining operation on the workpiece W. Furthermore, memory 30 stores a database 35 containing information about each tool T, T1 to Tn, and a judgment program (numerical control program) 34 that determines whether the information added to the database 35 by the operator is correct or incorrect.

[0017] Database 35 contains information, for example, about the tools T, T1 to Tn that are currently installed in machine tool 1, as well as information about tools that were previously installed in machine tool 1. As shown in Figure 5, database 35 also contains a tool group number (identification information) 36 that indicates the tool group to which each tool belongs, and a tool offset amount (control information) 37 that is set for each tool, all of which are registered in association with each other.

[0018] In this case, a tool group is a collection of all tools registered in the database 35 that share the same shape information, such as type, effective length, and diameter, and are interchangeable with each other. In this embodiment, each tool group contains at least two tools. The tool group number 36 is used to identify each tool group; in the example in Figure 5, numbers are used, but letters or symbols may also be used.

[0019] The tool offset amount 37 is a correction value set for each tool in order to eliminate the influence that the effective length or diameter of each tool has on the machining of the workpiece W.

[0020] The determination program 34 is a program that determines, for example, whether the tool offset amount (additional control information) 37' of the tool T' entered by the operator is within the appropriate range when adding a new tool T' to the tool magazine 6a.

[0021] The processor 40 reads and executes the machining program 33 from the memory 30 according to the system program 31 and application program 32 stored in the memory 30. The processor 40 also executes the determination program 34 stored in the memory 30 when the tool offset amount 37' is input by the operator.

[0022] The following section will explain in more detail the contents of the decision program 34 executed by the processor 40, using a block diagram that conceptually subdivides the processor 40 shown in Figure 3 based on its functions.

[0023] In the example shown in Figure 3, the processor 40 can be considered to comprise a plurality of functional blocks, namely an acquisition unit 41, a determination unit 42, an output unit 43, and a registration unit 44. When a new tool T' is added to the tool magazine 6a, the acquisition unit 41 acquires the tool group number (additional identification information) 36' and the tool offset amount 37' of the tool T' input by the operator.

[0024] The determination unit 42 selects a tool group number 36 from the database 35 that is the same as the tool group number 36' acquired by the acquisition unit 41, and extracts a plurality of tool offset amounts 37 associated with the selected tool group number 36. For example, in the example shown in Figure 5, if the tool group number 36' acquired by the acquisition unit 41 was 103, the determination unit 42 extracts seven tool offset amounts 37.

[0025] Furthermore, the determination unit 42 calculates a normal distribution based on the mean value μ and standard deviation σ of the extracted multiple tool offset amounts 37, and the probability density function f(x) of that normal distribution. The determination unit 42 then determines whether the probability of existence of the tool offset amount 37' in the calculated normal distribution is below a predetermined threshold, for example, μ ± 3σ or less. The determination unit 42 also compares the magnitude of the mean value μ of the multiple tool offset amounts 37 extracted from the database 35 with the magnitude of the tool offset amount 37' acquired by the acquisition unit 41.

[0026] For example, if the probability of a tool offset amount 37' existing is below a predetermined threshold and greater than the average value of the extracted multiple tool offset amounts 37, the determination unit 42 determines that the tool offset amount 37' is excessively large compared to the appropriate range. Also, if the probability of a tool offset amount 37' existing is below a predetermined threshold and less than the average value of the extracted multiple tool offset amounts 37, the determination unit 42 determines that the tool offset amount 37' is insufficient compared to the appropriate range. On the other hand, if the probability of a tool offset amount 37' existing is greater than a predetermined threshold, the determination unit 42 determines that the tool offset amount 37' is within the appropriate range. In other words, the determination unit 42 determines whether the input value is within the appropriate range by comparing the input tool offset amount 37' with the tool offset amounts 37 set for other multiple tools having the same tool group number.

[0027] The output unit 43 outputs a signal corresponding to the result of the determination unit 42's determination. For example, if the determination unit 42 determines that the input tool offset amount 37' is outside the appropriate range, the output unit 43 outputs a signal to that effect to the display device 50. On the other hand, if the determination unit 42 determines that the input tool offset amount 37' is within the appropriate range, the output unit 43 transmits a signal to that effect to the registration unit 44 and the display device 50. Upon receiving the signal, the registration unit 44 associates the input tool offset amount 37' with the same tool group number 36' that was input at the same time and registers it in the database 35.

[0028] The display device 50 is, for example, a monitor such as a liquid crystal display or a touch panel display, and displays various information such as the machining program 33 and the operating status of the machine tool 1. The display device 50 also displays an input screen for inputting the tool group number 36' and tool offset amount 37' of tool T', and the result of the judgment program 34 by the processor 40.

[0029] The numerical control method using the numerical control device 10 configured in this embodiment will be described below. In the following description, the case of adding a new tool T' to the ATC 6 will be explained as an example, following the conceptual block diagram shown in Figure 3 and the flowchart shown in Figure 6.

[0030] After the operator places the tool T' to be added to the ATC 6 into an empty tool holder 6b in the tool magazine 6a, they operate the input device 20 to input various information about the added tool T'. For example, the operator inputs the tool group number 36', which is a tool group classified based on the shape elements of the tool T', and the tool offset amount 37', which is determined according to the effective length and diameter dimensions of the tool T'.

[0031] In this case, the processor 40 executes the determination program 34. As a result, the acquisition unit 41 acquires the tool group number 36' and tool offset amount 37' of the tool T' input by the operator (step S1). The acquired tool group number 36' and tool offset amount 37' are passed to the determination unit 42. The determination unit 42 searches the database 35 stored in the memory 30 and selects a tool group number 36 that is the same as the received tool group number 36' (step S2). Furthermore, the determination unit 42 extracts a plurality of tool offset amounts 37 from the database 35 that are associated with the selected tool group number 36 (step S3).

[0032] The determination unit 42 then calculates the mean value μ and standard deviation σ of the extracted tool offset amounts 37. Furthermore, the determination unit 42 calculates the probability ft of the existence of μ±3σ in the normal distribution of the extracted tool offset amounts 37 (step S4). Specifically, the determination unit 42 calculates a value by substituting a predetermined threshold value of μ±3σ for x in the following equation (1).

[0033] Similarly, the determination unit 42 substitutes the acquired tool offset amount 37' into x in equation (1) above and calculates the probability fd of the existence of the tool offset amount 37' in the calculated normal distribution (step S5).

[0034] Next, the determination unit 42 compares the calculated existence probability fd with the existence probability ft (step S6). If the existence probability fd is smaller than the existence probability ft, the determination unit 42 compares the acquired tool offset amount 37' with the average value μ (step S7). If the tool offset amount 37' is smaller than the average value μ, the determination unit 42 determines that the input tool offset amount 37' is less than the corresponding tool offset amounts 37 in the database 35. The result of this determination is sent to the display device 50 by the output unit 43, and the display device 50 displays text indicating that the input tool offset amount 37' is less than the average value μ.

[0035] Conversely, if the determination unit 42 compares the tool offset amount 37' with the average value μ and finds that the tool offset amount 37' is greater than the average value μ, the determination unit 42 determines that the tool offset amount 37' is excessive. The result of this determination is then sent to the display device 50 by the output unit 43, and the display device 50 displays text indicating that the input tool offset amount 37' is excessive (step S9).

[0036] On the other hand, if the determination unit 42 compares the probability of existence fd with the probability of existence ft and finds that the probability of existence fd is greater than the probability of existence ft, the determination unit 42 determines that the input tool offset amount 37' is within the appropriate range. This determination result is then sent to the registration unit 44 and the display device 50. In this case, the registration unit 44 registers the input tool offset amount 37' in the database 35, associating it with the same tool group number 36' that was entered at the same time (step S10). The display device 50 also displays text indicating that the input tool offset amount 37' is correct and that it has been successfully registered in the database 35.

[0037] In this way, the execution of the judgment program 34 determines whether the input value is correct or incorrect based on a comparison between the tool offset amount 37' entered by the operator and the tool offset amounts 37 of multiple identical tools stored in the memory 30 beforehand. This allows the system to detect even if the operator enters an incorrect value when inputting the tool offset amount 37'. The operator can then be notified of the incorrect input by the text displayed on the display device 50. Therefore, it is possible to prevent the system from registering an incorrectly sized tool offset amount 37' in the numerical control device 10, which could lead to inappropriate machining of the workpiece W or operations that place an excessive load on the machine tool 1.

[0038] Furthermore, in this embodiment, the database 35 has at least two tool offset amounts 37 registered for each tool group classified by the same tool. Therefore, the input tool offset amount 37' can be compared with the tool offset amounts 36 of multiple identical tools, making it possible to more reliably detect incorrect input of the tool offset amount 37'.

[0039] Furthermore, in this embodiment, not only is it possible to determine if an incorrect input of the tool offset amount 37' is occurring, but the operator can also be made aware of whether the tool offset amount 37' is excessive or insufficient compared to the appropriate range. Therefore, the operator can more easily grasp the cause of the incorrect input.

[0040] In this embodiment, the processor 40 determines the correctness of the input tool offset amount 37' based on the average value of the corresponding multiple tool offset amounts 37 and their probability of existence in a normal distribution. Alternatively, the correctness of the input tool offset amount 37' may be estimated based on either the average value of the corresponding multiple tool offset amounts 37 or their probability of existence in a normal distribution. This reduces the computational load on the processor 40 when determining whether or not an input tool offset amount 37' is incorrect.

[0041] Furthermore, although this embodiment illustrates a configuration in which the numerical control device 10 is equipped with an input device 20, the numerical control device 10 may instead be configured to not be equipped with an input device 20 and to be connected to an external input device 20.

[0042] Furthermore, in this embodiment, the system determined whether or not there was an error in the input of the tool offset amount 37' by the operator. Alternatively, it may be used to determine whether or not there was an error in the input of the allowable feed rate (control information) or the allowable rotational speed (control information) of the tool T'. In this case, the feed rate data set for each tool and the tool group number 36 assigned to each tool should be associated and registered in the database 35.

[0043] Furthermore, in this embodiment, the user was notified of an incorrect input of the tool offset amount 37' by a text display on the display device 50, but the method of notifying the user of an incorrect input is not limited to this. For example, the user may be notified of an incorrect input by an alarm such as a warning sound, or by highlighting the value that is presumed to be an incorrect input.

[0044] As described above, the embodiments of the present disclosure have been described in detail. However, the present disclosure is not limited to the individual embodiments described above. These embodiments can be variously added, replaced, changed, partially deleted, etc., without departing from the gist of the invention or without departing from the spirit and scope of the invention derived from the content described in the claims and its equivalents. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as an example and are not limited thereto.

[0045] With respect to the above embodiments and modifications, the following additional notes are disclosed. (Note 1) A numerical control device for controlling a machine tool on which a plurality of tools are detachably mounted, comprising at least one memory and at least one processor, wherein the memory stores identification information for a plurality of tool groups to which at least two or more tools belong, each of which is a plurality of tool groups classified based on shape information relating to the shape of the respective tools, and stores control information used for controlling the machine tool set for each tool, associated with the identification information of the tool group to which the corresponding tool belongs, and the processor acquires additional identification information to be added as identification information and additional control information to be added as control information, and compares the control information of each tool belonging to the tool group having the same identification information as the additional identification information with the additional control information. (Note 2) The numerical control device according to Note 1, wherein the processor performs the comparison based on the average value of the control information of each tool belonging to the tool group having the same identification information as the additional identification information. (Note 3) A numerical control device according to Note 1 or Note 2, wherein the processor performs the comparison using the probability density function of a normal distribution of the control information of each tool belonging to the tool group having the same identification information as the additional identification information. (Note 4) A numerical control device according to any one of Notes 1 to 3, comprising an input device for receiving input of the additional identification information and the additional control information. (Note 5) A numerical control device according to any one of Notes 1 to 4, wherein the control information is the tool offset amount of each tool. (Note 6) A numerical control device according to any one of Notes 1 to 5, wherein the processor stores the additional control information in memory in association with the same identification information as the additional identification information based on the result of the comparison. (Note 7) A numerical control device according to any one of Notes 1 to 6, wherein the processor notifies the result of the comparison.(Note 8) A numerical control method for controlling a machine tool to which a plurality of tools are detachably attached, comprising: a plurality of tool groups to which the plurality of tools are classified based on shape information relating to their respective shapes, each storing identification information for a tool group to which at least two or more tools belong; storing control information used for controlling the machine tool, set for each tool, in association with the identification information of the tool group to which the corresponding tool belongs; acquiring additional identification information added as identification information and additional control information added as control information; and comparing the control information of each tool belonging to the tool group having the same identification information as the additional identification information with the additional control information. (Note 9) A numerical control program for controlling a machine tool to which multiple tools are detachably attached, wherein the program causes a computer to perform the following actions: storing identification information for a tool group to which at least two or more tools belong, a plurality of tool groups to which the plurality of tools are classified based on shape information relating to their respective shapes, and storing control information used for controlling the machine tool, set for each tool, in association with the identification information for the tool group to which the corresponding tool belongs; acquiring additional identification information added as identification information and additional control information added as control information; and comparing the control information of each tool belonging to the tool group having the same identification information as the additional identification information with the additional control information.

[0046] 1 Machine tool 10 Control device 20 Input device 30 Memory 36 Tool group number (identification information) 36' Tool group number (additional identification information) 37 Tool offset amount, feed rate (control information) 37' Tool offset amount (additional control information) 40 Processor T, T', T1 to Tn Tool

Claims

1. A numerical control device for controlling a machine tool to which multiple tools are detachably mounted, comprising at least one memory and at least one processor, wherein the memory stores identification information for a plurality of tool groups to which at least two or more tools belong, each of which is a plurality of tool groups classified based on shape information relating to the shape of the respective tools, and stores control information used for controlling the machine tool set for each tool, associated with the identification information of the tool group to which the corresponding tool belongs, and the processor acquires additional identification information to be added as identification information and additional control information to be added as control information, and compares the control information of each tool belonging to the tool group having the same identification information as the additional identification information with the additional control information.

2. The numerical control device according to claim 1, wherein the processor performs the comparison based on the average value of the control information of each tool belonging to the tool group having the same identification information as the additional identification information.

3. The numerical control device according to claim 1 or 2, wherein the processor performs the comparison using the probability density function of a normal distribution of the control information of each tool belonging to the tool group having the same identification information as the additional identification information.

4. A numerical control device according to any one of claims 1 to 3, comprising an input device for receiving the additional identification information and the additional control information.

5. The numerical control device according to any one of claims 1 to 4, wherein the control information is the tool offset amount of each tool.

6. The numerical control device according to any one of claims 1 to 5, wherein the processor stores the additional control information in the memory in association with the same identification information as the additional identification information, based on the result of the comparison.

7. The numerical control device according to any one of claims 1 to 6, wherein the processor notifies the result of the comparison.

8. A numerical control method for controlling a machine tool to which multiple tools are detachably attached, comprising: storing identification information for a tool group to which at least two or more tools belong, wherein the multiple tools are classified into multiple tool groups based on shape information relating to their respective shapes; storing control information used for controlling the machine tool, set for each tool, in association with the identification information of the tool group to which the corresponding tool belongs; acquiring additional identification information added as identification information and additional control information added as control information; and comparing the control information of each tool belonging to the tool group having the same identification information as the additional identification information with the additional control information.

9. A numerical control program for controlling a machine tool to which multiple tools are detachably attached, wherein the program stores identification information for a tool group to which at least two or more tools belong, a plurality of tool groups to which the plurality of tools are classified based on shape information relating to their respective shapes, and stores control information used for controlling the machine tool, set for each tool, in association with the identification information of the tool group to which the corresponding tool belongs, an additional identification information added as the identification information and an additional control information added as the control information, and causes a computer to perform the following actions:

Images