JP2023025564A - Machine tool - Google Patents

Abstract

To provide a machine tool which can prevent deterioration of processing accuracy caused by heat transmission from one tool to another tool and a turret.SOLUTION: A machine tool 10 includes: a cutter holder 16; a turret 18 to which multiple tools 60 is attachable through tool holders 62; a discharge nozzle 22 which discharges a coolant; a robot 20 which holds the discharge nozzle 22; and a controller 26. Measuring points are set in at least a part of the tool holders 62. The controller 26 is configured to monitor temperatures and positions of the measuring points to determine whether or not cooling is needed for each measuring point based on its temperature, and control the driving of the discharge nozzle 22 and the robot 20 to discharge the coolant from the discharge nozzle 22 to the measuring point where it is determined that cooling is needed.SELECTED DRAWING: Figure 1

Description

This specification discloses a machine tool with a turret to which a plurality of tools can be mounted via tool holders.

A machine tool having a turret on which a plurality of tools can be mounted via tool holders is widely known. In such a machine tool, turning the turret automatically switches the tool used for cutting. Here, when a workpiece is machined with a tool, heat is generated in the tool and a tool holder that holds the tool due to friction and the like. In order to remove such heat, conventionally, coolant has been discharged to the tool or workpiece during execution of the cutting process.

JP 2019-98479 A JP 2017-94420 A

Conventionally, however, such coolant is often supplied only to tools that are actually performing cutting, and coolant is not supplied to tools that are not currently being used for cutting. As a result, conventionally, the heat of the tool immediately after cutting has been transferred to other tools and the turret, resulting in deterioration of machining accuracy.

For example, consider a case where a workpiece is subjected to a first cutting process using a first tool and then a second cutting process using a second tool. In conventional machine tools, coolant is supplied to the first tool during the first cutting operation. On the other hand, when the first cutting process is completed and the second cutting process is started, the coolant is supplied to the second tool without supplying the coolant to the first tool. However, the first tool often remains hot for a while after the first cutting process is completed. The heat of such a first tool is transferred to a turret, another tool (for example, a second tool), etc. via a tool holder that holds the first tool, and the cutting accuracy of the other tool is improved. had a negative impact on

Patent Document 1 discloses a technique of installing a robot in a processing chamber and using the robot to discharge coolant to a desired position. However, Patent Literature 1 does not specify the selection of the position for discharging the coolant.

In addition, Patent Document 2 discloses a technique for identifying a location where heat is generated in a machining chamber as an adhesion position of chips, and applying a liquid to the location from a nozzle provided on a robot to remove chips from the machining chamber. is disclosed. However, Patent Document 2 does not take into account any reduction in machining accuracy due to heat transfer from one tool to another tool or turret.

In other words, the conventional technology cannot solve the problem of reduced machining accuracy due to heat transfer from one tool to another tool or turret. Accordingly, the present specification discloses a machine tool capable of preventing a decrease in machining accuracy due to heat transfer from one tool to another tool or turret.

The machine tool disclosed in this specification includes a tool post that moves within a machining chamber, and a turret attached to the tool post. A turret that rotates to change the positions and postures of the plurality of tools, thereby switching the tools for cutting a workpiece; a discharge nozzle that discharges coolant; and a position of the discharge nozzle that holds the discharge nozzle. and a robot that changes its attitude, and a controller, wherein measuring points are set on at least some of the tool holders, the controller monitors the temperature and position of each of the measuring points, and based on the temperature, and controls the driving of the discharge nozzle and the robot so as to discharge the coolant from the discharge nozzle to the measurement point determined to require cooling. characterized in that

In this case, the controller may identify the temperature and position of the measurement point based on the operation history of the machine tool when machining the workpiece.

Further, the controller identifies the temperature at the measurement point based on the detection result of a temperature sensor provided in the vicinity of the measurement point, and based on the operation history of the machine tool when machining the workpiece. , may identify the location of the measurement point.

Moreover, when there are a plurality of the measurement points that require cooling, the controller may cause the discharge nozzles to alternately discharge the coolant to the plurality of the measurement points.

Further, when there are a plurality of the measurement points that require cooling, the controller may discharge coolant from the discharge nozzle to one of the measurement points selected from the plurality of measurement points.

In this case, the controller may discharge coolant from the discharge nozzle to the measurement point having the highest temperature among the measurement points requiring cooling.

Further, the controller calculates the degree of influence on the machining accuracy of the workpiece for each of the plurality of measurement points that require cooling, and for one of the measurement points selected based on the degree of influence, the A coolant may be discharged from the discharge nozzle.

Further, among the plurality of tool holders, an active holder, which is a tool holder that holds a tool currently used for cutting, has a flow path that communicates with the interior of the tool post, and through the flow path: The coolant may be supplied to the active holder from inside the tool post, and the controller may exclude measurement points set on the active holder from the monitoring targets.

According to the machine tool disclosed in this specification, the temperature of the measurement point set in the tool holder is monitored, based on this temperature, the necessity of cooling the measurement point is determined, and the measurement point requiring cooling is , supplying coolant. Therefore, heat transfer from one tool to another tool or turret can be suppressed, and a decrease in machining accuracy due to the heat transfer can be prevented.

1 is a schematic configuration diagram of a machine tool; FIG. It is a block diagram of the main part of a machine tool. It is a schematic diagram which shows an example of the coolant supply mechanism incorporated in the tool post. 4 is a flow chart showing the flow of coolant supply by a robot;

The configuration of the machine tool 10 will be described below with reference to the drawings. FIG. 1 is a schematic block diagram of a machine tool 10, and FIG. 2 is a block diagram of main parts of the machine tool 10. As shown in FIG. In the following description, the direction parallel to the rotation axis of the workpiece 70 is the Z-axis, the direction parallel to the movement direction perpendicular to the Z-axis of the tool post 16 is the X-axis, and the direction perpendicular to the X-axis and the Z-axis is the Y-axis. called an axis.

The machine tool 10 is a metal processing machine that cuts a work 70 held by a headstock 14 with a tool 60 held by a tool post 16 . More specifically, the machine tool 10 is an NC controlled turning center with a turret 18 holding a plurality of tools 60 . Further, as will be described in detail later, inside the tool rest 16, a rotary motor 42 for rotating the rotary tool is built. Therefore, the machine tool 10 can perform both turning work in which the tool 60 is pressed against the rotating work 70 to cut it, and milling work in which the rotating tool 60 is pressed against the work 70 for cutting.

The machine tool 10 has a machining chamber 12 covered with a cover (not shown). In the machining chamber 12, a tip of a spindle 30 rotatably supported by a headstock 14, a tailstock (not shown), a tool post 16, and a robot 20 are installed. A member such as a chuck 31 for attaching the workpiece 70 is provided at the tip of the spindle 30 . Note that the member for attaching the work is not limited to the one that holds the work from the outer periphery with the claws 32 as shown in the figure, and may be one that holds the work with a collet or the like. The headstock 14 incorporates a spindle motor (not shown) for rotating the spindle 30 together with the workpiece 70 . By driving the spindle motor, the work 70 rotates about the work rotation axis Rw extending in the Z-axis direction.

The tailstock is arranged facing the spindle 30 in the Z-axis direction and supports the other end of the workpiece 70 held by the chuck 31 . The tailstock is movable in the Z-axis direction so that it can come into contact with and separate from the workpiece 70 . Alternatively, or in addition to the tailstock, a counter spindle may be provided. The opposed spindle is a spindle device arranged to face the headstock 14 in the Z-axis direction, and the headstock 14 is a spindle device that rotatably holds another workpiece 70 .

The tool rest 16 holds a tool 60 . The tool 60 held here may be a turning tool such as a turning tool, or a rotating tool such as an end mill. The tool rest 16 is entirely movable in the Z-axis direction, that is, in a direction parallel to the axis of the workpiece 70 . Further, the tool post 16 as a whole can move forward and backward in the X-axis direction, that is, in the radial direction of the workpiece 70 . Note that the X-axis is tilted with respect to the horizontal direction so that the machine tool 10 is viewed from the front and moves upward toward the back. As the tool post 16 moves in the Z-axis direction and the X-axis direction, the tool 60 held by the turret 18 moves, thereby adjusting the depth of cut and the position of the cut.

A turret 18 capable of holding a plurality of tools 60 is provided at one end of the tool rest 16 in the Z-axis direction. The turret 18 has a polygonal shape when viewed in the Z-axis direction, and is rotatable around an indexing axis Rd parallel to the Z-axis. A plurality of mounting portions 40 are arranged on the turret 18 at regular intervals in the circumferential direction. The attachment portion 40 is a portion to which the tool holder 62 is attached. The attachment portion 40 is, for example, a hole or groove formed in the Z-axis direction end face or peripheral face of the turret 18 and into which a part of the tool holder 62 is inserted.

The turret 18 rotates around the indexing axis Rd to switch the attitude of each tool 60 with respect to the workpiece 70 and, in turn, switch the tool 60 to be used for cutting. In addition, hereinafter, among the plurality of tools 60 held by the turret 18, the tool currently used for cutting the workpiece 70 is referred to as the "active tool", and the tool not currently used for cutting is referred to as the "standby tool". call. Further, the tool holder 62 holding the "active tool" is called "active holder", and the tool holder 62 holding the standby tool is called "standby holder".

Inside the tool post 16, as shown in FIG. 2, a rotary motor 42 for rotating the rotary tool and a power transmission mechanism 43 for transmitting the power of the rotary motor 42 to the mounting portion 40 are provided. there is The power transmission mechanism 43 includes, for example, a plurality of gears, a rotating shaft, bearings that support the rotating shaft, and the like. The tool rest 16 may have only one such rotary motor 42 . In this case, the power transmission mechanism 43 may transmit the power of the rotary motor 42 only to a specific mounting portion 40, or may switch the mounting portion 40 to which power is transmitted using a clutch or the like. . As another form, the tool post 16 may have two or more rotary motors 42 .

A tool 60 is mounted on the turret 18 via a tool holder 62 . The tool holder 62 can be detachably attached to the attachment portion 40 of the turret 18 as described above. A tool 60 is detachably attached to the end of the tool holder 62 . Here, some of the tool holders 62 hold rotating tools. The tool holder 62 for such a rotary tool has therein a power transmission mechanism 63 for transmitting the rotational power transmitted from the mounting portion 40 to the rotary tool. This power transmission mechanism 63 includes, for example, a plurality of gears, a rotating shaft, bearings that support the rotating shaft, and the like.

The tool post 16 has a mechanism for supplying coolant to the active holder. FIG. 3 is a schematic diagram showing an example of a coolant supply mechanism built into the tool post 16. As shown in FIG. As shown in FIG. 3, inside the main body of the tool post 16, a first flow path 80a through which coolant flows is formed. Inside the turret 18, there is a second flow path 80b radially extending from the center toward each mounting portion 40. Inside the tool holder 62, there is a third flow path 80c communicating with the second flow path 80b. , respectively, are formed. The end of the first channel 80a communicates with only one specific second channel 80b and one specific third channel 80c among the plurality of second channels 80b. Since the third flow path 80c penetrates to the end surface of the tool holder 62, the coolant supplied to the third flow path 80c is discharged from the end surface of the tool holder 62 to the outside. The coolant cools the tool 60 held by the tool holder 62 .

The second flow path 80b and the third flow path 80c communicating with the first flow path 80a are switched by rotating the turret 18 with respect to the main body of the tool post 16 . In other words, coolant is supplied only to the tool holders 62 that have a predetermined positional relationship with respect to the tool post 16 . The tool 60 held by the tool holder 62 having this predetermined positional relationship becomes the active tool used for cutting. By emitting coolant from the active holder that holds the active tool, the active tool and workpiece 70 can be effectively cooled during cutting.

A robot 20 is further provided inside the processing chamber 12 . In this example, the robot 20 is a serial manipulator or articulated robot in which a plurality of links 50 are connected in a row via joints 52 . In the example of FIG. 1, the robot 20 is installed on the side of the processing chamber 12. As will be described in detail later, the robot 20 can discharge coolant to the measurement point Pm that requires cooling. The installation location and configuration may be changed as appropriate. For example, the robot 20 may be attached to the top surface of the processing chamber 12, the tool post 16, the spindle 30, the tailstock, or the like.

A discharge nozzle 22 for discharging coolant is provided at the end of the robot 20 . A coolant is a liquid refrigerant that exchanges heat with an object to cool it. Inside the discharge nozzle 22, an on-off valve (not shown) is provided for switching between coolant output and output stop. In addition, since the ejection nozzle 22 is attached to the end of the robot 20 as described above, the position and attitude of the ejection nozzle 22 are also changed by changing the attitude of the robot 20 .

The machine tool 10 is also provided with a coolant source 24 that supplies coolant to the discharge nozzle 22 . The coolant source 24 includes, for example, a tank that stores coolant and a pump that pumps the coolant from the tank to the discharge nozzle 22 .

The ejection nozzle 22 may be attached/detached from the robot 20 according to the progress of processing. In other words, the end effector attached to the robot 20 may be changed according to the progress of machining. Therefore, for example, the discharge nozzle 22 is attached to the end of the robot 20 as an end effector during cutting, and the hand mechanism is attached to the end of the robot 20 as an end effector when exchanging the workpiece 70. may

The controller 26 controls driving of each part of the machine tool 10 . The controller 26 is physically a computer having a processor 26a that executes various calculations and a memory 26b that stores programs and data. This "computer" also includes a microcontroller that incorporates a computer system into a single integrated circuit. Alternatively, the controller 26 may be a computer that functions as a numerical controller. The numerical control device analyzes the machining program and commands the tool path for the workpiece, work steps required for machining, etc. with numerical information composed of numbers and codes in order to operate the machine tool 10 . Such a controller 26 controls the driving of the headstock 14, the tool post 16, the turret 18, etc. in order to machine the workpiece 70. As shown in FIG. Further, as will be described in detail later, the controller 26 also controls the driving of the robot 20 and the discharge nozzles 22 so as to discharge the coolant to hot spots.

By the way, as is well known, a large amount of heat is generated between the tool 60 and the workpiece 70 during cutting. Moreover, when a rotary tool is used, a large amount of heat is also generated in the power transmission mechanisms 43 and 63 for transmitting rotational power to the rotary tool. When the temperature of the tool 60, the tool holder 62, the turret 18, etc. rises due to such heat, the machining accuracy is lowered. Therefore, conventionally, coolant is supplied from the inside of the tool post 16 to the tool 60 used for cutting, ie, the active tool, to cool the active tool.

However, in the case of the mechanism supplying coolant from the tool post 16, coolant was supplied only to the active tool (more precisely, the active holder holding the active tool). Therefore, in the conventional technology, it was not possible to sufficiently suppress the decrease in machining accuracy caused by the heat of the standby tool that is not currently performing cutting.

For example, consider a case where a first tool is used to perform a first cutting process, and then a second tool is used to perform a second cutting process. In this case, when the second tool starts cutting, the second tool becomes the active tool, and the first tool becomes the standby tool. However, even if the first tool becomes a stand-by tool, the temperature of the first tool is often high because it has been used for cutting work immediately before. In particular, when the first tool is a rotating tool, a large amount of heat is often generated in the rotating shaft, bearings, and gears provided inside the first tool holder. The heat of the first tool and the first tool holder is transmitted to the turret 18 and the second tool, which sometimes causes a decrease in machining accuracy.

Therefore, the controller 26 of this example sets measurement points Pm on at least some of the tool holders 62 and monitors the temperature of the measurement points Pm. Then, the controller 26 determines whether or not cooling of the plurality of measurement points Pm is necessary based on the temperature of the measurement points Pm, and supplies coolant to the measurement points Pm determined to require cooling. This will be described in detail below.

As described above and as shown in FIG. 2, the measurement point Pm is set on the tool holder 62 in this example. This measurement point Pm may be set for all of the tool holders 62 attached to the turret 18 or may be set for only some of the tool holders 62 . Therefore, for example, of the tool holders 62 mounted on the turret 18, only the tool holder 62 that holds the rotating tool may be set to the measurement point Pm. The tool holder 62 set with such a measurement point Pm may become an active holder or a standby holder depending on the progress of machining.

Controller 26 monitors the temperature at this measurement point Pm. Machine tool 10 may have one or more temperature sensors 58 inside tool holder 62 or turret 18 (e.g., near mount 40, etc.) to measure the temperature at measurement point Pm. In this case, the controller 26 identifies the temperature at the measurement point Pm based on the temperature detected by the temperature sensor 58 and the positional relationship between the temperature sensor 58 and the measurement point Pm.

Also, as another form, the controller 26 may estimate the temperature at the measurement point Pm based on the operation history of the machine tool 10 . The operation history of the machine tool 10 includes the number of rotations of the spindle, the amount of movement of the tool post 16, the turning position of the turret 18, the number of rotations of the rotary tool, and the like. The controller 26 acquires the operation history of the machine tool 10 by communicating with the numerical controller or by interpreting the machining program. Then, from the obtained operation history, machining conditions such as the cutting depth and rotation speed of the tool 60 in cutting may be specified, and the temperature at the measurement point Pm may be estimated based on these machining conditions.

When the temperatures of the plurality of measurement points Pm are obtained, the controller 26 determines the necessity of cooling each measurement point Pm based on the temperature of each measurement point Pm. This determination of the need for cooling may be made based only on the temperature at the measurement point Pm, or may be determined by considering other factors in addition to the temperature at the measurement point Pm. Therefore, for example, the controller 26 may determine that cooling of the measurement point Pm is necessary when the temperature of the measurement point Pm is higher than the prescribed reference temperature.

As another form, the controller 26 calculates the degree of influence of the heat at the measurement point Pm on the active tool based on the temperature of the measurement point Pm. You may judge that cooling is necessary. In this case, in order to calculate the degree of influence, the controller 26 presets a position coefficient according to the positional relationship between the measurement point Pm and the active tool, and adds the temperature of the obtained measurement point Pm to the position coefficient may be calculated as the degree of influence. In this case, the position coefficient may be set to be higher as the distance between the measurement point Pm and the active tool is shorter. In calculating the degree of influence, the structure of the tool holder 62 to which the measurement point Pm is set (for example, the material, presence or absence of a power transmission mechanism, etc.) may be taken into consideration.

In any case, the controller 26 determines whether cooling of the measurement point Pm is necessary based on the temperature of the measurement point Pm. When there is a measurement point Pm that requires cooling, the controller 26 adjusts the posture of the robot 20, supplies coolant from the discharge nozzle 22 to the measurement point Pm to be cooled, and moves the tool holder 62 to which the measurement point Pm is set. Cooling.

Here, there may be multiple measurement points Pm that require cooling. In this case, the controller 26 may select the measurement point Pm with the highest temperature or degree of influence from among the plurality of measurement points Pm that satisfy the conditions, and supply coolant only to the selected measurement point Pm. Alternatively, the controller 26 may alternately supply coolant to a plurality of measurement points Pm that satisfy predetermined cooling conditions.

Further, as described above, coolant is supplied from the tool rest 16 to the active holder among the plurality of tool holders 62 . Therefore, this active holder may be excluded from the targets for coolant supply from the robot 20 . That is, the controller 26 may exclude the measurement point Pm provided on the active holder from the monitoring target and monitor only the measurement point Pm on the standby holder.

FIG. 4 is a flow chart showing the flow of coolant supply by the robot 20. As shown in FIG. As shown in FIG. 4, the controller 26 first acquires the temperature of each of the plurality of measurement points Pm (S10). The controller 26 also acquires the positions of each of the plurality of measurement points Pm (S12). This position can be identified from the movement position of the tool post 16, the turning angle of the turret 18, and the like. Subsequently, the controller 26 determines whether or not cooling is necessary for each of the plurality of measurement points Pm based on the obtained temperature (S14). As a result of determination, if there is no measurement point Pm that requires cooling, the controller 26 returns to step S10 and continues temperature monitoring.

On the other hand, if there is a measurement point Pm that requires cooling, the controller 26 drives the robot 20 and the discharge nozzle 22 to supply coolant to the measurement point Pm (S18). At this time, if there are a plurality of measurement points Pm that require cooling, the coolant may be supplied only to one of the measurement points Pm, or the coolant may be alternately supplied to the plurality of measurement points Pm. good. After that, the above processing is repeated until the processing of the workpiece 70 is completed (until S20 becomes Yes).

As is clear from the above description, in this example, the temperature of the measurement point Pm is monitored, the necessity of cooling the measurement point Pm is determined based on the temperature, and the robot 20 is used at the measurement point Pm that requires cooling. By supplying the coolant to a part of the tools 60 and the tool holders 62, it is possible to prevent the temperature from becoming excessively high. As a result, it is possible to effectively prevent a decrease in machining accuracy due to heat from some of the tools 60 and tool holders 62 . In particular, in this example, the temperature of not only the active tool used for cutting but also the standby tool not used for cutting is monitored, and coolant is supplied as necessary. Therefore, it is possible to effectively prevent the deterioration of the machining accuracy due to the heat of the standby tool or the standby holder.

10 machine tool, 12 machining chamber, 14 headstock, 16 tool post, 18 turret, 20 robot, 22 discharge nozzle, 24 coolant source, 26 controller, 30 spindle, 31 chuck, 40 mounting portion, 42 rotary motor, 43, 63 Power transmission mechanism, 50 link, 52 joint, 58 temperature sensor, 60 tool, 62 tool holder, 70 workpiece, 80a to 80c flow paths.

Claims (8)

a tool post that moves within the processing chamber;
A turret attached to a tool post, wherein a plurality of tools are mountable via tool holders, and pivots relative to the tool post to change the position and orientation of the plurality of tools, thereby providing a workpiece a turret for switching the tool for cutting the
a discharge nozzle for discharging coolant;
a robot that holds the ejection nozzle and changes the position and orientation of the ejection nozzle;
a controller;
and measuring points are set on at least some of the tool holders,
The controller monitors the temperature and position of each of the measurement points, determines whether or not cooling is required for each of the measurement points based on the temperature, and supplies coolant from the discharge nozzle to the measurement points determined to require cooling. is configured to control the driving of the ejection nozzle and the robot so as to eject the
A machine tool characterized by: A machine tool according to claim 1,
A machine tool, wherein the controller identifies the temperature and position of the measurement point based on the operation history of the machine tool when machining the workpiece. A machine tool according to claim 1,
The controller identifies the temperature at the measurement point based on the detection result of a temperature sensor provided near the measurement point, and determines the A machine tool characterized by identifying the position of a measuring point. A machine tool according to any one of claims 1 to 3,
A machine tool characterized in that, when there are a plurality of measurement points that require cooling, the controller alternately discharges coolant from the discharge nozzle to the plurality of measurement points. A machine tool according to any one of claims 1 to 4,
A machine tool characterized in that, when there are a plurality of measurement points that require cooling, the controller discharges coolant from the discharge nozzle to one of the measurement points selected from the plurality of measurement points. A machine tool according to claim 5,
The machine tool, wherein the controller discharges coolant from the discharge nozzle to the measurement point having the highest temperature among the measurement points requiring cooling. A machine tool according to claim 5,
The controller calculates the degree of influence on the machining accuracy of the workpiece for each of the plurality of measurement points that require cooling, and controls the discharge nozzle for one of the measurement points selected based on the degree of influence. A machine tool characterized by discharging coolant from. A machine tool according to any one of claims 1 to 7, further comprising:
having a flow path communicating between an active holder, which is a tool holder that currently holds a tool used for cutting among a plurality of tool holders, and the inside of the tool post,
the coolant is supplied from the inside of the tool post to the active holder through the flow path;
The controller excludes the measurement point set in the active holder from the monitoring target.
A machine tool characterized by:

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