Machine tool

Abstract

To provide a machine tool which can shorten a processing time, exhibit high parting performance to cut chips, and reduce defects caused by the cut chips as much as possible.SOLUTION: A machine tool includes a rotation table 1 on which a workpiece W is placed and fixed, a cutting tool 2 which cuts the workpiece W placed and fixed on the rotation table 1, and a coolant jetting part 3 which jets high-pressure coolant to a periphery of an edge of the cutting tool 2. The machine tool is configured to control movement of the cutting tool 2 on the basis of a numerical control program. The cutting tool 2 is configured to move while alternately repeating feed movement and stoppage by the numerical control program. The coolant jetting part 3 is configured to jet the high-pressure coolant to the cut chips in a periphery of the edge 2a of the cutting tool 2 during cutting processing.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a machine tool. [Background technology]

[0002] When a machine tool performs grooving on a workpiece, the cutting produces long, continuous chips that can become entangled around the cutting tool, causing machining defects and equipment failures.

[0003] To solve this problem of entangled cutting chips, machine tools have been proposed in the past, such as those shown in Patent Document 1, which have a vibration cutting function that performs processing by vibrating the cutting tool in the feed direction, and those shown in Patent Document 2, which have an oscillating cutting function that performs processing while cutting the cutting tool back once the cutting tool has cut a predetermined amount into the workpiece, breaking up the cutting chips with this return movement. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-285701 [Patent Document 2] Japanese Patent Application Publication No. 2017-182336 Summary of the Invention [Problem to be solved by the invention]

[0005] However, machine tools with an oscillating cutting function such as that shown in Patent Document 2 (hereinafter referred to as "conventional examples") have problems such as longer processing times and chip breakage caused by chips getting caught between the cutting tool and the workpiece, and furthermore, the cutting chip breaking performance is not high.

[0006] The present invention has been made in consideration of the problems associated with the conventional examples, and aims to provide a machine tool that shortens processing time compared to oscillating cutting, exhibits high cutting chip breaking performance, and minimizes the risk of the broken chips getting caught between the cutting tool and the workpiece, causing problems such as damage to the cutting edge (chip). [Means for solving the problem]

[0007] The gist of the present invention will be explained with reference to the accompanying drawings.

[0008] A machine tool is provided with a rotary table 1 on which a workpiece W is placed and fixed, a cutting tool 2 which cuts the workpiece W placed and fixed on the rotary table 1, and a coolant ejection unit 3 which ejects high-pressure coolant toward the vicinity of the cutting edge of the cutting tool 2, and the movement of the cutting tool 2 is controlled based on a numerical control program, and the cutting tool 2 is During cutting, the cutting edge 2a does not separate from the workpiece W and always abuts against the workpiece W, and further, the cutting tool 2 is The numerical control program is configured to move the robot while alternately repeating feed movement and stoppage, Also , The numerical control program is programmed to feed the cutting tool 2 at a constant feed rate for a predetermined time, and after the predetermined time has elapsed, immediately reduce the feed rate to zero to immediately stop the cutting tool 2, and also to stop the feed movement of the cutting tool 2 for a stop time that is set to be longer than the predetermined time, and after the stop time has elapsed, immediately feed the cutting tool 2 at the constant feed rate; and further The coolant ejection portion 3 is The ejection pressure was set to 1MPa to 10MPa. The high-pressure coolant is sprayed onto chips in the vicinity of the cutting edge 2a of the cutting tool 2 during cutting. The cutting chips are broken up The present invention relates to a machine tool characterized by being configured to: [Effects of the Invention]

[0009] Because the present invention is configured as described above, it results in a machine tool that has a shorter processing time than oscillating cutting, exhibits high cutting chip breaking performance, and minimizes the risk of chip breakage and other problems caused by the broken chips getting caught between the cutting tool and the workpiece. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is an explanatory diagram showing a cutting processing state in this embodiment. [Figure 2] FIG. 2 is an enlarged explanatory view of a main part during cutting processing in this embodiment. [Figure 3] FIG. 3 is an enlarged explanatory plan view of the area enclosed by the dotted line in FIG. 2. [Figure 4] FIG. 10 is an explanatory diagram showing the thickness of cutting chips generated in this embodiment. [Figure 5] 10A to 10C are diagrams illustrating an example of an operation pattern of the cutting feed stop function of the present embodiment. [Figure 6] 10A to 10C are diagrams illustrating an example of an operation pattern of the cutting feed stop function of the present embodiment. [Figure 7] 10A to 10C are diagrams illustrating an example of an operation pattern of the cutting feed stop function of the present embodiment. [Figure 8] 1 is an image diagram showing a cutting processing state (operation of a cutting tool) in this embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] A preferred embodiment of the present invention will be briefly described below, illustrating the operation of the present invention with reference to the drawings.

[0012] In the present invention, the cutting tool 2 performs cutting by alternately repeating feed movement and stopping during cutting processing based on the feed time and stop time for the cutting feed movement of the cutting tool 2 set in the numerical control program.Therefore, the thickness of the cutting chips generated by the stopping action of the feed movement becomes thinner, and as the thickness of these cutting chips becomes thinner, the cutting chips become easier to break up.

[0013] Moreover, as described above, in the present invention, the cutting tool 2 performs machining by alternately repeating feed movement and stoppage based on the feed time and stoppage time set in the numerical control program during cutting processing, but since the cutting edge 2a of the cutting tool 2 does not move away from the workpiece W, there is no loss of return movement as in the conventional example, and as a result, the machining time is shortened and productivity is improved.

[0014] Furthermore, in the present invention, the high-pressure coolant ejected from the coolant ejection portion 3 is sprayed onto the thinned cutting chips, so that the high-pressure coolant has a cutting action on the cutting chips, improving the cutting chip breaking performance and enabling the cutting chips generated by cutting processing to be broken up reliably.

[0015] Furthermore, in the present invention, the fragmented cutting chips are blown away and removed using high-pressure coolant, which minimizes the risk of the cutting chips getting caught between the cutting tool 2 and the workpiece W, causing problems such as damage to the cutting edge 2a. [Example]

[0016] Specific embodiments of the present invention will be described with reference to the drawings.

[0017] 1, this embodiment is a machine tool that includes a rotary table 1 on which a workpiece W is placed and fixed, a cutting tool 2 that cuts the workpiece W placed and fixed on this rotary table 1, and a coolant ejection unit 3 that ejects high-pressure coolant toward the vicinity of the cutting edge 2a (chip 2a) of this cutting tool 2, and specifically, is an NC machine tool configured so that the movement of the cutting tool 2 is controlled based on a numerical control program. In the figure, reference numeral 4 denotes a jaw portion that chucks (fixes) the workpiece W, and reference numeral 5 denotes a leveling table on which the workpiece W is placed.

[0018] Specifically, the high-pressure coolant ejected from the coolant ejection section 3 has an ejection pressure set to 1 MPa to 10 MPa, and the coolant ejection section 3 is configured, as shown in Figures 2 and 3, so that the high-pressure coolant set to the above-mentioned ejection pressure is ejected onto chips near the cutting edge 2a of the cutting tool 2 during cutting processing.

[0019] That is, this embodiment is configured so that high-pressure coolant set at 1 MPa to 10 MPa is sprayed (sprayed) onto the cutting chips, thereby causing the high-pressure coolant to cut (break) the cutting chips.

[0020] In addition, this embodiment has a cutting feed stop function in the numerical control program that controls the feed movement of the cutting tool 2 during cutting processing, and this cutting feed stop function is configured to cause the cutting tool 2 to move while alternately repeating feed movement and stopping.

[0021] Specifically, the cutting feed stop function can be enabled or disabled using an M-code (address used in NC programming) command. By enabling this cutting feed stop function, the cutting tool 2 moves while repeatedly feeding and stopping (speed 0) during cutting processing, and by stopping the cutting tool 2, the thickness of the cutting chips generated by cutting processing becomes as thin as possible, as shown in Figure 4, making it easier to break the cutting chips.

[0022] In other words, when the cutting tool 2 does not stop (when the feed movement is performed continuously), the cutting chips are generated at the same thickness (t1), as shown by the dotted line in Figure 4. However, when the cutting feed stop function is enabled and the cutting tool 2 alternately feeds and stops during cutting, the movement speed of the cutting tool 2 gradually decreases as the cutting tool 2 stops, and as the movement speed decreases, the thickness of the generated cutting chips gradually becomes thinner, as shown by the solid line in Figure 4. At the time the cutting tool 2 stops, the thickness of the generated cutting chips reaches its thinnest thickness (t2), and the formation of this thin portion makes the cutting chips more susceptible to breaking up.

[0023] In this embodiment, the feed rate of the cutting tool 2 is determined by the set value of the feed override, and the feed rate can be changed by changing the set value of this feed rate.

[0024] Specifically, the feed rate is determined by the programmed feed rate and feed time, which are specified by arguments in the program. Note that the stop time for the feed movement is also specified by arguments in the program, as described above.

[0025] In addition, the operation of the cutting tool 2 during the stop time can be selected from two ways. The first is an operation in which, as shown in Figures 5 and 6, the feed speed of the cutting tool 2 gradually (stepwise) decelerates from a predetermined speed (specified speed) during the set stop time, stops once, and then gradually (stepwise) increases the feed speed until it reaches the predetermined speed (original feed speed).

[0026] Specifically, for example, as shown in FIG. 5, the specified feed rate is set to 100%, and the feed rate during the stop time is set to the deceleration rate and acceleration rate in stages as follows: 100% → 95% → 80% → 50% → 25% → 5% → 0% → 5% → 25% → 50% → 80% → 95% → 100%, and the above operation is executed.

[0027] In addition, during this operation, as shown in Figure 6, ,stop If the stop time is set to a long time, not only will the time at speed 0 become longer, but the time at each stage will also become longer, and the overall time to reach speed 0 and to return to the specified speed will become longer. In other words, the deceleration time and acceleration time are configured (programmed) to become longer.

[0028] The second is an operation in which, as shown in Figure 7, when the stop time arrives, the cutting tool 2 immediately stops without slowing down the feed speed, the feed movement of the cutting tool 2 stops for the set stop time, and once the stop time has elapsed, the feed movement immediately starts at the specified speed.

[0029] Specifically, if the specified feed rate is 100%, the above operation is executed by setting it as 100% → 0% → 100%.

[0030] Furthermore, the feed time and stop time in the cutting feed stop function are set so that the stop time is longer than the feed time, as shown in FIGS.

[0031] That is, in this embodiment, the length of the generated cutting chips is shortened by shortening the feed time (because the length of the cutting chips generated by cutting processing is proportional to the feed time), and the thickness of the cutting chips is reduced by lengthening the stop time. of The length is increased to improve the ability to separate, thereby enabling chips generated during cutting to be reliably separated at short intervals.

[0032] The following is a comparative evaluation that supports the effects of this embodiment.

[0033] In this evaluation, the machining time was compared between this example and a conventional example when cutting a workpiece under the same cutting conditions. Note that in this example, a process was added in which high-pressure coolant with a jetting pressure of 8 MPa was sprayed (sprayed) onto the cutting chips from the coolant jetting part 3 during cutting.

[0034] Table 1 shows the cutting conditions and processing times in this embodiment and the conventional example, and FIG. 8 is an image diagram showing the working state (operation of the cutting tool 2) in this embodiment.

[0035] [Table 1]

[0036] In the cutting conditions of this embodiment, the operation of the cutting tool 2 during the stop time was set to a pattern in which the feed rate was gradually decreased and gradually increased, as shown in Fig. 5. Therefore, the stop time includes the time for deceleration and acceleration.

[0037] When cutting was performed under the same cutting conditions as shown in Table 1, the machining time for this example was 32 minutes, while the machining time for the conventional example was 76 minutes.

[0038] In this way, it was confirmed that the processing time of this embodiment was 44 minutes shorter than that of the conventional example, and that the processing time could be reduced to 1 / 2 or less.

[0039] Furthermore, in this embodiment, as shown in FIG. 8, the cutting chips are broken up into short chips at each stop time when the feed movement of the cutting tool 2 is stopped, and these generated chips are removed (blown away) by the high-pressure coolant, and the cutting chips do not become entangled with the cutting tool 2 or get caught between the cutting tool 2 and the workpiece W, and a good machining state was confirmed.

[0040] In this way, this embodiment can dramatically reduce processing time compared to conventional oscillating cutting processes, and also exhibits high cutting chip breaking performance. Since the broken chips are blown away and removed using high-pressure coolant, it is an innovative machine tool with excellent productivity that minimizes the risk of chips getting caught between the cutting tool and the workpiece, causing problems such as chip breakage.

[0041] Furthermore, as described above, in this embodiment, cutting chips are broken up by the interaction of the cutting feed stop function and the high-pressure coolant, so there is no need to use ultra-high-pressure coolant (approximately 14 MPa to 20 MPa) as the coolant; high-pressure coolant of approximately 1 MPa to 10 MPa can be used to achieve sufficient results, which also reduces equipment costs.

[0042] The present invention is not limited to the present embodiment, and the specific configuration of each component can be designed as appropriate. [Explanation of symbols]

[0043] 1 Rotary Table 2 cutting tools 2a cutting edge 3 Coolant outlet double work

Claims

[Claim 1] A machine tool is provided with a rotary table on which a workpiece is placed and fixed, a cutting tool for cutting the workpiece placed and fixed on the rotary table, and a coolant ejection unit for ejecting high-pressure coolant toward the vicinity of the cutting edge of the cutting tool, the movement of the cutting tool being controlled based on a numerical control program, wherein the cutting edge of the cutting tool is not separated from the workpiece during cutting but is always in contact with the workpiece, and the cutting tool is configured to move while alternately repeating feed movement and stoppage in accordance with the numerical control program, and the numerical control program is configured to control the movement of the cutting tool by repeating feed movement and stoppage in accordance with the numerical control program, the machine tool is programmed to feed a tool at a constant feed rate for a predetermined time, and after the predetermined time has elapsed, immediately reduce the feed rate to zero to immediately stop the cutting tool, and also stop the feed movement of the cutting tool for a stop time that is set to be longer than the predetermined time, and after the stop time has elapsed, immediately feed the cutting tool at the constant feed rate; and further, the coolant ejection unit is configured to eject the high-pressure coolant, the ejection pressure of which is set to 1 MPa to 10 MPa, onto cutting chips near the cutting edge of the cutting tool during cutting, thereby breaking up the cutting chips.

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