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 process generates long, continuous pieces of chips. These long, continuous chips can become entangled around the cutting tool, causing machining defects and equipment failures.

[0003] In order to solve this problem of tangled 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 preventing the continuous generation of cutting chips by moving the cutting tool back once the cutting tool has cut a specified amount into the workpiece, and this return movement breaks up the cutting chips. [Prior art documents] [Patent documents]

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

[0005] However, machine tools having an oscillating cutting function as shown in Patent Document 2 (hereinafter referred to as the "conventional example") have problems such as longer processing times and chip breakage and other malfunctions caused by cutting 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 which shortens processing time compared to oscillating cutting, exhibits high cutting chip-cutting performance, and minimizes the occurrence of defects such as damage to the cutting edge (chip) caused by the cut chips getting caught between the cutting tool and the workpiece. [Means for solving the problem]

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

[0008] This machine tool comprises a rotating 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 rotating 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 is configured so that the movement of the cutting tool 2 is controlled based on a numerical control program, wherein the cutting tool 2 is configured to move by alternately repeating feed movement and stopping based on the numerical control program, and further wherein the coolant ejection unit 3 is configured so that the high-pressure coolant is ejected onto cutting chips near the cutting edge 2a of the cutting tool 2 during cutting.

[0009] Moreover, in the machine tool described in claim 1, the numerical control program is programmed so that the feed speed of the cutting tool 2 gradually decelerates from a predetermined speed during a set stop time, and after stopping once, the feed speed is gradually increased until it reaches the predetermined speed.

[0010] Moreover, in the machine tool described in claim 1, the numerical control program is programmed to immediately stop the cutting tool 2 without slowing down the feed speed, and to stop the feed movement of the cutting tool 2 for a set stop time.

[0011] The present invention relates to a machine tool according to claim 2, characterized in that the stop time is set to be longer than the feed time during which the cutting tool 2 is fed.

[0012] The present invention relates to a machine tool, characterized in that the stop time is set to be longer than the feed time during which the cutting tool 2 is fed.

[0013] The present invention relates to a machine tool according to any one of claims 1 to 5, characterized in that the ejection pressure of the high-pressure coolant is set to 1 MPa to 10 MPa. Effect of the Invention

[0014] Since 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-cutting performance, and minimizes the risk of the cut chips getting caught between the cutting tool and the workpiece, causing problems such as chip breakage. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 is an explanatory diagram showing a cutting processing state in this embodiment. [Diagram 2] FIG. 4 is an enlarged explanatory view of a main part during cutting processing in this embodiment. [Diagram 3] 3 is an enlarged explanatory plan view of a portion enclosed by a dotted line in FIG. 2. [Figure 4] FIG. 4 is an explanatory diagram showing the thickness of cutting chips generated in this embodiment. [Diagram 5] 11A to 11C are diagrams illustrating an example of an operation pattern of the cutting feed stop function of the present embodiment. [Figure 6] 11A to 11C are diagrams illustrating an example of an operation pattern of the cutting feed stop function of the present embodiment. [Figure 7] 11A to 11C 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 PREFERRED EMBODIMENTS

[0016] A preferred embodiment of the present invention will be briefly described below with reference to the drawings to illustrate the operation of the present invention.

[0017] In the present invention, the cutting tool 2 performs cutting by alternately repeating feed movement and stopping during cutting 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 of the feed movement becomes thinner, and the thinner cutting chips make them easier to break up.

[0018] Moreover, as described above, in the present invention, the cutting tool 2 performs machining by alternately repeating feed movement and stopping based on the feed time and stop time set in the numerical control program during cutting processing. 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.

[0019] 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 exerts a cutting action on the cutting chips, improving the cutting chip-breaking performance and enabling the cutting chips generated by the cutting process to be reliably broken up.

[0020] Furthermore, in the present invention, the broken cutting chips are blown away and removed by high-pressure coolant, which minimizes the occurrence of problems such as the cutting chips getting caught between the cutting tool 2 and the workpiece W, causing damage to the cutting edge 2a. EXAMPLES

[0021] A specific embodiment of the present invention will now be described with reference to the drawings.

[0022] 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 the rotary table 1, and a coolant ejection unit 3 that ejects high-pressure coolant toward the vicinity of a cutting edge 2a (tip 2a) of the 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 straightening table on which the workpiece W is placed.

[0023] Specifically, the high-pressure coolant ejected from the coolant ejection part 3 has an ejection pressure set to 1 MPa to 10 MPa, and the coolant ejection part 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 the cutting chips in the vicinity of the cutting edge 2a of the cutting tool 2 during cutting processing.

[0024] 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, whereby the high-pressure coolant acts to cut (cut) the cutting chips.

[0025] In addition, in this embodiment, the numerical control program has a cutting feed stop function that controls the feed movement of the cutting tool 2 in cutting processing, and this cutting feed stop function is configured to move the cutting tool 2 while alternately repeating feed movement and stopping.

[0026] 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 the cutting processing becomes as thin as possible, as shown in Figure 4, making it easier to break up the cutting chips.

[0027] 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 feed movement and stopping of the cutting tool 2 are repeated alternately during cutting processing, 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 when the cutting tool 2 stops, the thickness of the generated cutting chips becomes the thinnest thickness (t2). The formation of this thin portion makes the cutting chips more likely to be broken up.

[0028] Furthermore, in this embodiment, the feed speed of the cutting tool 2 is determined by the set value of the feed override, and the feed speed can be changed by changing the set value of this feed speed.

[0029] Specifically, the feed speed is determined by the programmed feed speed and feed time, which are specified by arguments in the program. The stop time when the feed movement stops is also specified by arguments in the program, as described above.

[0030] In addition, the operation of the cutting tool 2 during the stop time can be selected from two different 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 (designated 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).

[0031] Specifically, for example, as shown in FIG. 5, the specified feed rate is set to 100%, and the deceleration rate and acceleration rate during the stop time are set in stages as follows: 100%→95%→80%→50%→25%→5%→0%→5%→25%→50%→80%→95%→100%, and the above operation is executed.

[0032] Furthermore, in this operation, as shown in FIG. 6, if the display 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 each configured (programmed) to be longer.

[0033] The second is an operation in which, as shown in Figure 7, when the stopping 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 stopping time, and when the stopping time has elapsed, the feed movement immediately starts again at the specified speed.

[0034] Specifically, if the specified feed rate is 100%, the above operation is executed by setting it as 100%→0%→100%.

[0035] Furthermore, the feed time and stop time in the cutting feed stop function are set such that the stop time is longer than the feed time, as shown in FIGS.

[0036] That is, in this embodiment, the feed time is shortened to shorten the length of the cutting chips generated (because the length of the cutting chips generated by cutting processing is proportional to the feed time), and the stop time is lengthened to extend the period during which the thickness of the cutting chips becomes thin, thereby improving the breakability, so that the cutting chips generated during cutting processing can be reliably broken up at short intervals.

[0037] The following is a comparative evaluation that supports the effects of this embodiment.

[0038] In this evaluation, the machining time was compared between this embodiment and the conventional example when cutting a workpiece under the same cutting conditions. Note that in this embodiment, a process was added in which high-pressure coolant with a jet pressure of 8 MPa was sprayed (sprayed) from the coolant jetting part 3 onto the cutting chips during cutting.

[0039] 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.

[0040] [Table 1]

[0041] 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 speed was gradually decelerated and gradually increased, as shown in Fig. 5. Therefore, the stop time includes the time for deceleration and acceleration.

[0042] As shown in Table 1, when cutting was performed under the same cutting conditions, the machining time for this embodiment was 32 minutes, while the machining time for the conventional example was 76 minutes.

[0043] In this manner, it was confirmed that the processing time in this embodiment was 44 minutes shorter than that in the conventional example, and the processing time could be reduced to less than half.

[0044] Moreover, in this embodiment, as shown in FIG. 8, the cutting chips are broken up and generated as short cutting chips at each timing when the feed movement of the cutting tool 2 is stopped, and these generated cutting chips are removed (blown away) by the high-pressure coolant. As a result, the cutting chips do not get entangled with the cutting tool 2 or get caught between the cutting tool 2 and the workpiece W, and good machining conditions were confirmed.

[0045] In this way, this embodiment can drastically reduce processing time compared to conventional oscillating cutting processes, and also exhibits high cutting chip breaking performance. The broken chips are blown away and removed using high-pressure coolant, which minimizes the risk of chips getting caught between the cutting tool and the workpiece, causing problems such as chip breakage, resulting in an innovative machine tool with excellent productivity.

[0046] Moreover, as described above, in this embodiment, the cutting chips are broken up by the interaction between 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 obtain sufficient effects, which also reduces equipment costs.

[0047] It should be noted that 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]

[0048] 1 Rotating table 2 cutting tools 2a Cutting edge 3 Coolant outlet Double work

Claims

1. A machine tool comprising a rotating table on which a workpiece is placed and fixed, a cutting tool which cuts the workpiece placed and fixed on the rotating table, and a coolant spraying unit which sprays high-pressure coolant toward the vicinity of the cutting edge of the cutting tool, the movement of the cutting tool being configured to be controlled based on a numerical control program, the cutting tool being configured to move by alternately repeating feed movement and stops based on the numerical control program, and the coolant spraying unit being configured to spray the high-pressure coolant onto cutting chips near the cutting edge of the cutting tool during cutting.

2. 2. The machine tool according to claim 1, wherein the numerical control program is programmed so that the feed speed of the cutting tool gradually decelerates from a predetermined speed during a set stop time, and after being temporarily stopped, the feed speed is gradually increased until it reaches the predetermined speed.

3. 2. The machine tool according to claim 1, wherein the numerical control program is programmed to immediately stop the cutting tool without slowing down the feed rate, and to stop the feed movement of the cutting tool for a set stop time.

4. 3. The machine tool according to claim 2, wherein the stop time is set to be longer than a feed time during which the cutting tool is fed.

5. 4. The machine tool according to claim 3, wherein the stop time is set to be longer than a feed time during which the cutting tool is fed.

6. 6. The machine tool according to claim 1, wherein the ejection pressure of the high-pressure coolant is set to 1 MPa to 10 MPa.

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