Working machinery

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

[0006]

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

Background Art

[0002] In a machine tool, when performing grooving on a workpiece, cutting chips are generated in a state where they are long and connected, and these long-connected cutting chips get entangled with cutting tools and the like, causing machining defects and device failures.

[0003] Conventionally, in order to solve such problems of cutting chip entanglement, there are machine tools having a vibration cutting function in which a cutting tool as shown in Patent Document 1 is vibrated in the feed direction, and a machine tool having a rocking cutting function in which a cutting tool as shown in Patent Document 2 once cuts a workpiece by a predetermined amount and then moves the cutting tool back, and the cutting chips are segmented by this backward movement, and machining is performed while preventing continuous generation of cutting chips.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, a machine tool having a rocking cutting function as shown in Patent Document 2 (hereinafter referred to as "conventional example") has problems such as an increase in machining time, cutting chips being sandwiched between the cutting tool and the workpiece, causing problems such as chip breakage, and furthermore, the cutting chip segmentation performance is not high.

[0006] This invention has been made in view of the problems of such conventional methods, and aims to provide a machine tool that shortens the processing time compared to oscillating cutting, exhibits high chip breaking performance, and minimizes the occurrence of problems such as damage to the cutting edge (tip) caused by the broken chip getting stuck between the cutting tool and the workpiece. [Means for solving the problem]

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

[0008] A machine tool comprising a rotary table 1 on which a workpiece W is placed and fixed, a cutting tool 2 for cutting the workpiece W placed and fixed on the rotary table 1, and a coolant ejection unit 3 for ejecting high-pressure coolant toward the vicinity of the cutting edge of the cutting tool 2, wherein 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 detach from the workpiece W and remains in constant contact with the workpiece W, and furthermore, the cutting tool 2 is The system is configured to move by repeatedly alternating between forward movement and stopping, according to the numerical control program. Also , The numerical control program is programmed to feed the cutting tool 2 at a constant feed rate for a predetermined time, immediately stop the cutting tool 2 by immediately reducing the feed rate to zero after the predetermined time has elapsed, and to stop the feeding movement of the cutting tool 2 for a stop time set to be longer than the predetermined time, and immediately resume feeding the cutting tool 2 at the constant feed rate after the stop time has elapsed, and further, The coolant ejection section 3 is The ejection pressure is set to 1 MPa to 10 MPa. The high-pressure coolant is sprayed onto the cutting chips near the cutting edge 2a of the cutting tool 2 during machining. The cutting chips were broken apart. This invention relates to a machine tool characterized by being configured in such a way. [Effects of the Invention]

[0009] As the present invention is configured as described above, the processing time is shorter compared to oscillating cutting, and it exhibits high chip-breaking performance. Furthermore, the machine tool is configured to minimize the occurrence of problems such as chip damage caused by the broken chips getting stuck between the cutting tool and the workpiece. [Brief explanation of the drawing]

[0010] [Figure 1] This is an explanatory diagram showing the cutting process in this embodiment. [Figure 2] This is an enlarged explanatory diagram of the main parts during the cutting process in this embodiment. [Figure 3] This is an enlarged explanatory plan view of the area enclosed by the dotted line in Figure 2. [Figure 4] This is an explanatory diagram showing the thickness of the cutting chips generated in this embodiment. [Figure 5] This figure shows an example of the operation pattern of the cutting feed stop function in this embodiment. [Figure 6] This figure shows an example of the operation pattern of the cutting feed stop function in this embodiment. [Figure 7] This figure shows an example of the operation pattern of the cutting feed stop function in this embodiment. [Figure 8] This is an illustrative diagram showing the cutting process (operation of the cutting tool) in this embodiment. [Modes for carrying out the invention]

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

[0012] In this invention, based on the feed time and stop time related to the cutting feed movement of the cutting tool 2 set in the numerical control program, the cutting tool 2 performs machining by repeatedly alternating between feed movement and stopping during machining. As a result, the thickness of the cutting chips generated by the stopping action of the feed movement becomes thinner, and this thinner thickness of the cutting chips makes them easier to break apart.

[0013] Moreover, as described above, in the present invention, the cutting tool 2 performs machining by alternately feeding and stopping based on the feed time and stop time set in the numerical control program during cutting. However, since the cutting edge 2a of the cutting tool 2 does not escape 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 part 3 is ejected onto the cutting chips with a reduced thickness, so that a cutting action by the high-pressure coolant acts on the cutting chips, improving the cutting performance of the cutting chips and enabling the cutting chips generated by the cutting process to be reliably cut.

[0015] Moreover, in the present invention, the high-pressure coolant blows off and removes the cut cutting chips, so that it is possible to reduce as much as possible the occurrence of problems such as the cutting chips being caught between the cutting tool 2 and the workpiece W and damaging the cutting edge 2a.

Embodiment

[0016] Specific embodiments of the present invention will be described based on the drawings.

[0017] As shown in FIG. 1, this embodiment is a machine tool including a rotary table 1 for placing and fixing a workpiece W, a cutting tool 2 for cutting the workpiece W placed and fixed on the rotary table 1, and a coolant ejection part 3 for ejecting high-pressure coolant toward the vicinity of the cutting edge 2a (tip 2a) of the cutting tool 2. Specifically, it is a NC machine tool configured such that the movement of the cutting tool 2 is controlled based on a numerical control program. In the figure, reference numeral 4 denotes a claw part (for chucking and fixing) the workpiece W, and reference numeral 5 denotes a flat table on which the workpiece W is placed.

[0018] Specifically, the high-pressure coolant ejected from the coolant ejection part 3 has an ejection pressure set to 1 MPa to 10 MPa. As shown in FIGS. 2 and 3, the coolant ejection part 3 is configured such that the high-pressure coolant set to the ejection pressure is ejected onto the cutting chips in the vicinity of the cutting edge 2a of the cutting tool 2 during cutting.

[0019] That is, this embodiment is configured such that by driving (water jetting) the high-pressure coolant set to 1 MPa to 10 MPa into the cutting chips, a cutting (breaking) action of the cutting chips by the high-pressure coolant occurs.

[0020] Furthermore, this embodiment includes a cutting feed stop function in the numerical control program that controls the feed movement of the cutting tool 2 during cutting, and is configured such that the cutting tool 2 moves while alternately repeating feed movement and stopping due to this cutting feed stop function.

[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 the cutting process. When the cutting tool 2 stops, as shown in Figure 4, the thickness of the cutting chips generated by the cutting process is made as thin as possible, making it easier to break up the chips.

[0022] In other words, if the cutting tool 2 does not stop (if the feed movement is performed continuously), the chips are generated with the same thickness (t1), as shown by the dashed line in Figure 4. However, if the cutting feed stop function is activated and the feed movement and stopping of the cutting tool 2 are repeated alternately during cutting, the movement speed of the cutting tool 2 gradually decreases as the cutting tool 2 stops. As the movement speed decreases, the thickness of the generated chips gradually decreases, as shown by the solid line in Figure 4. The thickness of the generated chips becomes the thinnest (t2) when the cutting tool 2 stops, and the formation of this thin section makes the chips more easily broken apart.

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

[0024] Specifically, the feed rate is determined by the programmed feed rate and feed time, which are specified as arguments in the program. Similarly, the stop time during which the feed movement stops is also specified as an argument in the program.

[0025] Furthermore, there are two possible operation methods for the cutting tool 2 during the stop time. The first is as shown in Figures 5 and 6, in which the feed rate of the cutting tool 2 gradually decreases from a predetermined speed (specified speed) during the set stop time, stops briefly, and then gradually increases the feed rate to reach the predetermined speed (original feed rate).

[0026] Specifically, as shown in Figure 5, for example, the operation is performed by setting the specified feed rate to 100%, and then gradually setting the deceleration and acceleration rates during the stop time in the following order: 100% → 95% → 80% → 50% → 25% → 5% → 0% → 5% → 25% → 50% → 80% → 95% → 100%.

[0027] Furthermore, in this operation, as shown in Figure 6, ,stop When the stopping time is set to a long duration, not only does the time at zero speed increase, but the time spent at each stage also increases. As a result, the overall time to reach zero speed and the time to return to the specified speed increase are both increased. In other words, the deceleration time and acceleration time are both increased.

[0028] The second method, as shown in Figure 7, involves the cutting tool 2 stopping immediately without any reduction in feed rate when the stop time is reached, the feed movement of the cutting tool 2 stopping for the set stop time, and then immediately starting to feed at the specified speed once the stop time has elapsed.

[0029] Specifically, if the specified feed rate is set to 100%, the aforementioned operation is executed by setting it in the order of 100% → 0% → 100%.

[0030] Furthermore, as shown in Figures 5-7, 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.

[0031] In other words, this embodiment reduces the length of the cutting chips generated by shortening the feed time (because the length of the cutting chips generated by cutting is proportional to the feed time), and also reduces the thickness of the cutting chips by increasing the stop time. of The length is increased to improve the ability to break up debris, thereby ensuring that cutting chips generated during machining are reliably broken up at short intervals.

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

[0033] In this evaluation, the machining time was compared between this embodiment and the conventional example when the workpiece was machined under equivalent cutting conditions. In this embodiment, an additional process is added during machining in which high-pressure coolant, set to a jet pressure of 8 MPa, is injected (sprayed) onto the cutting chips from the coolant jet section 3.

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

[0035] [Table 1]

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

[0037] As shown in Table 1, when machining was performed under equivalent cutting conditions, the machining time for this embodiment was 32 minutes, while the machining time for the conventional example was 76 minutes.

[0038] Thus, this embodiment was found to reduce the processing time by 44 minutes compared to the conventional example, confirming that the processing time can be reduced to less than half.

[0039] Furthermore, in this embodiment, as shown in Figure 8, the cutting chips are broken up at each stopping time when the feed movement of the cutting tool 2 is stopped, generating short cutting chips. These generated cutting chips are removed (blown away) by the high-pressure coolant, preventing the cutting chips from becoming entangled with the cutting tool 2 or getting stuck between the cutting tool 2 and the workpiece W, thus confirming a good machining condition.

[0040] Thus, this embodiment dramatically reduces processing time compared to conventional oscillating cutting processes, exhibits high chip-breaking performance, and removes the broken chips by blowing them away with high-pressure coolant. As a result, the likelihood of chips getting stuck between the cutting tool and the workpiece, causing problems such as chip damage, is minimized, making it a groundbreaking machine tool with excellent productivity.

[0041] Furthermore, as described above, this embodiment breaks up the cutting chips through the interaction between the cutting feed stop function and the high-pressure coolant. Therefore, it is not necessary to use ultra-high-pressure coolant (around 14 MPa to 20 MPa), and sufficient effect can be obtained with high-pressure coolant of around 1 MPa to 10 MPa, thereby reducing equipment costs.

[0042] It should be noted that the present invention is not limited to this embodiment, and the specific configuration of each constituent element can be designed as appropriate. [Explanation of Symbols]

[0043] 1 Rotating Table 2 cutting tools 2a Cutting edge 3. Coolant spray outlet Double job

Claims

[Claim 1] A machine tool comprising a rotary table for mounting and fixing a workpiece, a cutting tool for cutting the workpiece mounted 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, wherein the movement of the cutting tool is controlled based on a numerical control program, the cutting edge of the cutting tool does not detach from the workpiece during cutting and is always in contact with the workpiece, and furthermore, the cutting tool is configured to move while alternately repeating feed movement and stopping according to the numerical control program, and the numerical control program controls the cutting The machine tool is programmed to feed the tool at a constant feed rate for a predetermined time, immediately stop the cutting tool by immediately reducing the feed rate to zero after the predetermined time has elapsed, and to stop the feeding movement of the cutting tool for a stop time set to be longer than the predetermined time, and immediately resume feeding the cutting tool at the constant feed rate after the stop time has elapsed, and furthermore, the coolant ejection unit is configured such that the high-pressure coolant, set to an ejection pressure of 1 MPa to 10 MPa, is injected into the cutting chips near the cutting edge of the cutting tool during cutting, thereby breaking up the cutting chips.

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