JP2017104927A - Cutting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting tool capable of cooling effectively, while avoiding thermal crack, to a tip of the cutting tool for cutting intermittently.SOLUTION: A cutting device 1 has a cutting tool 10 provided with a tip 12 for cutting intermittently a material M to be cut on the tip of a base 11, first coolant supply means 20 for supplying a first coolant A comprising gas from the inside of the base 11 to the surface of the tip 12, and second coolant supply means 30 for supplying a second coolant W having higher cooling capacity than the first coolant A to the surface of the cutting tool 10.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a cutting apparatus, and more particularly to a cutting tool that performs intermittent cutting of a work material and a cutting apparatus that includes a cooling mechanism that cools the cutting tool.

  In a cutting tool that cuts a work material, such as a milling tool, when the cutting edge (cutting edge) of the tool is heated along with the cutting, the cutting edge is easily worn. Therefore, in order to suppress heating during processing, cooling is often performed by bringing a coolant into contact with an area including the cutting edge of the tool. Various refrigerants such as liquid water, mist-like water (mist), and air are used as the refrigerant. As a method for supplying the coolant, there is a method for supplying the coolant through the inside of the tool as described in Patent Document 1, as well as a method for supplying the coolant from the outside of the tool using a nozzle or the like.

JP 2012-176486 A

  As described above, various refrigerants are used for cooling the cutting tool. Among the above listed, when using mist or air, the cutting edge is low because the cooling capacity is lower than that of (liquid) water. From the standpoint of sufficiently suppressing the temperature rise, it may be necessary to reduce the cutting speed in accordance with the cooling capacity of the refrigerant. On the other hand, water has a very high cooling ability due to its large heat of vaporization, but cracks due to temperature amplitude (thermal cracks) occur in the tool by rapidly cooling the cutting edge that has become hot due to cutting. There is a case. In particular, the cutting tool performs intermittent cutting in which the cutting edge is in contact with the work material and the cutting state is alternately repeated, such as a milling tool, and the cutting edge is not in contact with the work material. In this case, thermal cracks are likely to occur when the cutting edge is exposed to a large temperature amplitude. At the part where the cutting edge is in contact with the work material, the movement of the blade edge in contact with the work material causes water to be blown off from the contact part between the two, and cold water is difficult to contact the cutting edge itself. Although thermal cracks are unlikely to occur, thermal cracks are likely to occur at a portion where the cutting edge is not in contact with the work material, because low-temperature water directly contacts the cutting edge that has become hot during the previous cutting.

  The problem to be solved by the present invention is to provide a cutting tool capable of effectively cooling the cutting edge of a cutting tool that performs intermittent cutting while avoiding thermal cracks.

  In order to solve the above problems, a cutting device according to the present invention includes a cutting tool in which a cutting edge for performing intermittent cutting of a work material is provided at the tip of a base, and a first refrigerant made of gas from the inside of the base. A first refrigerant supply means for supplying the surface of the cutting edge; and a second refrigerant supply means for supplying a second refrigerant having a higher cooling capacity than the first refrigerant to the surface of the cutting tool.

  Here, the second refrigerant may be made of an aqueous liquid.

  The first refrigerant may be air having a temperature equal to or higher than that of the second refrigerant.

  The cutting device further includes a rotational drive shaft that rotates the cutting tool, the cutting tool is a rotary cutting tool that performs intermittent cutting while rotating the shaft, and the first refrigerant supply unit includes: The second coolant supply means is coupled to the rotary drive shaft, and has a tube structure having an opening facing the cutting edge on the surface of the base portion and passing through the base portion of the cutting tool. It is good to consist of the nozzle member provided in the outer side of the cutting tool.

  In the cutting apparatus according to the above invention, by performing the cutting while supplying the second coolant having a high cooling capacity to the surface of the cutting tool, the heating of the cutting tool accompanying the cutting and the wear of the cutting tool resulting therefrom are suppressed. be able to. At this time, the first refrigerant made of a gas having a relatively low cooling capacity is supplied to the cutting edge of the cutting tool, and the second refrigerant is prevented from coming into contact with the cutting edge by applying a force away from the cutting edge. be able to. Thereby, it can suppress that a blade edge contacts the 2nd refrigerant | coolant, and is cooled rapidly, and a thermal crack is produced. Although the cutting edge is not directly cooled by the second refrigerant having a high cooling capacity, the cutting edge is also indirectly cooled with high cooling efficiency because the efficiency of heat removal from the base cooled by the second refrigerant is increased. .

  Here, when the second refrigerant is made of an aqueous liquid, the second refrigerant can be used at low cost, and high cooling efficiency can be obtained by the heat of vaporization of water. In this case, if the second refrigerant comes into contact with the blade edge due to the high cooling capacity of the aqueous liquid, thermal cracks are likely to occur at the blade edge. However, as described above, the first refrigerant is used in combination. Thereby, generation | occurrence | production of a thermal crack can be suppressed, enjoying the high cooling capability of a 2nd refrigerant | coolant.

  Moreover, when the first refrigerant is made of air having a temperature equal to or higher than that of the second refrigerant, the first refrigerant can be used at a low cost and the cutting edge can be effectively protected from rapid cooling.

  The cutting device further includes a rotation drive shaft that rotates the cutting tool, and the cutting tool is a rotary cutting tool that performs intermittent cutting while rotating the shaft. A pipe structure having an opening passing through the inside of the base and facing the blade edge on the surface of the base, and the second refrigerant supply means is coupled to the rotary drive shaft and is provided by a nozzle member provided outside the cutting tool. In this case, while the cutting tool rotates, it is possible to easily maintain a state in which the first refrigerant is supplied while being concentrated in a narrow region including the cutting edge. On the other hand, a 2nd refrigerant | coolant can be supplied to the wide area | region of the surface of a cutting tool, and it can utilize for the efficient heat removal from a blade edge | tip.

It is a top view which shows the cutting tool vicinity about the cutting device concerning one Embodiment of this invention. It is XX sectional drawing in FIG.

  Below, the cutting device concerning one embodiment of the present invention is explained, referring to drawings. FIG. 1 is a top view showing a configuration in the vicinity of a cutting tool of a cutting apparatus 1 according to an embodiment of the present invention. FIG. 2 shows an XX cross section in FIG.

[Configuration of cutting device]
The cutting apparatus 1 includes a rotary cutting tool 10 and cuts a workpiece M made of a metal material. A cutting tool 10 provided in the cutting device 1 includes a base 11 as a tool main body attached to the cutting device 1 and a cutting edge (cutting blade) 12 provided at the tip of the base 11 and capable of cutting the work material M. And have. The blade edge 12 is formed integrally or separately with the base portion 11 and is fixed to the base portion 11, and a plurality of blade edges 12 are arranged around the central axis of the base portion 11 in an axisymmetric manner. The cutting tool 10 is coupled via a holder 40 to a processing machine tool spindle (rotary drive shaft) (not shown). The processing machine tool spindle is rotated at a high speed by a drive source such as a motor, and the cutting tool 10 is rotated at a high speed around a rotation axis R coinciding with the central axis of the base 11.

  In the present cutting apparatus 1, an internal supply path 20 is provided as a first refrigerant supply means, taking a tubular structure embedded in the holder 11 and the base 11 of the cutting tool 10. As a specific configuration of the internal supply path 20, for example, a configuration like the cooling water path 32 described in Patent Document 1 can be diverted. The internal supply path 20 is substantially aligned with the rotation axis R of the cutting tool 10, and has a main pipe portion 21 provided in a straight line from the inside of the holder 40 to the inside of the base 11 of the cutting tool 10, and each cutting edge. 12 has a branch portion 22 provided in a branched shape from the tip of the main pipe portion 21. The tip of the branch portion 22 extends to the immediate vicinity of each blade edge 12, but does not reach the blade edge 12. At the tip of the branch portion 22, an opening 23 in which the buried tube structure is opened on the surface of the base 11 is provided. The opening 23 is formed so as to face each blade edge 12, and the gas pushed out from the main pipe portion 21 toward the tip of the branch portion 22 can be blown onto the surface of the blade edge 12.

  The proximal end side of the main pipe portion 21 of the internal supply path 20 is provided so as to penetrate to the machining tool tool spindle, and is connected to an air compressor (not shown). Thereby, while the cutting tool 10 is axially rotated by the processing machine tool main shaft, air is sent from the proximal end of the main pipe portion 21 toward the distal end of each branch portion 22, and from the opening 23 to the surface of the blade edge 12, The air stream A can be supplied in such a manner as to be sprayed.

  Furthermore, in this cutting device 1, as shown in FIG. 1, an external supply nozzle 30 is provided as the second refrigerant supply means. The external supply nozzle 30 is a device that can eject water W from its tip. The distal end of the external supply nozzle 30 is directed to the cutting tool 10, and water W can be supplied to the surface of a wide area of the cutting tool 10 including the cutting edge 12 and the base 11 so as to be sprayed. In the present embodiment, two external supply nozzles 30 are provided symmetrically across the rotation axis R of the processing machine tool main shaft. The external supply nozzle 30 is coupled to the processing machine tool main shaft of the cutting apparatus 1 and is rotated around the rotation axis R in synchronization with the shaft rotation of the cutting tool 10. Thereby, even while the cutting tool 10 is rotating, the water W can be continuously supplied to the surface thereof.

  In addition, the cutting apparatus 1 has a fixing jig 50 for fixing the work material M. Moreover, as a structure of parts other than those described above, a structure similar to that of a conventional general cutting device such as a milling machine can be applied.

[Operation of cutting equipment]
A method for cutting the workpiece M using the cutting apparatus 1 described above will be described.

  As shown in FIG. 1, when cutting, the work material M is fixed to the rotation axis R with a fixing jig 50, and one of the blade edges 12 is brought into contact with the work material M. Then, the air flow A is supplied from the proximal end side to the main pipe portion 21 of the internal supply path 20. Further, water W is ejected from the external supply nozzle 30. From this state, the rotation of the processing machine tool spindle is driven, and the cutting tool 10 is rotated about the rotation axis R as indicated by an arrow in FIG. 1 (direction D1 in FIG. 1). The workpiece M is subjected to cutting by the rotation of the cutting tool 10. Simultaneously with the shaft rotation, the predetermined range of the work material M can be cut by causing the cutting tool 10 to translate with respect to the work material M (direction D2 in FIG. 1). At each moment during cutting, there is only one cutting edge 12 in contact with the workpiece M and actually cutting (the cutting edge 12a in FIG. 1), and the other cutting edges 12 (for example, the cutting edge 12b) It is not in contact with the cutting material M. That is, each cutting edge 12 intermittently contacts the workpiece M and performs intermittent cutting.

  While the cutting is in progress, the water W is supplied from the external supply nozzle 30, so that a wide area of the cutting tool 10 is always covered with the liquid water W. Due to the centrifugal force that accompanies the rotation of the cutting tool 10, the water W is brought into a state where it forms a film on the surface of the cutting tool 10.

  Water that is about to adhere to the surface of the cutting edge 12 with the wind pressure when the air flow A is blown toward each cutting edge 12 from the opening 23 at the tip of the internal supply path 20 provided in the cutting tool 10. W receives a force in a direction away from the blade edge 12. As a result, in the cutting tool 10, the air flow A from the internal supply path 20 acts like an air curtain on the cutting edge 12, and the surface of the cutting edge 12 is not substantially in contact with water W, that is, water W is not in contact, or the contact amount of water W is kept small compared to the base 11.

  At the time of cutting, each cutting edge 12 generates heat by friction with the work material M, but cutting is performed while supplying water W having a large heat of vaporization as a coolant from the external supply nozzle 30 to the surface of the cutting tool 10. Thus, heating of the cutting tool 10 can be suppressed. Thereby, abrasion of the cutting tool 10 accompanying heat generation can be reduced. As described above, the surface of the blade edge 12 is maintained in a state where the water W is not substantially in contact with the surface. Therefore, the base 11 that is continuous or in close contact with the blade edge 12 is not directly cooled by the water W. By being cooled by the water W, heat removal of the blade edge 12 through the base 11 is promoted, and the cooling efficiency of the blade edge 12 is also enhanced by the use of the water W.

  On the other hand, generation of thermal cracks in the blade edge 12 can be suppressed by maintaining the surface of the blade edge 12 in a state where the surface of the blade edge 12 is not substantially in contact with the supply of the air flow A from the internal supply path 20. If the supply of the air flow A from the internal supply path 20 is not performed, the surface of the blade edge 12 is also wet with the water W, like the base portion 11. At the time of cutting, each blade edge 12 becomes high temperature due to friction with the work material M, but when cold water W comes into contact with the surface of the blade edge 12 in a high temperature state and is cooled rapidly, the temperature amplitude thereof Due to (temperature difference), thermal cracks (cracks due to temperature amplitude) may occur on the surface of the blade edge 12. In the cutting apparatus 1, each cutting edge 12 of the cutting tool 10 performs intermittent cutting in synchronization with the rotation of the shaft around the rotation axis R, and a work material among the plurality of cutting edges 12 at a certain rotational position. Since the cutting edge in contact with M (the cutting edge 12a in FIG. 1) is in a state of moving with respect to the work material M in contact with the work material M, water W is formed on the surface of the cutting edge 12a. Even if they come into contact with each other, the movement causes water W to be instantaneously removed from the surface of the blade edge 12a, and thermal cracks are unlikely to occur. On the other hand, since the cutting edge (the cutting edge 12b in FIG. 1) that is not in contact with the work material M is in an idle state without being in contact with the work material M, water W enters the cutting edge 12b. When contacted, the surface of the blade edge 12b remains wet. This cutting edge 12b is heated to a high temperature by cutting prior to it, and when the cold water W stays on the surface of the cutting edge 12b that has become high temperature, thermal cracks are likely to occur.

  Actually, as described above, the air flow A is supplied from the internal supply path 20 and the surface of the blade edge 12 is maintained in a state where the surface of the blade edge 12 is not substantially in contact with the surface. The generation of thermal cracks due to rapid cooling of the cutting edge 12 is suppressed. As a result, even when cutting is performed while rotating the cutting tool 10 at a high speed, the cutting tool 10 is cooled by utilizing the high cooling capacity of the water W, so that cutting can be performed with high efficiency and the influence of thermal cracks. By avoiding the change in the state of the blade edge 12 due to the above, good quality cutting can be continuously performed on the work material M. Further, by avoiding thermal cracks, the life of the cutting edge 12 can be extended and the cost required for maintenance of the cutting tool 10 can be suppressed.

  By supplying the air flow A to the surface of the blade edge 12 using the internal supply path 20 and preventing the blade edge 12 from being rapidly cooled with the water W, compared to the case where the air flow A is not supplied, The cooling efficiency of the cutting edge 12 in the sense of maintaining the temperature as low as possible is low. Then, wear of the cutting edge 12 caused by continuing cutting at a high temperature becomes difficult to be suppressed. However, by supplying the airflow A to the blade edge 12, the cooling efficiency of the blade edge 12 can be increased in the sense that the temperature amplitude given to the blade edge 12 is kept small. As a result, damage to the blade edge 12 due to thermal cracks can be suppressed, and wear of the blade edge 12 starting from the thermal cracks can be suppressed. Thus, by using the air flow A together with the water W, the wear of the cutting edge 12 as a total can be reduced. That is, the air flow A supplied from the internal supply path 20 to the blade edge 12 functions as a protective material from the water W rather than a refrigerant, and is rather from the viewpoint of suppressing the temperature amplitude given to the blade edge 12 to be small. The temperature of the air stream A is preferably higher. For example, it is good to comprise so that warm air may be supplied from the base end of the internal supply path 20 instead of normal temperature air. The temperature of the warm air may be set higher than the water W and lower than the cutting edge 12 heated by cutting.

  In the above, air A is used as the first refrigerant supplied from the internal supply passage 20 that is the first refrigerant supply means, and water W is used as the second refrigerant that is cooled from the external supply nozzle 30 that is the second refrigerant supply means. Although both are inexpensive, air A is an excellent combination in that it has an excellent ability to protect the cutting edge 12 from contact with the water W, and the water W has a high cooling ability. However, the specific type of refrigerant is not limited to this combination, and the second refrigerant has a higher cooling capacity than the first refrigerant, that is, the amount of heat taken from the object per unit mass is large, Various combinations can be employed. The first refrigerant is a gas because it is necessary to apply a pressure that can be removed from the surface of the cutting edge 12 to the second refrigerant, and the second refrigerant is a gas. It doesn't matter. However, from the viewpoint of providing a high cooling capacity, the second refrigerant is preferably a liquid, particularly an aqueous liquid. The aqueous liquid is a liquid mainly composed of water and / or a water-soluble substance, and a cooling liquid to which various additives other than water can be used.

  The specific configurations of the first refrigerant supply means and the second refrigerant supply means are not limited to those described above. However, the first coolant supply means is configured such that the first coolant can be supplied from the inside of the base portion 11 of the cutting tool 10 toward the blade edge 12 as in the internal supply path 20 described above, so that the blade edge 12 can move at high speed. The first coolant is locally supplied to only the surface of the blade edge 12 or the surface of the narrowest region including the blade edge 12 even when the blade is rotated, and pressure in the direction away from the blade edge 12 is applied to the second refrigerant. Can do. From the viewpoint of increasing the cooling efficiency of the cutting tool 10 by the second refrigerant, the area where the first refrigerant contacts the region other than the cutting edge 12 of the cutting tool 10 is preferably small. On the other hand, the second refrigerant supply means supplies the second refrigerant from the outside of the cutting tool 10 while being coupled to the spindle of the processing machine tool and rotating coaxially with the cutting tool 10 like the external supply nozzle 30 described above. By being configured, the second coolant is supplied to a wide range of the surface of the cutting tool 10, the entire cutting tool 10 is effectively cooled, and heat removal from the blade edge 12 can be effectively performed. . The second refrigerant supply means can also be provided inside the cutting tool 10 as in the internal supply path 20 as the first refrigerant supply means, but the cutting tool 10 is wide while being partitioned from the first refrigerant supply means. If the second coolant supply means capable of cooling the region is provided inside the cutting tool 10, the configuration becomes complicated.

  Hereinafter, the present invention will be described more specifically with reference to examples.

[Test method]
In the cutting apparatus according to the above embodiment, in order to verify the effect of using both the supply of air from the internal supply passage and the supply of water from the external supply nozzle, the same cutting as shown in FIGS. A device was prepared. Here, as the cutting tool, one having five cutting edges made of coated cemented carbide in axial symmetry was used. As a work material to be processed, a SUS304 block subjected to solution heat treatment was used.

Then, in the same manner as shown in FIG. 1, the cutting tool was translated in one direction while rotating the cutting tool to perform cutting. At this time, the cutting conditions were as follows.
・ Peripheral speed: 150 m / min
・ Feeding: 0.9mm / tooth, 6714mm / min
・ Axis cutting depth: 1mm
-Diameter cutting depth: 30mm
・ Cutting distance: 3m

  Cutting under the above conditions was performed by applying the cooling method shown in Table 1. Here, the temperature of the air supplied from the internal supply path and the temperature of the water supplied from the external supply nozzle were the same as the room temperature. And when each cooling method was applied, the maximum value of the width | variety of the wear trace at the time of observing the flank of a cutting tool with a microscope was measured as a tool wear amount. In addition, the ratio of the number of the five cutting edges in which thermal cracks occurred was defined as the thermal crack occurrence probability. Thermal cracks are confirmed by a microscope as a unique narrow and deep crack structure different from wear caused by heating.

[Test results]
Table 1 below shows the amount of tool wear and the probability of thermal cracking in each cooling method. In the column of the cooling method, “air” indicates the supply of air from the internal supply path, and “water” indicates the supply of water from the external supply nozzle. In addition, “◯” indicates that each refrigerant is used, and “X” indicates that each refrigerant is not used.

  In the results of Table 1, the amount of tool wear is reduced by performing the water cooling of Comparative Example 3 as compared with the case of not performing the cooling of Comparative Example 1 or the case of cooling only with the air of Comparative Example 2. It has been. This is a result of the temperature rise of the tool being suppressed by water cooling. However, thermal cracks are generated with a probability of 100%.

  In contrast, in Example 1, the occurrence of thermal cracks is eliminated by using both air cooling and water cooling. This result shows that water contact with the blade edge is prevented and the occurrence of thermal cracks is suppressed by using air cooling of the blade edge together with water cooling that can effectively reduce tool wear. . Furthermore, by using air cooling in combination with water cooling, even if the amount of wear of the tool due to the heating of the tool increases, the wear that occurs as a part of the flank face of the blade tip is missing starting from the thermal crack is suppressed, It is interpreted that the amount of tool wear as a whole is kept small.

  The embodiments and examples of the present invention have been described above. The present invention is not particularly limited to these embodiments and examples, and various modifications can be made.

DESCRIPTION OF SYMBOLS 1 Cutting device 10 Cutting tool 11 Base 12 Cutting edge 20 Internal supply path (1st refrigerant | coolant supply means)
21 Main pipe portion 22 Branch portion 23 Opening portion 30 External supply nozzle (second refrigerant supply means)
A Air (first refrigerant)
M Work material R Rotating shaft W Water (second refrigerant)

Claims (4)

A cutting tool in which a cutting edge for performing intermittent cutting of the work material is provided at the tip of the base,
A first refrigerant supply means for supplying a first refrigerant made of gas from the inside of the base to the surface of the cutting edge;
A cutting apparatus comprising: a second refrigerant supply unit configured to supply a second refrigerant having a higher cooling capacity than the first refrigerant on a surface of the cutting tool.   The cutting apparatus according to claim 1, wherein the second refrigerant is made of an aqueous liquid.   The cutting apparatus according to claim 1 or 2, wherein the first refrigerant is made of air having a temperature equal to or higher than that of the second refrigerant. The cutting device further includes a rotation drive shaft that rotates the cutting tool.
The cutting tool is a rotary cutting tool that performs intermittent cutting while rotating the shaft,
The first refrigerant supply means has a tube structure that has an opening that passes through the base of the cutting tool and faces the blade edge on the surface of the base.
The cutting apparatus according to any one of claims 1 to 3, wherein the second refrigerant supply unit includes a nozzle member that is coupled to the rotary drive shaft and is provided outside the cutting tool.

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