JP4652187B2 - Rotary cutting tool - Google Patents

Description

  The present invention relates to a rotary cutting tool for suppressing high-efficiency and high-efficiency machining by suppressing self-excited vibration when cutting by a machine tool.

  For machining shapes that tend to cause interference between the spindle of the processing machine, tool holder, and workpiece, such as deep holes, use a long tool with a large protruding amount relative to the tool diameter, and a rotary cutting tool such as an end mill or milling cutter at the tip. It is necessary to install and process. A long tool has low rigidity at the tip, so that self-excited vibration is likely to occur, which has adverse effects such as deterioration of surface roughness, dimensional accuracy, and tool breakage. Similarly, self-excited vibration is likely to occur when the workpiece rigidity is low, such as when processing thin plates. As means for suppressing such self-excited vibration, a method for improving the rigidity and damping characteristics of an arbor to which a tool is attached has been proposed. On the other hand, it is known that the self-excited vibration can be suppressed by unequally dividing the dividing pitch of the cutting edge of the rotary tool. For example, Japanese Patent Laid-Open No. 2000-714 (Patent Document 1) discloses dividing the pitch. Methods have been proposed.

JP 2000-714 A

  However, in a rotary cutting tool having a plurality of cutting edges, when trying to suppress self-excited vibration by making the dividing angles of the cutting edges unequal, the natural frequency of the processing machine or workpiece and the use If the number of rotations of the tool is different, the optimum division pitch changes. Therefore, it is necessary to manufacture unequal pitch rotating cutting tools for different processing machines and workpieces each time, or to manufacture a large number of unequal pitch rotating cutting tools of various patterns in advance.

  The purpose of the present invention is to achieve various cutting edge split pitches with a single rotary cutting tool in order to solve the above problems, and to suppress cutting self-excited vibration even if the processing machine or workpiece to be processed changes, An object of the present invention is to provide a rotary cutting tool that enables high-efficiency machining by machining with a high depth of cut and reduces the cost at the manufacturing site.

  In order to achieve the above object, the present invention divides a rotary cutting tool having a plurality of cutting edges into a plurality of tool members, and fits a key or the like with a combination of a key groove or the like between the divided tool members. By combining, various cutting edge pitches can be realized with one rotary cutting tool.

  In addition, the present invention can be configured by combining a plurality of tool members provided with cutting edges and provided with a plurality of key grooves, and the division angle pitch of the cutting edges can be changed depending on the combination of key grooves to be used. It is a rotary cutting tool characterized by being.

  Further, according to the present invention, in the rotary cutting tool, the cutting edge is composed of four blades, and the difference in the angle pitch of the keyway is ½ of the difference in the divided angle pitch of the cutting edge. It is characterized by that.

  Moreover, the present invention is characterized in that, in the rotary cutting tool, the difference in the split angle pitch of the cutting edges is in an angle range of 2 ° to 10 °.

  According to the present invention, a plurality of tool members to which cutting edges are attached are provided with key grooves having different pitches, and the combination of key grooves to be used can be changed to change the dividing angle pitch of the cutting edges. By configuring, for example, even if the protrusion length of the tool holder, the spindle rigidity of the processing machine, or the rigidity of the workpiece to be processed changes, it is possible to achieve the optimum cutting edge split angle pitch with a single rotary cutting tool Therefore, machining efficiency can be improved by suppressing self-excited vibration.

  Embodiments of a rotary cutting tool according to the present invention will be described with reference to the drawings.

  FIG. 1 is an exploded perspective view of an embodiment of a rotary cutting tool according to the present invention. FIG. 2 is a perspective view showing the rotary cutting tool in a state where the key groove 21 of the tool body 2 and the key groove 31 of the tool body 3 according to the present invention are combined by the key 5 so as to have the same phase. FIG. 3 is a perspective view showing the rotary cutting tool in a state where the key groove 22 of the tool body 2 and the key groove 32 of the tool body 3 according to the present invention are combined by the key 5 so as to have the same phase.

  In FIG. 1, for example, two throwaway tips 1 are attached to each of the tool bodies 2 and 3 so as to be substantially opposed to each other about the axis between the tool bodies. The tool body 2 is provided with a key groove 21 and a key groove 22 on the outer periphery thereof. On the other hand, the tool body 3 is also provided with a key groove 31 and a key groove 32 on the outer periphery thereof. The key 5 can be attached to any key groove provided in the tool body 3. The outer diameter of the boss portion 23 of the tool body 2 is the same as the inner diameter of the hole portion 33 of the tool body 3, and both of them are cutter arbor (shown by 51 in FIG. 9) using a bolt (fixing member) 4. And can be used as, for example, a four-blade rotary cutting tool 10.

  In FIG. 1, the key groove 21 and the key groove 22 of the tool body 2 form an angle θ2. Further, the key groove 31 and the key groove 32 of the tool body 3 form an angle of θ3.

  FIG. 2 shows a state where the keyway 21 of the tool body 2 and the keyway 31 of the tool body 3 are combined so as to have the same phase. The key groove 21 of the tool body 2 and the key groove 31 of the tool body 3 are combined so as to have the same phase, and the key 5 is inserted into both grooves. The four cutting edges 1 are designed in advance so that the angular pitch of the cutting edges is 90 ° in the state of FIG. On the other hand, FIG. 3 shows a state in which the keyway 22 of the tool body 2 and the keyway 32 of the tool body 3 are combined so as to have the same phase. The key 5 is inserted into the key groove 32. In this case, the dividing angle pitch of the cutting edge is φ1 and φ2.

  FIG. 3 shows a state in which the key groove is rotated by a difference (θ3−θ2) in the angle pitch of the keyway. Therefore, the split angle pitches φ1 and φ2 of the cutting edge in FIG. 3 are expressed by the following equations (1) and (2).

φ1 = 90 ° + (θ3-θ2) (1)
φ2 = 90 ° − (θ3−θ2) (2)
From the above formulas (1) and (2), the difference (θ3-θ2) in the key groove angle pitch is expressed by the following formula (3).

θ3-θ2 = (φ1-φ2) / 2 (3)
= Α / 2
However, (alpha) is a difference of the division | segmentation angle pitch of a cutting edge, and is (alpha) = phi1-phi2.

  Therefore, the tool body 2 and the tool body 3 may be provided with the key grooves 21, 31; 22, 32 having a pitch difference that is ½ of the difference α of the cutting edge division angle pitch.

  The tool body 2 and the tool body 3 shown in FIG. 2 have a plurality of the key grooves 21, the key grooves 22, the key grooves 31, and the key grooves 32 in the same manner with a plurality of positions facing each other around the axis. A combination of key grooves (not shown) is provided, and furthermore, the difference α of the dividing angle pitch of the cutting edges can be changed variously. In the present embodiment, the arrangement of the key grooves is designed so that the difference α of the dividing angle pitch of the cutting edges can be four states of 0 °, 3 °, 5 °, and 7 °.

  As shown in FIG. 9, a rotary cutting tool 10 is constructed by attaching a tool having a diameter of about 50 mm and a length of about 4 mm and a length of about 50 mm to a long arbor 51 having a length of 350 mm. FIG. 4 shows the state of occurrence of self-excited vibration when the workpiece 41 of S50C material is machined by using the cutting tool and cutting is performed by changing the rotational speed of the rotary cutting tool 10 and the axial cut. 7. The circles in the figure indicate that a self-excited vibration does not occur and the cutting state is stable. Further, the x mark indicates an unstable case where self-excited vibration occurs and the surface roughness of the processed surface is extremely deteriorated.

FIG. 4 shows the case where the difference α of the cutting edge division angle pitch is 0 °, that is, the case of equal pitch. The cutting depth that can be cut in a stable state is 0.4 mm regardless of the number of rotations. FIG. 5 shows a case where the difference α of the dividing angle pitch of the cutting edge is 3 °. At the rotational speed of 730 min ⁻¹ , the axial cutting depth is 0.6 mm, but at the rotational speed of 600 min ⁻¹ , self-excited vibration occurs, and the stable limit cutting depth is 0.5 mm. Similarly, as shown in FIG. 6, when the difference α of the cutting edge split angle pitch is 5 °, the stability limit cutting is improved to 0.8 mm at a rotational speed of 600 min ⁻¹ . FIG. 7 shows a case where α is set to 7 °. It can be processed stably until the rotational speed 580Min ^-1 in cuts 0.6mm, but in 600 min ^-1 stability limit depth of cut has a 0.4 mm.

  From the above, if the difference α (= φ1−φ2) of the split angle pitch of the cutting edge is changed to be an unequal pitch, the stability limit cutting amount may be improved, but depending on the number of rotations used and the split pitch, It can be seen that the effect changes.

On the other hand, it is known that the amount of wear at the tool tip is easily affected by the peripheral speed of the rotary cutting tool. When the rotational speed of the tool is increased and the peripheral speed is increased, the tool wear increases, and when the peripheral speed is decreased, the tool wear is reduced. In addition, since the feed rate of the tool is expressed by the product of the feed amount per blade, the number of blades, and the tool rotation speed of the rotary tool, when the feed amount per blade and the number of blades are fixed, the higher the rotation speed, The feed rate can be increased and the machining efficiency can be improved. Therefore, it can be said that increasing the number of revolutions can improve the machining efficiency, but may reduce the tool life, and reducing the number of revolutions may improve the tool life although the tool life may be improved. Therefore, in the cutting process, it is necessary to determine the number of rotations of the tool in consideration of a trade-off between both machining efficiency and tool life. In this embodiment, when cutting the S50C material, the tool diameter is about 50 mm and the peripheral speed of the tool is 100 m / min or less, so the rotation speed is 600 min ⁻¹ .

FIG. 8 shows the stability limit cutting with respect to the division angle pitch of various cutting edges at a rotational speed of 600 min ⁻¹ . In a four-blade rotary tool, if the difference α of the cutting edge split angle pitch is 5 °, the stability limit cutting can be improved most, and the stability limit compared to the case of equal pitch, that is, α is 0 °. It shows that the depth of cut can be doubled.

  As described above, in the present embodiment, for example, a four-blade rotary cutting tool is divided into tool members (tool bodies) 2 and 3 each having two opposing cutting blades as one set, and each tool member 2 is divided. By changing the combination of the plurality of key grooves provided in 3, it is possible to suppress self-excited vibration and improve the stability limit cutting depth with a single rotary cutting tool. This makes it possible to improve both the machining efficiency and the tool life, and to suppress an increase in tool cost, for example, by preparing unequal pitch tools with various patterns.

  In the present embodiment, four types of division pitch patterns are provided by arranging a plurality of key grooves with different angle divisions, but it is also possible to set more patterns by providing a large number of key grooves. . Furthermore, by providing serrations instead of keyways, finer pitch adjustment is possible.

  Moreover, the case where the protrusion length of a tool holder is changed according to a process target arises. For example, when shallow machining is performed, it is conceivable that the long arbor 51 is shortened to increase the depth of cut and cut efficiently. Further, for example, a range of a length of a four-blade tool attached to the long arbor 51 is approximately 200 mm to 600 mm. Further, depending on the processing machine, the main shaft rigidity changes. In addition, depending on the object to be processed, the rigidity changes depending on the size and material. As described above, for example, even if the protrusion length of the tool holder, the main shaft rigidity of the processing machine, or the rigidity of the object to be processed changes, it is possible to achieve an optimum cutting edge division angle pitch with a single rotary cutting tool. In addition, the processing efficiency can be improved by suppressing the self-excited vibration.

  Moreover, in the said embodiment, although the diameter of the tool was demonstrated about 50 mm, it is possible to apply to about 40 mm-100 mm in diameter.

  Moreover, although the said embodiment demonstrated the case where the number of cutting blades was four, it is applicable to the case of the even number of 2 sheets-10 sheets or less. When the number of cutting edges is two, the cutting edge 1 provided on the tool member (tool body) 2 and the cutting edge 1 provided on the tool member (tool body) 3 are in a state of equiangular pitch. Are arranged symmetrically (opposite) with respect to the axis of the center. When the number of cutting edges is six, the cutting edges 1 are provided on the tool members (tool bodies) 2 and 3 at an angular interval of 120 °, and the tool members (tool bodies) have an equiangular pitch. In this state, the phase of the cutting edge is shifted by 60 °. When the number of cutting edges is 8, the cutting edges 1 are provided on the tool members (tool bodies) 2 and 3 at an angular interval of 90 °, and an equiangular pitch is provided between the tool members (tool bodies). In this state, the phase of the cutting edge is shifted by 45 °. When the number of cutting edges is 10, the cutting edges 1 are provided on each tool member (tool body) 2, 3 at an angular interval of 72 °, and an equiangular pitch is provided between the tool members (tool body). In this state, the phase of the cutting edge is shifted by 36 °. However, if the number of cutting edges is increased to 6 or more, there is a possibility that a chip pocket for discharging chips may not be taken, so 2 or 4 is optimal. Further, when the number of cutting edges is three, which is an odd number, the tool body needs to be divided into three stages, resulting in a complicated configuration.

  Further, in the above embodiment, the difference α (= φ1−φ2) of the dividing angle pitch of the cutting edge has been described as 3 °, 5 °, and 7 °, but it is possible to take a range of 2 ° to 10 °. It is. As a result, the key groove angle pitch difference ranges from 1 ° to 5 °. In any case, each of the divided tool members (tool bodies) is provided with a plurality of key grooves having different angular pitch differences, and the combination of the key grooves is changed to obtain the difference α of the divided angular pitches of various cutting edges. By obtaining, for example, even if the protruding length of the tool holder, the main shaft rigidity of the processing machine, or the rigidity of the object to be processed changes, it is possible to achieve the optimum cutting edge split angle pitch with a single rotary cutting tool. In addition, the processing efficiency can be improved by suppressing the self-excited vibration.

It is a disassembled perspective view which shows the case of the 4-blade which consists of two division tool bodies which are one Embodiment of the rotary cutting tool which concerns on this invention. It is a figure which shows the state combined so that a cutting blade may become equal pitch in one Embodiment shown in FIG. It is a figure which shows the state combined so that a cutting blade may become an unequal pitch in one Embodiment shown in FIG. When the rotary cutting tool according to the present invention is configured by attaching a tool having a diameter of about 50 mm and a length of about 4 mm to a long arbor having a length of 350 mm, the difference α in the split angle pitch of the cutting edges is expressed as follows. It is the figure which showed the stability at the time of setting it as 0 degree. In the case where the rotary cutting tool according to the present invention is configured by attaching a tool having a diameter of about 50 mm and a length of about 4 mm to a long arbor having a length of 350 mm, the difference α in the split angle pitch of the cutting edges is given. It is the figure which showed stability at the time of setting it as 3 degrees. When the rotary cutting tool according to the present invention is configured by attaching a tool having a diameter of about 50 mm and a length of about 4 mm to a long arbor having a length of 350 mm, the difference α in the split angle pitch of the cutting edges is expressed as follows. It is the figure which showed stability at the time of setting it as 5 degrees. When the rotary cutting tool according to the present invention is configured by attaching a tool having a diameter of about 50 mm and a length of about 4 mm to a long arbor having a length of 350 mm, the difference α in the split angle pitch of the cutting edges is expressed as follows. It is the figure which showed stability at the time of setting it as 7 degrees. In the case where the rotary cutting tool according to the present invention is configured by attaching a tool having a diameter of about 50 mm and a length of about 4 mm to a long arbor having a length of 350 mm, the rotation speed of the tool is set to 600 min ^−1. It is the figure which showed the difference (alpha) of the division | segmentation angle pitch of the optimal cutting edge. It is the figure which showed the condition processed using the rotary cutting tool which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Tip, 2 ... Tool body (tool member), 21 ... Key groove, 22 ... Key groove, 3 ... Tool body (tool member), 31 ... Key groove, 32 ... Key groove, 4 ... Bolt (fixing member), 5 ... Key, 41 ... Work, 51 ... Arbor.

Claims (4)

A rotary cutting tool that cuts the same region with respect to the rotation axis direction using a plurality of cutting edges on the same plane, the rotary cutting tool being divided into two tool members, and the divided tool The rotary cutting tool characterized in that the plurality of cutting edges can have a first angular pitch and a second angular pitch by fitting the members together . The first tool member of the two tool members is provided with a plurality of key grooves having a third angular pitch, and the second tool member of the two tool members has a fourth groove . A plurality of key grooves having an angular pitch are provided, and by combining the plurality of key grooves of the first tool member and the plurality of key grooves of the second tool member, the first of the cutting blade rotary cutting tool according to claim 1, characterized in that the the angle pitch second angular pitch is changed. The rotation according to claim 2 , wherein a difference between the third angular pitch and the fourth angular pitch is 1/2 of a difference between the first angular pitch and the second angular pitch. Cutting tools. The rotary cutting tool according to claim 3 , wherein a difference between the first angle pitch and the second angle pitch is in an angle range of 2 ° to 10 °.

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