Processing device and chip cutting device
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- NAT UNIV CORP TOKAI NAT HIGHER EDUCATION & RES SYST
- Filing Date
- 2024-01-29
- Publication Date
- 2026-07-02
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
[Technical Field]
[0001] The present disclosure relates to a technique for cutting chips of a workpiece discharged from a rotary tool. [Background technology]
[0002] Drilling, especially deep-hole drilling, is prone to problems with drill breakage due to chip clogging in the hole. To avoid drill breakage, a technique called "step feed" is used, in which the drill is interrupted, the drill is withdrawn from the hole, the chips are removed, and then the drill is restarted. To prevent chip clogging, high-pressure cutting fluid is supplied through the center, and the drill's chip flute surface is polished or a low-friction coating is applied. Chip clogging is more likely to occur when the depth to diameter (L / D) ratio is 3 or greater. In deep-hole drilling with an L / D of 30 or greater, high-pressure cutting fluid is supplied, the chip flute surface is polished and a low-friction coating is applied, and step feed is sometimes used.
[0003] Patent Document 1 discloses a drill having a cutting edge formed at the tip of the drill body, a rake face at the tip of the drill body, and a chip flute extending from the rake face toward the rear end of the drill body, with a chip guide provided on the rake face along the extension direction of the chip flute.The drill disclosed in Patent Document 1 allows linear chips to flow continuously along the chip flute due to the chip guide, preventing clogging of the chip flute. [Prior art documents] [Patent documents]
[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-136789 Summary of the Invention [Problem to be solved by the invention]
[0005] When continuous, long linear chips are discharged from a drill, the linear chips can become entangled in the drill. Patent Document 1, therefore, discloses a cutting element that uses centrifugal force to cut linear chips that have left the chip discharge groove. However, because the cutting element in Patent Document 1 is positioned away from the drill, depending on the machining conditions, the cutting element may not be able to cut the linear chips properly.
[0006] The present disclosure has been made in view of these circumstances, and its purpose is to provide a technology that realizes high efficiency in hole drilling. [Means for solving the problem]
[0007] A processing apparatus according to one aspect of the present disclosure is a processing apparatus for drilling holes in a workpiece, the processing apparatus comprising: a tool having a chip discharge groove and discharging linear chips from the chip discharge groove; a chip cutting device for cutting the linear chips discharged from the chip discharge groove, the chip cutting device having a first opening through which the tool is inserted and a second opening through which the cut chips are discharged to the outside; and a support device for supporting the chip cutting device. In this processing apparatus, the chip cutting device is not fixed to the workpiece, and the tool is movable in the axial direction relative to the chip cutting device.
[0008] Another aspect of the chip cutting device of the present disclosure is a chip cutting device that cuts linear chips discharged from a chip discharge groove of a tool, and includes a plate portion having an opening through which the tool is inserted, and a columnar member that is arranged vertically from the plate portion, with the edge at the circumferential end of the inner surface of the columnar member forming a cutting blade, and the inner surface of the columnar member forming a guide surface that guides the rotation of the tool so that the side cutting edge of the tool does not bite into the cutting blade.
[0009] Any combination of the above components and conversion of the expressions of the present disclosure into methods, devices, systems, etc. are also valid aspects of the present disclosure. [Brief explanation of the drawings]
[0010] [Figure 1] 1 is a diagram showing a configuration of a processing apparatus according to an embodiment; [Figure 2] 1A and 1B are diagrams illustrating an example of a tool that discharges linear chips. [Figure 3] FIG. 2 is a diagram illustrating an example of a chip guide portion. [Figure 4] FIG. [Figure 5] FIG. 10 shows another chip cutting device. [Figure 6] FIG. 10 shows another chip cutting device. [Figure 7] 1 is a schematic development example of a tool side cutting edge and a chip cutting edge. [Figure 8] FIG. 10 is a diagram for explaining an appropriate guide position. [Figure 9] 10 is another example of a schematic development view of a tool side cutting edge and a chip cutting edge. DETAILED DESCRIPTION OF THE INVENTION
[0011] FIG. 1 shows the configuration of a processing device 1 according to an embodiment. The processing device 1 is a cutting device that drills holes in a workpiece 8 fixed to a fixed table 9. The processing device 1 includes a spindle housing 5 that rotatably holds a spindle 6, and a tool 10 is held in a tool holder 7 attached to the spindle 6. In this embodiment, the tool 10 is a rotary tool, and may be a drill for drilling holes, or a tap for thread cutting. The processing device 1 includes a rotation mechanism 2 that rotates the spindle 6, a movement mechanism 3 that moves the rotation mechanism 2 vertically, and a control device 4 that controls the rotation of the spindle 6 by the rotation mechanism 2 and the vertical movement of the rotation mechanism 2 by the movement mechanism 3.
[0012] The rotation mechanism 2 has a spindle motor that rotates the spindle 6, and the movement mechanism 3 has a feed motor that moves the spindle housing 5. The rotation mechanism 2 is fixed to the spindle housing 5, and the movement mechanism 3 is connected to the spindle housing 5 and moves the spindle housing 5 in the vertical direction. The processing apparatus 1 of this embodiment is equipped with a chip cutting device 40 through which a tool 10 is inserted and which cuts linear chips discharged from the tool 10. In the processing apparatus 1, the chip cutting device 40 is not fixed to the workpiece 8, but is pressed vertically against the workpiece 8 so that the underside of the chip cutting device 40 is in close contact with the surface of the workpiece 8. Because the chip cutting device 40 is not fixed to any structure on the spindle 6 side, the tool 10 can move axially relative to the chip cutting device 40.
[0013] FIG. 2 shows an example of a tool 10 that discharges linear chips. The tool 10 of this embodiment is a drill that drills a hole in a workpiece 8 and has a drill body 20 and a shank 21. In the example shown in FIG. 2, a portion of the drill body 20 in the axial direction is omitted. Arrow R indicates the rotation direction of the tool 10, and angle α indicates the helix angle of the chip discharge flute 23, i.e., the helix angle of the tool side cutting edge. The tool 10 shown in FIG. 2 is a right-hand helix drill.
[0014] The tool 10 is attached to the processing device 1 by holding the shank 21 in the tool holder 7. The rotational force of the rotation mechanism 2 is transmitted to the shank 21 via the tool holder 7, and the tool 10 rotates around its axis in the direction indicated by the arrow R (clockwise when viewed from above).
[0015] The drill body 20 includes cutting edges 22 formed at the tip of the drill body 20 and a chip discharge flute 23 that has a rake face 24 at the tip side of the drill body 20 and extends from the rake face 24 toward the rear end of the drill body 20. Two cutting edges 22 are symmetrically provided at the tip of the drill body 20, and two chip discharge flutes 23 are spirally recessed into the outer circumferential surface of the drill body 20 corresponding to these two cutting edges 22. A side cutting edge is formed between the two chip discharge flutes 23. The chip discharge flute 23 forms the rake face 24 of the cutting edges 22 at the tip side and has the function of discharging chips generated by the cutting edges 22 from the cut hole to the outside during cutting.
[0016] The flank 25 is provided to reduce the contact area between the tip of the drill body 20 and the workpiece 8 during cutting, thereby suppressing cutting resistance. The cutting edge 22 is formed on the ridge between the flank 25 and the rake face 24.
[0017] In conventional drill cutting, upward and lateral curls occur in chips. The upward curl is a curl around an axis parallel to the cutting edge 22 and is caused by friction between the chip and the rake face. The lateral curl is a curl around a normal to the rake face and is mainly caused by the difference in speed between the inner and outer diameters of the cutting edge 22. In particular, in the tool 10, the cutting edge 22 extends from approximately the center position to the outer diameter of the drill, so the diameter of the lateral curl roughly matches the diameter of the drill, resulting in strong lateral curl. When upward and lateral curls occur in chips, the chips are generated by curling three-dimensionally from the cutting edge 22. Therefore, they collide with the inner wall of the chip flute and are broken up. This can lead to clogging in the flute, especially if the hole is deep and the chip flute is narrow.
[0018] Therefore, the tool 10 of the embodiment includes a chip guide portion 30 provided on the rake face 24 substantially along the extension direction of the chip discharge flutes 23. The chip guide portion 30 is preferably provided in a direction that coincides with the extension direction of the chip discharge flutes 23, and may be provided in a direction that is approximately the same. The "approximately the same direction" includes a direction that is at an angle of, for example, 20 degrees or less with respect to the extension direction of the chip discharge flutes 23. The chip guide portion 30 suppresses curling of generated chips and regulates the outflow direction of the chips. The chip guide portion 30 is provided along the extension direction of the chip discharge flutes 23, and the cross section of the rake face 24 cut perpendicular to the extension direction of the chip discharge flutes 23 may have a concave shape (including a concave shape such as a V-shaped groove or a U-shaped groove), a convex shape (including a shape that protrudes in a mountain-like shape in the opposite direction to the groove (e.g., an inverted V-shape)), or a stepped shape (one or more steps). The cross section of the rake face 24 may have a shape that combines two or more of a concave shape, a convex shape, and a stepped shape.
[0019] FIG. 3 shows an example of an enlarged view of the chip guide portion 30. As shown in the figure, the chip guide portion 30 is provided on the rake face 24 substantially along the extension direction of the chip discharge groove 23. The chip guide portion 30 has one or more guide channels extending substantially along the extension direction of the chip discharge groove 23 from the ridge portion or the vicinity of the ridge portion where the cutting edge 22 is provided. In the example shown in FIG. 3, the guide channels are guide grooves formed by cutting out the rake face 24, and multiple guide channels are provided. A cross section of the guide channel taken perpendicular to its extension direction may be concave, convex, or stepped. While the guide channels can have various cross-sectional shapes, they must function as a curl suppression portion that suppresses curling of the generated chips.
[0020] By forming the chip guide portion 30 on the rake face 24 of the machining device 1, when the cutting edge 22 cuts the workpiece 8, the plastically deformed portion of the chip that contacts the rake face 24 fits into the guide path of the chip guide portion 30, and the chip is guided so that it flows out in a direction along the guide path while remaining in the guide path. Sideward curling is suppressed by the plastically deformed portion fitting into the guide path, and upward curling is suppressed because the chip, to which the guide path shape has been transferred, does not have a flat structure in the direction of the upward curl and is therefore less likely to bend (the moment of inertia that resists the upward curl is increased). This allows two-dimensional chips, i.e., linear chips, to flow out in a direction along the guide path, i.e., in the substantial extension direction of the chip discharge groove 23. This allows the linear chips to flow continuously along the chip discharge groove 23, preventing clogging in the chip discharge groove 23.
[0021] To effectively suppress upward curl and sideways curl, the chip guide 30 may have multiple recesses (e.g., guide grooves), multiple protrusions (ridges), or multiple steps between both ends of the cutting edge 22. While FIG. 3 shows the chip guide 30 having multiple recesses (guide grooves) spaced at equal intervals, the spacing between the multiple recesses does not have to be equal. To enhance the curl suppression effect and outflow direction regulation effect, the guide path in the chip guide 30 has at least a guide surface facing outward from the rotation axis, and the guide surface is preferably arranged approximately parallel to the extension direction of the chip discharge groove 23 and has an inclination angle close to perpendicular to the radial direction of the rotary tool.
[0022] Furthermore, in order to enhance the curl suppression effect and the outflow direction regulation effect, the shape of the recessed, protruding, or stepped portion is preferably formed to be deeper than twice the chip thickness. Furthermore, the guide path is preferably formed to be longer than the contact length of the chip (for example, approximately three times the depth of cut). The guide path may be shorter than the contact length, but in that case, it is preferably formed to gradually become shallower with increasing distance from the cutting edge 22 so as not to impede outflow. In this way, the tool 10 of this embodiment continuously discharges linear chips from the chip discharge groove 23.
[0023] Returning to FIG. 1 , the chip cutting device 40 has an opening through which the tool 10 is inserted, and the tool 10 is inserted into the opening so as to be axially movable. The chip cutting device 40 has one or more cutting blades therein, and the cutting blades cut linear chips discharged from the chip discharge groove 23 of the rotating tool 10. The chip cutting device 40 is arranged above the cutting hole, and the cutting blades cut the linear chips immediately after they are discharged from the cutting hole. The chip cutting device 40 has an opening 64 on its side through which chips cut by the cutting blades are discharged to the outside.
[0024] The chip cutting device 40 is supported by a support device 11 attached to the spindle housing 5 and is not fixed to any structure on the workpiece 8 or spindle 6 side. The support device 11 includes a rod-shaped member 14 extending in the axial direction, a support member 15 extending horizontally from the lower end of the rod-shaped member 14 and attached to the chip cutting device 40, and a guide member 13 that guides the movement of the rod-shaped member 14. A portion of the rod-shaped member 14 is inserted into a guide hole 13a provided in the guide member 13, thereby restricting its movement. Specifically, the guide member 13 allows only axial movement and rotation about the axis of the rod-shaped member 14, and restricts other movements of the rod-shaped member 14. The support device 11 supports the chip cutting device 40, allowing the chip cutting device 40 to move in the axial direction and rotate about the axis of the rod-shaped member 14. By inserting the tool 10 into the chip cutting device 40, the rotational movement of the chip cutting device 40 around the rod-shaped member 14 as the axis is restricted.
[0025] The support device 11 further includes a biasing member 12 disposed between the guide member 13 and the support member 15, and in the state shown in FIG. 1 , the biasing member 12 applies a force to the support member 15 in a direction pressing it downward. In this embodiment, the biasing member 12 is a coil spring fitted around the rod-shaped member 14, and by pressing the support member 15 downward with the spring force, a force is applied to the chip cutting device 40 in a direction pressing it against the workpiece 8, and the underside of the chip cutting device 40 is brought into close contact with the surface of the workpiece 8. The chip cutting device 40 may be fixed to the support member 15, which is a separate component, or the chip cutting device 40 and the support member 15 may be formed integrally.
[0026] Although the chip cutting device 40 is supported by the support device 11 in this way, the support rigidity is not very high. However, because the tool 10 is inserted into an opening in the center of the chip cutting device 40 so as to be movable in the axial direction, the chip cutting device 40 is guided by the tool 10 and positioned at a predetermined position. In other words, the chip cutting device 40 is automatically guided by the rotating tool 10 so that its central axis coincides with the center of rotation of the tool 10.
[0027] As described above, the position of the chip cutting device 40 in two horizontal directions and the rotational position around those directions are determined by the tool 10. In this sense, the tool 10 guides the position of the chip cutting device 40, but since this guiding relationship is relative, hereinafter, the parts and structures of the chip cutting device 40 will be referred to as "guide plates," "guide holes," "guide surfaces," etc. that guide the tool 10.
[0028] Fig. 4(a) shows a top view of the chip cutting device 40, and Fig. 4(b) shows a side view of the chip cutting device 40. The chip cutting device 40 has one or more cutting blades 60 that cut continuous linear chips discharged from the tool 10. In this example, the chip cutting device 40 has four cutting blades 60 arranged at equal intervals in the circumferential direction.
[0029] The chip cutting device 40 includes an upper first guide plate 50, a lower second guide plate 54, and four pillar-shaped members 58 connecting the first guide plate 50 and the second guide plate 54. The pillar-shaped members 58 are arranged vertically (vertically downward in this case) from the first guide plate 50 and vertically (vertically upward in this case) from the second guide plate 54. Adjacent pillar-shaped members 58 are arranged at 90-degree angular intervals in the circumferential direction. When viewed from the central axis, the inner peripheral surface of the pillar-shaped member 58 (an arcuate surface equidistant from the central axis) forms a guide surface 62 that guides the rotating tool 10, and the edge at the circumferential end of the inner peripheral surface of the pillar-shaped member 58 forms a cutting blade 60. In this example, the edge extending vertically at the rear end of the inner peripheral surface when viewed counterclockwise forms the cutting blade 60. The helix angle of the cutting edge 60 is different from the helix angle α of the side cutting edge of the tool 10, and the difference in the helix angles corresponds to the opening angle of the scissors. In the example shown in Figure 4, the cutting edge 60 is a vertically formed edge, and therefore the helix angle is zero.
[0030] The first guide plate 50 has a guide hole 52 through which the tool 10 is inserted, and the second guide plate 54 has a guide hole 56 through which the tool 10 is inserted. The first guide plate 50 is positioned on the vertical upper side (spindle side), and the second guide plate 54 is positioned on the vertical lower side (workpiece side). The first guide plate 50 and the second guide plate 54 may be flat plates with a uniform thickness, or the first guide plate 50 and the second guide plate 54 may have the same thickness. The guide holes 52 and 56 are coaxial and have the same diameter, forming an opening through which the tool 10 is inserted. The diameter of the guide hole is substantially equal to the diameter of the tool 10, and in practice, is slightly larger than the diameter of the tool 10 to ensure smooth rotation of the tool 10. The difference between the guide hole diameter and the tool diameter may be, for example, within 1 mm.
[0031] By making the guide hole diameter substantially equal to the tool diameter, the chip cutting device 40 is guided by the inner peripheral surface of the guide hole (guide surface in the guide hole) and the plurality of guide surfaces 62 so that the centers of the plurality of cutting blades 60 coincide with the rotation axis of the tool 10. In the processing apparatus 1 of the embodiment, the chip cutting device 40 is not fixed to the structure on the workpiece 8 and spindle 6 side, so it needs to be guided by the inner peripheral surface of the guide hole and the plurality of guide surfaces 62 so that the central axis of the chip cutting device 40 coincides with the rotation axis of the tool 10. The inner peripheral surfaces of the columnar members 58 extending vertically from the first guide plate 50 and the second guide plate 54 function as guide surfaces 62 that guide the rotation of the tool 10 so that the side blades of the tool 10 do not bite into the cutting blades 60, allowing the tool 10 to rotate stably within the chip cutting device 40.
[0032] When the tool 10 is rotating, the distance between the cutting blade 60 and the side blade of the tool 10 at their closest point is preferably smaller than the thickness of the chips, allowing the cutting blade 60 to efficiently cut (sever) linear chips discharged from the tool 10. The chip cutting device 40 has a structure in which the first guide plate 50 and the second guide plate 54 are connected by four pillar-shaped members 58, and therefore an opening 64 is formed between two adjacent pillar-shaped members 58. By having the opening 64 open to the outside, the chip cutting device 40 can discharge chips cut by the cutting blade 60 to the outside through the opening 64, preventing clogging of the cutting hole. Note that the first guide plate 50 and the second guide plate 54 may be connected by a single pillar-shaped member 58 or a plurality of pillar-shaped members other than four.
[0033] Fig. 5(a) shows a top view of another chip cutting device 42, and Fig. 5(b) shows a side view of the chip cutting device 42. The chip cutting device 42 has one or more cutting blades 70 that cut continuous linear chips discharged from the tool 10. In this example, the chip cutting device 42 has one cutting blade 70 with a helix angle opposite to the helix angle of the side cutting edge of the tool 10. Note that the chip cutting device 42 may have multiple cutting blades 70 with opposite helix angles.
[0034] The chip cutting device 42 includes an upper first guide plate 50, a lower second guide plate 54, and a single pillar-shaped member 72 connecting the first guide plate 50 and the second guide plate 54. A plurality of pillar-shaped members 72 may be provided. When the pillar-shaped member 72 is viewed from the central axis, the inner peripheral surface of the pillar-shaped member 72 (an arc-shaped surface equidistant from the central axis) forms a guide surface 74 that guides the rotating tool 10, and an edge at the circumferential end of the inner peripheral surface of the pillar-shaped member 72 forms the cutting blade 70. In this example, the edge extending diagonally on the left side of the inner peripheral surface forms the cutting blade 70. The direction of the helix angle β of the cutting blade 70 is opposite to the direction of the helix angle α of the side cutting edge of the tool 10.
[0035] The first guide plate 50 has a guide hole 52 for inserting the tool 10, and the second guide plate 54 has a guide hole 56 for inserting the tool 10. The first guide plate 50 is disposed on the upper side in the vertical direction (spindle side), and the second guide plate 54 is disposed on the lower side in the vertical direction (workpiece side). The guide holes 52 and 56 are formed coaxially and with the same diameter, and form an opening through which the tool 10 is inserted. The guide hole diameter is approximately equal to the diameter of the tool 10.
[0036] By making the guide hole diameter substantially equal to the tool diameter, the chip cutting device 42 is guided by the inner peripheral surface of the guide hole (the guide surface of the guide hole) and the guide surface 74 so that the central axis of the chip cutting device 42 coincides with the rotation axis of the tool 10. The inner peripheral surfaces of the columnar members 72 extending vertically from the first guide plate 50 and the second guide plate 54 function as guide surfaces 74 that guide the rotation of the tool 10 so that the side blade of the tool 10 does not bite into the cutting blade 70, allowing the tool 10 to rotate stably within the chip cutting device 42.
[0037] When the tool 10 is rotating, the distance between the cutting blade 70 and the side blade of the tool 10 at their closest point is preferably smaller than the thickness of the chips, which allows the cutting blade 70 to efficiently cut (divide) the linear chips discharged from the tool 10. The chip cutting device 42 has a structure in which the first guide plate 50 and the second guide plate 54 are supported by a single pillar-shaped member 72, and therefore the side portions where the pillar-shaped member 72 is not formed are open to the outside. In this way, the chip cutting device 42 has an opening 76 that opens to the outside, so that chips cut by the cutting blade 70 can be discharged to the outside from the opening 76, preventing clogging of the cutting hole.
[0038] The above chip cutting devices 40, 42 have two guide plates at the upper and lower ends to guide the position of the chip cutting devices 40, 42 relative to the rotating tool 10, thereby preventing the side blade of the tool 10 from biting into the cutting blade.
[0039] When using one guide plate, the height of the chip cutting device can be reduced compared to when using two guide plates, and the length of the rotary tool can be shortened accordingly. Furthermore, when the lower guide plate is eliminated, chips discharged from the cutting hole can be cut more quickly. However, since the guide plate also serves to support the columnar member with the cutting blade, when using only one guide plate, it is necessary to satisfy conditions for proper guiding. Below, we will explain the conditions under which the side blade of the tool 10 does not bite into the cutting blade when using only one guide plate.
[0040] Fig. 6(a) shows the top surface of another chip cutting device 44, and Fig. 6(b) shows a side surface of the chip cutting device 44. The chip cutting device 44 has a configuration in which the second guide plate 54, which is the lower plate, is removed from the chip cutting device 40 shown in Fig. 4.
[0041] In the chip cutting device 44, in the upper part where the first guide plate 50 is provided, the guide hole 52 is guided by the tool 10, so the radial position of the cutting blade 60 is determined at a position with an appropriate small clearance relative to the side blade of the tool 10. However, in the lower part where no guide plate is provided, the cutting blade 60 and the guide surface 62 connected to the cutting blade 60 in the circumferential direction must act as a guide for the side blade of the tool 10 intermittently at multiple rotational positions to prevent the side blade of the tool 10 from biting into (biting into) the cutting blade 60.
[0042] Below, we will consider conditions for preventing the side cutting edge of the tool 10 from biting into (biting or catching on) the chip cutting edge in the lower part where there is no guide plate. FIG. 7 is a schematic diagram showing a development of the tool-side cutting edge and the chip-cutting edge. The horizontal axis indicates the rotational position in the circumferential direction, and the vertical axis indicates the height position of the cutting edge. Here, the axial height of the cutting edge is L. Note that the chip-cutting device shown in the development of FIG. 7 has three chip-cutting edges spaced equally apart in the circumferential direction, and is different from the chip-cutting device 44 shown in FIG. 6. In the example shown in FIG. 7, the tool-side cutting edge has a helix angle α (see FIG. 2), and the chip-cutting edge formed on the chip-cutting device has a reverse helix angle β that is opposite to the helix angle α.
[0043] In this example, the guide surface connected to the chip cutting edge is an arcuate surface (angle θ) with substantially the same diameter as the chip cutting edge, as shown in guide surface 62 in Figure 6. Therefore, the guide surface has no clearance angle, and guiding is performed over the entire width of each guide surface (hatched area) and the entire intersection of the tool-side cutting edge. In Figure 7, there are four guide points enclosed by dashed ellipses. In this schematic diagram, the tool-side cutting edge is likely to bite into the cutting edge at the moment when the lowest point of the cutting edge (the point closest to the workpiece within the axial range of the cutting edge) begins to intersect with the tool-side cutting edge. In this example, the tool-side cutting edge is most likely to bite into the cutting edge at the moment when the horizontal axis is at the rotational position π.
[0044] The tool side cutting edge is formed along the chip discharge groove 23 (see FIG. 2), and is therefore twisted in a direction lagging behind the rotation direction from the tip to the base of the tool. In FIG. 7, the tool side cutting edge is formed with a right-upward twist and moves (rotates) to the left relative to the cutting edge during machining. As described above, the cutting edge has an opposite twist (left-upward twist). In order to prevent the tool side cutting edge from biting into the cutting edge, it is necessary for the chip cutting device to be properly guided to a predetermined position at the moment when the tool side cutting edge and the cutting edge begin to intersect at rotation position π.
[0045] Specifically, it is necessary that guiding is performed appropriately at angular positions less than 90 degrees to the left and right of the intersection start position. Here, "guiding appropriately" means guiding the tool side blade in the left and right vicinity of the tool side blade so that the tool side blade does not bite into the cutting blade. In the example of Figure 7, the closest guide point on the left side of the intersection start position is "a", and the closest guide point on the right side of the intersection start position is "b", and it is necessary that guide points a and b are each less than 90 degrees from the intersection start position. Here, the height of guide point a is l a , the angle from the intersection start position is λ a Let the height of guide point b be l b , the angle from the intersection start position is λ b Let's say.
[0046] FIG. 8 is a diagram illustrating an appropriate guide position. In FIG. 8, the tool-side cutting edge 80 rotates clockwise and approaches the cutting edge 82 at a rotational position π. A guide surface 84 is connected to the cutting edge 82. Here, if guide point a is within the range of π / 2 to π and guide point b is within the range of π to 3π / 2, the tool cannot move leftward (i.e., the cutting edge 82 cannot move rightward). Therefore, the tool-side cutting edge 80 does not bite into the cutting edge 82, and the tool inserted in the chip cutting device can continue to rotate stably.
[0047] In the following, the diameter of the guide hole is D, the number of teeth on the side cutting edge of the tool is n, the twist angle of the side cutting edge of the tool is α, the number of teeth on the cutting edge of the chip cutting device is m, the axial height is L, the reverse twist angle (positive when it is in the opposite direction to the twist angle of the tool) is β, and the angle of the guide surface is θ. At this time, L > l a , l b π / 2 > λ a , λ b is necessary to avoid a situation in which the tool side edge 80 bites into the cutting edge 82. Therefore, the conditions for preventing biting to achieve stable rotation and chip cutting are expressed by the following equations (1) to (4).
[0048] L>l a twist
number
number
number
number
[0049] (Condition A) Here, when the following conditions (condition A) are set: D = 8 mm, n = 2, α = 30 deg, m = 3, L = 20 mm, β = 20 deg, θ = 28.6 deg, all of the conditions in equations (1) to (4) are met. When a chip-cutting device was created under this condition A and experiments were conducted, it was confirmed that stable rotation and chip-cutting were possible.
[0050] Figure 9 shows another example of a development view of the tool side blade and the chip cutting blade. The chip cutting device shown in Figure 9 has two chip cutting blades equally spaced in the circumferential direction, which is different from the chip cutting device shown in Figure 7.
[0051] (Condition B) Here, when D = 8 mm, n = 2, α = 30 deg, m = 2, L = 20 mm, β = 20 deg, θ = 28.6 deg (condition B), λ b When a chip cutting device was created under this condition B and an experiment was carried out, it was confirmed that the tool side cutting edge 80 was biting into the cutting edge 82, making it impossible to perform stable rotation.
[0052] Next, consider the configuration of the chip cutting device 40 shown in Figure 4 without the upper first guide plate 50. Therefore, the chip cutting device includes a lower second guide plate 54. In this case, the chip cutting device can be made smaller in height compared to a configuration with upper and lower guide plates. However, compared to the chip cutting device 44 without the lower guide plate, it cannot cut the chips discharged from the drilled hole as quickly. However, because the lower second guide plate 54 guides the chip cutting device, it is possible to prevent the tool-side cutting edge from biting into the cutting edge at the moment when the lowest point of the cutting edge (the upper end of the second guide plate 54) begins to intersect with the tool-side cutting edge. Generally, the chip discharge grooves and side cutting edges of hole-making tools are twisted in a direction that lags the rotation direction from the tip to the base of the tool to discharge chips. However, because it is easy to set an appropriate opening angle by twisting the cutting edge of the chip cutting device in the opposite direction, the height position at which the cutting edge begins to intersect with the tool-side cutting edge is naturally the lowest end of the cutting edge. Therefore, for example, when it is important to reduce the height of the chip cutting device and there is no need to cut the chips discharged from the machined hole more quickly, the chip cutting device can be configured to have the second guide plate 54 as the lower plate and to remove the first guide plate 50 as the upper plate, thereby achieving stable rotation and chip cutting.
[0053] While it is possible to use a chip cutting device without either the upper or lower guide plates, since the guide plates also serve to connect multiple cutting blades, there is little practical point in omitting both the upper and lower guide plates. Even so, if both guide plates are omitted, the chip cutting device must guide two radial directions at two or more positions at different axial heights in order to constrain four of the six degrees of freedom, excluding rotation and axial movement (which are not constrained for machining). To guide two radial directions at each height, there must be at least three contact points between the tool side blade, the chip cutting blade, and the guide surface connected to it, at angles less than 180 degrees. If both upper and lower guide plates are omitted, a plate portion (which does not have a tool guide function) may be provided to connect multiple columnar members circumferentially.
[0054] In the above-mentioned (Condition A), the guide surface is sufficiently wide that both ends of the guide surface can be considered to have two contact points, thus providing the required six or more points of support. However, if the guide surface is narrow, or if both the chip-cutting blade and the rotating tool have positive clearance angles, there will be an area that does not meet the condition of three or more contact points at an angle of less than 180 degrees, and the condition for stable rotation may not be met. In such cases, the six or more points of contact can be achieved by increasing the number of teeth, the helix angle, the reverse helix angle, or the axial height of the cutting blade.
[0055] According to the present disclosure, tool 10 discharges linear chips, thereby enabling hole drilling without the need for step feed. Even if the feed rate is increased to allow thick chips to flow, clogging does not occur, allowing for even higher efficiency with a larger feed rate. Furthermore, because thick linear chips can be discharged using a chip discharge flute with a smaller cross-sectional area than conventional ones, the drill cross-sectional area can be increased, which improves the strength of the drill and allows for even greater feed rates.
[0056] Furthermore, according to the present disclosure, the chip cutting device cuts the linear chips immediately after they are discharged from the cutting hole, thereby preventing the linear chips from becoming entangled in the tool and achieving high efficiency and low cost hole processing.
[0057] The present disclosure has been described above based on the embodiments. These embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of the respective components and the respective treatment processes, and that such modifications are also within the scope of the present disclosure.
[0058] In the embodiment, the support device 11 that supports the chip cutting devices 40, 42, 44 is attached to the spindle housing 5, but the support device 11 may also be provided on a fixed table 9 that fixes the workpiece 8. The fixed table 9 may be a table that is movable in the horizontal direction. Even in this case, the support device 11 supports the chip cutting devices 40, 42, 44 by the same function as the support device 11 shown in FIG. 1 , has a biasing member that applies a force to at least the chip cutting devices 40, 42, 44 in a direction pressing them against the workpiece 8, and is equipped with a means for restricting the chip cutting devices 40, 42, 44 from rotating together with the tool 10.
[0059] An overview of an aspect of the present disclosure is as follows. One aspect of the present disclosure is a processing device for drilling a hole in a workpiece, the processing device comprising: a tool having a chip discharge groove and discharging linear chips from the chip discharge groove; a chip cutting device for cutting the linear chips discharged from the chip discharge groove, the chip cutting device having a first opening through which the tool is inserted and a second opening through which the cut chips are discharged to the outside; and a support device for supporting the chip cutting device. The chip cutting device is not fixed to the workpiece, and the tool is movable axially relative to the chip cutting device.
[0060] According to this aspect, the chip cutting device cuts the linear chips immediately after they are discharged from the cutting hole, thereby preventing the linear chips from becoming entangled in the tool. The support device preferably has a biasing member that applies a force to the chip cutting device in a direction pressing it against the workpiece.
[0061] The chip cutting device may have a plate portion having a first opening and a columnar member provided perpendicularly to the plate portion, an edge at a circumferential end of an inner peripheral surface of the columnar member forming a cutting blade, and the inner peripheral surface of the columnar member forming a guide surface that guides the rotation of the tool so that the side cutting edge of the tool does not bite into the cutting blade. The chip cutting device may have a plurality of columnar members, and a second opening may be formed between adjacent columnar members.
[0062] The helix angle of the cutting edge is preferably different from the helix angle of the side cutting edge of the tool. The direction of the helix angle of the cutting edge may be opposite to the direction of the helix angle of the side cutting edge of the tool. The distance between the cutting edge and the side cutting edge of the tool is preferably smaller than the thickness of the chip.
[0063] Another aspect of the present disclosure is a chip cutting device that cuts linear chips discharged from a chip discharge groove of a tool, comprising a plate portion having an opening through which the tool is inserted, and a columnar member that is arranged perpendicular to the plate portion, wherein an edge at the circumferential end of the inner peripheral surface of the columnar member forms a cutting blade, and the inner peripheral surface of the columnar member forms a guide surface that guides the rotation of the tool so that the side cutting edge of the tool does not bite into the cutting blade.
[0064] According to this aspect, the chip cutting device cuts the linear chips immediately after they are discharged from the cutting hole, thereby preventing the linear chips from becoming entangled with the tool. The diameter of the first opening is preferably slightly larger than the diameter of the tool, and the difference in diameter may be, for example, within 1 mm. [Explanation of symbols]
[0065] 1 Processing device, 2 Rotation mechanism, 3 Moving mechanism, 4 Control device, 5 Spindle housing, 6 Spindle, 7 Tool holder, 8 Workpiece, 10 Tool, 11 Support device, 12 Pressing member, 13 Guide member, 13a Guide hole, 14 Rod-shaped member, 15 Support member, 20 Drill body, 21 Shank, 22 Cutting edge, 23 Chip discharge groove, 24 Crack face, 25...flank face, 30...chip guide portion, 40, 42, 44...chip cutting device, 50...first guide plate, 52...guide hole, 54...second guide plate, 56...guide hole, 58...columnar member, 60...cutting blade, 62...guide surface, 64...opening, 70...cutting blade, 72...columnar member, 74...guide surface, 76...opening, 80...tool side blade, 82...cutting blade, 84...guide surface.
Claims
1. A machining device for drilling holes in a workpiece, A tool having a chip discharge groove, which discharges linear chips from the chip discharge groove, A chip cutting device for cutting linear chips discharged from the chip discharge groove, the chip cutting device having a first opening through which the tool is inserted and a second opening for discharging the cut chips to the outside, The chip cutting device is supported by a support device, The chip cutting device is not fixed to the workpiece, the tool is movable axially relative to the chip cutting device, and the chip cutting device is guided so that its central axis coincides with the rotational center of the tool. A processing apparatus characterized by the following features.
2. The support device has a biasing member that applies a force to the chip cutting device in a direction that presses it against the workpiece. The processing apparatus according to feature 1.
3. The aforementioned chip cutting device is The plate portion having the first opening, It has a columnar member provided vertically from the plate portion, The edges at the circumferential ends of the inner surface of the columnar member constitute a cutting blade. The inner circumferential surface of the columnar member constitutes a guide surface that guides the rotation of the tool so that the side blade of the tool does not bite into the cutting blade. The processing apparatus according to feature 1.
4. The chip cutting device has a plurality of columnar members, The second opening is formed between adjacent columnar members. The processing apparatus according to feature 3.
5. The helix angle of the cutting blade is different from the helix angle of the side blade of the tool. The processing apparatus according to feature 3.
6. The direction of the helix angle of the cutting blade is opposite to the direction of the helix angle of the side blade of the tool. The processing apparatus according to feature 5.
7. The distance between the cutting blade and the side blade of the tool is smaller than the thickness of the chip. The processing apparatus according to feature 4.
8. A chip cutting device for cutting linear chips discharged from the chip discharge groove of a tool when drilling holes in a workpiece, A plate portion having an opening through which the aforementioned tool is inserted, The system comprises a columnar member provided vertically from the plate portion, The edges at the circumferential ends of the inner surface of the columnar member constitute a cutting blade. The inner circumferential surface of the columnar member is configured as a guide surface that guides the rotation of the tool so that the side blade of the tool does not bite into the cutting blade. The chip cutting device is not fixed to the workpiece, but is guided so that its central axis coincides with the rotation center of the tool. A chip cutting device characterized by the following features.
9. The diameter of the opening is slightly larger than the diameter of the tool. The chip cutting apparatus according to feature 8.
10. A machining apparatus for drilling holes in a workpiece, A tool having a chip discharge groove, which discharges linear chips from the chip discharge groove, A chip cutting device for cutting linear chips discharged from the chip discharge groove, The chip cutting device is supported by a support device, The aforementioned chip cutting device is A first guide plate having a first guide hole through which the tool is inserted, A second guide plate having a second guide hole through which the tool is inserted, It has an opening for discharging the cut chips to the outside, The chip cutting device is not fixed to the workpiece, the tool is movable axially relative to the chip cutting device, and the chip cutting device is guided by the inner surfaces of the first and second guide holes so that its central axis coincides with the rotation center of the tool. A processing apparatus characterized by the following features.
11. The diameters of the first guide hole and the second guide hole are slightly larger than the diameter of the tool. The processing apparatus according to feature 10.
12. A chip cutting device for cutting linear chips discharged from the chip discharge groove of a tool when drilling holes in a workpiece, A first guide plate having a first guide hole through which the tool is inserted, A second guide plate having a second guide hole through which the tool is inserted, The system comprises a columnar member connecting the first guide plate and the second guide plate, The edges at the circumferential ends of the inner surface of the columnar member constitute a cutting blade. The chip cutting device is not fixed to the workpiece, but is guided by the inner surfaces of the first and second guide holes so that its central axis coincides with the rotation center of the tool. A chip cutting device characterized by the following features.
13. The diameters of the first guide hole and the second guide hole are slightly larger than the diameter of the tool. The chip cutting apparatus according to claim 12.