JP7040504B2 - Cutting tool - Google Patents

Description

The present invention relates to a cutting tool or the like having excellent vibration damping properties.

Cutting is performed by relatively moving the work (geographical feature) to be machined and the tool equipped with the cutting tool. Cutting mainly includes turning where the work is fixed and the tool is rotated, and turning where the tool is fixed and the work is rotated, but most of the recent machine tools perform turning.

By the way, in order to secure the quality of cutting (precision of machined surface, surface roughness, etc.) and productivity, it is necessary to suppress chatter vibration generated by self-excited vibration or forced vibration of the tool. Therefore, various proposals have been made to improve the vibration damping property of cutting tools (particularly shanks, holders, etc.) having excellent vibration damping property that can suppress chatter vibration, and there are descriptions related to the following patent documents.

Japanese Unexamined Patent Publication No. 2005-74558 Japanese Unexamined Patent Publication No. 2006-102837 Japanese Unexamined Patent Publication No. 2012-757752 Japanese Unexamined Patent Publication No. 2017-42863

Patent Document 1 encloses a fluid (liquid or fine solid) in a space provided along the tapered outer peripheral surface of a tool holder (collet chuck) to prevent vibration generated during cutting. However, the fluid is enclosed in a portion (grip portion) corresponding to a node of the bending primary intrinsic mode, which is the main cause of self-excited chatter vibration. Therefore, the tool holder of Patent Document 1 cannot sufficiently suppress self-excited chatter vibration.

In Patent Document 2, a block-shaped vibration damping piece that can rotate coaxially with the main body of the tool is built in a pocket (hollow portion) provided in the main body of the tool to prevent vibration of the cutting tool. When the main body vibrates, the vibration damping piece collides with the wall of the pocket due to a phase delay, and damps the chatter vibration (torsional vibration) of the main body caused by the torsional force during cutting. However, when applied to rolling to rotate a tool such as an end mill, it is not easy to incorporate the vibration damping piece separated from the main body into the main body while ensuring high accuracy (coaxiality, etc.).

In Patent Document 3, the divided weight members are housed in the hollow portion of the tool holder, and the vibration of the tool holder is damped by the sliding friction between the weight members. Such a weight member is required to have high accuracy, and can significantly increase the manufacturing cost of the tool.

Patent Document 4 proposes a holder for a cutting tool in which a rod member and powder are housed in a hollow portion. The rod member is in a floating state in the powder and changes its posture independently of the holder. Such a rod member causes an imbalance that causes vibration during rotation. In particular, when the tool rotation axis changes from the vertical direction to the horizontal direction, such as a machining center for multi-axis machining, such a holder tends to generate vibration due to imbalance.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a cutting tool or the like having a new structure different from the conventional one and having excellent vibration damping properties.

As a result of diligent research to solve this problem, the present inventor has conceived to provide a wing portion for sending a fluid to the cutting tool side (one end side) in the hollow shaft portion of the cutting tool used for milling. We realized this and confirmed its effect. By developing this result, the present invention described below was completed.

<< Cutting Tool 1 >>
(1) The present invention is a cutting tool composed of a shank that rotates with respect to a fixed work, and the shank has a holder portion that can hold a cutting tool for cutting the work on one end side and the other end side. A grip portion that can be gripped by a machine tool, a shaft portion between the holder portion and the grip portion, a hollow portion that forms an inclusion space in the shaft portion, and a shaft portion that rotates in the shaft portion. It is a cutting tool having a wing portion that sends the fluid filled in the inclusion space to the one end side together with the blade portion.

(2) The cutting tool of the present invention (also simply referred to as a "tool") has excellent vibration damping properties and can suppress chatter vibration generated in the cutting tool during machining. Therefore, when the tool of the present invention is used, for example, good cutting (rolling) can be performed even in a region of high L / D (L: protrusion length of shank, D: outer diameter thereof).

The reason why the tool of the present invention is excellent in vibration damping property is considered as follows at present. First, when the shank rotates, the fluid in the inclusion space is caused by friction between the fluids (for example, powder particles) and friction between the fluid and the wall surface constituting the inclusion space (simply referred to as "inner wall surface"). Vibration energy is converted into heat energy and dissipated. Further, the fluid moves with a phase delay with respect to the shank due to its own inertia, collides with the inner wall surface and the like, and suppresses the vibration (amplitude) of the shank.

Further, the tool of the present invention has a wing portion in the shaft portion that rotates with the shaft portion. When the shank (shaft) rotates, the wing sends the fluid in the inclusion space to the cutting tool side (one end side). As a result, during the cutting process, the fluid is in a state of being pressurized (further, in a state of being pressure-welded) to the inner wall surface on the cutting tool side. The above-mentioned vibration reduction is enhanced by the fluid being forcibly moved to the vicinity of the ventral side of the bending primary intrinsic mode, which is the main cause of the self-excited chatter vibration.

Further, the fluid is pressed toward the cutting tool side during the rotation of the shank, and the morphological change is suppressed. Therefore, even if the rotation axis of the shank is tilted during cutting, the amount of eccentricity between the rotation axis and the center of gravity of the tool containing the fluid is suppressed, and a rotation unbalance that causes vibration is less likely to occur.

By the way, when the fluid is in a pressure contact state with the inner wall surface, the movement (sliding) of the fluid is reduced on the outermost surface of the inner wall surface, and the wear of the inner wall surface due to the fluid can be suppressed.

<< Cutting tool 2 >>
(1) The present invention can also be grasped as a cutting tool having no wing portion. That is, it is a cutting tool consisting of a shank that rotates with respect to a fixed work, and the shank has a holder portion that can hold a cutting tool for cutting the work on one end side and a machine tool on the other end side. It has a grip portion that can be gripped, a shaft portion between the holder portion and the grip portion, and a hollow portion that forms an inclusion space in the shaft portion, and the inclusion space is filled with only a fluid. It may be a cutting tool.

(2) As described above, even if the inclusion space is filled with the fluid, the vibration energy is reduced and the vibration damping property of the tool is ensured. Further, in the case of the present invention, only the fluid is filled in the inclusion space, and the massive vibration damping piece or the like is not in the hollow portion. Therefore, during the cutting process (during the rotation of the shank), the amount of eccentricity between the center of gravity of the tool containing the fluid and the rotating shaft is suppressed. As a result, in the case of the present invention, even if the rotation axis of the shank is tilted, a large rotation imbalance does not occur, and vibration due to the unbalance is unlikely to occur.

<< Manufacturing method of cutting tools >>
The present invention can also be grasped as a method for manufacturing a cutting tool. The cutting tool described above is manufactured by, for example, a powder laminating method.

According to the powder laminating method, it is possible to form an inclusion space or a wing portion having a desired size and shape with a high degree of freedom and high accuracy. Further, according to the powder laminating method, the powder remaining in the inclusion space can be used as a fluid. That is, filling or encapsulation of the fluid in the inclusion space can be omitted.

"others"
(1) The cutting tool referred to in the present invention may be provided with at least the above-mentioned shank. The cutting tool of the present invention may be, for example, a single shank (shank only), a shank and a cutting tool, or may be provided with other elements. The cutting tool (cutting blade) may be detachable from the shank or fixed to the shank (non-detachable).

(2) In the present specification, unless otherwise specified, the cutting tool side (holder portion side) is referred to as one end side, and the machine tool side (grip portion side) is referred to as the other end side.

(3) Unless otherwise specified, "x to y" in the present specification includes a lower limit value x and an upper limit value y. A range such as "a to b" may be newly established with any numerical value included in the various numerical values or numerical ranges described in the present specification as a new lower limit value or upper limit value. Further, unless otherwise specified, "x to ymm" in the present specification means xmm to ymm. The same applies to other unit systems.

It is a vertical sectional view and a horizontal sectional view which shows one form example (sample 1) of a tool. It is a front view showing only the spiral body (wing part) extracted. It is a perspective view which showed only another form example of a wing part. It is a perspective view which shows the deformation example of a tool (the rotation direction of a tool and the spiral direction of a wing part). It is a vertical sectional view and a horizontal sectional view which shows another example of a form (sample 2) of a tool. It is a vertical cross-sectional view and a cross-sectional view which showed each tool (sample 1, 2, C1) subjected to a cutting process collectively. It is a photograph showing the state of the cutting process test. It is a graph which shows the relationship between the depth of cut which concerns on a tool of a sample 1 and the surface roughness (surface roughness) of a machined surface. It is a graph which shows the relationship between the depth of cut and the surface roughness which concerns on a tool of a sample 2. It is a graph which shows the relationship between the depth of cut and the surface roughness which concerns on a tool of a sample C1.

One or more components arbitrarily selected from the present specification may be added to the components of the present invention. The contents described in the present specification appropriately apply not only to the cutting tool of the present invention but also to the manufacturing method thereof. Even a methodical component can be a component of an object.

《Fluid》
The fluid may be a solid, a liquid, or a mixture thereof (solid-liquid mixture). The solid or liquid may be only one kind, or a plurality of kinds having different compositions (components), forms (structures) and the like may be mixed.

The fluid may contain at least powder. As the fluid, a liquid such as a processing oil (cutting fluid, cooling liquid, etc.) or a lubricating oil (silicone oil, etc.) may be mixed with the powder. The processing oil may be supplied to the cutting tool not only in the hollow portion (inclusion space) but also through an oil passage provided in the shank.

Hereinafter, a case where the fluid is a powder will be described as a typical example. As described above, the powder filled in the encapsulation space may come into contact with or collide with the wall surface (constituent surface of the hollow portion and the surface of the wing portion) constituting the encapsulation space, or the powder particles may come into contact with or collide with each other. , Vibration energy is converted into thermal energy. In this way, the resonance peak of chatter vibration is reduced.

The filling rate of the powder in the inclusion space may be, for example, 20% to 90%, more preferably 30% to 80%. When the powder laminating method is used, the filling rate is about 40% to 70%, although it depends on the particle size of the raw material powder. The filling factor of the powder can be appropriately adjusted by introducing or removing the powder into the inclusion space. The filling rate is calculated as follows.
Filling rate (%) = (Vp / V) x 100
V: Total volume of inclusion space, Vp: Total volume of filled powder

The particle size of the powder is appropriately selected. When the powder laminating method is adopted, the particle size of the powder is, for example, 5 to 300 μm, 10 to 150 μm, 15 to 100 μm, 20 to 63 μm in consideration of formability, powder availability, handleability, quality and the like. Is preferably 25 to 45 μm.

Unless otherwise specified, the particle size of the powder referred to in the present specification is specified by a sieving method for classifying using a sieve having a predetermined mesh size. For example, the particle size "x-y" means that the particles are sized so that the mesh opening does not pass through the x (μm) sieve and the mesh opening passes through the y (μm) sieve. The particle size "less than y" or "-y" means that the particles are sized to pass through a mesh having a mesh opening of y (μm).

The powder may be ceramic powder or the like as well as metal powder. Metal powder includes various steel materials (tool steel, mold steel, stainless steel, etc.), cemented carbide, polymerized gold with a higher specific gravity than steel materials (specific gravity of 10 or more), and light alloys with lower specific gravity than steel materials (specific gravity of 5 or less). ) Etc. The powder may be only one kind or may be different kinds depending on the part. Further, in the case of the powder laminating method, the powder to be encapsulated in the hollow portion (also referred to as “encapsulated powder” as appropriate) may be the same as or different from the raw material powder constituting the shank. If the encapsulating powder has a higher specific density than the raw material powder, further improvement in vibration damping property is expected. Further, in consideration of the usage environment of the cutting tool and the like, a powder made of a non-magnetic material may be used. Each powder is obtained, for example, as an atomized powder. The inner wall surface in contact with the powder may have improved wear resistance by surface modification, coating, or the like.

《Inclusive space》
The inclusion space is a space formed in the shaft portion. The inclusion space may be a closed closed space or an open space communicating with the outside. There may be only one inclusion space or two or more inclusion spaces. The inclusion space may be formed at least in the vicinity of the holder portion (cutting tool side / one end side). If the inclusion space is long in the axial direction, it should extend to the vicinity of the holder. When there are a plurality of inclusion spaces, it is preferable that at least one of them is near the holder portion. As a result, the amplitude on the ventral side where the amplitude of the chatter vibration becomes large is reduced, and the chatter vibration on the cutting tool side is easily suppressed. When there are a plurality of inclusion spaces (for example, when a plurality of inclusion spaces are arranged in the axial direction), the form (shape, size, etc.) of each inclusion space may be the same or different.

The inclusion space may expand radially on one end side rather than on the other end side. As a result, it becomes easy to secure the vibration damping property and also to secure the static rigidity and strength of the grip portion side of the shank on which a large stress acts.

The general shape of the inclusion space formed in the rotating shaft portion is preferably a circular cross section. For example, the inclusion space may be a drop shape (tear drop type) in which circular cross sections whose diameters decrease from one end side to the other end side are laminated, except for the end portion.

Unless otherwise specified, the above-mentioned contents regarding "fluid" and "encapsulation space" can be applied to a tool without a wing and a tool with a wing. In the case of a tool without a wing portion, the wall surface forming the hollow portion is usually the wall surface forming the inclusion space. In the case of a tool having a wing portion, the area (maximum virtual area) constituting the hollow portion is usually defined by the envelope surface of the wall surface (outer peripheral surface) constituting the inclusion space.

《Wings》
The wing portion is arranged in the shaft portion (or the hollow portion), and by rotating with the shaft portion, the fluid filled in the inclusion space is sent (pressurized) to one end side. When there is a wing portion, the inclusion space is a space formed by the hollow portion and each surface (also referred to as “wall surface”) of the wing portion.

The wing portion may be formed integrally with the shaft portion, may be formed separately from the shaft portion, or may be a mixture thereof, as long as it rotates with the shaft portion. If at least a part of the wing portion is integrally formed with the shaft portion, the manufacturing cost required for machining and assembling the tool can be reduced.

The wing portion that is separate from the shaft portion may be restricted from freely moving with respect to the shaft portion after being charged into the hollow portion. The regulation may be made by abutting (pressure contact) between the constituent surfaces of the wing portion and the hollow portion, or may be made by a regulating member such as a pin or a screw. Further, the wing portion may rotate synchronously with the shaft portion, or may rotate with a phase difference or a speed difference with respect to the shaft portion. In the present specification, unless otherwise specified, both are referred to as "accompaniment".

The wings may be continuous or intermittent. For example, the wing portion may be a continuous spiral body (screw, spiral, etc.) in whole or a part thereof, or may be a divided blade (for example, a spiral piece). In any case, it is preferable that the constituent surface (blade surface) of the wing portion is not vertical or horizontal with respect to the rotation axis of the tool, but is inclined. The inclination angle (θ) of the blade surface is an inclination angle (θ: 0 ° <θ <90 ° or 90 ° <θ <180 °) that can send the fluid in the inclusion space to one end side with respect to the axis of rotation. It is good.

The inclination angle may be the same or different among the plurality of blade surfaces. The tilt angle may also change within one blade surface. The wing portion may be composed of wing surfaces having different morphologies. The blade surface may be flat or curved, or a mixture thereof.

In order to send the fluid to one end side, the wing portion may be formed, for example, along a spiral trajectory traveling from one end side to the other end side around the rotation direction at the time of cutting when viewed from one end side. Specifically, when viewed from one end side (holder side, cutting tool side), when the tool turns clockwise (clockwise) during machining, the wing part is formed along a spiral trajectory similar to a right-handed screw. good. On the contrary, when the tool turns counterclockwise (counterclockwise) when viewed from one end side, the wing portion may be formed along a spiral trajectory similar to a left-handed screw.

The orbit on which the wing portion is formed may be a single row (row) or a plurality of rows (row). For example, a wing portion formed along a plurality of trajectories has a large distance (lead) that can convey a fluid per rotation, like a multi-thread screw, and can efficiently send the fluid to one end side. .. For example, the wing portion may be formed along a multiple spiral.

The wing portion may be grasped as a convex portion (corresponding to a screw thread) formed in the hollow portion or as a concave portion (corresponding to a screw valley) formed in the hollow portion. Further, the wing portion may be grasped like a "female screw" formed on the inner peripheral surface side of the hollow portion, or may be grasped like a "male screw" charged in the hollow portion. The wing portion may have a pipeline extending in the axial direction. For example, a straight tubular (cylindrical) space extending in the axial direction may be formed in the center of the hollow portion.

《Cutting tool》
Cutting tools basically consist of shanks. The tip side of the shank is the holder part, and the root side of the shank is the grip part attached to the machine tool. The holder portion may be integrally molded with the shank, or may be a head joined to the tip end side of the shank by welding, brazing, or the like. The head may be made of shank and dissimilar material. For example, the shank may be made of cemented carbide and the head may be made of steel. Further, the shank may be manufactured by a powder laminating method, and the head may be manufactured by forging, cutting or the like. A non-detachable cutting tool may be directly provided on the holder portion (head), but usually, the removable cutting tool is fixed by a screw or the like.

The shank may be a rod shape having the same cross section, a stepped shape having a different cross section, a tapered shape, or the like, except for the holder portion. Further, the grip portion may be expanded (diameter expanded) more than other portions.

The filling of the powder, the formation of the wing portion, and the like may be performed by a plurality of steps, or may be performed by a single step (in-process) by a powder lamination method or the like. In the former case, it is preferable to fill the hollow portion with powder or charge the wing portion from the opening of the hollow portion, and then fix the lid to the opening to close the hollow portion. The lid can be fixed by, for example, fastening (screws or the like), joining (welding, brazing, bonding, press-fitting (including shrink fitting), or the like.

《Powder laminating method》
The tool of the present invention is obtained, for example, by a powder laminating method. The powder lamination method is a kind of layered manufacturing method using powder (so-called three-dimensional modeling method, 3D printer method) or additive manufacturing method (AM: Additive Manufacturing). It may be a law. According to the powder sintering layered manufacturing method, the raw material powder of each layer is irradiated with a high energy beam as a heating source, and the raw material powder is sequentially sintered (including melt solidification) to obtain a modeled product. can get. According to the powder-fixed laminated molding method, an adhesive (ink) is sequentially sprayed onto the raw material powder of each layer, and the raw material powder is sequentially bound to obtain a modeled product.

The powder sintering laminated molding method may be a powder bed fusion method (PBF) or a directed energy deposition method (DED). The PBF scans a high-energy beam (laser, electron beam, etc.) in a predetermined path every time a thin layer of the raw material powder is laid, and melts and solidifies the raw material powder. By repeating this, a modeled product (bulk body) having a desired shape can be obtained. In DED, the raw material powder projected near the focal point of the high energy beam is melt-coagulated, and the melt-coagulation position is scanned (moved) to obtain a model having a desired shape.

In the powder laminating method, raw material powders made of various materials (metals, resins, compounds, etc.) can be used. A typical example is metal powder (steel powder, cemented carbide powder, etc.).

Multiple types of shanks (cutting tools) were manufactured, and their vibration damping properties (surface roughness of the machined surface) were evaluated. The present invention will be described in more detail below with reference to such specific examples.

<< First form / Sample 1 >>
(1) Basic Form Shank 1, which is an example of a form of a cutting tool, is shown in FIGS. 1A and 1B (both are collectively referred to as “FIG. 1”). FIG. 1A is a vertical cross section in the axial direction and an AA cross section (cross section) shown in the vertical cross section. FIG. 1B is a front view showing only the spiral body 102 integrally formed in the hollow portion 101, as will be described later.

The shank 1 is an elongated substantially columnar shape, and is located on the shaft portion 10, the holder portion 11 on the tip end side (one end side, right side of FIG. 1A), and the root side (other end side, left side of FIG. 1A). It has a grip portion 12.

The holder portion 11 has a head 111 for holding a throw-away tip c (simply referred to as “tip c”), which is a cutting tool, and a bolt (screw) for fixing the tip c to the head 111 on the tip side thereof. It has an internal thread 112 (threaded portion) to be screwed.

The grip portion 12 has a columnar shape and is clamped to a collet chuck (simply referred to as "chuck") of a machine tool.

The tip c is attached to the holder portion 11 and the grip portion 12 is attached to the machine tool. When the machine tool is operated, the insert c is rotated through the shank 1 and the workpiece is milled. When the grip portion 12 is mounted on the chuck, the distance (L) from the tip surface of the chuck to the tip of the holder portion 11 (or the cutting edge of the tip c) is the protrusion length. The distance (L) and the outer diameter of the shaft portion 10 (shank diameter: D) define L / D as a guideline for the occurrence of chatter vibration.

By the way, the shank 1 has a substantially drop-shaped hollow portion 101 and a spiral body 102 in the shaft portion 10. A substantially spiral space k (encapsulation space) is formed in a region (void) excluding the spiral body 102 from the hollow portion 101. The space k is filled with the powder p.

The hollow portion 101 and the spiral body 102 are composed of an axially short conical tip portion and a long conical main portion that gradually narrows toward the root side. That is, the main portion has a large-diameter circular cross section on the tip side and a small-diameter circular cross section on the root side.

The spiral body 102 has a double spiral shape having the spiral body 1021 and the spiral body 1022. The shank 1 rotates counterclockwise during cutting when viewed from the tip side. Therefore, the spiral body 102 also has a shape in which the lead advances from the tip side to the root side along the counterclockwise direction like a left-handed screw.

Both the spiral body 1021 and the spiral body 1022 are formed by spirally winding a curved surface convex toward the tip end side. In FIG. 1B, only the spiral body 102 is extracted and shown. However, in reality, the outer peripheral surface 1021a of the spiral body 1021 and the outer peripheral surface 1022a of the spiral body 1022 are integrated with the shaft portion 10. The spiral body 1021 and the spiral body 1022 form a continuous space extending in the axial direction near the center of the axis. The envelope surface of the outer peripheral surface 1021a and the outer peripheral surface 1022a may be considered as a virtual boundary surface of the hollow portion 101. Incidentally, the specific form of the spiral body 102 is set so as to obtain a desired vibration damping property in consideration of the type (material, particle size, etc.) of the powder p, the rotation speed range of the shank 1, and the like.

(2) Modification 1
The wing portion 52, which is a modified example of the spiral body 102, is shown in FIG. 2A. The wing portion 52 is composed of a spiral group 521 composed of spiral pieces (blades) obtained by dividing the spiral body 1021 at predetermined intervals, and a spiral group 522 composed of spiral pieces obtained by dividing the spiral body 1022 at predetermined intervals. In this case, the powder p is also filled in the gap (a part of the inclusion space) between the adjacent spiral pieces.

(3) Modification 2
Shank 6 and shank 7, which are variants of shank 1, are shown in FIG. 2B. The same parts as those described above are designated by the same reference numerals, and their explanations are omitted (the same applies hereinafter).

The shank 6 has a hollow portion 601 and a spiral body 602 in the shaft portion 10. The spiral body 602 has a single spiral shape. Like the shank 1, the shank 6 rotates counterclockwise during cutting when viewed from the tip side. Therefore, the spiral body 602 also has a shape in which the lead advances from the tip side to the root side along the counterclockwise direction like a left-handed screw.

The shank 7 has a hollow portion 701 and a spiral body 702 in the shaft portion 10. The spiral body 702 is also a single spiral. The shank 7 has a rotation direction opposite to that of the shank 1, and rotates clockwise when viewed from the tip side. Therefore, the spiral body 702 also has a shape in which the lead advances from the tip side to the root side along the clockwise direction like a right-handed screw.

<< Second form / Sample 2 >>
A shank 2 which is another example of the form of the cutting tool is shown in FIG. FIG. 3 shows a vertical cross section in the axial direction and a BB cross section (cross section) shown in the vertical cross section. The shank 2 is a form in which the spiral body 102 is removed from the shank 1. That is, the shank 2 includes a drop-shaped hollow portion 201 in the shaft portion 10, and the hollow portion 201 is filled with only powder p.

《Cutting test》
The shanks of the three samples shown in FIG. 4 were prepared. Using the shank of each sample, the processing shown in FIG. 5 was performed. For each sample, the surface roughness when the depth of cut is changed is shown in FIGS. 6A to 6C (collectively referred to as “FIG. 6”). The test conditions were as follows.

(1) Sample Sample 1 and sample 2 correspond to the above-mentioned shank 1 and shank 2. Sample C1 is a medium substance having no hollow portion in the shaft portion. Each sample was manufactured by the powder lamination method (PBF) based on the shape (shank diameter: φ19.5 mm (D) × total length 160 mm) of a commercially available shank (ARPF20S20 manufactured by Mitsubishi Hitachi Tool Co., Ltd.).

PBF was carried out using a so-called 3D printer (SLM280HL manufactured by SLM Solutions). As the raw material powder, a commercially available H13 powder (component composition: equivalent to JIS SKD61, particle size: 10 to 45 μm) was used. In this case, the filling rate of the powder in the hollow portion was about 60%.

(2) Processing A cutting tool (ZCFW200-R2.0-PTH08M manufactured by Mitsubishi Hitachi Tool Co., Ltd.) was attached to the shank tip side (holder part) of each sample. After that, each shank was set in a machining center (VERTEX550-5X manufactured by Mitsui Seiki Co., Ltd.). At this time, each shank root side (grip portion) was clamped to the collet chuck so that L / D (protrusion length / shank diameter) = 6.

Using these, the end face of the work (made of pre-hardened steel (NAK55) / width 40 mm x thickness 5 mm) installed on the cutting power meter (9257A manufactured by Nippon Kistler Co., Ltd.) was side-processed. The cutting process was a downcut with a rotation speed of 4600 rpm and a feed of 0.2 mm / rev for one blade. The depth of cut at this time was set to 4 levels (0.20 mm, 0.25 mm, 0.30 mm, 0.35 mm).

(3) Measurement
The surface roughness of each machined surface was measured with a small surface roughness measuring machine (SJ-310 (0.75mN type) manufactured by Mitutoyo Co., Ltd.). The measurement was performed near the center of the end face (width 40 mm x thickness 5 mm) of the work. The surface roughness was measured according to the JIS standard (B 0601: 2001), and the maximum height (Rz / μm) when the measurement length was 4.8 mm. The measurement was carried out by changing the depth of cut for each shank of each sample. Processing and surface roughness measurement were repeated 3 times for each condition (n = 3).

"evaluation"
The following can be seen from FIG. 6 showing the measurement results. In FIG. 6, the dot-shaped marker indicates the arithmetic mean value (n = 3) of the surface roughness (Rz), and the linear (I-type) marker indicates the variation range of the surface roughness.

First, as is clear from FIG. 6C, when the solid shank according to the sample C1 is used, when the depth of cut exceeds 0.25 mm and further becomes 0.3 mm or more, chatter vibration occurs and the surface roughness of the machined surface becomes rough. Has deteriorated significantly. For example, the surface roughness when the cutting amount is 0.2 mm is about 2.6 times the surface roughness when the cutting amount is 0.3 mm, and the surface roughness when the cutting amount is 0.35 mm is about 2.6 times. It increased by about 4.2 times.

On the other hand, as is clear from FIGS. 6A and 6B, when the shanks related to Samples 1 and 2 were used, chatter vibration hardly occurred even if the depth of cut increased, and the surface roughness was good. .. Specifically, their surface roughness was at the same level as the theoretical finished surface roughness (Rz): 0.5 μm under the present processing conditions.

Looking at the variation width of the surface roughness, it was sample 1: 0.05 to 0.21 μm, sample 2: 0.23 to 0.52 μm, and sample C 1: 0.29 to 0.75 μm. Therefore, it was found that the shanks of Sample 1 and Sample 2 are also excellent in processing stability. In particular, when a shank having a spiral body (wing portion) capable of pumping the contained powder to the cutting tool side as in sample 1 is used, the chattering vibration of the cutting tool is suppressed and the desired surface roughness is stably secured for cutting. It became clear that processing is possible.

From the above, it was confirmed that the cutting tool of the present invention exhibits high vibration damping properties and enables high-precision (including surface roughness) machining even in a high L / D range.

1 Shank (cutting tool)
10 Shaft part 11 Holder part 12 Grip part 101 Hollow part 102 Spiral body (wing part)
k comprehension space p powder

Claims (6)

A cutting tool consisting of a shank that rotates with respect to a fixed workpiece.
The shank is
A holder part that can hold a cutting tool for cutting the work on one end side,
A gripping part that can be gripped by the machine tool on the other end side,
The shaft portion between the holder portion and the grip portion,
A hollow portion that forms an inclusion space in the shaft portion,
A wing portion that rotates with the shaft portion in the shaft portion and sends the fluid filled in the inclusion space to the one end side.
Cutting tool with. The cutting tool according to claim 1, wherein at least a part of the wing portion is a continuous spiral body. The cutting tool according to claim 1, wherein at least a part of the wing portion is a divided blade. The cutting tool according to any one of claims 1 to 3, wherein at least a part of the wing portion is integrally formed with the shaft portion. The cutting according to any one of claims 1 to 4, wherein the wing portion is formed along a spiral trajectory traveling from the one end side to the other end side around the rotation direction at the time of cutting when viewed from the one end side. Tools. The cutting tool according to any one of claims 1 to 5, wherein the wing portion is formed along a plurality of trajectories.

Images