JP2022001385A - Tool holding structure, load detection structure, and tool state monitoring system - Google Patents

Abstract

To provide a tool holding structure that has both a function of holding a rod-like tool and a function of detecting a thrust load placed on the rod-like tool, and can supply cutting oil to the held rod-like tool.SOLUTION: A tool holding structure that holds a rod-like tool and also detects a thrust load placed on the rod-like tool comprises: a cylindrical main body part such that the rod-like tool is inserted into an opening on one end side; a tool clamping part which clamps the rod-like tool inserted into the opening of the main body part; a strain inducer which is arranged inside the cylindrical main body part more on the other end side than the opening of the cylindrical main body part; a strain gauge which is fitted to the strain inducer; and a supply path which is provided inside the cylindrical main body part, and supplies cutting oil to the rod-like tool. The tool holding structure holds the rod-like tool in contact with the strain inducer so as to detect the thrust load.SELECTED DRAWING: Figure 7

Description

The present invention relates to a tool holding structure, a load detecting structure, and a tool condition monitoring system.

Drilling into a workpiece using a drill blade is widely performed. When machining a workpiece using a drill blade, the drill blade is rotated in a milling machine, machining center, hand drill, or the like. On the other hand, in a lathe or the like, a drill blade is used as a fixing tool to rotate a workpiece.

It is known to detect cutting resistance when machining a workpiece using a drill bit. Patent Document 1 discloses a hand drill including a thrust indicator assembly for displaying a drilling thrust.

Special Table 2014-530119

When a rod-shaped tool such as a drill blade is used as a fixing tool in a lathe or the like, a structure capable of detecting the thrust load applied to the rod-shaped tool is required. The thrust indicator assembly described in Patent Document 1 is an assembly applied when a drill blade is used as a rotary tool, and has a complicated structure. Therefore, it cannot be said that it is appropriate to divert it.

The present invention has a tool holding structure capable of supplying cutting oil to a rod-shaped tool that has both a function of holding a rod-shaped tool such as a drill blade and a function of detecting a thrust load applied to the rod-shaped tool, and a tool holding structure. It is an object of the present invention to provide a load detection structure used in the above and a tool condition monitoring system including the tool holding structure.

According to the first aspect of the present invention,
It is a tool holding structure that holds a rod-shaped tool and detects the thrust load applied to the rod-shaped tool.
A cylindrical main body into which the rod-shaped tool is inserted into the opening on one end side, and
A tool holding portion for holding the rod-shaped tool inserted into the opening of the main body portion, and a tool holding portion.
A strain-causing body arranged inside the tubular main body on the other end side of the opening of the tubular main body.
The strain gauge attached to the strain-causing body and
It is provided inside the cylindrical main body and is provided with a supply path for supplying cutting oil to the rod-shaped tool.
A tool holding structure is provided in which the rod-shaped tool is brought into contact with and held by the strain-causing body in order to detect the thrust load.

In the tool holding structure of the first aspect, the strain-causing body may be arranged on the shaft of the tubular main body portion, and the rod-shaped tool may be arranged on the shaft of the tubular main body portion. The space between the inner peripheral surface of the tubular main body and the outer edge of the strain-causing body may form a part of the supply path.

The tool holding structure of the first aspect may further include a strain-causing body support portion that supports the strain-causing body on the other end side of the strain-causing body of the tubular main body portion, and the strain-causing body may be further provided. The support portion may support the outer edge of the strain-causing body so that a closed space is formed between the strain-causing body and the strain-causing body support portion, and the strain gauge is arranged in the closed space. It may have been done.

The tool holding structure of the first aspect is a long position adjusting portion, and the cylinder is inside the cylindrical main body at the other end side of the strain-causing body of the tubular main body. A position adjusting portion which is arranged along the axis of the main body portion and is movable in the axial direction integrally with the strain-causing body may be further provided.

In the tool holding structure of the first aspect, the position adjusting portion may be arranged on the axis of the cylindrical main body portion, and the inner peripheral surface of the tubular main body portion and the outer peripheral surface of the position adjusting portion. The space between and may form a part of the supply path.

In the tool holding structure of the first aspect, the position adjusting portion includes a male screw formed on at least a part of the outer peripheral surface of the position adjusting portion, and one side and the other side of the male screw in the longitudinal direction of the position adjusting portion. The male screw of the position adjusting portion may be screwed into the female screw formed on the inner peripheral surface of the tubular main body portion.

In the tool holding structure of the first aspect, the outer diameter of the position adjusting portion in the region where the male screw is formed may be larger than the outer diameter in the other region of the position adjusting portion.

The tool holding structure of the first aspect is attached to the strain-causing body support portion that supports the strain-causing body on the other end side of the strain-causing body of the tubular main body portion and the strain-causing body support portion. A strain gauge for compensation and a long position adjusting portion, wherein the tubular main body is inside the tubular main body on the other end side of the strain-causing body of the tubular main body. The strain-causing body support portion may be further provided with a position adjusting portion which is arranged along the axis of the portion and is movable in the axial direction integrally with the strain-causing body. The outer edge of the strain-causing body may be supported so that a closed space is formed between the strain-causing body support portion, and the position adjusting portion is formed by the strain-causing body support portion and the position adjusting portion. The outer edge of the strain-causing body support portion may be supported so that a closed space is formed between the strain gauges, and the strain gauge is arranged in the closed space between the strain-causing body and the strain-causing body support portion. The compensating strain gauge may be arranged in a closed space between the strain-causing body support portion and the position adjusting portion.

The tool holding structure of the first aspect may be further provided with a flow path bolt attached to the opening on the other end side of the main body portion and having an oil supply port for supplying cutting oil to the supply path. The position adjusting portion may penetrate the bolt with a flow path and project to the rear of the main body portion.

In the tool holding structure of the first aspect, the strain-causing body may have a film-like strain-causing portion, and the strain gauge may be attached to the strain-causing portion.

In the tool holding structure of the first aspect, the strain-causing body may have a protrusion protruding from the film-like strain-raising portion toward the one end side of the main body portion, and the tool holding structure may have the above-mentioned tool holding structure. The rod-shaped tool may be held in a state where the rod-shaped tool is in contact with the protrusion.

In the tool holding structure of the first aspect, the tool holding portion may be a holding member separate from the main body portion, which is fitted into one end of the main body portion to hold the rod-shaped tool.

In the tool holding structure of the first aspect, the holding member may be a collet.

According to the second aspect of the present invention,
It is a tool holding structure that holds a rod-shaped tool and detects the thrust load applied to the rod-shaped tool. A load detection structure used in a tool holding structure including a tool holding portion for holding the inserted rod-shaped tool.
On the other end side of the opening of the cylindrical main body, a strain-causing body arranged inside the tubular main body and with which the rod-shaped tool is abutted.
A strain gauge and a long-shaped position adjusting portion attached to the strain-causing body, at the other end of the tubular main body portion from the strain-generating body, inside the tubular main body portion. A position adjusting portion is provided along the axis of the cylindrical main body portion so as to be movable in the axial direction together with the strain-causing body.
A load detection that constitutes a supply path for supplying cutting oil to the rod-shaped tool between the inner peripheral surface of the tubular main body and the load detection structure in a state of being arranged inside the tubular main body. The structure is provided.

In the load detection structure of the second aspect, the position adjusting portion includes a male screw formed on at least a part of the outer peripheral surface of the position adjusting portion, and one side and the other side of the male screw in the longitudinal direction of the position adjusting portion. It may have a communication passage that communicates with.

In the load detection structure of the second aspect, the outer diameter of the position adjusting portion in the region where the male screw is formed may be larger than the outer diameter of the other region of the position adjusting portion.

According to the third aspect of the present invention,
The tool holding structure of the first aspect and
A tool condition monitoring system including a control unit for determining whether or not a rod-shaped tool needs to be replaced based on a detection result of a strain gauge of the tool holding structure is provided.

According to the present invention, a tool holding structure capable of supplying cutting oil to a rod-shaped tool having both a function of holding a rod-shaped tool such as a drill blade and a function of detecting a thrust load applied to the rod-shaped tool and capable of supplying cutting oil to the rod-shaped tool. A load detection structure used in a holding structure and a tool condition monitoring system including the tool holding structure are provided.

FIG. 1 is a perspective view of a tool holding structure according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of the tool holding structure according to the embodiment of the present invention. FIG. 3A is a cross-sectional view of the main body portion cut along a surface including the central axis of the main body portion. FIG. 3B is a cross-sectional view taken along the line IIIB-IIIB of FIG. 3A. FIG. 4 is a cross-sectional view of the refueling section cut along a surface including the central axis of the refueling section. FIG. 5A is a cross-sectional view of the position adjusting portion cut along a surface including the central axis of the position adjusting portion. 5 (b) is a cross-sectional view taken along the line VB-VB of FIG. 5 (a). FIG. 6 is a cross-sectional view of the load detection unit cut along a surface including the central axis of the load detection unit. FIG. 7 is a cross-sectional view of the tool holding structure according to the embodiment of the present invention cut along a surface including the central axis of the tool holding structure. FIG. 8 is a schematic view showing the configuration of a lathe to which a tool holding structure is attached. FIG. 9 is an explanatory diagram for explaining a supply flow path for cutting oil defined inside the tool holding structure. FIG. 10 is a cross-sectional view of the tool holding structure according to the modified example of the present invention cut along a surface including the central axis of the tool holding structure. FIG. 11 is a cross-sectional view of the tool holding structure according to another modification of the present invention cut along a surface including the central axis of the tool holding structure.

<Embodiment>
The tool holding structure 100 and the load detection structure 110 according to the embodiment of the present invention will be described as an example in which the drill blade is fixed to the lathe by using the tool holding structure 100 and the workpiece (workpiece) is turned. ..

As shown in FIGS. 1 and 2, the tool holding structure 100 has a long shape having a central axis X, and has a cylindrical main body portion 1, a refueling portion 2 attached to one end side of the main body portion 1, and a main body portion. It has a position adjusting unit 3 and a load detecting unit 4 arranged inside the body 1, and a tool holding unit 5 for sandwiching the drill D on the other end side of the main body 1.

In the following description, the extending direction of the central axis X is referred to as the axial direction of the tool holding structure 100, and the radial direction extending from the central axis X and the direction around the central axis X are the radial direction and the circumferential direction of the tool holding structure 100, respectively. Called. In the axial direction, the tool holding portion 5 side and the refueling portion 2 side of the main body portion 1 are referred to as front side and rear side, respectively.

The main body 1 is made of metal (for example, tool steel (for example, SK material)). The main body 1 has a cylindrical shape having a shaft (central shaft) A1 and has an inner hole 1h extending along the shaft A1 (FIGS. 2 and 3). The axis A1 of the main body 1 is equal to the central axis X of the tool holding structure 100.

The main body portion 1 includes a held region 11 and a front end region 12 in order from the rear side in the axial direction.

Three planes p1, p2, and p3 orthogonal to the radial direction of the main body 1 are formed on the outer peripheral surface OS 1 of the main body 1 in the held region 11 (FIG. 3 (b)). The normals of the planes p1 and p3 coincide with each other, and the normals of the planes p2 are orthogonal to the normals of the planes p1 and p3. The planes p1 and p3 face opposite to each other. The planes p1, p2, and p3 are rectangular in plan view, and extend over substantially the entire axial direction of the held region 11. The outer diameter of the main body 1 in the held region 11 is constant over substantially the entire axial direction, and may be, for example, about 10 mm to 40 mm, more preferably about 20 mm to 32 mm. It should be noted that the outer peripheral surface OS1 may only have at least one of the planes p1 to p3 formed, and the planes p1 to p3 may not be formed.

In the held region 11, the cross-sectional shape of the inner peripheral surface IS1 defining the inner hole 1h (the shape of the cross-section of the plane orthogonal to the axial direction) is circular over the entire axial direction.

In the held region 11, the inner peripheral surface IS1 includes the rear large diameter region IS1a, the small diameter region IS1b, and the front large diameter region IS1c in this order from the rear side in the axial direction. The rear large diameter region IS1a and the small diameter region IS1b, and the small diameter region IS1b and the front large diameter region IS1c are connected in a tapered shape.

The diameter of the inner hole 1h defined by the rear large diameter region IS1a may be, for example, about 10 mm to 15 mm. A female screw FS is formed in a region near the rear end of the rear large diameter region IS1a.

The diameter of the inner hole 1h defined by the small diameter region IS1b is smaller than the diameter of the inner hole 1h defined by the rear large diameter region IS1a, and may be, for example, about 8 mm to 13 mm. A female screw FS is formed in the small diameter region IS1b over the entire area in the axial direction.

The diameter of the inner hole 1h defined by the front large diameter region IS1c is larger than the diameter of the inner hole 1h defined by the small diameter region IS1b, and as an example, the diameter of the inner hole 1h defined by the rear large diameter region IS1a. Can be the same as.

A male screw MS is formed on the outer peripheral surface OS1 of the main body 1 in the front end region 12.

In the front end region 12, the cross-sectional shape of the inner peripheral surface IS1 defining the inner hole 1h (the shape of the cross-section of the plane orthogonal to the axial direction) is circular over the entire axial direction. The inner peripheral surface IS1 of the main body 1 in the front end region 12 is formed in a tapered shape that expands toward the front side in the axial direction. That is, in the front end region 12, the diameter of the inner hole 1h is the smallest at the rear end and gradually increases toward the front side.

As shown in FIGS. 1 and 3A, in the present embodiment, a flange F is formed on the outer peripheral surface OS1 of the main body 1 so as to straddle the held region 11 and the front end region 12.

The refueling unit 2 is a portion that provides a refueling port for supplying cutting oil to the inner hole 1h of the main body portion 1.

As shown in FIGS. 1 and 2, the refueling unit 2 includes a flow path bolt 21 attached to the rear end portion of the main body portion 1 and a hose joint 22 attached to the flow path bolt 21.

As shown in FIG. 4, the bolt 21 with a flow path is a bolt having a shaft (central shaft) A2, and includes a head portion 21H and a shaft portion 21A extending forward along the shaft A2 from the head head 21H.

The head 21H has a hexagonal columnar shape. The head 21H connects the inner holes 21h1 and 21h2 extending along the axis A2, the screw holes th recessed on the outer peripheral surface of the head 21H, and the inner holes 21h2 extending in the radial direction and the screw holes th. A connecting hole ch is formed. The head 21H has a hexagonal columnar shape in the present embodiment, but is not limited to this, and may have an arbitrary shape such as a cylindrical shape.

The inner hole 21h2 is located in front of the inner hole 21h1 and has a larger diameter than the inner hole 21h1. The diameter of the inner hole 21h1 may be about 4 mm to 8 mm as an example, and the diameter of the inner hole 21h2 may be about 6 mm to 10 mm as an example. The inner hole 21h1 and the inner hole 21h2 communicate with each other to form a through hole that penetrates the head portion 21H in the axial direction. _{A groove G 21} is formed on the peripheral surface defining the inner hole 21h1 over the entire area in the circumferential direction.

The communication hole ch communicates with the inner hole 21h2 in the vicinity of the connection portion between the inner hole 21h1 and the inner hole 21h2.

The shaft portion 21A has a cylindrical shape. A male screw MS is formed on the outer peripheral surface of the shaft portion 21A. An inner hole 21h3 extending along the shaft A2 is formed in the center of the shaft portion 21A. The inner hole 21h3 communicates with the inner hole 21h2 of the head 21H. The diameter of the inner hole 21h2 and the diameter of the inner hole 21h3 can be the same.

The hose joint 22 (FIGS. 1 and 2) has a cylindrical shape having a through hole 22h, and has a hose connection portion 221, a hexagonal portion 222, and a male screw portion 223 along the axial direction. As the hose joint 22, for example, a commercially available bamboo shoot joint or a general hole / pipe inlet can be used.

The hose joint 22 is connected to the flow path bolt 21 by screwing the male threaded portion 223 into the screw hole th of the head portion 21H of the flow path bolt 21.

As shown in FIG. 7, the refueling unit 2 screwes the male screw MS of the shaft portion 21A of the flow path bolt 21 into the female screw FS formed in the rear small diameter region IS1a of the inner peripheral surface IS1 of the main body portion 1. It is attached to the rear end of the main body 1. In this state, the shaft A2 of the flow path bolt 21 coincides with the shaft A1 of the main body 1. Further, an annular gasket GK is sandwiched between the rear end surface of the main body 1 and the front surface of the head portion 21H of the flow path bolt 21 in close contact with these surfaces. This prevents the cutting oil from leaking when the cutting oil is poured inside the tool holding structure 100 (details will be described later).

The position adjusting unit 3 (FIG. 5) supports the load detecting unit 4 (details will be described later) from behind, and moves in the axial direction integrally with the load detecting unit 4 to adjust the axial position of the load detecting unit 4. It is a member.

The position adjusting portion 3 is a substantially cylindrical member made of a metal such as carbon steel (SC material as an example) or stainless steel, and has an inner hole 3h extending along a shaft (central shaft) A3. The position adjusting unit 3 includes the rear end region 31, the extending region 32, the large diameter region 33, and the support region 34 in order from the rear end side in the axial direction.

As shown in FIGS. 1 and 2, a D-cut portion DC is formed in the rear end region 31, and the D-cut surface DCs extend in a plane parallel to the axis A3 (FIG. 1). In addition, another D-cut surface parallel to the D-cut surface DCs may be further provided on the D-cut portion DC. In this case, the position adjusting unit 3 can be rotated by sandwiching the two D-cut surfaces with a spanner or the like.

The outer diameter of the position adjusting portion 3 in the extending region 32 is larger than the outer diameter of the position adjusting portion 3 in the rear end region 31, and may be about 4 mm to 8 mm as an example.

The outer diameter of the position adjusting portion 3 in the large diameter region 33 is larger than the outer diameter of the position adjusting portion 3 in the extending region 32, and may be about 8 mm to 13 mm as an example. The vicinity of the rear end of the large diameter region 33 has a tapered diameter and is connected to the extending region 32. Similarly, the vicinity of the front end of the large diameter region 33 has a tapered diameter and is connected to the support region 34.

In the large diameter region 33, a male screw MS is formed on the outer peripheral surface OS 3 of the position adjusting portion 3. Further, in the large diameter region 33, grooves (continuous passages) G ₃₃ extending in the axial direction are formed at three locations in the circumferential direction of the outer peripheral surface OS 3. The grooves G ₃₃ extend over the entire area of the large diameter region 33 in the axial direction, and are open to the front side and the rear side of the large diameter region 33, respectively. In the present embodiment, the three grooves G ₃₃ are provided at equal intervals in the circumferential direction, but the present invention is not limited to this. The number and arrangement of the grooves G _{33 may be changed as appropriate.}

The outer diameter of the position adjusting portion 3 in the support region 34 is smaller than the outer diameter of the position adjusting portion 3 in the large diameter region 33, and may be about 6 mm to 12 mm as an example. A recess R3 is formed in a region near the front end of the support region 34. The concave portion R3 is a concave hole having a circular cross section formed in the central portion of the front end surface 3fs of the position adjusting portion 3, and the depth thereof is about 1 / of the axial length of the support region 34 in the present embodiment. It is about 2. The front end of the inner hole 3h is open on the bottom surface of the recess R3.

_{The inner hole 3h is a passage for passing the wirings W 42} and W ₄₄ (FIG. 7) extending from the load detection unit 4, and may have an arbitrary diameter.

As shown in FIG. 7, the position adjusting portion 3 is inserted into the inner hole 1h of the main body portion 1 coaxially with the main body portion 1. In this state, the male screw MS of the outer peripheral surface OS3 in the large diameter region 33 is screwed into the female screw FS of the small diameter region IS1b of the inner peripheral surface IS1 of the main body 1. Further, the extending region 32 penetrates the inner holes 21h1 to 21h3 of the flow path bolt 21 of the refueling unit 2, and the rear end region 31 projects to the rear of the main body portion 1 and the refueling unit 2.

An O-ring OR is arranged in _{the groove G 21} provided in the inner hole 21h1 of the flow path bolt 21. The O-ring OR is in close contact with the outer peripheral surface OS3 of the extending portion 32 of the position adjusting portion 3 penetrating the inner hole 21h1. This prevents the cutting oil from leaking when the cutting oil is poured inside the tool holding structure 100 (details will be described later).

The load detection unit 4 is a diaphragm type load cell that detects a load (thrust load) applied to the drill blade D in the axial direction while the tool holding structure 100 holds the drill blade D.

As shown in FIG. 6, the load detection unit 4 includes a strain-causing body 41, a detection strain gauge 42 attached to the strain-causing body 41, a strain-causing body support unit 43 that supports the strain-causing body 41, and a riser. It has a compensating strain gauge 44 attached to the strain body support portion 43.

The strain-causing body 41 is made of a metal such as iron, stainless steel (SUS) or aluminum (aluminum alloy) as an example.

The strain-causing body 41 has a circular film-shaped strain-causing portion 411 that extends around the axis A4 in a plane orthogonal to the axis A4, and a protrusion 412 that protrudes from the central portion of the strain-causing portion 411 to one side in the axis A4 direction. A wall portion 413 that rises from the outer peripheral portion of the strain-causing portion 411 in the same direction as the protrusion 412, and a flange portion 414 that protrudes outward in the radial direction from the tip of the wall portion 413. The strain-causing portion 411, the protrusion portion 412, the wall portion 413, and the flange portion 414 may be integrally formed.

The outer diameter of the strain-causing portion 411 may be, for example, about 6 mm to 12 mm, and the thickness may be, for example, about 0.5 mm to 2 mm. Since the strain-causing portion 411 is in the form of a film, it is more easily deformed than other portions, and is easily deformed by being pushed in the direction of the axis A4 by the protrusion 412 to cause strain (details will be described later).

The protrusion 412 has a substantially conical shape, and the tip tp is rounded. The protrusion 412 is provided so that the central axis of the protrusion 412 coincides with the axis A4. The length of the protrusion 412 is not limited, but may be about 2 mm to 10 mm as an example. The diameter of the protrusion 412 may be about 1 to 4 mm at the connection with the strain-causing portion 411.

The wall portion 413 is provided in the entire circumferential direction of the strain generating portion 411. The inner surface 413i of the wall portion 413 is tilted with respect to the axis A4.

The flange portion 414 is provided in the entire circumferential direction of the wall portion 413.

The detection strain gauge 42 is attached to the surface of the strain generating portion 411 opposite to the surface on which the protrusion 412 is formed. The structure of the detection strain gauge 42 is arbitrary, but as an example, a strain gauge provided with four strain-sensitive elements may be used.

In the present embodiment, the detection strain gauge 42 is attached to the central portion of the strain generating portion 411.

In the present embodiment, the strain-causing body support portion 43 is made of the same material as the strain-causing body 41.

The strain-causing body support portion 43 is a substantially cylindrical member with the axis A4 as the central axis, and includes a large-diameter region 43L and a small-diameter region 43S arranged in the axis A4 direction. The outer diameter of the large diameter region 43L is the same as the outer diameter of the flange portion 414 of the strain generating portion 41, and is equal to the outer diameter of the support region 34 of the position adjusting portion 3. The outer diameter of the small diameter region 43S is smaller than the outer diameter of the large diameter region 43L. An annular stepped surface ss is defined at the connection portion between the large diameter region 43L and the small diameter region 43S.

In the large diameter region 43L of the strain-causing body support portion 43, a recess R4 extending from the end surface 43Ls in the axis A4 direction is formed. The cross-sectional shape of the recess R4 is circular.

An inner hole 43h extending along the shaft A4 is formed between the bottom surface of the recess R4 and the end surface 43Ss on the small diameter region 43S side of the strain generating body support portion 43. The inner hole 43h is a hole for _{passing the wiring W 42} (FIG. 7) extending from the detection strain gauge 42, and may have an arbitrary dimension.

As shown in FIG. 6, the strain-causing body 41 and the strain-causing body support portion 43 are tightly fitted by fitting the strain-causing portion 411 and the wall portion 413 of the strain-causing body 41 into the recess R4 of the strain-causing body support portion 43. It is integrally bonded by bonding. In a state where the strain-causing body 41 and the strain-causing body support portion 43 are coupled, the strain-causing body 41 and the strain-causing body support portion 43 are coaxial, and the strain-causing body is supported by the flange portion 414 of the strain-causing body 41. The end faces 43Ls of the portion 43 are in contact with each other.

In a state where the strain-causing body 41 and the strain-causing body support portion 43 are coupled, a closed space surrounded by the strain-causing body 41 and the strain-causing body support portion 43 is defined inside the recess R4, and the strain for detection is defined. The gauge 42 is arranged in the space. The depth of the recess R4 is designed so that the strain-causing portion 411 and the detection strain gauge 42 do not come into contact with the strain-causing body support portion 43 when the strain-causing body 41 is strained. As a result, the accuracy of load detection in the load detection unit 4 is maintained.

The compensating strain gauge 44 is attached to the end surface 43Ss on the small diameter region 43S side of the strain generating body support portion 43. The structure of the compensating strain gauge 44 is arbitrary, but the same strain gauge as the detection strain gauge 42 may be used.

As shown in FIG. 7, the load detection unit 4 couples the small diameter region 43S of the strain-causing body support portion 43 to the position adjustment portion 3 by a tight fitting coupling by fitting the small diameter region 43S of the support portion 34 of the position adjustment portion 3 into the recess R3. Has been done. In this state, the load detection unit 4 is arranged inside the inner hole 1h of the main body unit 1 with the shaft A4 aligned with the axis A1 of the main body unit 1.

_{The wiring W 42} extending from the detection strain gauge 42 extends to the rear end side of the tool holding structure 100 via the inner hole 43h of the strain generating body support portion 43 and the inner hole 3h of the position adjusting portion 3. _{The wiring W 44} extending from the compensating strain gauge 44 extends to the rear end side of the tool holding structure 100 via the inner hole 3h of the position adjusting portion 3.

The tool holding portion 5 (FIGS. 1 and 2) has a structure for holding the drill D.

The tool holding portion 5 is screwed into a collet CL that is fitted into the inner hole 1h at the front end of the main body portion 1 to hold the drill D and a male screw MS formed on the outer peripheral surface OS 1 of the front end region 12 of the main body portion 1. Includes a collet nut CN for fixing the position of the collet CL.

Collet CL is a general collet (collet chuck). That is, it is a substantially cylindrical shape having an inner hole CLh, has a plurality of slits S extending in the axial direction, and is configured to elastically deform and reduce the outer diameter and the inner diameter when receiving a radial inward force. ing. The diameter (grasping diameter) of the inner hole CLh can be, for example, about 0.5 mm to 13 mm. In the present invention, the "collet" is a cylindrical or substantially cylindrical member having an inner hole, having at least one slit extending in the axial direction, and being configured such that the outer diameter and the inner diameter are reduced by elastic deformation. Means.

The collet CL has a large diameter portion MX having the largest outer diameter in the vicinity of one end in the axial direction, and a first tapered region T1 in which the outer diameter becomes smaller toward the one end portion from the large diameter portion MX, and a large diameter. It has a second tapered region T2 whose outer diameter becomes smaller toward the other end from the portion MX. The taper angle of the second taper region T2 is smaller than the taper angle of the first taper region T1.

The collet nut CN is a general collet nut, and has a cylindrical main body MP and a lid LP (FIG. 7) provided at one end of the main body MP. A plurality of engaging grooves EG (FIGS. 1 and 2) for engaging the fastening tool are provided on the outer peripheral surface of the main body MP at equal intervals along the circumferential direction.

The inner peripheral surface of the main body MP is between a tapered region T3 (FIG. 7) whose inner diameter increases toward the other end from the end where the lid LP is provided, and between the tapered region T3 and the other end. Has a threaded region S1 of. The taper angle of the taper region T3 is substantially equal to the taper angle of the first taper region T1 of the collet CL. A female screw FS is formed in the screw region S1.

A circular through hole LPh (FIG. 7) is formed in the central portion of the lid portion LP. The diameter of the through hole LPh can be, for example, about 0.5 mm to 13 mm. As will be described later, since the cutting oil is ejected to the drill D through the through hole LPh, the smaller the through hole LPh is, the higher the speed is ejected.

As shown in FIG. 7, in the collet CL of the tool holding portion 5, the second tapered region T2 is the inner hole of the front end region 12 of the main body portion 1 in a state where the rear end region DR of the drill blade D is arranged in the inner hole CLh. It is fitted in 1h. Since the outer diameter of the large diameter portion MX is larger than the diameter of the inner hole 1h at the front end of the main body portion 1, the large diameter portion MX is located outside the main body portion 1 in the axial direction.

As shown in FIG. 7, in the female screw FS of the collet nut CN of the tool holding portion 5, the drill blade D penetrates the through hole LPh of the lid portion LP, and the outer peripheral surface of the first tapered region T1 of the collet CL is the tapered region T3. It is screwed into the male screw MS of the front end region 12 of the main body 1 in a state of being in contact with the inner peripheral surface.

In this state, if the collet nut CN is tightened, the collet CL is pushed backward and enters the inner hole 1h, and the diameter of the inner hole CLh of the collet CL becomes smaller. Therefore, the drill bit D is sandwiched by the collet CL and held by the tool holding structure 100. In this state, the central axis of the drill bit D coincides with the central axis X of the tool holding structure 100.

That is, in the tool holding structure 100, the drill blade D extends forward from the front end of the tool holding structure 100 along the central axis X, and the tip TP (FIG. 8) of the drill blade D is located in front of the tool holding structure 100. Holds the drill bit D.

If the collet nut CN is loosened, the collet CL can move forward, that is, in a direction in which the collet CL falls off from the inner hole 1h. Therefore, the diameter of the inner hole CLh of the collet CL becomes large, and the drill blade D can be removed.

Inside the tool holding structure 100 having the above-mentioned structure, the peripheral surface and the position defining the through hole 22h of the hose joint 22, the connection hole ch of the bolt 21 with a flow path, and the inner holes 21h2 and 21h3 of the bolt 21 with a flow path are defined. Space between the outer peripheral surface OS 3 of the adjusting unit 3 and space between the inner peripheral surface IS1 of the main body 1 and the outer peripheral surface OS 3 of the position adjusting unit 3 (female screw FS of the small diameter region IS2b and male screw MS of the large diameter region 33). The supply flow for cutting oil is provided by the groove G ₃₃ ), the space between the inner peripheral surface IS1 of the main body 1 and the outer edge of the load detection unit 4, and the slit S of the collet CL in the region where The road is constructed.

Of the tool holding structure 100 having the above-mentioned structure, the load detection unit 4 and the position adjustment unit 3 constitute the load detection structure 110 (FIG. 2) of the present embodiment.

Next, a method of using the tool holding structure 100 of the present embodiment will be described.

(1) Attaching the Drill Blade D to the Tool Holding Structure 100 When attaching the drill blade D to the tool holding structure 100, first, the position adjusting section 3 is rotated to move the position adjusting section 3 and the load detecting section 4 to the rear. Move it. Specifically, the tool is engaged with the D-cut portion DC of the rear end region 31 of the position adjusting portion 3 to rotate the position adjusting portion 3 around the axis A3. As a result, the position adjusting portion 3 in which the male screw MS of the large diameter portion 33 is screwed into the female screw FS of the inner peripheral surface IS1 of the main body portion 1 moves in the axial direction with respect to the main body portion 1.

Next, the collet nut CN of the tool holding portion 5 is loosened, and the rear end region DR of the drill blade D is inserted into the inner hole CLh of the collet CL via the through hole LPh of the collet nut CN.

After adjusting the axial position of the drill blade D to a desired position, the collet nut CN of the tool holding portion 5 is tightened, and the drill blade D is held by the collet CL. By adjusting the position of the drill blade D with the load detection unit 4 retracted rearward, the position of the drill blade D can be freely adjusted without being interfered by the load detection unit 4.

After determining the position of the drill blade D, the position adjusting unit 3 is rotated and moved in the axial direction to bring the load detection unit 4 into contact with the drill blade D. Specifically, on the axis A1 of the main body 1, the top tp of the protrusion 412 of the strain generating body 41 is brought into contact with the rear end surface Dbs of the drill blade D from the rear (FIG. 7).

(2) Attaching the Tool Holding Structure 100 to the Lathe 1000 Next, the tool holding structure 100 holding the drill blade D is attached to the lathe 1000.

As shown in FIG. 8, the lathe 1000 includes a base 300, a headstock 400 provided on one end side of the base 300, a spindle 500 rotatably supported by the headstock 400, and a bed 600 extending in the direction of the shaft 500X of the headstock 500. , Mainly has a tool post 700 that can be moved along the bed 600. The lathe 1000 further includes a control unit 810, a display unit 820, and a cutting oil tank 900 provided on the base 300.

The spindle 500 is driven by a motor (not shown) and can rotate at high speed around the shaft 500X. A workpiece (work) W is attached to the spindle 500 via a chuck (not shown).

The tool post 700 is slidably connected to the bed 600 at the lower end. Further, the tool base 700 has a holding hole 700h extending coaxially with the shaft 500X of the main shaft 500.

The tool holding structure 100 is attached to the tool base 700 of the lathe 1000. Specifically, the held region 11 of the main body 1 of the tool holding structure 100 is set so that the front end of the tool holding structure 100 faces the spindle 500, that is, the tip TP of the drill blade D faces the spindle 500. It is inserted into the holding hole 700h of the tool base 700.

After that, the tool holding structure 100 is fixed by passing a fixing bolt (not shown) through a through hole (not shown) penetrating the peripheral wall of the holding hole 700h. As a result, the tool holding structure is in a state where the central axis X of the tool holding structure 100 and the central axis of the drill blade D coincide with the central axis 500X of the spindle 500 and the tip TP of the drill blade D faces the spindle 500. 100 is attached to the lathe 1000. By pressing the tip of the fixing bolt against any of the flat surfaces p1 to p3 of the main body 1, the rotation of the tool holding structure 100 can be prevented.

_{Wiring W 42} and W ₄₄ extending from the detection strain gauge 42 and the compensation strain gauge 44 are connected to the control unit 810. Further, a refueling hose (not shown) extending from the cutting oil tank 900 is connected to the hose joint 22 of the refueling unit 2.

(3) Supply of cutting oil
During machining of the workpiece W using the drill blade D, the cutting oil of the cutting oil tank 900 is passed through the supply path for the cutting oil of the tool holding structure 100 to the drill blade D and the workpiece as follows. It is supplied to the contact point with the work piece W.

The cutting oil stored in the cutting oil tank 900 is sent to the refueling unit 2 via the refueling hose by a pump (not shown) arranged on the path of the refueling hose (not shown). The cutting oil sent to the oil supply unit 2 flows through the supply path for cutting oil configured inside the tool holding structure 100, and is sprayed on the contact point between the drill blade D and the workpiece W.

In the supply path for cutting oil, the cutting oil flows as follows (Fig. 9).

The cutting oil is flowed through the through hole 22h of the hose joint 22 and the connecting hole ch of the flow path bolt 21 to the inner holes 21h2 and 21h3 of the flow path bolt 21.

In the inner holes 21h2 and 21h3 of the bolt 21 with a flow path, the cutting oil is a cylindrical space SP1 between the inner peripheral surface defining the inner hole 21h2 and the outer peripheral surface OS3 in the extending region 32 of the position adjusting portion 3. Flows toward the front side in the axial direction. In the inner hole 21h3, the cutting oil directs the cylindrical space SP2 between the inner peripheral surface defining the inner hole 21h3 and the outer peripheral surface OS3 in the extending region 32 of the position adjusting portion 3 toward the front side in the axial direction. Flows.

After that, the cutting oil is applied to the cylindrical space SP3 between the rear large diameter region IS1a of the inner peripheral surface IS1 of the main body 1 and the outer peripheral surface OS3 in the extending region 32 of the position adjusting portion 3, and the main body 1. The cylindrical space SP4 between the small diameter region IS1b of the inner peripheral surface IS1 and the outer peripheral surface OS3 in the extending region 32 of the position adjusting portion 3 flows in this order toward the front side in the axial direction. In the region where the male screw MS of the large diameter region 33 of the position adjusting portion 3 is screwed into the female screw FS of the small diameter region IS1b of the inner peripheral surface IS1 of the main body portion 1, the cutting oil is the large diameter region 33 of the position adjusting portion 3. It flows to the front side of the large diameter region 33 through the three grooves G _{33 formed in.}

The cutting oil that has passed through the groove G ₃₃ is then discharged into a tubular space SP5 between the front large diameter region IS1c of the inner peripheral surface IS1 of the main body 1 and the outer peripheral surface OS3 in the support region 34 of the position adjusting portion 3. It flows through the tubular space SP6 between the large diameter region IS1c on the front side of the inner peripheral surface IS1 of the main body 1 and the load detection unit 4, and reaches the front side of the load detection unit 4. Then, it flows forward through the slit S of the collet CL, and is ejected toward the contact point between the drill blade D and the workpiece W through the through hole LPh of the lid LP of the collet nut CN.

That is, the cutting oil is formed around the load detection structure 110 including the position adjusting unit 3 and the load detecting unit 4 inside the inner holes 21h2 and 21h3 of the oil supply unit 2 and inside the inner hole 1h of the main body unit 1. It flows in the space toward the front side in the axial direction.

Here, the detection gauge 42 is sealed in a closed space surrounded by the strain-causing body 41 and the strain-causing body holding portion 43, and the compensation gauge 44 is sealed in a closed space surrounded by the strain-causing body holding portion 43 and the position adjusting portion 3. Since they are arranged in the space, the detection gauge 42 and the compensation gauge 44 do not come into contact with the cutting oil. The "sealed space" means a space that is sealed so as to prevent the inflow of cutting oil. Therefore, the space open to the external space where cutting oil does not exist is also included in the "closed space".

The cutting oil sprayed on the contact point between the drill blade D and the workpiece W may be collected in a drain tank (not shown), filtered by a filter, and returned to the cutting oil tank 900.

(4) Detection of cutting resistance (thrust load) using the tool holding structure 100 Machining of the workpiece W using the drill blade D and detection of the thrust load applied to the drill blade D during machining are as follows. To do.

Machining of the workpiece W (here, drilling) is performed by moving the tool base 700 toward the spindle 500 while rotating the spindle 500. As a result, the tip TP of the drill blade D held on the tool base 700 via the tool holding structure 100 is pushed into the workpiece W that rotates integrally with the spindle 500, and a hole is formed in the workpiece W. ..

When the tip TP of the drill blade D is pushed into the workpiece W, an axial load (thrust load) is applied to the drill blade D by the reaction force from the workpiece W. The magnitude of the thrust load is detected by the tool holding structure 100 as follows.

When a thrust load is applied to the drill blade D, the collet CL of the tool holding portion 5 that holds the drill blade D is slightly elastically deformed. As a result, the collet CL moves slightly backward in the axial direction, and the drill blade D also moves slightly backward in the axial direction of the tool holding structure 100.

The drill blade D that moves rearward in the axial direction of the tool holding structure 100 presses the protrusion 412 of the strain-causing body 41 that abuts on the rear end surface Dbs of the drill blade D rearward in the axial direction. Therefore, the central portion of the strain-causing portion 411 provided with the protrusion 412 is also pressed backward in the axial direction. As a result, the magnitude of the force that the protrusion 412 pushes against the strain-causing portion 411, which is in the form of a film that is easily deformed, and the magnitude of the thrust load applied to the drill blade D. Distortion occurs.

The detection strain gauge 42 attached to the strain-causing portion 411 changes the resistance value of the strain-sensitive element according to the magnitude of the strain generated in the strain-causing portion 411. The control unit 810 connected to the detection strain gauge 42 via the wiring W ₄₂ obtains the magnitude of the thrust load applied to the drill blade D based on the change in the resistance value, and displays it on the display unit 820.

The magnitude of the thrust load applied to the drill D during machining of the workpiece W may increase as the cutting edge of the drill D becomes chipped or dull, that is, as the state of the cutting edge deteriorates. Therefore, the control unit 810 may compare the obtained thrust load with a predetermined threshold value, and when the thrust load exceeds the predetermined threshold value, display information prompting the replacement of the drill D on the display unit 820.

In the manufacture of the tool holding structure 100 of the present embodiment, the main body portion 1 and the tool holding portion 5 may be provided by a commercially available collet holder. The main body of the collet holder provides the main body 1, and the collet and collet nut of the collet holder provide the tool holding portion 5.

In this case, the tool holding structure 100 of the present embodiment can be easily manufactured by inserting the load detection structure 110 of the present embodiment with a slight additional work on a commercially available collet holder.

The effects of this embodiment are summarized below.

In the tool holding structure 100 of the present embodiment, a supply path for supplying cutting oil to a tool such as a drill D is provided inside the main body 1. Therefore, the cutting oil can be easily and suitably supplied to the tool held by the tool holding structure 100.

In the tool holding structure 100 of the present embodiment, the load detecting unit 4 for detecting the cutting resistance (thrust load) is arranged inside the main body portion 1 to which the tool holding portion 5 for holding the drill blade D is attached. Has been done. Therefore, it has both a tool holding function and a thrust load detecting function, and has a simple structure.

In the tool holding structure 100 of the present embodiment, the strain-causing body 41 of the load detection unit 4 is arranged on the central axis of the main body unit 1, and a supply path for cutting oil is provided around the central axis. Therefore, while having a supply path for cutting oil, the thrust load of the drill blade D can be applied to the strain generating body 41 on the central axis of the main body 1 to maintain high measurement accuracy.

In the tool holding structure 100 of the present embodiment, the tool holding portion 5 holds the drill blade D by the collet CL. Therefore, it is possible to easily hold the drill blade D in a suitable state in which the central axis of the drill blade D coincides with the central axis of the tool holding structure 100.

The tool holding structure 100 and the load detection structure 110 of the present embodiment are configured such that the load detection unit 4 is movable in the axial direction and the position adjustment unit 3 adjusts the axial position of the load detection unit 4. .. Therefore, by changing the position of the load detection unit 4 according to the length of the drill blade D, the drill blade D having various dimensions can be held in a state where refueling is possible and the thrust load can be detected.

The load detection unit 4 of the tool holding structure 100 and the load detection structure 110 of the present embodiment includes a film-like strain-causing portion 411, and the amount of deformation of the strain-causing portion 411 according to the applied thrust load is relatively large. .. Therefore, even when the thrust load is small, the load detection using the detection strain gauge 42 can be performed with high accuracy.

In the tool holding structure 100 and the load detection structure 110 of the present embodiment, the strain-causing body 41 of the load detecting unit 4 has a protrusion 412 extending from the center of the strain-causing portion 411, and the strain-causing body 41 has a protrusion 412. , It is in contact with the drill blade D at the protrusion 412. In this way, instead of directly abutting the film-like strain-causing portion 411 and the drill blade D, the substantially rod-shaped protrusion 412 extending in the axial direction from the strain-causing portion 411 is brought into contact with the drill blade D. The strain-causing body 41 can be suitably brought into contact with a drill blade D having various shapes.

Specifically, for example, even when the drill blade D is short and the rear end surface Dbs of the drill blade D is located in front of the rear end of the collet CL of the tool holding portion 5, the protrusion 412 is used as the inner hole CLh of the collet CL. It can be inserted and brought into contact with the rear end surface Dbs of the drill blade D. Further, even when the diameter of the drill blade D is small and the inner hole CLh of the collet CL holding the drill blade D is also small, the protrusion 412 is inserted into the inner hole CLh of the collet CL and brought into contact with the rear end surface Dbs of the drill blade D. be able to.

In the tool holding structure 100 and the load detection structure 110 of the present embodiment, since the load detection unit 4 has the compensating strain gauge 44, the accuracy of load measurement is high. That is, by referring to the output of the compensating strain gauge 44 attached to the strain-causing body support portion 43, which is not deformed by the load from the drill blade D and only expands / contracts according to the ambient temperature change. , Temperature error can be suppressed at the time of load detection.

In the manufacture of the tool holding structure 100 of the present embodiment, a commercially available collet holder can be utilized to reduce the manufacturing cost and the manufacturing period.

<Modification example>
In the tool holding structure 100 of the above embodiment, the following deformation mode can also be used.

In the tool holding structure 100 of the above embodiment, the refueling unit 2 is attached to the rear end of the main body 1 and the cutting oil is refueled on the rear end side of the main body 1. However, it is not limited to this.

Specifically, for example, as in the tool holding structure 100'of the modified example shown in FIG. 10, cutting oil may be supplied on the front end side of the main body portion 1'. The differences between the tool holding structure 100'of the modified example and the tool holding structure 100 of the above embodiment are as follows.

In the modified tool holding structure 100'shown in FIG. 10, the inner peripheral surface IS1'of the main body 1'is not divided into a rear large diameter region IS1a, a small diameter region IS1b, and a front large diameter region IS1c. That is, the diameter of the inner hole 1h'defined by the inner peripheral surface IS1'is constant over the entire axial direction. On the other hand, a screw hole th'that penetrates the main body 1'in the radial direction is provided at the front end of the held region 11'of the main body 1', and a hose joint 22'is screwed into the screw hole th'. ..

In the tool holding structure 100'of the modified example, the bolt 21'with a flow path does not have the screw hole th and the communication hole ch, and the hose joint 22 is not connected. The flow path bolt 21'mainly functions to fix the radial position of the position adjusting portion 3'by the inner hole 21h1'.

In the tool holding structure 100'of the modified example, the large diameter region 33'and the support region 34'of the position adjusting portion 3'have substantially the same outer diameter. Further, although the male screw MS is cut in the large diameter region 33', the groove G ₃₃ is not formed. The male screw MS in the large diameter region 33'is screwed into the female screw FS formed on the inner peripheral surface IS1'of the main body 1', and the position adjusting portion 3'is rotated by rotating the position adjusting portion 3'. It can move in the axial direction.

In the tool holding structure 100'of the modified example, the outer diameter in the support area 34'of the position adjusting portion 3', the outer diameter of the flange portion 414' of the strain generating body 41'of the load detecting portion 4', and the strain generating body support. The outer diameter of the large diameter region 43L'of the portion 43'is substantially equal to the inner diameter of the main body portion 1'. Therefore, the support region 34'of the position adjusting portion 3'and the load detecting portion 4'are close to the inner peripheral surface IS1'of the main body portion 1'to the extent that they can be slidable.

In the tool holding structure 100'of the modified example, the cutting oil supplied through the hose joint 22'flows only in the space in the inner hole 1h', which is in front of the strain generating portion 411'of the load detecting portion 4. , It is ejected toward the drill D through the slit S of the collet CL. Further, even if the cutting oil leaks rearward through between the outer peripheral surface of the position adjusting unit 3 or the load detecting unit 4 and the inner peripheral surface IS1'of the main body 1, the inner hole of the bolt 21'with a flow path. The O-ring OR provided in the groove G _{21 of} 21h1'prevents the leakage of cutting oil to the outside of the tool holding structure 100'.

In the tool holding structure 100'of the modified example having the above-mentioned structure, the load detection unit 4'and the position adjusting unit 3'form the load detection structure 110' of the modified example.

As another modification, in the tool holding structure 100 of the above embodiment, the lubrication section 2 is replaced with the flow path bolt 21'of the above modification, and the hose joint 22'of the above modification is an arbitrary of the main body 1. At the position, the main body 1 may be screwed into a screw hole penetrating in the radial direction. When the position of the screw hole is in front of the small diameter region IS1b of the inner peripheral surface IS1, the groove G ₃₃ of the large diameter region 33 of the position adjusting portion 3 may be omitted.

In the tool holding structure 100 of the above embodiment, the female screw FS of the small diameter region IS1b of the inner peripheral surface IS1 of the main body 1 and the male screw MS of the large diameter portion 33 of the position adjusting portion 3 are screwed together. _{Cutting oil is circulated through the groove G 33} provided in the diameter portion 33, but the present invention is not limited to this.

Specifically, for example, a flow path (communication passage) that penetrates the large diameter portion 33 and communicates the front side and the rear side of the large diameter portion 33 is provided inside the large diameter portion 33, and the flow path is provided through the flow path. Cutting oil may be poured. Alternatively, the small diameter region IS1b of the inner peripheral surface IS1 may be provided with a groove extending in the axial direction and opening on the front side and the rear side of the small diameter region IS1b, and cutting oil may flow through the groove.

In the tool holding structure 100 and the load detection structure 110 of the above embodiment, the strain-causing body 41 of the load detection unit 4 does not have to have the protrusion 412. In this case, for example, the rear end surface Dbs of the drill blade D may be brought into direct contact with the strain generating portion 411. In the present invention, "the strain-causing body comes into contact with the rod-shaped tool" is not limited to the case where the strain-causing body and the rod-shaped tool come into direct contact with each other, but also some inclusions (in between the strain-causing body and the rod-shaped tool). It shall also include the case where there is a member that transmits the load).

In the tool holding structure 100 and the load detection structure 110 of the above-described embodiment, a column (cylinder) type strain-causing body 45 may be used instead of the strain-causing body 41 having the film-like strain-causing portion 411 (FIG. 11). ). In this case, for example, with the central axis of the strain generating body 45 aligned with the central axis of the main body 1, one end surface of the strain generating body 45 is brought into contact with the bottom surface of the recess R4, and the other end surface of the drill blade D is used. It is brought into contact with the rear end surface Dbs. The strain gauge 42 (not shown in FIG. 11) is attached to the outer peripheral surface of the strain-causing body 45 and is protected by covering it with an oil-resistant film or the like, if necessary. _{The wiring W 42} extending from the strain gauge 42 may be guided to the inner hole 43h through a groove formed on the bottom surface and the inner peripheral surface of the recess R4, for example. Also in this embodiment, the strain-causing body 45 abuts on the drill blade D on the axis A1 of the main body 1. In the present invention, when the strain-causing body and the drill blade (rod-shaped tool) abut on the shaft, the strain-causing body and the rod-shaped tool actually abut on the shaft, as well as the strain-causing body. It also includes a mode in which the rod-shaped tool abuts so that the center of gravity of the load applied from the rod-shaped tool to the strain-causing body is located on the axis.

In the tool holding structure 100 and the load detection structure 110 of the above-described embodiment, the strain-causing body 41 and the strain-causing body support portion 43 of the load detection unit 4 are formed of the same material, but the present invention is not limited to this. .. The strain-causing body support portion 43 can be formed of any material having a linear expansion coefficient equal to or similar to that of the material forming the strain-causing body 41. If the coefficient of linear expansion is the same or similar between the material forming the strain-causing body 41 and the material forming the strain-causing body support portion 43, the compensating strain gauge attached to the strain-causing body support portion 43 44 can fulfill the temperature error compensation function.

In the tool holding structure 100 and the load detection structure 110 of the above embodiment, the strain generating body holding portion 43 may be omitted and the strain generating body 41 may be held by the position adjusting portion 3.

In the tool holding structure 100 and the load detecting structure 110 of the above embodiment, the strain-causing body holding portion 43 and the compensating strain gauge 44 of the load detecting section 4 may be omitted. In this case, for example, the position adjusting unit 3 may be brought into contact with the strain generating body 41.

In the tool holding structure 100 and the load detection structure 110 of the above embodiment, the detection strain gauge 42 may be attached to an arbitrary position capable of fulfilling the load detection function, and the compensation strain gauge 44 may be attached to an arbitrary position capable of fulfilling the compensation function. It may be attached. When it comes into contact with cutting oil at the mounting position, it may be covered with an oil-resistant film or the like to protect it, if necessary.

In the tool holding structure 100 and the load detection structure 110 of the above embodiment, the wiring W ₄₂ extending from the detection strain gauge 42 and / or the wiring W ₄₄ extending from the compensation strain gauge 44 is omitted, and the detection signal is transmitted wirelessly. It may be configured. Further, in this case, the inner hole 3h of the position adjusting unit 3 and the inner hole 43h of the strain-causing body support portion 43 of the load detection unit 4 may be omitted.

In the tool holding structure 100 of the above embodiment, the load detection unit 4 may be fixed in position inside the main body unit 1. In this case, the position adjusting unit 3 and the movement restricting unit 4 may be omitted.

In the tool holding structure 100 of the above embodiment, the tool holding portion 5 has a collet nut CN and a collet CL having a tapered shape, but the present invention is not limited to this. The tool holding portion 5 fixes the drill blade D in the circumferential direction with a strength that does not cause rotation during turning, and in the axial direction, the drill blade D is fixed with a strength that allows minute movement. Can be pinched.

Specifically, for example, the collet CL does not have to have a tapered shape. Even with such a collet, the inner diameter is reduced by the tapered inner peripheral surface of the front end region 12 of the main body portion 1, and the drill blade D can be sandwiched.

Instead of the collet CL and the collet nut CN, the rear end region DR of the drill blade D is sandwiched by two or more wedge-shaped holding tools, and the wedge-shaped holding tool and the rear end region DR of the drill blade D are held. It may be fitted into the front end region 12 of the main body 1.

All or part of the tool holding portion 5 does not necessarily have to be a separate member from the main body portion 1. For example, the vicinity of the rear end of the drill blade D may be simply fitted to the front end side of the main body portion 1 and the drill blade D may be held by tightening. In this case, a key and a key groove may be provided on the main body 1 and the drill blade D to prevent the drill blade D from rotating in the circumferential direction. Further, a fixture for giving a key or a keyway to the drill blade D may be attached to the rear end region DR of the drill blade D. In this case, for example, a supply path for cutting oil may be provided inside the drill blade D.

In the above embodiment, the case where the drill bit D is fixed to the lathe 1000 has been described as an example, but the present invention is not limited to this. The tool holding structure 100 can hold an arbitrary rod-shaped tool as a stationary tool in a machine tool. In addition to drill blades, rod-shaped tools include, for example, taps and reamers.

A tool condition monitoring system may be configured by the tool holding structure of the above-described embodiment and the modified mode and the control unit 800 included in the lathe 1000. For example, this tool state monitoring system obtains the cutting resistance (thrust load) applied to the drill blade D based on the output of the detection strain gauge 42, and the drill blade is compared with the obtained cutting resistance and a predetermined threshold value. It is determined whether or not D needs to be replaced. Specifically, for example, when the obtained cutting resistance exceeds a predetermined threshold value, it is determined that the drill blade D needs to be replaced. The determination result may be displayed on any display unit.

Each of the above modifications can be applied in combination as long as they do not conflict with each other.

In the present invention and the present specification, the "cutting oil" includes various types that can be used in cutting, such as oil-based cutting oils and water-soluble cutting oils (cutting agents).

As long as the features of the present invention are maintained, the present invention is not limited to the above-described embodiment, and other embodiments considered within the scope of the technical idea of the present invention are also included within the scope of the present invention. ..

1 Main body, 2 Refueling unit, 3 Position adjustment unit, 4 Load detection unit, 5 Tool pinching unit, 21 Distortion body, 211 Distortion unit, 212 protrusion, 22 Detection strain gauge, 23 Distortion body holding unit, CL collet, CN collet nut, D drill bit, 1000 lathe

Claims (17)

It is a tool holding structure that holds a rod-shaped tool and detects the thrust load applied to the rod-shaped tool.
A cylindrical main body into which the rod-shaped tool is inserted into the opening on one end side, and
A tool holding portion for holding the rod-shaped tool inserted into the opening of the main body portion, and a tool holding portion.
A strain-causing body arranged inside the tubular main body on the other end side of the opening of the tubular main body.
The strain gauge attached to the strain-causing body and
It is provided inside the cylindrical main body and is provided with a supply path for supplying cutting oil to the rod-shaped tool.
A tool holding structure that holds the rod-shaped tool in contact with the strain-causing body in order to detect the thrust load. The strain-causing body is arranged on the axis of the cylindrical main body portion, and is arranged.
The rod-shaped tool abuts on the strain-causing body on the axis of the cylindrical main body portion, and the rod-shaped tool abuts on the strain-causing body.
The tool holding structure according to claim 1, wherein the space between the inner peripheral surface of the tubular main body and the outer edge of the strain-causing body constitutes a part of the supply path. Further, a strain-causing body support portion for supporting the strain-causing body is further provided on the other end side of the tubular main body portion with respect to the strain-causing body.
The strain-causing body support portion supports the outer edge of the strain-causing body so that a closed space is formed between the strain-causing body and the strain-causing body support portion.
The tool holding structure according to claim 1 or 2, wherein the strain gauge is arranged in the enclosed space. A long position adjusting portion, which is arranged inside the tubular main body along the axis of the tubular main body on the other end side of the strain-causing body of the tubular main body. The tool holding structure according to any one of claims 1 to 3, further comprising a position adjusting portion that is integrated with the strain-causing body and is movable in the axial direction. The position adjusting portion is arranged on the axis of the cylindrical main body portion.
The tool holding structure according to claim 4, wherein the space between the inner peripheral surface of the tubular main body portion and the outer peripheral surface of the position adjusting portion constitutes a part of the supply path. The position adjusting portion has a male screw formed on at least a part of the outer peripheral surface of the position adjusting portion, and a communication passage for communicating one side and the other side of the male screw in the longitudinal direction of the position adjusting portion. ,
The tool holding structure according to claim 4 or 5, wherein the male screw of the position adjusting portion is screwed into a female screw formed on the inner peripheral surface of the cylindrical main body portion. The tool holding structure according to claim 6, wherein the outer diameter of the position adjusting portion in the region where the male screw is formed is larger than the outer diameter in the other region of the position adjusting portion. A strain-causing body support portion that supports the strain-causing body on the other end side of the strain-causing body of the cylindrical main body, and a strain-causing body support portion.
Compensation strain gauge attached to the strain-causing body support,
A long position adjusting portion, which is arranged inside the tubular main body along the axis of the tubular main body on the other end side of the strain-causing body of the tubular main body. Further, a position adjusting unit that can move in the axial direction as a unit with the strain-causing body is further provided.
The strain-causing body support portion supports the outer edge of the strain-causing body so that a closed space is formed between the strain-causing body and the strain-causing body support portion.
The position adjusting portion supports the outer edge of the strain generating body support portion so that a closed space is formed between the strain generating body support portion and the position adjusting portion.
The strain gauge is arranged in a closed space between the strain-causing body and the strain-causing body support portion, and the compensating strain gauge is placed in the closed space between the strain-causing body support portion and the position adjusting portion. The tool holding structure according to claim 1 or 2 arranged in. Further provided with a bolt with a flow path attached to the opening on the other end side of the main body portion and having an oil supply port for supplying cutting oil to the supply path.
The tool holding structure according to any one of claims 4 to 8, wherein the position adjusting portion penetrates the bolt with a flow path and projects rearward of the main body portion. The tool holding structure according to any one of claims 1 to 9, wherein the strain-causing body has a film-like strain-causing portion, and the strain gauge is attached to the strain-causing portion. The strain-causing body has a protrusion protruding from the film-like strain-causing portion toward the one end side of the main body portion.
The tool holding structure according to claim 10, wherein the tool holding structure holds the rod-shaped tool in a state where the rod-shaped tool is in contact with the protrusion. The tool holding structure according to any one of claims 1 to 11, wherein the tool holding portion is fitted into one end of the main body portion to hold the rod-shaped tool, and is a holding member separate from the main body portion. .. The tool holding structure according to claim 12, wherein the holding member is a collet. It is a tool holding structure that holds a rod-shaped tool and detects the thrust load applied to the rod-shaped tool. A load detection structure used in a tool holding structure including a tool holding portion for holding the inserted rod-shaped tool.
On the other end side of the opening of the cylindrical main body, a strain-causing body arranged inside the tubular main body and with which the rod-shaped tool is abutted.
A strain gauge and a long-shaped position adjusting portion attached to the strain-causing body, at the other end of the tubular main body portion from the strain-generating body, inside the tubular main body portion. A position adjusting portion is provided along the axis of the cylindrical main body portion so as to be movable in the axial direction together with the strain-causing body.
A load detection that constitutes a supply path for supplying cutting oil to the rod-shaped tool between the inner peripheral surface of the tubular main body and the load detection structure in a state of being arranged inside the tubular main body. structure. The position adjusting portion has a claim having a male screw formed on at least a part of the outer peripheral surface of the position adjusting portion and a communication passage for communicating one side and the other side of the male screw in the longitudinal direction of the position adjusting portion. Item 14. The load detection structure according to item 14. The load detection structure according to claim 15, wherein the outer diameter of the position adjusting portion in the region where the male screw is formed is larger than the outer diameter of the other region of the position adjusting portion. The strain-causing body has a protrusion protruding from the film-like strain-causing portion toward the one end side of the main body portion.
The tool holding structure according to claim 10, wherein the tool holding structure holds the rod-shaped tool in a state where the rod-shaped tool is in contact with the protrusion.

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