Connection structure and tool holder

Abstract

To provide a tool holder and its connecting member capable of preventing decay of a coolant liquid, extending the life of a cutting tool, and efficiently removing chips adhering to a workpiece or tool. The connection structure (100C) includes a machine spindle (9C) having a first coolant supply passage (98C), a tool holder (1) having a second coolant supply passage (12), and a connection member (20C) having a third coolant supply passage. The connection member (20C) is provided in the third coolant supply passage and has a through hole extending in the axial direction. The connection member (20C) includes a fine bubble generating member (30) that generates fine bubbles in the coolant liquid within the through hole, and a retaining mechanism that prevents the fine bubble generating member (30) from falling out of the third coolant supply passage.

Description

[Technical Field]

[0001] The present invention relates to a connection structure and a tool holder, and more particularly to a connection structure and a tool holder that receive and hold the shank of a cutting tool and inject coolant onto the cutting edge of the cutting tool through a coolant supply passage extending in the axial direction. [Background technology]

[0002] Generally, machine tools machine workpieces while supplying large amounts of cutting fluid or cleaning fluid to the machining area to cool, lubricate, and remove chips from the workpieces and tools. When machining such workpieces, a tool holder is used that is configured to supply cutting fluid or cleaning fluid, such as coolant, from the spindle of the machine tool toward the cutting edge of the cutting tool. Examples of documents disclosing such technology include JP 2013-063483 A (Patent Document 1) and WO 2009 / 135660 A (Patent Document 2).

[0003] Patent Document 1 discloses that the holder body has a through hole extending axially from the machine tool spindle toward the cutting tool side, and that liquid is supplied to the through hole from the center-through coolant spindle to form a liquid passage.

[0004] Patent Document 2 discloses that a workpiece is machined while an oil mist generated by mixing oil and high-pressure air is supplied to a machining section. The document discloses that the working spindle and the chuck are provided with through-holes that penetrate in the axial direction, and that a connecting sleeve, a nozzle pipe, a connecting pipe, and an adapter sleeve that generate the oil mist are disposed in the through-holes. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-063483 [Patent Document 2] International Publication No. WO2009 / 135660 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the inventors have discovered that conventional tool holders still need to be improved. To meet the current demands for high-precision machining using machine tools, it is necessary to prevent the coolant from spoiling, extend the life of cutting tools, and efficiently remove chips that adhere to workpieces and tools.

[0007] The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a connection structure and tool holder that can prevent coolant from spoiling, extend the life of cutting tools, and efficiently remove chips and the like that adhere to workpieces and tools. [Means for solving the problem]

[0008] To this end, one embodiment of the present invention provides a connection structure comprising: a machine spindle having a first coolant supply passage extending in the axial direction; a tool holder that receives and holds the shank of a cutting tool and injects coolant onto the cutting edge of the cutting tool via a second coolant supply passage extending in the axial direction; and a connecting member that is disposed between the machine spindle and the tool holder and extends in the axial direction, and has a third coolant supply passage connecting the first coolant supply passage with the second coolant supply passage. The connecting member is provided with a fine bubble generating member that is provided within the third coolant supply passage and has a through hole that extends in the axial direction, and that generates fine bubbles in the coolant within the through hole; and a retaining mechanism that prevents the fine bubble generating member from falling out of the third coolant supply passage.

[0009] Preferably, the connecting member is a pull stud having one end fixed to the tool holder and the other end receiving a tensile force in the depth direction of the machine spindle, thereby fixing the tool holder to the machine spindle.

[0010] Preferably, the connecting member is a coolant pipe arranged between the machine spindle and the tool holder, with one end fixed to the tool holder and the other end connected to a first coolant supply passage provided in the machine spindle.

[0011] Preferably, the retaining mechanism includes a step portion that abuts against the tip end side of the fine bubble generating member, and a ring-shaped support portion that supports the rear end side of the fine bubble generating member.

[0012] Preferably, the through-hole of the fine bubble generating member extends spirally along the axial direction and has a cross-sectional shape with a narrowed radial center portion.

[0013] A tool holder according to another aspect of the present invention is a tool holder that receives and holds the shank of a cutting tool and injects coolant onto the cutting edge of the cutting tool through a coolant supply passage extending in the axial direction. The coolant supply passage has a through hole extending in the axial direction, and a fine bubble generating member that generates fine bubbles in the coolant is disposed in the through hole. [Effects of the Invention]

[0014] The connection structure and tool holder of the present invention can prevent the coolant from spoiling, extend the life of the cutting tool, and efficiently remove chips adhering to the workpiece or tool. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a cross-sectional view showing a tool holder according to a first embodiment of the present invention. [Figure 2] 2(B) is a front view of the fine bubble generating member; FIG. 2(C) is a cross-sectional view taken along line IIc-IIc in FIG. 2(B). [Figure 3] 1A and 1B are views showing a connecting member, in which (A) is a perspective view and (B) is a front view. [Figure 4] FIG. 2 is an enlarged view of a portion of FIG. [Figure 5] FIG. 3 is a cross-sectional view showing the flow of coolant in the tool holder according to the first embodiment of the present invention. [Figure 6] FIG. 10 is a cross-sectional view showing a tool holder according to a second embodiment of the present invention. [Figure 7] 7A and 7B are diagrams showing a connecting member, in which (A) is a plan view and (B) is a cross-sectional view taken along line VIIb-VIIb in FIG. 7A. [Figure 8] FIG. 10 is a cross-sectional view showing the flow of coolant in a tool holder according to a second embodiment of the present invention. [Figure 9] FIG. 10 is a cross-sectional view showing a tool holder according to a third embodiment of the present invention. [Figure 10] FIG. 10 is a cross-sectional view showing a part of a modified example of the connection structure. [Figure 11] 1A and 1B are diagrams showing a connecting member, in which (A) is a cross-sectional view and (B) is a left side view. [Figure 12] FIG. 10 is an enlarged cross-sectional view showing a mechanism for preventing a connection member from falling off. [Figure 13] FIG. 10 is a cross-sectional view showing a part of another modified example of the connection structure. [Figure 14] FIG. 4 is a cross-sectional view showing a connecting member. [Figure 15] FIG. 10 is an enlarged cross-sectional view showing a modified example of the mechanism for preventing the connection member from falling off. DETAILED DESCRIPTION OF THE INVENTION

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings, in which like reference numerals denote like or corresponding parts and will not be described repeatedly.

[0017] (Embodiment 1) A tool holder according to a first embodiment of the present invention will be described with reference to Figures 1 to 4. In Figure 1, the dashed dotted line O is an axis, the arrow T indicates the forward side in the axial direction (also referred to as the front end side or the tip side), and the opposite direction of the arrow T indicates the rear side in the axial direction (also referred to as the rear end side).

[0018] 1, the tool holder 1 receives and holds the shank of the cutting tool 50. The tool holder 1 injects coolant onto the cutting edge of the cutting tool 50 through a coolant supply passage extending in the axial direction.

[0019] Inside the holder body 10, a rear hole 11, a central hole 12, and a front hole 13 are formed, axially from rear to front. The rear hole 11 extends axially forward from the rear end of the holder body 10. The rear hole 11 has multiple steps, with its diameter being smallest at the front in the axial direction. A center through coolant pipe 20 is disposed at the tip side of the rear hole 11. The center through coolant pipe 20 will be described later.

[0020] The central hole 12 is connected to the front end of the rear hole 11 and extends forward in the axial direction. The inner diameter of the central hole 12 is approximately the same as or slightly smaller than the inner diameter of the rear hole 11 on the forward side in the axial direction. In the central hole 12, a fine bubble generating member 30 and a connecting member 40 are arranged in this order from the rear in the axial direction. The fine bubble generating member 30 and the connecting member 40 will be described later.

[0021] The front hole 13 is connected to the front end of the central hole 12 and extends forward in the axial direction. The front end of the rear hole 11, the central hole 12, and the front hole 13 have approximately the same inner diameter. The rear hole 11, the central hole 12, and the front hole 13 together form a through hole that extends from the front end to the rear end of the holder body 10.

[0022] A gripping flange 16 protruding outward is formed on the outer periphery of the holder body 10. The flange 16 is located in the axial center of the holder body 10, excluding the rear and front ends. A rear tapered shank 17, whose diameter decreases from the flange 16 toward the rear end, is formed in the axial rear end region of the holder body 10, including the rear end. The tool holder 1 is mounted to a spindle of a machine tool (not shown) using the rear tapered shank 17. A step is provided in the axial front end region of the holder body 10, including the front end, approximately in the center from the flange 16 toward the front end, and a front tapered shank 18, whose diameter gradually decreases, is formed toward the tip side of the step.

[0023] Next, the center-through coolant pipe 20, the fine bubble generating member 30, the connecting member 40, and the cutting tool 50, which are arranged in the holes 11, 12, and 13 of the holder body 10, will be described in detail.

[0024] As described above, the center through coolant pipe 20 is disposed on the tip side of the rear hole 11. The center through coolant pipe 20 has a fourth coolant flow path 21, which is a through hole that penetrates in the axial direction, formed inside it. The fourth coolant flow path 21 serves as a flow path for the coolant liquid. The center through coolant pipe 20 has a male thread 22 on the outer periphery of its tip, which threads into a female thread 14 formed on the inner circumferential surface of the rear hole 11 on the tip side.

[0025] The fine bubble generating member 30 is placed in the central hole 12 between the center through coolant pipe 20 and the connecting member 40. The fine bubble generating member 30 is used to generate minute bubbles (fine bubbles) in the coolant. Fine bubbles are generally tiny bubbles of 100 μm or less; those between 1 μm and 100 μm are called microbubbles, and those between a few nm and 1 μm are called ultrafine bubbles (nanobubbles), but this includes both.

[0026] The fine bubble generating member 30 includes a cylindrical body 31 and a first coolant flow path 32, which is a through-hole formed inside the cylindrical body 31 and extending in the axial direction. The cylindrical body 31 is sized to be able to be placed in the central hole 12 of the tool holder 1, and the outer diameter of the cylindrical body 31 is slightly smaller than the inner diameter of the central hole 12. The cylindrical body 31 is cylindrical so as to fit the shape of the central hole 12, but it may also be in the form of a prism, for example. The fine bubble generating member 30 is an elastic body made of a soft material, specifically plastic, etc. The fine bubble generating member 30 is manufactured, for example, by injection molding, etc.

[0027] 2(A), the first coolant flow path 32 extends spirally along the axial direction and has a cross-sectional shape that is constricted at the radial center. A cross-sectional shape that is constricted at the radial center means that the maximum diameter at the center is smaller than the maximum diameter at both axial ends of the first coolant flow path 32. Also, as shown in the figure, the angle of the first coolant flow path 32 changes between the inlet (on the center-through coolant pipe 20 side) and the outlet (on the connecting member 40), and as an example, it is shown to be rotated by approximately 90 degrees.

[0028] As shown in Figure 2(B), the shape of the inlet side of the first coolant flow path 32 is narrow in the radial center and wide (large area) at both radial ends in order to generate fine bubbles by swirling the coolant and reducing the pressure at the center of rotation due to the centrifugal force. The fine bubble generating member 30 does not rotate itself, but swirls the coolant as it passes through the first coolant flow path 32. For this reason, it is preferable that the position of the fine bubble generating member 30 within the central hole 12 is fixed, for example, by an O-ring.

[0029] The connecting member 40 is disposed between the fine bubble generating member 30 and the cutting tool 50 in the central hole 12. The connecting member 40 includes a main body 41 and a second coolant flow path 42, which is a through-hole formed inside the main body 41 and extending in the axial direction. The main body 41 is sized to be able to be disposed in the central hole 12 of the tool holder 1, and its outer diameter is slightly smaller than the inner diameter of the central hole 12. The main body 41 is also approximately the same as or slightly larger than the outer diameter of the fine bubble generating member 30. The main body 41 is cylindrical so as to fit the shape of the central hole 12. The connecting member 40 is formed from a hard material, specifically steel or the like.

[0030] 1, the rear end of the connecting member 40 abuts against the front end of the fine bubble generating member 30, and its front end abuts against the rear end of the cutting tool 50. Specifically, the rear end of the connecting member 40 is in close contact with the front end of the fine bubble generating member 30, and is joined at the end face, and the front end of the connecting member 40 is in close contact with the rear end of the cutting tool 50, and is joined at the end face. In this way, the connecting member 40 has the function of adjusting the axial length (protruding length) of the cutting tool 50.

[0031] 1 and 3, the second coolant flow path 42 has a step on its inner circumferential surface and includes a rear-end second coolant flow path 42b and a front-end second coolant flow path 42f. Coolant liquid that has passed through the fine bubble generating member 30 and contains fine bubbles passes through the rear-end second coolant flow path 42b and the front-end second coolant flow path 42f.

[0032] 4, the cross-sectional area A2b of the rear-end second coolant flow path 42b is larger than the cross-sectional area A2f of the front-end second coolant flow path 42f (A2b>A2f). The cross-sectional area A2b of the rear-end second coolant flow path 42b is larger than the cross-sectional area A1 of the front end of the first coolant flow path 32 of the fine bubble generating member 30 (A2b>A1). This allows all of the coolant liquid that has passed through the fine bubble generating member 30 and contains fine bubbles to be sent to the second coolant flow path 42 of the connecting member 40.

[0033] As shown in Fig. 1, the cutting tool 50 includes a shank portion 51 located at its rear end and a cutting portion 52 at its tip end. The shank portion 51 is disposed in the front hole 13 and fixed by shrink fitting. The cutting tool 50 is provided with a coolant third flow path 53 which is a through hole extending in the axial direction up to its cutting edge. The coolant in the coolant second flow path 42 of the connecting member 40 passes through the coolant third flow path 53. Although only one coolant third flow path 53 is provided in Fig. 1, two axially extending holes may be provided.

[0034] As described above, the rear end of the cutting tool 50 is joined to the front end of the connecting member 40 with end face contact, and the axial length (protrusion length) of the cutting tool 50 is adjusted by the connecting member 40. As shown in Fig. 4, the cross-sectional area A3 of the rear end of the coolant third flow path 53 of the cutting tool 50 is smaller than the cross-sectional area A2f of the front end of the coolant second flow path 42 of the connecting member 40 (A3 < A2f). Thereby, pressure can be applied to the coolant from the coolant second flow path 42 toward the coolant third flow path 53.

[0035] Thus, in the tool holder 1 of the present embodiment, the coolant supplied from the spindle of the machine tool passes through the coolant fourth flow path 21 of the center through coolant pipe 20, the coolant first flow path 32 of the fine bubble generating member 30, the coolant second flow path 42 of the connecting member 40, and the coolant third flow path of the cutting tool 50 in this order and is jetted to the cutting edge of the cutting tool 50. Therefore, these coolant flow paths 21, 32, 42, 53 form a "coolant supply passage".

[0036] Referring to Fig. 5, the flow of the coolant jetted from the tool holder 1 will be described.

[0037] In Fig. 5, the flow of the coolant is indicated by arrows. As described above, the rear-end side tapered shank portion 17 of the holder body 10 is fixed to the spindle of a machine tool (not shown), and the coolant is supplied from the spindle of the machine tool to the fourth coolant flow path 21 of the center through coolant pipe 20 and then to the first coolant flow path 32 of the fine bubble generating member 30. The first coolant flow path 32 of the fine bubble generating member 30 extends spirally along the axial direction and has a constricted cross-sectional shape at the radially central portion. Therefore, as the coolant advances along the axial direction, it swirls spirally, and when pressure is applied to the coolant, fine bubbles are generated in the liquid.

[0038] The coolant in which fine bubbles have been generated is supplied to the second coolant flow path 42 of the connecting member 40. At this time, as shown in Fig. 4, since the cross-sectional area A2b of the rear-end side second coolant flow path 42b of the connecting member 40 is larger than the cross-sectional area A1 of the first coolant flow path 32 of the fine bubble generating member 30 (A2b > A1), all of the coolant in which fine bubbles have been generated can be fed into the second coolant flow path 42 of the connecting member 40.

[0039] The coolant that reaches the front-end side second coolant flow path 42f via the rear-end side second coolant flow path 42b of the connecting member 40 is supplied to the third coolant flow path 53 of the cutting tool 50. At this time, since the cross-sectional area A3 of the third coolant flow path 53 of the cutting tool is smaller than the cross-sectional area A2f of the front-end side second coolant flow path 42f of the connecting member 40 (A3 < A2f), pressure can be applied to the coolant, and the momentum of the coolant ejected from the tip of the cutting edge of the cutting tool 50 can be increased. Even when two third coolant flow paths 53 are provided, the sum of the cross-sectional areas of the two holes is configured to be smaller than the cross-sectional area of the front-end side second coolant flow path 42f.

[0040] In this way, the tool holder 1 of this embodiment can generate fine bubbles in the coolant by arranging the fine bubble generating member 30 in the coolant supply passage. As a result, the coolant sprayed onto the cutting edge of the cutting tool 50 contains fine bubbles, and the impact of the fine bubbles exploding can efficiently remove chips adhering to the workpiece or tool. This improves the machining accuracy of the cut surface. Furthermore, since chips do not wrap around the cutting edge of the cutting tool 50 and damage the cutting edge, the life of the cutting tool can be extended.

[0041] Furthermore, by incorporating fine bubbles into the coolant, the tiny bubbles carry oxygen into the liquid, which suppresses the activation of anaerobic bacteria and prevents the coolant from spoiling.

[0042] Because the fine bubble generating member 30 is made of a soft material, if a cutting tool 50 is in direct contact with the fine bubble generating member 30 during machining, the cutting tool 50 may vibrate, causing wear to the fine bubble generating member 30. The tool holder 1 of this embodiment has a connecting member 40 made of a hard material disposed between the fine bubble generating member 30 and the cutting tool 50, preventing wear to the fine bubble generating member 30.

[0043] (Embodiment 2) A tool holder 1A according to a second embodiment will be described with reference to Figures 6 to 8. In the first embodiment, cutting tool 50 is held by shrink fitting in holder body 10, but in the second embodiment, cutting tool 50 is held using collet 60A and fastening member 70A, and the second embodiment differs in the structures of connecting member 40A and cutting tool 50A. Only the differences from the structure shown in the first embodiment will be described in detail below.

[0044] Referring to Figure 6, the front hole 13A of the holder body 10 extends from the rear end of the central hole 12 to the front end, and its inner diameter gradually increases toward the tip. This front hole 13A holds a collet 60A. The collet 60A is cylindrical and provided in the tip region of the holder body, with a tool insertion hole 61A formed in the inner periphery of the tip along the axial direction. The tool insertion hole 61A extends from the rear end to the front end and penetrates the collet 60A in the axial direction.

[0045] The collet 60A has a constricted portion 62A on its outer peripheral surface at its front end that engages with the fastening member 70A. The collet 60A has a plurality of axially extending slits 63A. The collet 60A has a plurality of slits 63A, specifically four slits 63A, spaced equally apart in the circumferential direction. The collet 60A can hold the cutting tool 50 by compressing the slits 63A. The slits 63A also function as a coolant supply passage for supplying coolant. The slits 63A will be described later.

[0046] The fastening member 70A is used to reduce the diameter of the collet 60A to tightly and firmly grip the cutting tool 50A to the holder body 10. The fastening member 70A is a cylindrical member that is fitted onto the outer periphery of the holder body 10 so as to be rotatable and movable in the axial direction of the tool attachment portion 18A.

[0047] The fastening member 70A is a cylindrical nut, and includes an internal thread 71A formed on the inner peripheral surface at the rear end thereof from the axial center toward the rear end, and a protrusion 72A provided on the inner peripheral surface at the tip end. The internal thread 71A engages with an external thread provided on the tool attachment portion 18A of the holder body 10. The protrusion 72A engages with the neck portion 62A of the fastening member 70A described above. In this manner, the holder body 10 holds the cutting tool 50 by fastening the collet 60A and the fastening member 70A together.

[0048] Further referring to FIG. 7, a connecting member 40A and a cutting tool 50A of the present embodiment will be described. The connecting member 40A of the present embodiment has the same shape as the connecting member 40A of the first embodiment, but is provided with a guide portion 44A that guides coolant liquid. The guide portion 44A is a radial passage that extends from the second coolant flow path 42 to the radial outer surface (radial outer edge) on its front end surface. As an example, four guide portions 44A are provided and arranged in a cross shape. The guide portions 44A are recesses (grooves) that recess from the front surface 43A of the connecting member 40A toward the rear end side. Furthermore, the cutting tool 50A has a solid shape with no through holes.

[0049] The flow of coolant in the tool holder 1A will be described with reference to FIG.

[0050] The flow of coolant is indicated by arrows in Figure 8. As described above, the coolant supplied from the spindle of the machine tool (not shown) is supplied to the rear hole 11 of the holder body 10, and then supplied to the first coolant flow path 32 of the fine bubble generating member 30. Fine bubbles are generated in the liquid as the coolant flows axially through the first coolant flow path 32 of the fine bubble generating member 30.

[0051] The coolant in which fine bubbles have been generated is supplied to the second coolant flow path 42 of the connecting member 40A, and the coolant that passes through the second coolant flow path 42 of the connecting member 40A flows radially in all four directions along guide portions 44A provided on the front end face and is supplied to the wall surface of the front hole 13. The coolant supplied to the wall surface of the front hole 13 is sprayed along the slits 63A in the collet 60A onto the cutting edge of the cutting tool 50. In this embodiment, the coolant supply passage is formed by the rear hole 11, the first coolant flow path 32 of the fine bubble generating member 30, the second coolant flow path 42 and guide portions 44A of the connecting member 40A, and the slits 63A in the collet 60A.

[0052] In this way, even if the cutting tool 50 does not have a through-hole, the coolant liquid that has passed through the fine bubble generating member 30 moves radially outward through the guide portion 44A of the connecting member 40A, reaches the wall surface of the front hole 13, and moves axially toward the front end through the slit 63A of the collet 60A. Therefore, even if the cutting tool 50A has a solid shape and does not have a through-hole, the coolant liquid can be sprayed toward the cutting edge of the cutting tool 50A.

[0053] (Embodiment 3) A tool holder 1B according to a third embodiment will be described with reference to Fig. 9. This embodiment differs from the second embodiment in that, in addition to the configuration of the second embodiment, a cap member 80B is provided at the tip of a fastening member 70B. Only the differences from the structure shown in the second embodiment will be described in detail below.

[0054] 9, fastening member 70B of the present embodiment has protrusion 72A that engages with constricted portion 62A of collet 60A, and also has engaging portion 73B at its tip end, into which cap member 80B described above is fitted.

[0055] Cap member 80B includes a main body 81B, a fifth coolant flow path 82B that is a through hole that is provided within main body 81B and passes through in the axial direction to hold cutting tool 50B, and an engaged portion 83B that screws into engaging portion 73B. An inner peripheral wall of fifth coolant flow path 82B is provided with a plurality of grooves spaced apart in the circumferential direction, and coolant liquid is sprayed from the grooves toward the tip of cutting tool 50A.

[0056] (Variation) Although multiple embodiments have been described above, the cutting tool may be provided with third coolant flow path 53 as in embodiment 1, or may be solid as in embodiments 2 and 3. Furthermore, when a solid cutting tool is used, the configuration is not limited to embodiments 2 and 3, and it is sufficient that a groove extending from the end of a radial passage (guide portion 44A) provided in the front end surface of connecting member 40A toward the cutting edge of cutting tool 50A is formed. For example, instead of using collet 60A, a groove extending in the axial direction (guide portion for coolant) may be formed in the wall surface of front hole 13 of holder body 10.

[0057] In the above description, the configuration of the fine bubble generating member 30 has been explained with reference to Fig. 3, but it is not limited to this shape. The fine bubble generating member 30 may have at least a first coolant flow path 32 extending in the axial direction, and may generate fine bubbles in the coolant liquid within the first coolant flow path 32.

[0058] In the above embodiment, it has been described that the fine bubble generating member 30 is made of a soft material and the connecting members 40, 40A, 40B are made of a hard material, but they may be made of materials of similar hardness, or the connecting members 40, 40A, 40B may be made of a material harder than the fine bubble generating member 30.

[0059] (Other variations) The above embodiment has been described as an example in which the fine bubble generating member 30 is arranged in the coolant supply passage of the tool holder 1. In the following description, although the fine bubble generating member 30 is arranged in the coolant supply passage, as a more specific configuration, connection structures 100C and 100D in which the fine bubble generating member 30 is built into connection members 20C and 20D provided between the tool holder 1 and the machine spindle 9 will be described with reference to Figs.

[0060] As shown in FIG. 10, the tool holder 1 is fixed to a machine spindle 9C of a machine tool. The machine spindle 9C is provided with a tapered hole 91C along its axial direction. This tapered hole 91C is a hole for attaching the rear-end tapered shank portion 17 of the tool holder 1, and has a shape that tapers toward the rear end (leftward on the page). A retraction portion 93C is provided on the rear end side of the tapered hole 91C for retracting and fixing a connecting member 20C, which will be described later. A first coolant supply passage 98C extending axially is provided within the machine spindle 9C along the extension direction of the retraction portion 93C.

[0061] The tool holder 1 is, for example, a BT shank tool holder, and has a central hole 12 (second coolant supply passage) extending in the axial direction provided therein. The tool holder 1 is fixed to the machine spindle 9C via a pull stud serving as a connecting member 20C. In other words, the connecting member 20C is provided between the tool holder 1 and the machine spindle 9C.

[0062] The connecting member 20C has its front end fixed to the tool holder 1 and its rear end receiving a tensile force in the depth direction (axial rear end side) of the machine spindle 9C, thereby fixing the tool holder 1 to the machine spindle 9C.

[0063] 11(A) and 11(B), the connecting member 20C includes a main body 21C and a third coolant supply passage 25C disposed within the main body 21C and extending in the axial direction. The main body 21C has a tip end 22C fixed to the tool holder 1, a flange 23C abutting against the rear edge of the tool holder 1, and a rear end 24C extending toward the rear end. The tip end 22C has a threaded portion on its outer diameter surface that threads onto the inner edge of the rear end of the tool holder 1. The rear end 24C is a gripping portion that engages with the retraction portion 93C and has a diameter larger than that of the shank.

[0064] The third coolant supply passage 25C is formed so that the inner diameter on the front end 22C side is smaller than the inner diameter on the flange 23C and rear end 24C sides, and a step 27C is provided at the boundary between them. The fine bubble generating member 30 is disposed in the third coolant supply passage 25C on the flange 23C and rear end 24C side, and is disposed so as to abut against this step 27C.

[0065] As shown in Fig. 12, an annular recess 29C is provided in the inner wall of the third coolant supply passage 25C on the rear end 24C side, and a ring-shaped support part 28C is provided in this recess 29C. The ring-shaped support part 28C is, for example, an O-ring. The ring-shaped support part 28C is, for example, an elastic member and also has a sealing function. The step part 27C and ring-shaped support part 28C described above form a retaining mechanism 26C that prevents the fine bubble generating member 30 from falling off the connecting member 20C.

[0066] As shown in Figures 10 and 11(A), the coolant liquid fed from the machine spindle 9C side passes through the first coolant supply passage 98C and then through the through holes of the fine bubble generating member 30 arranged in the third coolant supply passage 25C of the connecting member 20C, thereby generating fine bubbles.The coolant liquid in which the fine bubbles have been generated passes through the second coolant supply passage 12 in the tool holder 1 and is then sprayed toward the cutting edge.

[0067] 10 to 12 show an example in which the connection member 20C is a pull stud. An example in which the connection member 20D of the connection structure 100D is a coolant pipe will be described with reference to FIGS.

[0068] 13 is, for example, an HSK shank tool holder, and is fixed to a machine spindle 9D by a drawbar 94D via a connecting member 20D. The connecting member 20D is disposed between the machine spindle 9D and the tool holder 1D by having its front end fixed to the tool holder 1D and its rear end connected to a first coolant supply passage 98c provided in the machine spindle 9D.

[0069] 14, the connecting member 20D is, for example, a coolant pipe and includes a main body 21C and a third coolant supply passage 25C extending in the axial direction of the main body 21C. The main body 21C has a front end 22C that is fixed to the tool holder 1 and a rear end 24C that extends toward the rear end. A threaded portion is provided on the outer diameter surface of the front end 22C, and threads onto the inner edge of the rear end of the tool holder 1. The rear end 24C is inserted into the gripping portion 95D of the draw bar 94D.

[0070] 14, the third coolant supply passage 25C is formed so that the inner diameter on the front end 22C side is smaller than the inner diameter on the rear end 24C side, and a step 27C is provided at the boundary between them. The fine bubble generating member 30 is disposed in the third coolant supply passage 25C on the rear end 24C side so as to abut against this step 27C. As in the above-mentioned modified example, the coolant pipe connecting member 20D also has a retaining prevention mechanism 26C composed of the step 27C and a ring-shaped support member 28C.

[0071] Returning to FIG. 13, the retraction structure 94D provided in the machine spindle 9D includes a drawbar 96D extending in the axial direction, a gripper 95D provided at the tip end of the drawbar 96D, and a clamper 97D that presses the gripper 95D from the outer diameter side. The drawbar 96D is provided with a first coolant supply passage 98D. The gripper 95D grips the rear end 24C of the connecting member 20D, retracting the drawbar 96D toward the rear end in the axial direction (to the left in the drawing). At the same time, the outer diameter side of the gripper 95D abuts against the clamper 97D and is pushed outward, connecting the rear end tapered shank portion 17 of the tool holder 1D to the tapered hole 91D. This fixes the tool holder 1D to the machine spindle 9D via the connecting member 20D.

[0072] In this way, the connecting members 20C, 20D according to this modified example only require the fine bubble generating member 30 to be built into the third coolant supply passage 25C, and no additional processing is required on the tool holder 1 itself, making it possible to generate fine bubbles using existing tool holders.

[0073] In the above embodiment, the connecting members 20C, 20D have been described using pull studs and coolant pipes as examples. However, the connecting members 20C, 20D do not need to be fixed to the tool holders 1, 1D and the machine spindles 9C, 9D. They may simply be members that are disposed at least between the tool holders 1, 1D and the machine spindles 9C, 9D and have the third coolant supply passage 25C provided therein.

[0074] Although an O-ring has been used as an example of the ring-shaped support portion 28C of the retaining mechanism 26C, any structure may be used as long as it prevents the fine bubble generating member 30 from falling out of the third coolant supply passage 25C. For example, as shown in FIG. 15, the retaining mechanism 26E of the connecting member 20E may be formed of a snap ring 28E without any anti-slip function instead of the O-ring 28C. Although not shown, the snap ring 28E may be disposed in the recess 29C described for the O-ring 28C. In this way, the retaining mechanism 26C does not need to be a strong retaining mechanism, but it is sufficient that it has at least some retaining function.

[0075] In the above modified examples, the inner wall of the third coolant supply passage 25C of the connecting members 20C and 20E is provided with an annular recess 29C for placing the O-ring 28C, but a recess may be provided in the outer wall of the fine bubble generating member 30 and the O-ring 28C may be placed in that recess, or recesses may be provided in both the inner wall of the third coolant supply passage 25C and the outer wall of the fine bubble generating member 30 and the O-ring 28C may be placed between them.

[0076] Although the embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the illustrated embodiments. Various modifications and variations can be made to the illustrated embodiments within the same scope as the present invention or within an equivalent scope. [Industrial Applicability]

[0077] The present invention is advantageously used in machine tools. [Explanation of symbols]

[0078] 1, 1A, 1B, 1D Tool holder, 9C, 9D Machine spindle, 12 Second coolant supply passage, 20C Connection member (pull stud), 20D Connection member (coolant pipe), 20E Connection member, 25C Third coolant supply passage, 26C Retention prevention mechanism, 27C Step portion, 28C Ring-shaped support portion (O-ring), 28E Ring-shaped support portion (snap ring), 30 Fine bubble generating member, 32 Through hole, 50A, 50B Cutting tool, 94D Retraction structure, 98C, 98D First coolant supply passage, 100C, 100D Connection structure.

Claims

1. a machine spindle having a first coolant supply passage extending in an axial direction; a tool holder that receives and holds a shank of a cutting tool and injects coolant onto a cutting edge of the cutting tool through a second coolant supply passage that extends in an axial direction; a connecting member disposed between the machine spindle and the tool holder, extending in an axial direction, and having a third coolant supply passage connecting the first coolant supply passage and the second coolant supply passage, The connecting member is a fine bubble generating member provided in the third coolant supply passage, the fine bubble generating member having a through hole extending in an axial direction, the fine bubble generating member generating fine bubbles in the coolant liquid within the through hole; a stopper mechanism for preventing the fine bubble generating member from falling out of the third coolant supply passage.

2. 2. The connection structure according to claim 1, wherein the connecting member is a pull stud having one end fixed to the tool holder and the other end receiving a tensile force in the depth direction of the machine spindle, thereby fixing the tool holder to the machine spindle.

3. 3. The connection structure according to claim 1, wherein the connecting member is a coolant pipe arranged between the machine spindle and the tool holder, one end of which is fixed to the tool holder and the other end of which is connected to the first coolant supply passage.

4. 3. The connection structure according to claim 1, wherein the retaining mechanism includes a step portion that abuts against the tip side of the fine bubble generating member and a ring-shaped support portion that supports the rear end side of the fine bubble generating member.

5. 3. The connection structure according to claim 1, wherein the through-hole of the fine bubble generating member extends spirally along the axial direction, and the maximum diameter dimension at the central part in the axial direction is smaller than the maximum diameter dimensions at both ends in the axial direction.

6. A tool holder for receiving and holding a shank of a cutting tool, the tool holder injecting coolant onto a cutting edge of the cutting tool through a coolant supply passage extending in an axial direction, The coolant supply passage is provided with a through hole extending in the axial direction, and a fine bubble generating element that generates fine bubbles in the coolant liquid in the through hole and a fall-out prevention mechanism that prevents the fine bubble generating element from falling out are disposed in the tool holder.

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