Liquid spray device

Abstract

This liquid spray device comprises a nozzle for spraying a liquid onto a rotary tool of a machine tool, wherein the nozzle includes a cylindrical casing and a plurality of columnar bodies. The plurality of columnar bodies are arranged side by side in the casing. The casing has, between a receiving port for receiving a liquid from a supply source and a spraying port for spraying a liquid containing fine bubbles, a gradually decreasing portion in which a cross-sectional size in a flow path of the liquid gradually decreases from the receiving port side toward the spraying port side. The plurality of columnar bodies are provided in the gradually decreasing portion of the casing, and are arranged in a staggered manner in plan view from a direction in which the columnar bodies extend.

Description

liquid injection device

[0001] The present invention relates to a liquid ejection device, and more particularly to a liquid ejection device that ejects a liquid containing fine bubbles onto a rotary tool of a machine tool.

[0002] A liquid injection device that injects liquid onto a rotary tool is attached to a machine tool. By injecting liquid onto the rotary tool of the machine tool, the rotary tool can be cooled and chips adhering to the rotary tool can be removed. An example of such a liquid injection device attached to a machine tool is disclosed in Patent Document 1.

[0003] Patent Document 1 discloses a liquid injection device that injects a liquid (coolant) containing microbubbles (fine bubbles with a particle size of 1 μm or more) onto the grinding wheel of a grinding machine. The liquid injection device disclosed in Patent Document 1 includes a liquid storage tank that stores the liquid, a pump that delivers the liquid from the liquid storage tank, a fluid supply pipe that generates microbubbles, and a nozzle that injects the liquid delivered from the fluid supply pipe between the grinding wheel and the workpiece. Because the liquid injected from the nozzle contains microbubbles, it is believed that it can provide a stronger cooling and cleaning effect than when injecting a liquid that does not contain microbubbles.

[0004] However, in the liquid jetting device disclosed in Patent Document 1, a fluid supply pipe is provided upstream of the nozzle for generating microbubbles, which increases the size of the entire device and leads to an increase in manufacturing costs.

[0005] Patent No. 6245397

[0006] The present invention has been made to solve the above-mentioned problems, and aims to provide a liquid injection device that can inject liquid containing fine bubbles onto a rotary tool of a machine tool, while also making the device size compact and reducing manufacturing costs.

[0007] A liquid injection device according to one aspect of the present invention is a liquid injection device including a nozzle for injecting liquid onto a rotary tool of a machine tool, the nozzle including a cylindrical casing and a plurality of pillars. The cylindrical casing has an inlet opening at one end for receiving the liquid from a supply source and an injection port opening at the other end for injecting the liquid containing fine bubbles. The plurality of pillars are arranged side by side within the casing. In the liquid injection device according to this aspect, the casing has a tapered portion between the inlet and the injection port, in which the cross-sectional size of the liquid flow path gradually decreases from the inlet side toward the injection port side. In the liquid injection device according to this aspect, the plurality of pillars are disposed within the tapered portion of the casing and are arranged in a staggered pattern when viewed from above in the direction in which the pillars extend.

[0008] 1 is a diagram illustrating a configuration of a liquid injection device according to an embodiment; FIG. 2 is a side view illustrating a configuration of a liquid injection device; FIG. 3 is a plan view illustrating a configuration of a liquid injection device; FIG. 4 is a front view illustrating a configuration of a liquid injection device; FIG. 5 is a cross-sectional view illustrating a configuration of a nozzle as viewed from the side; FIG. 6 is a cross-sectional view illustrating a configuration of a nozzle as viewed from above; FIG. 7 is a cross-sectional view illustrating an arrangement of bubble generating pillars within a casing; FIG. 8 is a schematic view illustrating an ejection flow ejected from a nozzle; FIG. 9 is a view illustrating an arrangement of an air layer removing unit with respect to a grinding stone; FIG. 10 is a view illustrating a state in which an ejection flow collides with the outer peripheral surface of a grinding stone; FIG. 11 is a view illustrating a state of an ejection flow in a comparative example in which an air layer removing unit is not provided; FIG. 12 is a side view illustrating a configuration of a liquid injection device according to a first modification; FIG. 13 is a side view illustrating a configuration of a liquid injection device according to a second modification; FIG. 14 is a cross-sectional view illustrating a configuration of a pillar in a nozzle provided in a liquid injection device according to a third modification;

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the embodiments described below are merely illustrative of the present invention, and the present invention is not limited to the following embodiments except for the essential configuration.

[0010] [Embodiment] 1. Arrangement of Liquid Ejection Apparatus 1 The arrangement of a liquid ejection apparatus 1 according to this embodiment will be described with reference to FIG.

[0011] 1, the liquid injection device 1 is a device that injects a grinding fluid (liquid) onto a grinding wheel (rotary tool) 21 of a grinding device (machine tool) 20. The liquid injection device 1 is disposed adjacent to the grinding wheel 21. A liquid storage tank 2 is connected to the liquid injection device 1 via a pump 3, a pipe 4, a flexible pipe 5, and an opening / closing valve 6.

[0012] The liquid storage tank 2 is a tank that stores the grinding fluid. The liquid storage tank 2 is a supply source of the grinding fluid (liquid). The pump 3 sends the grinding fluid from the liquid storage tank 2 to the liquid injection device 1. The open / close valve 6 is a valve that can be closed to stop the injection of the grinding fluid to the grinding wheel 21 when the grinding device 20 is stopped, and can be opened when the grinding device 20 is operating. The flexible piping 5 is provided so that the injection position of the grinding fluid relative to the grinding wheel 21 can be adjusted with the liquid injection device 1 in a desired position.

[0013] The grinding wheel 21 rotates in the direction indicated by the arrow and moves relatively in a direction perpendicular to the plane of the paper in FIG. 1 with respect to the table on which the workpiece is placed.

[0014] 2. Structure of Liquid Ejection Apparatus 1 The structure of the liquid ejection apparatus 1 will be described with reference to FIGS. 2A, 2B, and 2C.

[0015] 2A and 2B, the liquid ejection device 1 includes a nozzle 11 and an air layer removal unit 12. The nozzle 11 has a receiving unit 11f provided on one side in the X direction and an ejection unit 11g provided on the other side in the X direction. As shown in FIG. 2A, the nozzle 11 has a tip end 11a, an intermediate unit 11b, a base end 11c, and a connecting unit 11d arranged from the ejection unit 11g side toward the receiving unit 11f side. The tip end 11a, the intermediate unit 11b, the base end 11c, and the connecting unit 11d are integrally formed.

[0016] The distal end 11a and the intermediate portion 11b have an external shape of a truncated quadrangular pyramid, the proximal end 11c has an external shape of a quadrangular cylinder, and the connecting portion 11d, to which the flexible pipe 5 is connected, has an external shape of a cylinder.

[0017] 2B , the nozzle 11 has walls on both sides in the Y direction that are parallel to each other. That is, when the nozzle 11 is viewed in a plan view from the Z direction, the nozzle 11 has a rectangular shape excluding the receiving portion 11 f.

[0018] 2C, the ejector 11g has an opening that is elongated in the Y direction and formed in a rectangular shape that is flattened in the Z direction. The ejector 11g has an opening area smaller than that of the opening formed in the receiver 11f. Note that the shape of the opening of the ejector 11g is not limited to a rectangular shape and may be an oval shape, for example.

[0019] The air layer removal unit 12 includes a partition plate 121 made of a material (e.g., a styrene board) that is less hard than the grindstone 21 (see FIG. 1 ), and support plates 122 and 123 made of metal plates or the like that are disposed so as to sandwich the partition plate 121 in the thickness direction. The air layer removal unit 12 also includes a bolt 124 for attachment to the nozzle 11.

[0020] As shown in Fig. 2A, the air layer removal unit 12 extends upward (outward) in the Z direction from the upper end of the nozzle 11 in the Z direction. Also, as shown in Fig. 2B, the partition plate 121 and the support plates 122, 123 of the air layer removal unit 12 each have a recessed portion 121a, 123a configured to recess downward in the Z direction from their upper ends. The recessed portion 121a of the partition plate 121 is formed so that its width W1 is approximately the same as the width of the grinding wheel 21. The recessed portions 123a of the support plates 122, 123 are formed so that their width W2 is wider than the width W1 and so as not to come into contact with the grinding wheel 21.

[0021] 3. Detailed Configuration of Nozzle 11 The detailed configuration of the nozzle 11 will be described with reference to FIGS. 3A and 3B.

[0022] As shown in Figures 3A and 3B, the nozzle 11 includes a casing 111 that forms the outer shell of the nozzle 11, a plurality of flow straightening columns (second columns) 112 arranged within the casing 111, and a plurality of bubble generating columns (first columns) 113 also arranged within the casing 111.

[0023] The casing 111 has a rectangular cylindrical shape composed of an upper wall 111a, a lower wall 111b, side walls 111c and 111d, and a cylindrical wall 111e, and has an inlet 111f at one end in the X direction and an outlet 111g at the other end. That is, the receiving portion 11f of the nozzle 11 has the inlet 111f, and the outlet portion 11g has the outlet 111g.

[0024] In this embodiment, the lower wall 111b is a flat wall portion that is formed to extend in the X and Y directions.

[0025] 3A , the upper wall 111a, which faces the lower wall 111b in the Z direction, is an inclined wall configured such that the distance between the inner wall surface of the upper wall 111a and the inner wall surface of the lower wall 111b gradually decreases from the inlet 111f side toward the outlet 111g side at the tip end 11a and the intermediate portion 11b. In this embodiment, the upper wall 111a is one of two second walls, and the lower wall 111b is the other. That is, the casing 111 has a tapered portion configured such that the cross-sectional size of the liquid flow path gradually decreases from the inlet 111f side toward the outlet 111g side at the tip end 11a and the intermediate portion 11b.

[0026] The upper wall 111a is formed so that the tip portion 11a has an inclination angle θ1 and the middle portion 11b has an inclination angle θ2 (see FIG. 2A ). In this embodiment, the casing 111 is configured so that the inclination angle θ2 of the portion constituting the outer shell of the middle portion 11b (the second tapered portion) is greater than the inclination angle θ1 of the portion constituting the outer shell of the tip portion 11a (the first tapered portion). In other words, the casing 111 is configured so that the degree of gradual decrease in the flow path size from the receiving port 111f side to the injection port 111g side is greater in the second tapered portion than in the first tapered portion. Note that the inclination angles θ1 and θ2 are angles formed between the upper wall 111a and the lower wall 111b.

[0027] The plurality of bubble generation columns 113 are accommodated in the casing 111 at the tip portion 11a. Each of the plurality of bubble generation columns 113 is configured to extend in the direction (Z direction) in which the upper wall 111a and the lower wall 111b face each other. And each of the plurality of bubble generation columns 113 has one end connected to the inner wall surface of the upper wall 111a and the other end connected to the inner wall surface of the lower wall 111b. As shown in FIG. 3B, the plurality of bubble generation columns 113 are arranged in a staggered pattern in a plan view from the Z direction.

[0028] The plurality (in this embodiment, three as an example) of rectifying columns 112 are accommodated in the casing 111 at the middle portion 11bb. Each of the plurality of rectifying columns 112 has one end connected to the inner wall surface of the side wall 111c and the other end connected to the inner wall surface of the side wall 111d. In this embodiment, the side wall 111c is one of the two first walls, and the side wall 111d is the other of the two first walls. And the side wall 111c and the side wall 111d are arranged parallel to each other, and the inner wall surfaces are also parallel.

[0029] As shown in FIG. 3A, the plurality of rectifying columns 112 are arranged such that the distance from the upstream end portion 111h, which is the boundary portion with the connection portion 11d at the base end portion 11c, to the injection port 111g gradually decreases the distance to the inner wall surface of the lower wall 111b. Specifically, the rectifying column 112 located on the side of the most upstream end portion 111h has an X-direction distance of L1 from the upstream end portion 111h and a Z-direction distance of H1 from the inner wall surface of the lower wall 111b. The rectifying column 112 separated from the most upstream end portion 111h has an X-direction distance of L3 from the upstream end portion 111h and a Z-direction distance of H3 from the inner wall surface of the lower wall 111b. The rectifying column 112 located in the middle in the X direction has an X-direction distance of L2 from the upstream end portion 111h and a Z-direction distance of H2 from the inner wall surface of the lower wall 111b. In this case, the plurality of rectifying columns 112 are arranged so as to satisfy the following relationship. H1 < H2 < H3 ··· (1) Incidentally, when assuming a virtual plane Ln1 connecting the axes of the plurality of rectifying columns 112, the virtual plane Ln1 is substantially parallel to the inner wall surface of the upper wall 111a in the middle portion 11b.

[0030] Each of the plurality of flow control columns 112 has an outer diameter of 0.4 mm to 10.0 mm. The outer diameter of the flow control columns 112 is set corresponding to the width of the grinding wheel 21, and the outer diameter increases as the width of the grinding wheel 21 increases. In the present embodiment, as an example, the outer diameter of each flow control column 112 is set to φ1.6 mm.

[0031] 4. Arrangement of the Bubble Generating Columns 113 The arrangement of the bubble generating columns 113 will be described with reference to FIG.

[0032] As shown in Fig. 4, the bubble generating columns 113 are arranged in a staggered pattern in a plan view. A virtual plane Ln2 is assumed to extend in the Z direction (a direction perpendicular to the paper surface of Fig. 4) parallel to the side walls 111c and 111d at the midpoint of the distance W3 between the side walls 111c and 111d in the Y direction. In this case, the bubble generating columns 113 are arranged symmetrically with respect to the virtual plane Ln2.

[0033] Among the plurality of bubble generating columns 113, the bubble generating columns 113 adjacent to each other in the X direction are arranged at a pitch W4.

[0034] In addition, in the X direction, the plurality of bubble generation columns 113 are arranged from a position spaced a distance L4 from the injection port 111g inward in the X direction, and the bubble generation columns 113 adjacent to each other in the Y direction are arranged at a pitch L5.

[0035] In this embodiment, the plurality of bubble generating columns 113 are arranged so that the pitch W4 and the pitch L5 satisfy the following relationship: W4<L5 (2) Specifically, in this embodiment, the pitch W4 is 2.0 mm, and the pitch L5 is 4.0 mm.

[0036] Each of the bubble generating columns 113 has an outer diameter of 0.4 mm to 6.0 mm. The outer diameter of the bubble generating columns 113 is set corresponding to the width of the grinding wheel 21, and the wider the grinding wheel 21, the larger the outer diameter becomes. In this embodiment, as an example, the outer diameter of each bubble generating column 113 is set to φ1.6 mm.

[0037] 5. Jet Flow JS Jetted from Nozzle 11 The jet flow JS jetted from the jet port 111g (jet portion 11g) of the nozzle 11 of the liquid jet device 1 according to this embodiment will be described with reference to FIG.

[0038] Fine bubbles are contained in the jet flow JS that is jetted from the jet port 111g of the nozzle 11 toward the outer circumferential surface of the grinding wheel 21 (see FIG. 1) as indicated by the arrow B1. This is because the casing 111 has a tapering portion (portions that constitute the tip portion 11a and the intermediate portion 11b) and the plurality of bubble generating columns 113 are disposed at the tip portion 11a, as described above.

[0039] As shown in Fig. 5, the fine bubbles contained in the jet flow JS form a longitudinal vortex (arrow B2) that rotates around an axis along the Y direction (direction perpendicular to the paper surface of Fig. 5), which is perpendicular to both the jet direction (X direction) and the direction in which the bubble generating columns 113 extend (Z direction). As a result, when the jet flow JS collides with the outer peripheral surface of the grinding wheel 21, the fine bubbles cling to the outer peripheral surface of the grinding wheel 21 (corender effect), and the collision with the outer peripheral surface of the grinding wheel 21 efficiently bursts the fine bubbles (cavitation phenomenon).

[0040] 6. Removal of Air Layer AL by Air Layer Removal Unit 12 The liquid ejection device 1 of this embodiment includes an air layer removal unit 12 attached to the casing 111 of the nozzle 11. The arrangement and function of the air layer removal unit 12 will be described with reference to Figures 6, 7A, and 7B.

[0041] During operation, the grinding wheel 21 of the grinding device 20 rotates in the direction indicated by the arrow in Fig. 1 and moves relatively in the width direction of the grinding wheel 21 with respect to the workpiece to be machined (arrow C in Fig. 6). The liquid injection device 1 moves in conjunction with the movement of the grinding wheel 21 in the width direction. Therefore, the air layer removal unit 12 of the liquid injection device 1 is configured to maintain a constant position relative to the grinding wheel 21.

[0042] As described above, the partition plate 121 of the air layer removal unit 12 has a recessed portion 121a formed to fit the shape of the grinding wheel 21. The grinding surface abutment portion 121b, which is the bottom of the recessed portion 121a, is disposed so as to abut against the outer circumferential surface (grinding surface) 21a of the grinding wheel 21. However, the grinding surface abutment portion 121b of the partition plate 121 does not necessarily have to abut against the grinding surface 21a of the grinding wheel 21, and may be close to the grinding surface 21a with almost no gap between them.

[0043] The partition plate 121 is also arranged so that side surface abutment portions 121c, which are side surfaces on both sides of the recessed portion 121a, abut against a part of the side surface 21c of the grinding wheel 21 (a portion continuing from the grinding surface 21a at a corner). However, the side surface abutment portions 121c of the partition plate 121 do not necessarily have to abut against the side surface 21b of the grinding wheel 21, and may be close to the side surface 21b with almost no gap between them.

[0044] Here, since the partition plate 121 is formed of a material softer than the grinding wheel 21, even when it comes into contact with the grinding surface 21a and side surface 21b of the grinding wheel 21, it is prevented from scratching the grinding surface 21a and side surface 21b of the grinding wheel 21.

[0045] Although not shown in detail, the liquid injection device 1 is configured so that the position of the air layer removal part 12 can be adjusted relative to the casing 111. This allows the position of the air layer removal part 12 relative to the grinding wheel 21 to be adjusted so that the partition plate 121 abuts against the grinding wheel 21 before the grinding device 20 starts operation or at the start of work.

[0046] 1, the air layer removal section 12 is disposed so as to be located upstream of the location of the injection section 11g of the nozzle 11 in the rotation direction (the direction indicated by the arrow in FIG. 1) of the grinding wheel 21. Therefore, as shown in FIG. 7A, the jet flow JS injected from the injection section 11g of the nozzle 11 can be made to cling to the grinding surface 21a of the grinding wheel 21 from which the air layer has been removed (corender effect).

[0047] Furthermore, the air layer removal unit 12 also removes a portion of the air layer on the side surface 21 b of the grinding wheel 21, thereby preventing air from flowing from the side surface 21 b to the grinding surface 21 a even when the grinding wheel 21 moves in the width direction. Therefore, in the liquid injection device 1 equipped with the air layer removal unit 12 configured as described above, the jet flow JS can be reliably sprayed onto the grinding surface 21 a of the grinding wheel 21, and the grinding wheel 21 can be effectively cooled and cleaned.

[0048] 7B , in the case where the air layer removal unit 12 is not provided, an air layer AL exists on the grinding surface 21 a and the side surface 21 b of the grinding wheel 21, and the jet flow JS is jetted toward the air layer AL. In this case, as shown by arrow D, part of the jet flow JS is prevented from reaching the grinding surface 21 a by the air layer AL covering the grinding surface 21 a.

[0049] Furthermore, in the comparative example, even if the air layer AL on the grinding surface 21 a is removed by the jet flow JS, the air remaining on the surface of the side surface 21 b flows around to the grinding surface 21 a as the grinding wheel 21 moves relative to the workpiece as indicated by the arrow C. For this reason, in the comparative example shown in Fig. 7B, it is considered that cooling and cleaning of the grinding wheel 21 is more difficult than in this embodiment.

[0050] 7. Effects In the liquid injection device 1 according to this embodiment, the casing 111 of the nozzle 11 has a tapered portion where the cross-sectional size of the liquid flow path gradually decreases from the inlet 111f side toward the outlet 111g side. As a result, in the liquid injection device 1, the static pressure of the liquid being delivered from the inlet 111f side of the casing 111 to the outlet 111g side decreases. Therefore, in the liquid injection device 1, by configuring the tapered portion so that the static pressure of the liquid reaches the saturated vapor pressure, it is possible to induce cavitation in the liquid.

[0051] Furthermore, in the liquid injection device 1, a plurality of bubble generating columns 113 arranged in a staggered pattern in a plan view are provided in the tapered portion of the casing 111. Therefore, in the liquid injection device 1, a mesh-like flow path is formed by the plurality of bubble generating columns 113. As a result, the liquid delivered to the portion of the casing 111 where the plurality of bubble generating columns 113 are provided (the tip end 11a) repeatedly branches and merges, generating a large number of fine vortices due to the flip-flop phenomenon.

[0052] Therefore, in the liquid injection device 1, fine bubbles can be generated by the nozzle 11 itself, so there is no need to provide a fluid supply pipe separate from the nozzle for bubble generation as in Patent Document 1, making it possible to make the device more compact and reduce manufacturing costs.

[0053] Furthermore, in the liquid injection device 1, each bubble generating column 113 is configured to extend in a direction (Z direction) perpendicular to the direction (X direction) connecting the inlet 111f and the injection port 111g. Therefore, in the liquid injection device 1, multiple bubble generating columns 113 are arranged side by side in a direction intersecting the direction (Z direction) in which the cross-sectional size of the flow path gradually decreases. Therefore, in the liquid injection device 1, the cavitation phenomenon and flip-flop phenomenon can be efficiently generated in the liquid within the casing 111 of the nozzle 11, and the liquid containing fine bubbles can be injected toward the grinding wheel 21 of the grinding device 20. Furthermore, in the injected liquid, the fine bubbles form longitudinal vortices that rotate vertically in the direction (Z direction) in which each bubble generating column 113 extends.

[0054] Furthermore, the liquid injection device 1 includes three straightening columns 112 in the casing 111 in the middle section 11b, and these straightening columns 112 extend in the Y direction, which intersects with the direction in which the bubble generating columns 113 extend (the Z direction). Therefore, in the liquid injection device 1, the flow of the liquid is straightened when the liquid passes through the portion (the middle section 11b) where the straightening columns 112 are provided. Therefore, the straightened liquid is supplied to the tip end 11a in the casing 111 where the bubble generating columns 113 are provided, thereby generating fine bubbles that move in a vortex flow in the same direction (the flip-flop phenomenon). As a result, the liquid injected from the injection section 11g clings to the grinding surface (outer peripheral surface) 21a of the grinding wheel 21 (the corer effect), and the bubbles tend to burst when they collide with the grinding surface 21a (the cavitation phenomenon), which is advantageous for cooling and cleaning the grinding wheel 21.

[0055] Furthermore, in the liquid injection device 1, the outer diameter of the bubble generating column 113 is in the range of 0.4 mm to 6.0 mm (for example, 1.6 mm), and the outer diameter of the flow straightening column 112 is in the range of 0.4 mm to 10.0 mm (for example, 1.6 mm), so that a liquid containing fine bubbles can be injected onto the target grinding wheel 21.

[0056] Furthermore, in the liquid injection device 1, multiple bubble generating columns 113 are arranged so as to satisfy the above relational expression (2), so that fine bubbles can be generated efficiently while suppressing an increase in loss of liquid circulating within the casing 111.

[0057] Furthermore, in the liquid injection device 1, the degree of gradual reduction of the casing 111 (the degree of gradual reduction in the cross-sectional size of the flow path from the inlet 111f side to the injection port 111g side) is greater in the middle portion 11b than in the tip portion 11a. Therefore, in the liquid injection device 1, the static pressure of the liquid passing through the casing 111 in the middle portion 11b can be sufficiently reduced, and fine bubbles can be efficiently generated in the casing 111 at the tip portion 11a.

[0058] The liquid injection device 1 further includes an air layer removal unit 12. Therefore, in the liquid injection device 1, the liquid is injected onto the outer peripheral surface 21a of the grinding wheel 21 with the air layer AL on the grinding surface (outer peripheral surface) 21a removed. Therefore, in the liquid injection device 1, the liquid containing fine bubbles injected from the injection unit 11g of the nozzle 11 can reach the grinding surface 21a of the grinding wheel 21 without being repelled, and can be cling to the grinding surface 21a of the grinding wheel 21 (counder effect).

[0059] Furthermore, in the liquid ejection device 1, the air layer removal unit 12 is configured to remove the air layer AL not only from the outer peripheral surface 21a of the grinding wheel 21 but also from both side surfaces 21b. Therefore, in the liquid ejection device 1, even if the grinding wheel 21 moves in the width direction, it is possible to prevent the air on the side surfaces 21b from flowing around to the grinding surface (outer peripheral surface) 21a. This allows the liquid to efficiently cling to the outer peripheral surface 21a of the grinding wheel 21.

[0060] As described above, the liquid injection device 1 according to this embodiment can inject a liquid containing fine bubbles onto the grinding wheel 21 of the grinding device 20, and can also achieve a compact device size and reduced manufacturing costs.

[0061] [Modification 1] A liquid ejecting device 7 according to Modification 1 will be described with reference to FIG. 8A.

[0062] 8A, a liquid ejecting device 7 according to this modification includes only a nozzle 11, and does not include an air layer removing unit 12. This is the difference from the above embodiment.

[0063] The liquid injection device 1 according to the above embodiment is a device that injects a liquid (grinding fluid) onto the grinding wheel 21 of the grinding device 20, and includes an air layer removal unit 12 for removing an air layer AL that forms on the grinding surface 21a of the grinding wheel 21, etc. In contrast, the liquid injection device 7 according to this modified example is a device that is applied when no air layer is formed on the surface of a rotary tool, or when the air layer does form but does not pose a problem for injecting the liquid. For example, the liquid injection device 7 can be installed in a machine tool such as a machining center, an NC lathe, or a turning machine.

[0064] The liquid ejecting device 7 according to this modification has the same configuration as the above embodiment except that it does not include the air layer removing unit 12, and therefore can obtain the same effects as the above embodiment regarding the nozzle 11.

[0065] [Modification 2] A liquid ejecting device 8 according to Modification 2 will be described with reference to FIG. 8B.

[0066] As shown in Fig. 8B , the liquid injection device 8 according to this modification includes a nozzle 81. The nozzle 81 includes a casing 811. In this modification, the configuration of the casing 811 differs from that of the above embodiment. Note that, although the air layer eliminator 12 is not shown in Fig. 8B , the liquid injection device 8 may include the air layer eliminator 12 as in the above embodiment, or may not include the air layer eliminator 12 as in the above modification 1.

[0067] Unlike the above embodiment, the casing 811 does not have a flat bottom wall 811b. Specifically, the bottom wall 811b is inclined toward the top wall 811a at the tip end 81a and the middle portion 81b of the nozzle 81.

[0068] In the casing 811, the upper wall 811a is configured to be inclined at the tip portion 81a and the middle portion 81b, as in the above embodiment, and in addition to the inclination of the upper wall 811a, the lower wall 811b is also configured to be inclined.

[0069] By providing a casing 811 with such a configuration, the tip portion 81a and the intermediate portion 81b of the nozzle 81 can be configured so that the cross-sectional size of the liquid flow path gradually decreases from the receiving port 811f side toward the injection port 811g side.

[0070] The degree of inclination of the lower wall 811b can be set within a range that prevents interference with the workpiece in relation to the machine tool to which it is applied and does not affect the working space.

[0071] The liquid ejection device 8 according to this modification has the same configuration as the above embodiment and modification 1, except for the difference in the configuration of the casing 811. Therefore, the liquid ejection device 8 can achieve the same effects as the above embodiment and modification 1.

[0072] [Modification 3] A liquid ejecting device according to Modification 3 will be described with reference to Fig. 9A. Note that Fig. 9A illustrates only a column 212 that can be used as the bubble generating column 113 or the flow straightening column 112 of the above embodiment. The liquid ejecting device according to this modification can employ the same configuration as the above embodiment and Modifications 1 and 2, except for the column 212.

[0073] 9A , the pillars 212 of this modification have an elliptical or oval cross section, which differs from the above-described embodiment in that the bubble generating pillars 113 and the flow straightening pillars 112 have circular cross sections.

[0074] 9A is used as at least one of the bubble generating columns and the flow straightening columns. However, this modification employs the same configuration as the above embodiment, except for the cross-sectional shape of the columns 212, and therefore can achieve the same effects as the above embodiment.

[0075] When the column 212 is used as a bubble generating column or a flow straightening column, the orientation of the longitudinal axis of the cross section relative to the liquid flow direction (the direction connecting the receiving port 111f and the injection port 111g) can be determined by taking into consideration the relationship between the generation of fine bubbles, the flow straightening effect, and the flow path resistance.

[0076] [Modification 4] A liquid ejecting device according to Modification 4 will be described with reference to Fig. 9B. Note that Fig. 9B illustrates only a column 312 that can be used as the bubble generating column 113 or the flow straightening column 112 of the above embodiment. The liquid ejecting device according to this modification can employ the same configuration as the above embodiment and Modifications 1 and 2, except for the column 312.

[0077] 9B , the pillar 312 of this modification has a cross-sectional shape of a rounded quadrangle (rounded square or rounded rectangle). In this respect, it differs from the above-described embodiment and modifications 1 and 2, which employ the bubble generating pillars 113 and flow straightening pillars 112 having a circular cross-sectional shape, and from modification 3, which employs the pillar 212 having a cross-sectional shape such as an ellipse.

[0078] 9B is used as at least one of the bubble generating columns and the flow straightening columns. However, this modification employs the same configuration as the above embodiment, except for the cross-sectional shape of the columns 312, and therefore can achieve the same effects as the above embodiment.

[0079] When the pillar 312 is used as a bubble generating pillar or a straightening pillar, the orientation of the corners in the cross section relative to the direction of the liquid flow (the direction connecting the receiving port 111f and the injection port 111g) can be determined by taking into consideration the relationship between the generation of fine bubbles, the straightening effect, and the flow path resistance.

[0080] [Other Modifications] Although not specifically mentioned above, the fine bubbles contained in the liquid ejected from the liquid ejection devices 1, 7, and 8 in the above-described embodiments refer to bubbles of less than 100 μm as defined in ISO 20480-1. Note that fine bubbles include microbubbles of 1 μm or more and ultrafine bubbles of less than 1 μm, but in the above-described embodiments, the term may be used to include both particle sizes, or may include only microbubbles, which are fine bubbles.

[0081] Furthermore, in the above embodiment, the liquid injection device 1 is configured with the air layer removal unit 12 attached to the nozzle 11, but the air layer removal unit 12 does not necessarily have to be attached to the nozzle 11 when it is attached to the grinding wheel 21 of the grinding device 20. For example, if the air layer removal unit 12 is already attached separately to an existing grinding device 20, there is no need to attach a liquid injection device 1 that includes an air layer removal unit 12. In this case, the liquid injection device 7 according to the above-described modified example 1 can be adopted.

[0082] In addition, in the above embodiment, a grinding device 20 is used as an example of the target machine tool, and therefore a grinding fluid (coolant) is used as the liquid to be sprayed from the liquid injection device 1, but the type of liquid to be sprayed from the liquid injection device can be selected appropriately depending on the type of machine tool.

[0083] Furthermore, in the above embodiment and the above modified examples 1 and 2, the pillars 112 and 113 have circular cross sections, the pillar 212 has an oval cross section or the like in the above modified example 3, and the pillar 312 has a rounded rectangular cross section in the above modified example 4. However, the present invention is not limited to these cross-sectional shapes of the pillars. For example, a pillar having a triangular, pentagonal, or polygonal cross section with more sides may also be used.

[0084] [Summary] A liquid injection device according to one aspect of the present invention is a liquid injection device including a nozzle for injecting liquid onto a rotary tool of a machine tool, the nozzle including a cylindrical casing and a plurality of pillars. The cylindrical casing has an inlet opening at one end for receiving the liquid from a supply source and an injection port opening at the other end for injecting the liquid containing fine bubbles. The plurality of pillars are arranged side by side within the casing. In the liquid injection device according to this aspect, the casing has a tapered portion between the inlet and the injection port, where the cross-sectional size of the liquid flow path gradually decreases from the inlet side toward the injection port side. In the liquid injection device according to this aspect, the plurality of pillars are disposed within the tapered portion of the casing and are arranged in a staggered pattern when viewed from above in the direction in which the pillars extend.

[0085] In the liquid injection device according to the above aspect, the nozzle casing has a tapered portion in which the cross-sectional size of the liquid flow path gradually decreases from the inlet side to the injection port side, so that the static pressure of the liquid delivered from the inlet side of the casing to the injection port side decreases. By configuring the tapered portion so that the static pressure of the liquid reaches the saturated vapor pressure, it is possible to induce cavitation in the liquid.

[0086] In the liquid injection device according to the above aspect, the tapered portion of the casing is provided with a plurality of columns arranged in a staggered pattern in a plan view, forming a mesh-like flow path, so that the liquid delivered to the portion of the casing where the columns are provided repeatedly branches and merges, generating a large number of minute vortices due to a flip-flop phenomenon.

[0087] Therefore, in the liquid injection device according to the above aspect, fine bubbles can be generated by the nozzle itself, and there is no need to provide a fluid supply pipe separate from the nozzle for bubble generation, as in Patent Document 1, making it possible to achieve a more compact device size and reduced manufacturing costs.

[0088] In this specification, the term "rotating tool" refers to a tool that rotates relative to a workpiece to be machined, and that comes into contact with the workpiece while rotating relative to it during machining.

[0089] In the liquid ejection device according to the above aspect, the casing may be formed into a rectangular shape in a cross section perpendicular to a direction connecting the inlet and the ejection port, with the liquid flow path being surrounded by four inner wall surfaces. In this case, the four inner wall surfaces may be composed of inner wall surfaces of two first walls arranged opposite to each other and parallel to each other, and inner wall surfaces of two second walls arranged opposite to each other so that the distance between them gradually decreases from the inlet side to the ejection port side in the tapered portion. Furthermore, each of the plurality of pillars may have one end connected to the inner wall surface of one of the second walls and the other end connected to the inner wall surface of the other of the second walls.

[0090] In the liquid injection device according to the above aspect, each pillar is configured to extend between the inner wall surfaces of the second wall, so that multiple pillars are arranged in a direction intersecting the direction in which the cross-sectional size of the flow path gradually decreases. Therefore, in the liquid injection device according to the above aspect, cavitation and flip-flop phenomena can be efficiently induced in the liquid within the nozzle casing, and the liquid containing fine bubbles can be injected toward the rotating tool of a machine tool. Furthermore, in the injected liquid, the fine bubbles rotate vertically in the direction in which each pillar extends.

[0091] The liquid ejecting device according to the above aspect may further include a second pillar. When each of the plurality of pillars is a first pillar, the second pillar may be provided on the side of the receiving port relative to a region in the tapered portion of the casing where the plurality of first pillars are arranged. Furthermore, the second pillar may extend in the direction in which the first walls face each other, and may have one end connected to an inner wall surface of one of the first walls and the other end connected to an inner wall surface of the other first wall.

[0092] In the liquid injection device according to the above aspect, a second column is provided in the casing separately from the first column, and the second column is configured to extend in a direction intersecting the direction of extension of the first column (the direction in which the second walls face each other). As a result, the liquid is rectified as it passes through the portion where the second column is provided. Therefore, the rectified liquid is supplied to the portion of the casing where the first column is provided, generating fine bubbles that move in a vortex flow in the same direction (flip-flop phenomenon). As a result, the injected liquid clings to the surface of the rotary tool (counder effect) and the bubbles tend to burst when they collide with the surface of the rotary tool (cavitation phenomenon), which is suitable for cooling and cleaning the rotary tool.

[0093] In the liquid ejecting device according to the above aspect, the first pillar and the second pillar may both be cylindrical. In this case, the first pillar may have an outer diameter of 0.4 mm to 6.0 mm. The second pillar may have an outer diameter of 0.4 mm to 10.0 mm.

[0094] In the liquid injection device according to the above aspect, the outer diameters of the first cylinder and the second cylinder are set within the above range, so that a liquid containing fine bubbles can be injected onto the target rotary tool.

[0095] In the liquid injection device according to the above aspect, the plurality of first pillars may be arranged so that the pitch between adjacent first pillars in the direction in which the first walls face each other is narrower than the pitch between adjacent first pillars in the direction connecting the receiving port and the injection port.

[0096] In the liquid injection device according to the above aspect, the pitch between the first columns in the opposing direction of the first walls is set to be narrower than the pitch between the first columns in the connecting direction, so that fine bubbles can be generated efficiently while suppressing an increase in loss within the casing.

[0097] In the liquid injection device according to the above aspect, when the portion of the gradually decreasing portion that accommodates the plurality of first cylinders is defined as a first gradually decreasing portion in the direction connecting the receiving port and the injection port, and the portion of the gradually decreasing portion that accommodates the second cylinders is defined as a second gradually decreasing portion, the gradually decreasing portion of the casing may be configured such that the degree of gradual decrease in the distance between the inner wall surfaces of the second walls is greater in the second gradually decreasing portion than in the first gradually decreasing portion.

[0098] In the liquid injection device according to the above aspect, the casing is configured so that the degree of gradual decrease is greater in the second gradual decrease section than in the first gradual decrease section, so that the static pressure of the liquid passing inside the second gradual decrease section can be sufficiently reduced, thereby enabling fine bubbles to be efficiently generated inside the first gradual decrease section.

[0099] In the liquid injection device according to the above aspect, the machine tool may be a grinding machine. The rotary tool may be a grinding wheel having a disk shape. In this case, the liquid injection device may further include an air layer removal unit. The air layer removal unit is attached to the casing so as to be located upstream of the location of the injection nozzle in the rotation direction of the grinding wheel, and is configured to abut on or be in close proximity to the outer circumferential surface and both side surfaces of the grinding wheel to remove the air layer around the grinding wheel.

[0100] The liquid injection device according to the above aspect further includes an air layer removal unit, so that the liquid is injected onto the outer peripheral surface of the grinding wheel (rotary tool) with the air layer removed from the outer peripheral surface. Therefore, in the liquid injection device according to the above aspect, the liquid containing fine bubbles injected from the nozzle outlet can reach the outer peripheral surface of the grinding wheel without being bounced off, and can be made to cling to the outer peripheral surface of the grinding wheel (corender effect).

[0101] The reason why the air layer removal unit is configured to remove air layers not only from the outer peripheral surface of the grinding wheel but also from both sides is that the rotary tool in the grinding machine moves in the width direction of the grinding wheel (the direction connecting the side surfaces), and this is to prevent air that moves from the side surfaces as the tool moves from forming an air layer again on the outer peripheral surface. This allows the liquid to efficiently cling to the outer peripheral surface of the grinding wheel.

[0102] As described above, the liquid injection device according to each of the above aspects can inject a liquid containing fine bubbles onto a rotary tool of a machine tool, and can also achieve a compact device size and reduced manufacturing costs.

Claims

1. A liquid injection device equipped with a nozzle for injecting liquid onto a rotary tool of a machine tool, the nozzle comprising: a cylindrical casing having an inlet at one end for receiving the liquid from a supply source and an outlet at the other end for injecting the liquid containing fine bubbles; and a plurality of pillars arranged side by side within the casing, wherein the casing has a tapered portion between the inlet and the outlet where the cross-sectional size of the flow path of the liquid gradually decreases from the inlet side toward the outlet side, and the plurality of pillars are arranged within the tapered portion of the casing and are arranged in a staggered pattern when viewed from above in the direction in which the pillars extend.

2. The liquid injection device described in claim 1, wherein the casing is formed in a rectangular shape with the liquid flow path surrounded by four inner wall surfaces in a cross section perpendicular to the direction connecting the receiving inlet and the injection port, the four inner wall surfaces being composed of the inner wall surfaces of two first walls arranged opposite each other so as to be parallel to each other, and the inner wall surfaces of two second walls arranged opposite each other so that the distance between them gradually decreases in the tapered portion from the receiving inlet side to the injection port side, and wherein each of the plurality of pillars has one end connected to the inner wall surface of one of the second walls and the other end connected to the inner wall surface of the other of the second walls.

3. A liquid injection device as described in claim 2, wherein when each of the plurality of pillars is a first pillar, the device further comprises a second pillar which is provided on the side of the receiving port relative to the area in the tapered portion of the casing where the plurality of first pillars are arranged, extends in the opposing direction of the first walls, and has one end connected to the inner wall surface of one of the first walls and the other end connected to the inner wall surface of the other of the first walls.

4. The liquid injection device according to claim 3, wherein the first pillar and the second pillar are both cylindrical pillars, the first pillar having an outer diameter of 0.4 mm to 6.0 mm, and the second pillar having an outer diameter of 0.4 mm to 10.0 mm.

5. A liquid injection device as described in claim 3, wherein the plurality of first pillars are arranged so that the pitch between adjacent first pillars in the opposing direction of the first walls is narrower than the pitch between adjacent first pillars in the direction connecting the receiving port and the injection port.

6. A liquid injection device as described in claim 3, wherein, in the direction connecting the receiving port and the injection port, when the portion of the gradually decreasing portion that houses the plurality of first pillars is defined as a first gradually decreasing portion and the portion of the gradually decreasing portion that houses the second pillars is defined as a second gradually decreasing portion, the gradually decreasing portion of the casing is configured such that the degree of gradual decrease in the distance between the inner wall surfaces of the second walls is greater in the second gradually decreasing portion than in the first gradually decreasing portion.

7. A liquid injection device according to any one of claims 1 to 6, wherein the machine tool is a grinding device, the rotary tool is a grinding wheel having a disk shape, and the liquid injection device is attached to the casing so as to be located upstream of the location of the injection nozzle in the rotation direction of the grinding wheel, and further comprises an air layer removal unit configured to abut against or be in close proximity to the outer circumferential surface and both side surfaces of the grinding wheel and remove the air layer around the grinding wheel.

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