Liquid injection device

Abstract

The present invention provides a liquid injection device that can inject a liquid containing fine bubbles onto a rotating tool of a machine tool, while also achieving a compact device size and reduced manufacturing costs. [Solution] The liquid injection device includes a nozzle 11. The nozzle 11 comprises a cylindrical casing 111 with an inlet 111f opening at one end and an injection port 111g opening at the other end. The casing 111 has a portion formed such that the cross-sectional size of the flow path gradually decreases from the inlet 111f side to the injection port 111g side. The nozzle 11 comprises a plurality of bubble-generating columns 113 and a plurality of flow-straightening columns 112 provided inside the casing 111. The plurality of bubble-generating columns 113 are arranged at the tip portion 11a, which is the gradually decreasing portion, with one end of each 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. The plurality of bubble-generating columns 113 are arranged in a staggered pattern when viewed from the Z direction in plan view.

Description

Technical Field

[0001] The present invention relates to a liquid injection device, and particularly to a liquid injection device that injects a liquid containing fine bubbles into a rotating tool of a machine tool.

Background Art

[0002] A machine tool is equipped with a liquid injection device that injects a liquid against a rotating tool. By injecting a liquid against the rotating tool of the machine tool, cooling of the rotating tool and removal of chips adhering to the rotating tool can be achieved. 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 (bubbles with a particle size of 1 μm or more among fine bubbles) against a grinding wheel of a grinding machine. The liquid ejection device disclosed in Patent Document 1 includes a liquid storage tank for storing a liquid, a pump for sending out the liquid from the liquid storage tank, a fluid supply pipe for generating microbubbles, and a nozzle for injecting the liquid sent out from the fluid supply pipe between the grinding wheel and the workpiece. Since the liquid ejected from the nozzle contains microbubbles, it is considered that a higher cooling effect and cleaning effect can be achieved compared to the case of injecting a liquid not containing microbubbles.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the liquid ejection device disclosed in Patent Document 1, since a fluid supply pipe is provided upstream of the nozzle for generating microbubbles, the entire device becomes large-sized and the manufacturing cost increases.

[0006] The present invention aims to solve the above-mentioned problems and provides a liquid injection device that can inject a liquid containing fine bubbles onto a rotating tool of a machine tool, while also achieving a compact device size and reduced manufacturing costs. [Means for solving the problem]

[0007] A liquid injection device according to one aspect of the present invention is a liquid injection device equipped with a nozzle for injecting liquid onto a rotating tool of a machine tool, wherein the nozzle comprises a cylindrical casing having an inlet at one end for receiving the liquid from a supply source and an injection port at the other end for injecting the liquid containing fine bubbles, and a plurality of columnar bodies arranged side by side inside the casing, wherein the casing has a tapering 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 to the injection port side, and the plurality of columnar bodies are disposed within the tapering portion of the casing and are arranged in a staggered pattern in a plan view from the direction in which the columnar bodies extend.

[0008] In the liquid injection device according to the above embodiment, the nozzle casing has a tapering portion in which the cross-sectional size in 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 to the injection port side of the casing decreases. By configuring the tapering portion so that the static pressure of the liquid reaches the saturated vapor pressure, a cavitation phenomenon can be induced in the liquid.

[0009] Furthermore, in the liquid injection device according to the above embodiment, multiple columns are provided in the tapering portion of the casing, arranged in a staggered pattern in a plan view, so that a mesh-like flow path is formed by these multiple columns. As a result, the liquid delivered to the portion of the casing where the multiple columns are provided repeatedly splits and merges, generating numerous minute vortices through a flip-flop phenomenon.

[0010] Therefore, in the liquid injection device according to the above embodiment, fine bubbles can be generated by the nozzle itself, and there is no need to provide a fluid supply pipe separately 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.

[0011] In this specification, "rotating tool" means a tool that rotates relative to the workpiece being processed, and that comes into contact with the workpiece while rotating relative to it during processing.

[0012] In the liquid injection device according to the above embodiment, the casing may be configured such that, in a cross section perpendicular to the direction connecting the inlet and the injection port, the liquid flow path is formed in a rectangular shape surrounded by four inner wall surfaces, the four inner wall surfaces consist of two inner wall surfaces of two first walls arranged opposite to each other so as to be parallel to each other, and two inner wall surfaces of two second walls arranged opposite to each other so as to be gradually separated in the tapering portion from the inlet side to the injection port side, and each of the plurality of columnar bodies 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 second wall.

[0013] In the liquid injection device according to the above embodiment, each column is configured to extend between the inner wall surfaces of the second wall, so that multiple columns are arranged in parallel 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 embodiment, cavitation and flip-flop phenomena can be efficiently generated in the liquid within the nozzle casing, and a liquid containing fine bubbles can be injected onto the rotating tool of a machine tool. Furthermore, in the injected liquid, the fine bubbles rotate vertically in the direction in which each column extends.

[0014] In the liquid injection device according to the above embodiment, when each of the plurality of columns is designated as a first column, a configuration may be adopted in which a second column is further provided on the side of the receiving port side of the region in the gradual tapering portion within the casing where the plurality of first columns are arranged, extends in a direction opposite to 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 first wall.

[0015] In the liquid injection device according to the above embodiment, a second column is provided within the casing in addition to the first column, and the second column is configured to extend in a direction intersecting the direction in which the first column extends (the opposing direction of the second walls). As a result, the liquid is straightened as it passes through the portion where the second column is provided. Therefore, the straightened liquid is supplied to the portion of the casing where the first column is provided, making it possible to generate fine bubbles moving in the same direction as vortices (flip-flop phenomenon). For this reason, the injected liquid adheres to the surface of the rotating tool (coander effect), and when it collides with the surface of the rotating tool, the bubbles are more likely to burst (cavitation phenomenon), making it suitable for cooling and cleaning the rotating tool.

[0016] In the liquid injection device according to the above embodiment, the first column and the second column may both be cylindrical columns, wherein the first column has an outer diameter of 0.4 mm to 6.0 mm, and the second column has an outer diameter of 0.4 mm to 10.0 mm.

[0017] In the liquid injection device according to the above embodiment, since the outer diameters of the first column and the second column are set within the above range, a liquid containing fine bubbles can be injected onto the target rotating tool.

[0018] In the liquid injection device according to the above embodiment, the plurality of first columns may be arranged such that the pitch between adjacent first columns in the direction opposite to the first walls is narrower than the pitch between adjacent first columns in the direction connecting the receiving port and the injection port.

[0019] In the liquid injection device according to the above embodiment, 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 direction connecting them, so that fine bubbles can be efficiently generated while suppressing an increase in losses within the casing.

[0020] In the liquid injection device according to the above embodiment, when the portion of the tapering portion containing the plurality of first columns is designated as the first tapering portion and the portion of the tapering portion containing the second column is designated as the second tapering portion in the direction connecting the receiving port and the injection port, the tapering portion of the casing may be configured such that the degree of tapering of the distance between the inner wall surfaces of the second wall is greater in the second tapering portion than in the first tapering portion.

[0021] In the liquid injection device according to the above embodiment, the casing is configured such that the degree of reduction is greater in the second reduction section than in the first reduction section. This allows the static pressure of the liquid passing through the second reduction section to be sufficiently low, thereby efficiently generating fine bubbles within the first reduction section.

[0022] In the liquid injection device according to the above embodiment, the machine tool is a grinding device, the rotating tool is a disc-shaped grinding wheel, and the liquid injection device may be further equipped with an air layer removal unit that is attached to the casing so as to be located upstream of the location of the injection port in the rotational direction of the grinding wheel, and that contacts or is close to the outer circumferential surface and both sides of the grinding wheel to remove the air layer around the grinding wheel.

[0023] In the liquid injection device according to the above embodiment, an air layer removal unit is further provided, so that the liquid is injected onto the outer surface of the grinding wheel (rotating tool) with the air layer on the outer surface removed. Therefore, in the liquid injection device according to the above embodiment, the liquid containing fine bubbles injected from the nozzle opening can reach the outer surface of the grinding wheel without being repelled, and can adhere to the outer surface of the grinding wheel (Coander effect).

[0024] Here, the configuration in which the air layer removing part removes not only the outer peripheral surface of the grindstone but also the air layers on both side surfaces is considered in view of the fact that the rotating tool in the grinding device moves in the width direction of the grindstone (the direction connecting the side surfaces), and it is also for suppressing the formation of an air layer again on the outer peripheral surface by the air that has moved from the side surface during the movement. As a result, the liquid can be efficiently wound around the outer peripheral surface of the grindstone.

Effects of the Invention

[0025] The liquid injection device according to each of the above aspects can inject a liquid containing fine bubbles onto the rotating tool of the machine tool, and can achieve downsizing of the device size and reduction of the manufacturing cost.

Brief Description of the Drawings

[0026] [Figure 1] It is a diagram showing the configuration of the liquid injection device according to the embodiment. [Figure 2] It is a diagram showing the configuration of the liquid injection device, where (a) is a side view, (b) is a plan view, and (c) is a front view. [Figure 3] It is a diagram showing the configuration of the nozzle, where (a) is a cross-sectional view taken from the side, and (b) is a cross-sectional view taken from above. [Figure 4] It is a cross-sectional view showing the arrangement form of the bubble generation column in the casing. [Figure 5] It is a schematic diagram showing the ejection flow ejected from the nozzle. [Figure 6] It is a diagram showing the arrangement form of the air layer removing part with respect to the grindstone. [Figure 7] (a) is a diagram showing the state where the ejection flow collides with the outer peripheral surface of the grindstone, and (b) is a diagram showing the state of the ejection flow when the air layer removing part is not provided. [Figure 8] (a) is a side view showing the configuration of the liquid injection device according to Modification 1, and (b) is a side view showing the configuration of the liquid injection device according to Modification 2. [Figure 9](a) is a cross-sectional view showing the configuration of the column in the nozzle of the liquid injection device according to Modification 3, and (b) is a cross-sectional view showing the configuration of the column in the nozzle of the liquid injection device according to Modification 4. [Modes for carrying out the invention]

[0027] Embodiments of the present invention will be described below with reference to the drawings. The embodiments described below are illustrative examples of the present invention, and the present invention is not limited to these embodiments except for its essential configuration.

[0028] [Embodiment] 1. Arrangement configuration of liquid injection device 1 The arrangement of the liquid injection device 1 according to this embodiment will be explained with reference to Figure 1.

[0029] As shown in Figure 1, the liquid injection device 1 is a device that injects grinding fluid (liquid) onto the grinding wheel (rotating tool) 21 of the grinding machine (machine tool) 20, and is positioned adjacent to the grinding wheel 21. The liquid injection device 1 is connected to a liquid storage tank 2 via a pump 3, piping 4, flexible piping 5, and an on / off valve 6.

[0030] The liquid storage tank 2 is a tank for storing grinding fluid and is the source of the grinding fluid (liquid). The pump 3 sends grinding fluid from the liquid storage tank 2 to the liquid injection device 1. The on / off valve 6 is a valve that can be closed to stop the injection of grinding fluid to the grinding wheel 21 when the grinding device 20 is stopped, and opened when the grinding device 20 is in operation. The flexible piping 5 is provided so that the position of the injection of grinding fluid to the grinding wheel 21 can be adjusted to position the liquid injection device 1 in the desired position.

[0031] Furthermore, the grinding wheel 21 rotates in the direction indicated by the arrow and moves relative to the table on which the workpiece is placed in a direction perpendicular to the plane of the paper in Figure 1.

[0032] 2. Configuration of Liquid Injection Device 1 The configuration of the liquid injection device 1 will be explained using Figure 2.

[0033] As shown in Figures 2(a) and (b), the liquid injection device 1 comprises a nozzle 11 and an air layer removal unit 12. The nozzle 11 has a receiving portion 11f on one side in the X direction and an injection portion 11g on the other side in the X direction. As shown in Figure 2(a), the nozzle 11 has a tip portion 11a, an intermediate portion 11b, a base portion 11c, and a connecting portion 11d, which are arranged from the side of the injection portion 11g toward the side of the receiving portion 11f. The tip portion 11a, intermediate portion 11b, base portion 11c, and connecting portion 11d are integrally formed.

[0034] The tip portion 11a and the intermediate portion 11b have a truncated square pyramidal shape. The base portion 11c has a rectangular cylindrical shape. The connecting portion 11d is the part to which the flexible pipe 5 is connected and has a cylindrical shape.

[0035] As shown in Figure 2(b), the nozzle 11 has two walls in the Y direction that are parallel to each other. That is, when the nozzle 11 is viewed from the Z direction in a plan view, the portion of the nozzle 11 excluding the receiving portion 11f has a rectangular shape.

[0036] As shown in Figure 2(c), the injection section 11g has an opening that is elongated in the Y direction and flattened in the Z direction, forming a rectangular shape. The injection section 11g has a smaller opening area than the opening formed in the receiving section 11f. Note that the opening shape of the injection section 11g is not limited to a rectangular shape, but may also be oval or other shapes.

[0037] The air layer removal section 12 comprises a partition plate 121 made of a material with lower hardness than the grinding wheel 21 (see Figure 1) (for example, styrene board), and support plates 122 and 123 made of metal or the like, which are arranged to sandwich the partition plate 121 in the thickness direction. The air layer removal section 12 also includes bolts 124 for attachment to the nozzle 11.

[0038] As shown in Figure 2(a), the air layer removal section 12 extends upward (outward) in the Z direction from the upper end of the nozzle 11 in the Z direction. Also, as shown in Figure 2(b), the partition plate 121 and support plates 122, 123 of the air layer removal section 12 each have recessed portions 121a, 123a configured to be recessed 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 their width W1, and are configured so as not to come into contact with the grinding wheel 21.

[0039] 3. Detailed configuration of nozzle 11 The detailed configuration of nozzle 11 will be explained using Figure 3.

[0040] As shown in Figure 3, the nozzle 11 comprises a casing 111 that constitutes the outer shell of the nozzle 11, a plurality of flow straightening columns (second columns) 112 disposed within the casing 111, and a plurality of bubble generating columns (first columns) 113 also disposed within the casing 111.

[0041] The casing 111 has a rectangular tube shape composed of an upper wall 111a, a lower wall 111b, side walls 111c and 111d, and a cylindrical wall 111e. An inlet 111f is opened at one end in the X direction, and an injection port 111g is opened at the other end. That is, the receiving portion 11f of the nozzle 11 has an inlet 111f, and the injection portion 11g has an injection port 111g.

[0042] In this embodiment, the lower wall 111b is a flat wall portion and is formed to extend in the X and Y directions.

[0043] On the other hand, as shown in Figure 3(a), the upper wall 111a, which is positioned opposite the lower wall 111b in the Z direction, is configured with an inclined wall in the tip portion 11a and the intermediate portion 11b 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 side of the inlet 111f toward the side of the injection port 111g. 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 tapering portion in the tip portion 11a and the intermediate portion 11b, configured such that the cross-sectional size in the liquid flow path gradually decreases from the side of the inlet 111f toward the side of the injection port 111g.

[0044] The upper wall 111a is formed such that it has an inclination angle θ1 at the tip portion 11a and an inclination angle θ2 at the intermediate portion 11b (see Figure 2). In this embodiment, the casing 111 is configured such that the inclination angle θ2 of the part constituting the outer shell of the intermediate portion 11b (second gradually tapering portion) is larger than the inclination angle θ1 of the part constituting the outer shell of the tip portion 11a (first gradually tapering portion). In other words, the casing 111 is configured such that the degree of gradual reduction in the flow path size from the inlet 111f side to the injection port 111g side is greater in the second gradually tapering portion than in the first gradually tapering portion. Note that the inclination angles θ1 and θ2 are the angles made between the upper wall 111a and the lower wall 111b.

[0045] Multiple bubble-generating columns 113 are housed within a casing 111 at the tip 11a. Each of the multiple bubble-generating columns 113 is configured to extend in the opposing direction (Z direction) between the upper wall 111a and the lower wall 111b. One end of each of the multiple bubble-generating columns 113 is connected to the inner wall surface of the upper wall 111a, and the other end is connected to the inner wall surface of the lower wall 111b. As shown in Figure 3(b), the multiple bubble-generating columns 113 are arranged in a staggered pattern when viewed from the Z direction in plan view.

[0046] A plurality (in this embodiment, for example, three) of rectifying columns 112 are accommodated in the casing 111 in the intermediate portion 11b. 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. The side wall 111c and the side wall 111d are arranged parallel to each other, and the inner wall surfaces are also parallel to each other.

[0047] As shown in FIG. 3(a), 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) In addition, 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 intermediate portion 11b.

[0048] Also, each of the plurality of rectifying columns 112 is configured to have an outer diameter of 0.4 mm to 10.0 mm. The outer diameter of the rectifying column 112 is set corresponding to the width of the grindstone 21, and it becomes larger as the width of the grindstone 21 is wider. In this embodiment, as an example, the outer diameter of each rectifying column 112 is φ1.6 mm.

[0049] 4. Arrangement form of the plurality of bubble generation columns 113 The arrangement form of the plurality of bubble generation columns 113 will be described using FIG. 4.

[0050] As shown in Figure 4, the multiple bubble-generating columns 113 are distributed in a staggered pattern in a plan view. Assume a virtual plane Ln2 is located midway between the side walls 111c and 111d in the Y direction, at a point W3 between them, and extending in the Z direction (the direction perpendicular to the plane of the paper in Figure 4), parallel to the side walls 111c and 111d. In this case, the multiple bubble-generating columns 113 are arranged in a plane-symmetric relationship with respect to the virtual plane Ln2.

[0051] In the multiple bubble-generating columns 113, adjacent bubble-generating columns 113 in the X direction are arranged with a pitch W4.

[0052] Furthermore, in the X direction, the multiple bubble-generating columns 113 are positioned inward in the X direction from a distance L4 from the injection port 111g. In the multiple bubble-generating columns 113, adjacent bubble-generating columns 113 in the Y direction are positioned with a pitch L5.

[0053] In this embodiment, a plurality of bubble-generating columns 113 are arranged such that the pitch W4 and 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.

[0054] Each of the multiple bubble-generating columns 113 has an outer diameter of 0.4 mm to 6.0 mm. The outer diameter of the bubble-generating column 113 is set to correspond to the width of the grinding wheel 21, and becomes larger as the width of the grinding wheel 21 increases. In this embodiment, as an example, the outer diameter of each bubble-generating column 113 is set to φ1.6 mm.

[0055] 5. The ejected flow JS from nozzle 11 The ejected flow JS from the nozzle 111g (injection section 11g) of the nozzle 11 of the liquid injection device 1 according to this embodiment will be explained with reference to Figure 5.

[0056] The ejected stream JS, which is sprayed from the nozzle 11's nozzle opening 111g toward the outer surface of the grinding wheel 21 (see Figure 1) as indicated by arrow B1, contains fine bubbles. This is because, as described above, the casing 111 has tapering sections (parts constituting the tip section 11a and the intermediate section 11b), and multiple bubble-generating columns 113 are arranged at the tip section 11a.

[0057] As shown in Figure 5, the fine bubbles contained in the jet stream JS form a longitudinal vortex that rotates around an axis along the Y direction (the direction perpendicular to the plane of the paper in Figure 5), which is perpendicular to both the injection direction (X direction) and the direction in which the bubble generation column 113 extends (Z direction) (arrow B2). As a result, when the jet stream JS collides with the outer surface of the grinding wheel 21, the fine bubbles cling to the outer surface of the grinding wheel 21 (Coander effect), and the fine bubbles burst efficiently upon impact with the outer surface of the grinding wheel 21 (cavitation phenomenon).

[0058] 6. Removal of air layer AL by air layer removal unit 12 The liquid injection 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 explained with reference to Figures 6 and 7.

[0059] During operation, the grinding wheel 21 of the grinding device 20 rotates in the direction indicated by the arrow in Figure 1 and moves relative to the workpiece in the width direction of the grinding wheel 21 (arrow C in Figure 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 maintains a constant relative position to the grinding wheel 21.

[0060] As described above, the partition plate 121 of the air layer removal section 12 has a recessed portion 121a formed to conform to the shape of the grinding wheel 21. The grinding surface contact portion 121b, which is the bottom of the recessed portion 121a, is positioned to contact the outer circumferential surface (grinding surface) 21a of the grinding wheel 21. However, it is not necessarily required that the grinding surface contact portion 121b of the partition plate 121 contact the grinding surface 21a of the grinding wheel 21, and it may be positioned close to the grinding surface 21a with virtually no gap.

[0061] Furthermore, the partition plate 121 is positioned so that the side contact portions 121c, which are the sides of the recessed portion 121a, contact a part of the side surface 21c of the grinding wheel 21 (the portion that continues from the grinding surface 21a with respect to the corner). However, it is not necessarily required that the side contact portions 121c of the partition plate 121 contact the side surface 21b of the grinding wheel 21; they may be close to the side surface 21b with virtually no gap.

[0062] Here, since the partition plate 121 is made of a softer material than the grinding wheel 21, even if it comes into contact with the grinding surface 21a and side surface 21b of the grinding wheel 21, it prevents scratches from being made on the grinding surface 21a and side surface 21b of the grinding wheel 21.

[0063] Although detailed illustrations are omitted, the liquid injection device 1 is configured to allow adjustment of the position of the air layer removal unit 12 relative to the casing 111. This allows for adjustment of the position of the air layer removal unit 12 relative to the grinding wheel 21 before operation of the grinding device 20 or at the start of operation, so that the partition plate 121 comes into contact with the grinding wheel 21.

[0064] As shown in Figure 1, the air layer removal unit 12 is positioned upstream of the location of the nozzle 11's jet section 11g in the rotational direction of the grinding wheel 21 (indicated by the arrow in Figure 1). Therefore, as shown in Figure 7(a), the jet stream JS ejected from the nozzle 11's jet section 11g can coat the grinding surface 21a of the grinding wheel 21, which is in a state where the air layer has been removed (Coander effect).

[0065] Furthermore, the air layer removal unit 12 also removes some of the air layer on the side surface 21b of the grinding wheel 21, so even if the grinding wheel 21 moves in the width direction, air is prevented from flowing from the side surface 21b to the grinding surface 21a. Therefore, with the liquid spray device 1 equipped with the air layer removal unit 12 as described above, the jet stream JS can be reliably sprayed onto the grinding surface 21a of the grinding wheel 21, and the cooling and cleaning of the grinding wheel 21 can be effectively achieved.

[0066] In contrast, as shown in Figure 7(b), if the air layer removal unit 12 is not provided, an air layer AL exists on the grinding surface 21a and side surface 21b of the grinding wheel 21, and the ejected flow JS is sprayed toward this air layer AL. In this case, as indicated by arrow D, a portion of the ejected flow JS is prevented from reaching the grinding surface 21a by the air layer AL covering the grinding surface 21a.

[0067] Furthermore, even if the air layer AL on the grinding surface 21a is removed by the jet stream JS, the air remaining on the surface of the side 21b will flow back onto the grinding surface 21a due to the relative movement of the grinding wheel 21 with respect to the workpiece, as indicated by arrow C. For this reason, in the comparative example shown in Figure 7(b), it is conceivable that cooling and cleaning of the grinding wheel 21 will be more difficult than in this embodiment.

[0068] 7. Effects In the liquid injection device 1 according to this embodiment, the casing 111 of the nozzle 11 has a tapering portion in which the cross-sectional size in the liquid flow path gradually decreases from the inlet 111f side to the injection port 111g side. As a result, the static pressure of the liquid delivered from the inlet 111f side to the injection port 111g side of the casing 111 decreases. By configuring the tapering portion so that the static pressure of the liquid reaches the saturated vapor pressure, a cavitation phenomenon can be generated in the liquid.

[0069] Furthermore, in the liquid injection device 1, multiple bubble-generating columns 113 are provided in the tapering portion of the casing 111, arranged in a staggered pattern in a plan view. These multiple bubble-generating columns 113 form a mesh-like flow path. As a result, the liquid delivered to the portion of the casing 111 where the multiple bubble-generating columns 113 are provided (the tip portion 11a) repeatedly splits and merges, generating numerous minute vortices through a flip-flop phenomenon.

[0070] Therefore, in the liquid injection device 1, since the nozzle 11 itself can generate fine bubbles, there is no need to provide a fluid supply pipe separately from the nozzle for bubble generation, as in the above-mentioned Patent Document 1, making it possible to achieve a more compact device size and reduced manufacturing costs.

[0071] Furthermore, in the liquid injection device 1, each bubble-generating column 113 is configured to extend in a direction perpendicular to the direction (Z direction) of the X direction connecting the inlet 111f and the injection port 111g, so that multiple bubble-generating columns 113 are arranged in parallel 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, cavitation and flip-flop phenomena can be efficiently generated in the liquid within the casing 111 of the nozzle 11, and a liquid containing fine bubbles can be injected onto the grinding wheel 21 of the grinding device 20. In addition, 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.

[0072] Furthermore, the liquid injection device 1 is equipped with three flow straightening columns 112 within the casing 111 in the intermediate section 11b. These flow straightening columns 112 are configured to extend in the Y direction, which intersects with the direction in which the bubble generation column 113 extends (Z direction). As a result, the liquid is straightened as it passes through the section (intermediate section 11b) where the flow straightening columns 112 are provided. Therefore, straightened liquid is supplied to the tip section 11a within the casing 111 where the bubble generation column 113 is provided, enabling the generation of fine bubbles moving in the same direction as vortices (flip-flop phenomenon). Consequently, the liquid injected from the injection section 11g adheres to the grinding surface (outer surface) 21a of the grinding wheel 21 (Coander effect), and when it collides with the grinding surface 21a, the bubbles are more likely to burst (cavitation phenomenon), making it suitable for cooling and cleaning the grinding wheel 21.

[0073] Furthermore, in the liquid injection device 1, the outer diameter of the bubble generation column 113 is set to a 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 set to 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.

[0074] Furthermore, in the liquid injection device 1, multiple bubble-generating columns 113 are arranged to satisfy the above relation (2), so that fine bubbles can be efficiently generated while suppressing an increase in the loss of liquid flowing through the casing 111.

[0075] 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 intermediate section 11b than in the tip section 11a. This allows the static pressure of the liquid passing through the casing 111 in the intermediate section 11b to be sufficiently low, enabling the efficient generation of fine bubbles within the casing 111 at the tip section 11a.

[0076] Furthermore, the liquid injection device 1 is further equipped with an air layer removal unit 12, so that the air layer AL on the grinding surface (outer surface) 21a is removed before the liquid is injected onto the outer surface 21a of the grinding wheel 21. Therefore, the liquid injection device 1 can ensure that the liquid containing fine bubbles injected from the injection unit 11g of the nozzle 11 reaches the grinding surface 21a of the grinding wheel 21 without being repelled, and can adhere to the grinding surface 21a of the grinding wheel 21 (Coander effect).

[0077] Furthermore, since the air layer removal unit 12 is configured to remove the air layer AL not only from the outer circumferential surface 21a of the grinding wheel 21 but also from the air layers AL on both sides 21b, it is possible to suppress the air on the sides 21b from flowing onto the grinding surface (outer circumferential surface) 21a even when the grinding wheel 21 moves in the width direction. This makes it possible to efficiently coat the outer circumferential surface 21a of the grinding wheel 21 with liquid.

[0078] 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 achieve a compact device size and reduced manufacturing costs.

[0079] [Example 1] The liquid injection device 7 according to Modification 1 will be explained using Figure 8(a).

[0080] As shown in Figure 8(a), the liquid injection device 7 according to this modified example is equipped only with a nozzle 11 and does not have an air layer removal unit 12. This is the difference from the above embodiment.

[0081] The liquid injection device 1 according to the above embodiment is a device that injects liquid (grinding fluid) onto the grinding wheel 21 of the grinding device 20, and includes an air layer removal unit 12 for removing the air layer AL formed on the grinding surface 21a of the grinding wheel 21. In contrast, the liquid injection device 7 according to this modified example is a device that is applied when an air layer is not formed on the surface of the rotating tool, or even if it is formed, it does not pose a problem for spraying the liquid. For example, it can be installed on machine tools such as machining centers, NC lathes, and lathes.

[0082] Furthermore, since the liquid injection device 7 according to this modified example has the same configuration as the above embodiment except that it does not have an air layer removal unit 12, the same effects as the above embodiment can be obtained with respect to the nozzle 11.

[0083] [Differentiation 2] The liquid injection device 8 according to the modified example 2 will be explained using Figure 8(b).

[0084] As shown in Figure 8(b), the liquid injection device 8 according to this modified example includes a nozzle 81. The nozzle 81 includes a casing 811. In this modified example, the configuration of the casing 811 differs from that of the above embodiment. Although the air layer removal section 12 is not shown in Figure 8(b), the liquid injection device 8 may include an air layer removal section 12 as in the above embodiment, or it may not include one as in the above modified example 1.

[0085] Unlike the above embodiment, the casing 811 does not have a flat lower wall 811b. Specifically, at the tip portion 81a and the intermediate portion 81b of the nozzle 81, the lower wall 811b is configured to be inclined toward the upper wall 811a.

[0086] In the casing 811, the upper wall 811a is configured to be inclined at the tip portion 81a and the intermediate portion 81b, similar to the embodiment described above, and in addition to the inclination of the upper wall 811a, the lower wall 811b is also configured to be inclined.

[0087] 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 such that the cross-sectional size of the liquid flow path gradually decreases from the inlet 811f side to the injection port 811g side.

[0088] 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 being used and does not affect the workspace.

[0089] The liquid injection device 8 according to this modified example has the same configuration as the above embodiment and the above modified example 1, except that the configuration of the casing 811 is different, and therefore the same effects as the above embodiment and the like can be obtained.

[0090] [Difference 3] The liquid injection device according to Modification 3 will be explained using Figure 9(a). Note that Figure 9(a) only shows the column 212 which can be used as the bubble generation column 113 or flow straightening column 112 in the above embodiment. The liquid injection device according to this modification can adopt the same configuration as the above embodiment and Modifications 1 and 2, except for the column 212.

[0091] As shown in Figure 9(a), the column 212 of this modified example has an elliptical or oblong cross-sectional shape. In this respect, it differs from the above embodiment, which employs a bubble-generating column 113 and a flow-rectifying column 112 having a circular cross-sectional shape.

[0092] In the liquid injection device according to this modified example, the column 212 shown in Figure 9(a) is used as at least one of the bubble-generating column and the flow-rectifying column. However, since this modified example employs the same configuration as the above embodiment, except for the cross-sectional shape of the column 212, the same effects as the above embodiment can be obtained.

[0093] Furthermore, when the column 212 is used as a bubble-generating column or a flow-rectifying column, the orientation of the long axis of the cross-section relative to the liquid flow direction (the direction connecting the inlet 111f and the injection port 111g) can be determined by considering the relationship between the generation of fine bubbles, the flow-rectifying effect, and the flow resistance.

[0094] [Differentiation Example 4] The liquid injection device according to Modification 4 will be explained using Figure 9(b). Note that Figure 9(b) only shows the column 312 which can be used as the bubble generation column 113 or flow straightening column 112 in the above embodiment. The liquid injection device according to this modification can adopt the same configuration as the above embodiment and Modifications 1 and 2, except for the column 312.

[0095] As shown in Figure 9(b), the column 312 of this modified example has a rounded quadrilateral (rounded square, rounded rectangle) cross-sectional shape. In this respect, it differs from the above embodiment and modified examples 1 and 2, which employ a bubble-generating column 113 and a flow-rectifying column 112 having a circular cross-sectional shape, and from modified example 3, which employs a column 212 having an elliptical or other cross-sectional shape.

[0096] In the liquid injection device according to this modified example, the column 312 shown in Figure 9(b) is used as at least one of the bubble-generating column and the flow-rectifying column. However, since this modified example employs the same configuration as the above embodiment, except for the cross-sectional shape of the column 312, the same effects as the above embodiment can be obtained.

[0097] Furthermore, when the column 312 is used as a bubble-generating column or a flow-rectifying column, the orientation of the corners in the cross-section relative to the liquid flow direction (the direction connecting the inlet 111f and the injection port 111g) can be determined by considering the relationship between the generation of fine bubbles, the flow-rectifying effect, and the flow resistance.

[0098] [Other variations] The fine bubbles contained in the liquid sprayed from the liquid spraying devices 1, 7, and 8 in the above embodiments, although not specifically mentioned above, refer to bubbles smaller than 100 μm as defined in ISO 20480-1. Fine bubbles include microbubbles of 1 μm or larger and ultrafine bubbles of less than 1 μm, but in the above embodiments, both particle sizes may be included, or only microbubbles among the fine bubbles may be included.

[0099] Furthermore, in the above embodiment, a liquid injection device 1 in which an air layer removal unit 12 is attached to a nozzle 11 was used as an example. However, even when attached to a grinding wheel 21 of a grinding device 20, it is not necessary to attach the air layer removal unit 12 to the nozzle 11. For example, if an existing grinding device 20 already has an air layer removal unit 12 attached separately, it is not necessary to attach a liquid injection device 1 that also includes an air layer removal unit 12. In this case, the liquid injection device 7 according to the above modified example 1 can be used.

[0100] Furthermore, in the above embodiment, a grinding device 20 was used as an example of the target machine tool, and therefore grinding fluid (coolant) was used as the liquid sprayed from the liquid spraying device 1. However, the type of liquid sprayed from the liquid spraying device can be appropriately selected depending on the type of machine tool.

[0101] Furthermore, while the above embodiments and modifications 1 and 2 employ columns 112 and 113 with circular cross-sections, modification 3 employs a column 212 with an oval cross-section, and modification 4 employs a column 312 with a rounded quadrilateral cross-section, the present invention is not limited to these cross-sectional shapes of the columns. For example, columns with triangular, pentagonal, or more polygonal cross-sections can also be employed. [Explanation of Symbols]

[0102] 1,7,8 Liquid injection device 2 Liquid storage tank (supply source) 11.81 nozzles 12 Air layer removal section 20. Grinding equipment (machine tools) 21. Grinding wheels (rotary tools) 111 Casing 112 Rectifying column (2nd column) 113 Bubble-generating column (first column) 121 Partition Plate

Claims

1. A liquid injection device equipped with a nozzle for spraying liquid onto a rotating tool of a machine tool, The aforementioned nozzle is A cylindrical casing having an inlet at one end for receiving the liquid from a supply source and an injection port at the other end for injecting the liquid containing fine bubbles, Multiple columns arranged side by side within the casing, Equipped with, The casing has a tapering portion between the receiving port and the injection port in which the cross-sectional size of the liquid flow path gradually decreases from the receiving port side to the injection port side. The plurality of columns are arranged within the tapering portion of the casing and are arranged in a staggered pattern when viewed from the direction in which the columns extend. Liquid injection device.

2. In a cross-section perpendicular to the direction connecting the inlet and the nozzle, the casing is formed in a rectangular shape in which the liquid flow path is surrounded by four inner wall surfaces. The four inner wall surfaces are composed of two inner wall surfaces of a first wall, which are arranged opposite each other so as to be parallel to each other, and two inner wall surfaces of a second wall, which are arranged opposite each other so as to be gradually separated in the tapering portion from the receiving end side to the injection port side. Each of the plurality of columns 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 second wall. The liquid injection device according to claim 1.

3. When each of the aforementioned plurality of columns is designated as the first column, The casing further comprises a second column provided on the side of the receiving opening rather than the region in the tapering portion within the casing where the plurality of first columns are arranged, extending in a direction opposite to the first walls, with 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 first wall. The liquid injection device according to claim 2.

4. The first and second prisms are both cylindrical prisms, The first column has an outer diameter of 0.4 mm to 6.0 mm. The second column has an outer diameter of 0.4 mm to 10.0 mm. The liquid injection device according to claim 3.

5. The plurality of first columns are arranged such that the pitch between adjacent first columns in the direction opposite to the first walls is narrower than the pitch between adjacent first columns in the direction connecting the receiving port and the injection port. The liquid injection device according to claim 3.

6. In the direction connecting the receiving port and the injection port, when the portion of the tapering portion in which the plurality of first columns are housed is designated as the first tapering portion, and the portion of the tapering portion in which the second column is housed is designated as the second tapering portion, The tapering portion of the casing is configured such that the degree of tapering of the distance between the inner wall surfaces of the second wall is greater in the second tapering portion than in the first tapering portion. The liquid injection device according to claim 3.

7. The aforementioned machine tool is a grinding device, The aforementioned rotating tool is a grinding wheel having a disc shape, The liquid injection device is mounted on the casing so as to be located upstream of the location of the injection nozzle in the rotational direction of the grinding wheel, and further comprises an air layer removal unit that contacts or is in close proximity to the outer circumferential surface and both sides of the grinding wheel to remove the air layer around the grinding wheel. A liquid injection device according to any one of claims 1 to 6.

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