JP2007203235A - In-liquid water jetting apparatus and cavitation eliminator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an in-liquid water jetting apparatus capable of controlling or eliminating cavitation force without inviting an increase in cost and cycle time, and a cavitation eliminator used for the same. <P>SOLUTION: The in-liquid water jetting apparatus comprises a main body having a through channel into which a high-pressure fluid pressurized by a pressurizing means is introduced and a jet nozzle fitted in the leading end channel of the main body for jetting the high-pressure liquid. A ring-like cavitation eliminator having an orifice with a predetermined diameter is installed on a position upstream of the jet nozzle within the channel of the main body. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a submerged water jet ejecting apparatus that utilizes a cavitation force generated by ejecting a water jet in a liquid, and more particularly, to a device equipped with a cavitation eraser for eliminating the cavitation effect.

  In many cases, a device that uses underwater water jet injection in a cleaning device or the like uses a cavitation effect. This utilizes an impact force when bubbles (cavitation) generated in a fluid due to a pressure drop locally caused by a flow velocity change in a high-speed fluid disappear in a high-pressure portion (for example, see Patent Document 1). .)

  However, this cavitation force has a very strong destructive force, and in some cases, the surface to be cleaned may be damaged. In order to weaken the cavitation force, conventionally, methods such as lowering the injection pressure or increasing the distance from the workpiece have been used.

Japanese Patent Laid-Open No. 4-43712

  However, in order to reduce the injection pressure in order to weaken the cavitation force, a pressure reducing circuit for reducing the pressure is separately provided for the flow path from the pressure generation source such as a pump, or the generated pressure is reduced. It becomes necessary to install another low pump, and the device design becomes complicated.

  Also, when trying to solve the problem by reducing the distance from the workpiece to reduce the cavitation force, it is necessary to consider a route that is separate from the normal workpiece or nozzle movement route. In the case of the two types, the tact time is increased.

  In view of the above-described problems, an object of the present invention is to provide an underwater water jet injection device capable of suppressing or eliminating cavitation force without causing an increase in cost and tact time, and a cavitation eraser used therefor.

  In order to achieve the above object, a submerged water jet injection device according to the first aspect of the present invention includes a main body including a through channel into which a high-pressure fluid pressurized through a pressurizing unit is introduced, In a submerged water jet injection device comprising: an injection nozzle that is fitted in a front-end flow channel of the main body and injects the high-pressure fluid; and has a predetermined diameter at a position upstream of the injection nozzle in the main body flow channel. A ring-shaped cavitation eraser having an orifice is provided.

  A submerged water jet injection device according to the invention described in claim 2 is the submerged water jet injection device according to claim 1, wherein the cavitation eliminating device is detachably mounted in the main body flow path. It is.

  A submerged water jet injection device according to the invention of claim 3 is the submerged water jet injection device according to claim 1, wherein the cavitation eliminating device is provided integrally with the injection nozzle. is there.

  A submerged water jet injection device according to a fourth aspect of the invention is the submerged water jet injection device according to any one of the first to third aspects, wherein the orifice diameter of the cavitation eraser is the orifice of the injection nozzle. It is characterized by being 1 to 1.7 times the aperture.

  A submerged water jet injection device according to a fifth aspect of the present invention is the submerged water jet injection device according to the first or second aspect, wherein the cavitation eliminating device is disposed at the end of the injection nozzle orifice. The position is within a distance range of 1 to 4 times the inner diameter of the main body channel.

  According to a sixth aspect of the present invention, there is provided a cavitation eliminator that introduces a high-pressure fluid supplied under pressure through a pressurizing means into a main body through-flow path and fits into a front-end flow path of the main body. The submerged water jet spraying device that sprays from the spray nozzle is detachably mounted at a position upstream of the spray nozzle in the main body flow path, and includes a ring-shaped member having an orifice with a predetermined diameter.

  The cavitation eraser according to the invention described in claim 7 is the cavitation eraser according to claim 6, wherein the orifice diameter of the ring-shaped member is not less than 1 time and not more than 1.7 times the orifice diameter of the injection nozzle. It is characterized by being.

  In the present invention, since a ring-shaped cavitation eraser having an orifice with a predetermined diameter is provided upstream of the injection nozzle in the main body flow path of the apparatus, the cost and tact time are increased. Water jet injection device equipped with this cavitation erasing device when it is possible to obtain a submerged water jet injection device that does not generate erosion even though it has a simple device configuration and does not require a cavitation effect such as a rinsing process By using this, it is possible to suppress the occurrence of cavitation and avoid damage to the workpiece.

  In the submerged water jet injection device according to the first aspect of the present invention, the submerged water jet that does not generate erosion only by providing a cavitation eliminator having a simple structure at the upstream side of the injection nozzle in the main body flow path. When a jet injection device can be obtained and a cavitation effect such as a rinsing process is not required, the use of a water jet injection device equipped with this cavitation eraser can suppress the occurrence of cavitation and avoid damage to the workpiece. It is possible.

  In addition, if this cavitation eraser is removable, it is possible to selectively use a state that generates erosion and a state that does not generate erosion during water jet injection in liquid. When cavitation effects such as strong dirt cleaning and deburring are required, water jet injection without cavitation eraser is used to maximize the cavitation effect and does not require rinsing process and other cavitation effects. In this case, it is possible to prevent damage to the work by suppressing the occurrence of cavitation by water jet injection with the cavitation erasing device attached.

  The cavitation eraser in the present invention as described above is composed of a ring-shaped member provided with an orifice having a predetermined diameter arranged upstream of the injection nozzle in the main body flow path of the injection device. The cavitation eliminating action by this member functions as follows.

  That is, when high-pressure fluid passes through the orifice of the cavitation eraser upstream of the injection nozzle, cavitation occurs near the inlet of the orifice, but the space after passing through the orifice is upstream of the cavitation eraser. Since the pressure is almost the same as the side pressure, the generated cavitation collapses without growing. Even when the occurrence of cavitation is not considered, the fluid after passing through the orifice portion is a ring-like vortex flow, and a flow (secondary flow) in a direction perpendicular to the flow axis is an excellent flow.

  A high pressure at the time of collapse is generated from cavitation that collapses after passing through the orifice, and the secondary flow component is further accelerated by this generated pressure. The flow that has reached the orifice of the injection nozzle with the secondary flow component prevailing becomes a radial flow that spreads greatly in the radial direction when injected from the nozzle, and the flow velocity in the radial direction cancels out the axial flow velocity of the jet flow. Become. As a result, the high shear layer with the fluid around the jet is not strongly formed, and the occurrence of cavitation due to the high shear layer is also weakened.

  The cavitation elimination effect as described above becomes more pronounced as the orifice diameter becomes smaller as will be described later in the examples. When the orifice diameter is 1.7 times or less than the orifice diameter of the injection nozzle, the amount of erosion becomes zero and the nozzle orifice diameter is 1 Since it was confirmed that the erosion marks on the workpiece disappeared completely when the diameter was reduced to the same size (same diameter), the orifice diameter of the cavitation eraser in the present invention was 1 or more times the orifice diameter of the injection nozzle, 1 0.7 or less is preferable.

  In addition, when the cavitation eraser is detachably disposed in the through-flow passage of the main body, a member such as a high pressure socket or a bush for fixing the cavitation eraser between the injection nozzle and the high pressure water supply pipe is necessary. As a result, the through-flow passage is long with a certain length due to the presence of these members. Therefore, the arrangement position needs to be within a distance range in which a good cavitation effect can be secured within the relatively long through-flow passage.

  Therefore, as a result of examination in the examples described later, it has been found that if the cavitation eliminator is within a specific distance range in the through channel, the excellent cavitation erasing effect is maintained without being impaired. In the specific distance range, the distance from the injection nozzle is a distance of 1 to 4 times the inner diameter of the main body through flow path, and it is preferable to arrange the cavitation eraser within this distance range.

  On the other hand, when trying to install a cavitation eraser without changing the existing water jet injection device as much as possible, the injection nozzle and the supply pipe are directly connected without the intervention of parts such as a high-pressure socket or bush that can fix the cavitation eraser. There is a case where it is attached to the injection device. Thus, when a certain length cannot be ensured in a penetration channel, the arrangement position of a cavitation eliminator turns into the position immediately upstream of an injection nozzle.

  Therefore, as described in the examples below, the cavitation eliminator is arranged immediately upstream of the injection nozzle because the main body structure is directly connected to the injection nozzle and the high-pressure water supply pipe and the through flow path is extremely short. As a result of examining the cavitation elimination effect for the case, an excellent cavitation elimination effect can be obtained by appropriately setting the distance from the injection target and the orifice diameter of the cavitation elimination device.

  Therefore, since it is possible to dispose the injection nozzle immediately upstream, the cavitation eliminator is not limited to a configuration in which it is detachably disposed in the through flow passage of the main body, but is integrally formed on the upstream side of the injection nozzle. It can be set as the structure provided.

  In addition, since the cavitation eliminating device according to the present invention described in claim 6 is composed of a ring-shaped member mounted at the upstream position of the injection nozzle in the main body flow path of the submerged water jet injection device, the diameter dimension thereof is set. By simply setting as appropriate, it can be easily incorporated into an existing submerged water jet injection device to reduce or eliminate the cavitation force. Therefore, the cavitation erasing device may be attached only during operations that do not require cavitation force such as rinsing or the like other than during cleaning and deburring operations that require a normal strong cavitation effect.

  In order to obtain an excellent cavitation erasing effect, it is desirable that the orifice diameter of the cavitation eliminator is 1 to 1.7 times the orifice diameter of the injection nozzle.

  A submerged water jet spray device according to a first embodiment of the present invention is shown in the schematic block diagram of FIG. FIG. 1A is a side sectional view of a main body portion of the present injection device, and FIG. 1B is a schematic front view of a cavitation eraser mounted in the main body.

  The submerged water jet injection device 1 includes a main body 2 having a through-flow passage 3 having an inner diameter D into which a high-pressure fluid is introduced, and an orifice diameter that is fitted in the front-end flow passage of the main body 2 to inject high-pressure fluid. a high-pressure fluid pressurized by a pressurization device (not shown) via a high-pressure nipple 11 on the rear end side of the through flow path 3 is sent to the main body 2. The incoming supply pipe 12 is connected.

  In the present embodiment, a ring-shaped cavitation eraser 6 having an orifice 7 having a predetermined diameter is detachably mounted at a position upstream of the injection nozzle 4 in the through-flow passage 3 of the main body 2 to eliminate cavitation. The water jet can be jetted with or without the container 6.

  That is, the main body 2 of the injection device 1 is formed by fixing the bushes (8a, 8b) arranged on both sides with the spacer 9 interposed therebetween by the high-pressure socket 10, and the bush (8a, 8b), the spacer 9, The cavitation eraser 6 can be placed and fixed in the through-flow passage of the main body by sandwiching the cavitation eraser 6 between them, and each member is separated by removing the high-pressure socket 10 to remove the cavitation eraser 6 and remove the cavitation eraser. The main body 2 can be reassembled without being attached.

  Using the submerged water jet injection device 1 having the above-described configuration, the cavitation elimination effect of the cavitation eraser 6 is obtained when the mass defect amount and the erosion mark after jet injection on the aluminum plate are not provided (the injection device). The experimental results examined in comparison with Type 1) are shown below.

  The conditions in this experiment are as follows. For an injection pressure of 4 MPa currently used for general cavitation cleaning, the orifice diameter d of the injection nozzle 4 is 1.5 mm, and the diameter k of the orifice 7 of the cavitation eraser 6 is the nozzle orifice. The case of 1.5 mm, which is the same as the diameter d (injection device type 3), and the case of 2.5 mm (injection device type 2) were examined with an injection time of 30 minutes. The distance (standoff distance) from the outlet of the injection nozzle 4 to the aluminum plate (material: A1050) is based on 37.5 mm, which is the distance that is the maximum erosion amount in a conventional type injection device without a cavitation eraser. .

  The method of evaluating the mass defect amount of the injection experiment to the aluminum plate in each type is the time injection set for the aluminum plate whose mass was measured in advance while keeping the pressure under the above conditions constant at a constant water depth. Subsequently, erosion is generated, mass measurement is performed again after the injection is completed, and the amount of mass change before and after the injection experiment is used as a mass defect amount as an index of erosion power. The measurement results are shown in Table 1.

  As shown in the results in Table 1, the injection device without the cavitation eraser 6 (type 1) has a mass defect in the aluminum plate, whereas the injection device with the cavitation elimination device 6 installed (type 2, type) In 3), the mass defect was zero. In addition, as shown in the photographs on the surfaces of the aluminum plates in FIG. 2, in the case of an injection device without the cavitation eraser 6, a large donut-shaped erosion mark that does not corrode the central part peculiar to submerged cavitation occurred. Thus, in the cavitation eraser-equipped type injection device, the erosion mark is small, and in the type 3 (FIG. 2 (c)) in which the orifice diameter k of the cavitation eraser is 1.5 mm, the erosion mark is not completely generated. It was.

  That is, as the orifice diameter k of the cavitation eraser 6 decreases, the erosion marks decrease. When the orifice diameter k is 1.5 mm and the same diameter as the orifice diameter d of the injection nozzle, the erosion marks are completely lost. It was. From the above results, it has been clarified that the cavitation can be suppressed by mounting the cavitation eraser 6.

  Normally, the amount of erosion caused by cavitation increases as the injection pressure increases. Therefore, as a second embodiment of the present invention, when the orifice diameter k of the cavitation eraser 6 is changed when the injection pressure is increased to 4 MPa, 6 MPa, and 8 MPa in the injection device 1 of FIG. The experimental results of examining the cavitation elimination effect of are shown below.

  Each cavitation erasing effect was evaluated by measuring the amount of erosion of the water jet with respect to the aluminum plate for each injection pressure by the same mass defect evaluation method as in Example 1. In the injection device 1 in this experiment, a horn-type injection nozzle 4 having an orifice diameter of 1.5 mm is attached to the main body 2 having an inner diameter D of 14.5 mm of the through passage 3 of the main body 2, and the cavitation erasing device 6 is connected to the end of the nozzle 4. It was mounted at a position 20 mm upstream from the distance.

  In addition, each of the injection experiments at each pressure was performed for an injection time of 30 minutes, and for each injection experiment, a standoff distance that was a maximum erosion amount in a state where the cavitation eliminator was not installed at each injection pressure was taken. Specifically, when the injection pressure is 4 MPa, the standoff distance is 37.5 mm (maximum erosion amount: 0.3427 g), and when the injection pressure is 6 MPa, the standoff distance is 56.25 mm (maximum erosion amount: 0.9087 g), 8 MPa. In this case, the stand-off distance was 62.5 mm (maximum erosion amount: 1.1886 g).

  The orifice caliber k of the examined cavitation eraser 6 is 1.5 mm, 2 mm, 2.5 mm, 5 mm, 7.5 mm, 10 mm, and 12.5 mm. The experimental results are shown in the diagram of FIG. 3 (horizontal axis: cavitation eraser orifice diameter (mm), vertical axis: mass defect amount (g)).

  As is apparent from the diagram shown in FIG. 3, if the orifice diameter k of the cavitation eraser 6 is 2.5 mm or less and about 1.7 times the orifice diameter d of the injection nozzle 4, any injection pressure can be obtained. Even in this case, it was confirmed that erosion could be suppressed.

  Next, as a third embodiment of the present invention, in the submerged water jet injection device 1, the position of the cavitation eraser 6 in the through passage 3 of the main body 2, that is, the distance from the injection nozzle 4 and the cavitation. The experimental results examining the relationship with the erasing effect are shown below.

  In this experiment, the position of the cavitation eliminator 6 is changed to the downstream position A (distance LA from the end of the injection nozzle 4: along the high-pressure socket 10 in the through-flow passage 3 as shown in the schematic sectional view of FIG. 20 mm), the central position B (distance LB: 40 mm), and the upstream position C (distance LC: 60 mm) at different orifice diameters k, respectively, with the same mass defect evaluation method as in Example 1. The amount of erosion of the water jet against the aluminum plate was measured.

  In the case of the injection nozzle 4 having an orifice diameter d of 1.5 mm and 2.5 mm, the standoff distance to the aluminum plate is the maximum erosion amount at each injection pressure (4 MPa, 8 MPa). The distance was 30 minutes. The experimental results are shown in the graph of FIG. 5 (horizontal axis: cavitation eraser orifice diameter (mm), vertical axis: mass defect amount (g)) when the orifice diameter is d = 1.5 mm and the injection pressure is 4 MPa and 8 MPa. The case where the diameter d = 2.5 mm and the injection pressure 4 MPa is shown in the diagram of FIG. 6 (horizontal axis: cavitation eraser orifice diameter (mm), vertical axis: mass defect amount (g)).

  As is clear from the results shown in FIG. 5 and FIG. 6, the same cavitation eraser 6 is used in the flow passage through the main body of the injection device at any injection pressure and at different injection nozzle orifice diameters. In the above arrangement range (position A to position C), there was almost no difference in the amount of erosion (mass defect amount) due to the difference in position.

  In particular, the range of the arrangement position examined in this experiment, that is, the range in which the orifice diameter k of the cavitation eraser 6 confirmed in the above embodiment of the high pressure socket shows an excellent cavitation elimination effect, that is, the orifice of the injection nozzle 4. When the cavitation eliminator 6 is within the above-described arrangement range in the range of 1 to 1.7 times the diameter d, the excellent cavitation erasing effect is maintained without being impaired. I understood. In the above arrangement range, the distance from the injection nozzle 4 is within a distance range of 1 to 4 times the inner diameter D of the main body passage 3.

  Further, in the above embodiment, as shown in FIG. 1, the bushes (8a, 8b), the spacer 9, and the high-pressure socket 10 are interposed between the injection nozzle 4 and the supply pipe 12, and are formed relatively long. Although the case where the cavitation eliminator 6 is arranged in the through-flow path 3 was examined, as a fourth embodiment of the present invention, the cavitation erasing effect when the cavitation eraser was arranged immediately upstream of the injection nozzle was examined. The experimental results are shown below.

  In this experiment, as shown in FIG. 7, the injection nozzle 4 and the high-pressure water supply pipe 12 are directly connected, and the orifice diameter d is set in the injection device in which a long through-flow passage is not formed. The cavitation eliminator 6 disposed immediately upstream of the 1.5 mm injection nozzle 4 is injected for 30 minutes with an injection pressure of 4 MPa for each case where the orifice diameter k is 1.5 mm, 2.5 mm, and 5.0 mm. The amount of erosion of the water jet with respect to the aluminum plate was measured by the same mass defect evaluation method as in Example 1 under the conditions of SOD 43.75 mm, injection pressure 8 MPa, injection for 30 minutes, and SOD 75 mm. The results are shown in Table 2.

  As is apparent from the results in Table 2, even when the cavitation eraser is arranged immediately upstream of the injection nozzle, the orifice diameter k is more than 1 times the orifice diameter d of the injection nozzle 4 to about 1.7 times. It was confirmed that a sufficient cavitation erasing effect was obtained when the erosion was suppressed when it was within the following range, and when the orifice diameter k was the same as the orifice of the injection nozzle. No erosion marks were found on the aluminum plate.

  From the above results, since the cavitation eraser can exert its effect even at a position immediately upstream of the injection nozzle, the cavitation eraser may be provided integrally with the injection nozzle. In this case, it is possible to select in advance an orifice diameter that provides a good cavitation elimination effect according to the orifice diameter of the injection nozzle.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram of the submerged water jet injection apparatus by Example 1 of this invention, (a) is a longitudinal cross-sectional view of this injection apparatus whole, (b) is the cavitation eraser with which the injection apparatus main body was mounted | worn. It is the schematic plan view seen from the front. It is drawing substitute photograph which shows the erosion mark of the aluminum plate which shows the result of the cavitation elimination experiment of Example 1, (a) without a cavitation eraser, (b) is the orifice diameter of a cavitation eraser of 2.5 mm In this case, (c) shows the case where the orifice diameter is 1.5 mm. It is a diagram (horizontal axis: cavitation eraser orifice diameter (mm), vertical axis: mass defect amount (g)) showing the results of a cavitation elimination experiment in Example 2 of the present invention. It is a general | schematic side longitudinal cross-sectional view which shows the cavitation eraser arrangement position in the submerged water jet injection apparatus used for the cavitation elimination experiment in Example 3 of this invention. FIG. 6 is a diagram (a horizontal axis: cavitation eraser orifice diameter (mm), a vertical axis: mass defect amount (g)) showing a result of a cavitation elimination experiment with an injection nozzle orifice diameter of 1.5 mm in Example 3, (a ) Shows an injection pressure of 8 MPa, and (b) shows an injection pressure of 4 MPa. The diagram which shows the result of the cavitation elimination experiment in case of injection nozzle orifice diameter 2.5mm in Example 3 and injection pressure 4MPa (horizontal axis: cavitation eraser orifice diameter (mm), vertical axis: mass defect amount (g) ). It is a schematic sectional side view which shows the structure of the submerged water jet injection apparatus used for the cavitation elimination experiment in Example 4 of this invention.

Explanation of symbols

1: Submerged water jet injection device 2: Main body 3: Through passage D: Through passage inner diameter 4: Injection nozzle 5: Orifice (of injection nozzle) d: Injection nozzle orifice diameter 6: Cavitation elimination device 7: (Cavitation elimination) Orifice k: Cavitation Eraser Orifice Diameter 8a, 8b: Bush 9: Spacer 10: High Pressure Socket 11: High Pressure Nipple 12: Supply Pipe

Claims (7)

A main body provided with a through-flow path into which high-pressure fluid pressurized through a pressurizing means is introduced, and an injection nozzle that is fitted in a front-end flow path of the main body and injects the high-pressure fluid. In the submerged water jet injection device,
A submerged water jet injection device comprising a ring-shaped cavitation eliminator having an orifice having a predetermined diameter at a position upstream of the injection nozzle in the main body flow path.   The submerged water jet spray device according to claim 1, wherein the cavitation eraser is detachably mounted in the main body flow path.   The submerged water jet spray device according to claim 1, wherein the cavitation eraser is provided integrally with the spray nozzle.   The submerged water jet injection device according to any one of claims 1 to 3, wherein the orifice diameter of the cavitation eraser is not less than 1 and not more than 1.7 times the orifice diameter of the injection nozzle.   The arrangement position of the cavitation eraser is within a distance range of 1 to 4 times the inner diameter of the main body flow channel from the end position of the injection nozzle orifice. The submerged water jet spray device.   The main body of the submerged water jet spraying device that introduces a high-pressure fluid supplied under pressure through a pressurizing means into the main body through-flow path and sprays it from a spray nozzle fitted in the front-end flow path of the main body. A cavitation erasing device comprising a ring-shaped member that is detachably mounted at an upstream position of an injection nozzle in a flow path and has an orifice having a predetermined diameter. The cavitation eraser according to claim 6, wherein the orifice diameter of the ring-shaped member is not less than 1 and not more than 1.7 times the orifice diameter of the injection nozzle.