JP2020032505A - Deburring device and deburring method - Google Patents

Abstract

To provide an efficient and low-cost deburring method.SOLUTION: In the deburring method, shock waves in liquid are generated by pulse discharge in a state where micro bubble is made to adhere to an object to be processed, a metal work-piece, then the shock waves in liquid are made to interfere with the micro bubble to generate rebound shock waves of the micro bubble, and burr of the object to be processed is removed by the rebound shock waves.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a deburring apparatus and a deburring method using rebound shock waves of microbubbles.

Burrs adhere to metal processed products depending on the manufacturing process. Conventionally, as a deburring method, manual work, blast polishing, removal with a water jet or ultrasonic waves, and the like have been performed. All of these methods have the problems of excessively damaging the metal surface other than the burr-attached portion, deforming the processed product, and increasing the cost.
As a method of performing deburring and cleaning over a wide range in a short time, Japanese Patent Application Laid-Open No. H11-163873 discloses a method in which an arc discharge is generated in the vicinity of a processing object immersed in a processing liquid, and the object to be processed is generated by a shock wave generated by the arc discharge. There has been proposed a method for removing burrs adhering to the surface.
The method described in Patent Document 1 is to directly apply a shock wave due to an arc discharge to an object to be processed. If the shock wave pressure is too strong, the shape of the object to be processed is plastically deformed, and the shock wave pressure is weak. If it is too much, burrs cannot be removed, and there is a problem that the distance range of installation of the object to be processed from the discharge electrode capable of removing burrs is narrow. In addition, although it corresponds to the removal of burrs on a simple shape surface on which a shock wave can act, there is a problem that it is difficult to remove burrs attached to a place where a processing hole intersects in a complicated manner.

JP 2006-150493 A

  An object of the present invention is to provide an efficient and low-cost deburring method.

The means for solving the above problems are as follows.
1. A processing tank for storing the liquid,
In the treatment tank, a pulse discharge device that generates a shock wave in the liquid by pulse discharge,
A microbubble generating device that makes at least a part of the liquid a microbubble dispersion,
Has,
A deburring device, wherein the microbubble is attached to an object to be processed which is a metal workpiece, the shock wave in the liquid is generated, and a burr of the object is removed by a rebound shock wave of the microbubble. .
2. The diameter of the microbubbles is not less than 5 μm and not more than 45 μm. 3. The deburring device according to 1.
3. A supply port for supplying the microbubble dispersion from the microbubble generator and an intake for transferring the microbubble dispersion to the outside of the processing tank are coaxial so that the object is located therebetween. It is characterized by being arranged on the top. Or 2. 3. The deburring apparatus according to 1.
4. In the state where microbubbles are attached to the object to be processed, which is a metal workpiece, a shock wave in the liquid is generated by pulse discharge,
Causing the microbubbles to interfere with the shock wave in the liquid to generate a rebound shockwave of the microbubbles;
A deburring method, comprising: removing burrs on the object by using the rebound shock wave.
5. 3. The diameter of the microbubbles is not less than 5 μm and not more than 45 μm. Deburring method described in 1.

ADVANTAGE OF THE INVENTION The deburring apparatus of this invention can remove a burr | burr by the rebound shock wave of the microbubble adhered to the to-be-processed object. ADVANTAGE OF THE INVENTION The deburring apparatus of this invention can remove | eliminate the burr | burr accompanying complicated shape and a narrow area | region which is difficult to deburr with a conventional method efficiently. Further, the deburring apparatus of the present invention can polish the surface of the deburring device by the rebound shock wave of the microbubbles attached to the portion having no burr.
The deburring apparatus of the present invention can remove burrs of a size to which microbubbles adhere. Therefore, by setting the diameter of microbubbles to 5 μm or more and 45 μm or less, it is possible to remove fine burrs on the order of microns. it can.

  A deburring apparatus in which a supply port for supplying a microbubble dispersion liquid and an intake port for transferring the microbubble dispersion liquid to the outside of the processing tank are coaxially arranged so that a substance to be processed is located therebetween, Since the attenuation of the shock wave in the liquid due to the microbubbles floating between the processing object and the discharge electrode is small, the shock wave in the liquid can efficiently interfere with the microbubbles attached to the surface of the processing object. At this time, by draining at least a part of the microbubble dispersion liquid taken in from the intake port, it is possible to suppress an increase in the conductivity of the liquid, so that the discharge voltage is maintained high and the pressure of the shock wave in the liquid is increased. Can be maintained.

FIG. 1 is a schematic view of a deburring apparatus according to a first embodiment of the present invention. FIG. 4 is a schematic view of a deburring apparatus according to a second embodiment of the present invention. FIG. 6 is a schematic view of a deburring apparatus according to a third embodiment of the present invention. FIG. 6 is a diagram showing a relationship between the cumulative number of discharges and the maximum height of burrs in Example 1 and Comparative Example 1.

When a microbubble interferes with a shock wave in liquid, the microbubble shrinks rapidly, the gas in the bubble is compressed, and when the bubble collapses, a rebound shock wave that is at least 10 times higher than the shock wave pressure in liquid is generated. It has been known.
In the present invention, the high-pressure rebound shock wave is applied to burrs of a workpiece to be processed, which is a metal workpiece, and the burrs are crushed to perform deburring. That is, when microbubbles are adhered to the surface of the object to be processed, more microbubbles adhere since the burr has a large surface area. When rebound shock waves are generated from microbubbles attached to the surface of the object to be processed, rebound shock waves from many microbubbles act on burrs, and the burrs are crushed little by little.

  In the present invention, the object to be deburred is not particularly limited as long as it is a metal processed product having burrs. The deburring apparatus of the present invention adheres microbubbles to burrs, and causes submerged shock waves to interfere with the microbubbles to crush the burrs. Can be removed. Therefore, as the object to be processed, a metal processed product in which processing holes intersect in a complicated manner, a metal processed product requiring surface smoothness, a precision processed product, and the like are preferable. Further, since the deburring apparatus of the present invention can polish the entire surface as described later, a medical device and a component, a medical instrument component, a medical implant, and an analyzer which require a smooth surface as an object to be processed are provided. Parts, semiconductor manufacturing equipment parts, and the like. The object to be treated according to the present invention is a metal workpiece. Since the resin molded product can be deformed so as to bend, the rebound shock wave is consumed as the energy of the deformation, and it is difficult for the burrs to break.

  In the deburring apparatus of the present invention, the size of the burrs to be removed is not particularly limited, but the deburring apparatus of the present invention has a size equivalent to that of the microbubbles in order to remove burrs of a size to which microbubbles can adhere. It can be suitably used for fine deburring of a certain micro order. Specifically, the maximum height of the burr from the surface of the processed product is preferably 100 μm or less, more preferably 50 μm or less, further preferably 30 μm or less, and most preferably 20 μm or less. .

Hereinafter, a deburring apparatus and a deburring method of the present invention will be described by taking an embodiment as an example.
"First embodiment"
FIG. 1 shows a deburring apparatus according to a first embodiment of the present invention.
The deburring apparatus according to the first embodiment includes a processing tank 1, a pulse discharge device 2, and a microbubble generator 3, and a liquid 4 circulates between the processing tank 1 and the microbubble generator 3. are doing.

  The processing tank 1 is for storing a liquid 4 and immersing the object 5 in the liquid. The size of the processing tank is not particularly limited as long as the part for deburring the processing object can be immersed in the liquid. The material is not particularly limited, and a metal, glass, plastic, ceramic, or the like can be used.

  The pulse discharge device 2 has a pulse power source 21, a discharge electrode 22, a lead wire 23, and a ground wire, and applies a high-voltage pulse between the discharge electrodes 22 arranged in a liquid to induce arc discharge. . When an arc discharge is induced in the liquid, plasma is generated from the discharge point, a shock wave is generated in the liquid, and the liquid is evaporated by the high-temperature plasma to generate a single bubble.

  In the present invention, the pulse discharge device is not particularly limited, and a commercially available pulse discharge device can be appropriately used. Here, when the discharge energy becomes large, the shock wave in the liquid becomes strong, so that the workpiece may be plastically deformed. Since the deburring apparatus of the present invention breaks burrs not by a shock wave in liquid but by a rebound shock wave having a pressure of 10 times or more the shock wave in liquid, strong discharge energy is not required and 20 J / pulse. The following is sufficient. Therefore, as the pulse discharge device, a pulse discharge device that operates with a household 100V power supply and has a discharge voltage of 50 kV or less and a discharge current value of 5 kA or less can be suitably used.

  The pulse width is preferably 10 nsec or more and 10 μsec or less because the narrower the pressure of the discharge-induced shock wave in the liquid increases, and the pressure of the rebound shock wave when the microbubbles collapse under the load of the liquid shock wave increases. More preferably, it is 1 μsec or more and 5 μsec or less. The number of pulses and the pulse frequency are not particularly limited as long as they can apply pressure enough to crush the burrs, but the pulse frequency is preferably 1 Hz or more and 100 Hz or less in order to shorten the processing time. If the frequency is lower than 1 Hz, the processing time becomes too long. If the frequency is higher than 100 Hz, the microbubbles may be broken by a shock wave in the liquid before adhering to the object.

  In the present invention, the material, shape, and arrangement of the discharge electrode are not particularly limited. However, the deburring apparatus of the present invention is to cause the shock wave in the liquid generated between the discharge electrodes to interfere with the microbubbles adhered to the surface of the object to be processed, and to move the position of the object to be processed within a range where the shock wave in the liquid reaches. In order to facilitate the adjustment, it is preferable that the discharge electrode is disposed horizontally below the workpiece.

The microbubble generating device 3 includes a microbubble generator 31 and a pump 32, and makes at least a part of the liquid 4 a microbubble dispersion liquid 41.
The mechanism for generating the microbubbles is not particularly limited, and is a pressure dissolution type, a swirling liquid flow type, a static mixer type, an ejector type, a venturi type, an ultra-fine hole type, an ultrasonic addition hollow needle nozzle type, a vapor condensation type, Microbubbles can be generated by a pressurizing / swirl type, a cavitation type, or the like. Note that the pump is not an essential component and is unnecessary depending on the mechanism for generating microbubbles. The liquid in which the microbubbles are dispersed is not particularly limited as long as pulse discharge can be performed in the liquid. Pure water, distilled water, purified water, tap water, industrial water, oil, electric discharge machining oil, silicone oil Etc. can be used. Of these, tap water or industrial water is preferable because of its low cost.

Here, a microbubble means a bubble having a diameter of about 1 μm to 100 μm (see ISO / TC281). In the present invention, the diameter of the microbubbles is not particularly limited, but the diameter of the microbubbles is preferably smaller, more preferably 45 μm or less, and preferably 40 μm or less, in order to adhere to the surface of the fine burrs of the processing object. It is more preferred that: It is preferable that the diameter of the microbubbles is small, but a device for generating fine microbubbles is expensive, and maintenance work for maintaining the bubble diameter is troublesome. Therefore, the diameter of the microbubbles is 5 μm or more. Preferably, it is not less than 10 μm.
In the present invention, the diameter of a microbubble means the diameter of a main-bubble contained in a microbubble dispersion measured by a particle size distribution analyzer.

  Here, as the diameter of the microbubble is smaller, the peak pressure of the rebound shock wave is stronger, but the time during which the rebound shock wave acts is shorter, and the impulse derived from one microbubble is smaller. The deburring device of the present invention continuously supplies microbubbles and repeatedly applies rebound shock waves by pulse discharge.Thus, even if the impulse of one microbubble is small, the rebound shock wave having a large peak pressure is repeatedly applied. It is possible to efficiently remove burrs.

  In the present invention, the microbubbles adhere to the surface of the object to be treated and are compressed by interference of a shock wave in the liquid to generate a high-pressure rebound shock wave when the bubble collapses. Since burrs have a large surface area, many microbubbles adhere thereto. Then, as more microbubbles adhere, more rebound shock waves act, so burrs are crushed little by little. Note that the rebound shock wave of the attached microbubbles also acts on portions other than the burrs of the object to be processed. Therefore, the surface of the object to be processed is uniformly smoothed by the rebound shock wave, as if polished.

The object to be processed is placed within a range where shock waves in the liquid due to the arc discharge reach. The number of objects to be processed is not limited to one, and a plurality of objects to be processed can be set within a range where a shock wave in the liquid reaches, and deburring can be performed simultaneously.
The object to be processed is installed such that the distance from the discharge electrodes is longer than the distance between the discharge electrodes. If the distance between the workpiece and the discharge electrode is shorter than the distance between the discharge electrodes, an arc discharge occurs between the discharge electrode and the workpiece, and the workpiece is damaged. The distance between the workpiece and the discharge electrode is preferably at least twice the distance between the discharge electrodes, more preferably at least three times. Further, the distance between the object to be processed and the discharge electrode is preferably within the range of the diameter of a single bubble generated after the generation of the shock wave in the liquid. Within this range, a direct pressure due to the collision of a single bubble can be applied to the object to be processed, and deburring can be performed more efficiently.

"Second embodiment"
FIG. 2 shows a deburring apparatus according to a second embodiment. In FIG. 2, the same members as those in the first embodiment are denoted by the same reference numerals.
The deburring apparatus according to the second embodiment includes a supply port 33 for the microbubble dispersion liquid 41 supplied from the microbubble generator 31 and an intake port 34 for transferring the microbubble dispersion liquid 41 out of the processing tank 1. Are arranged coaxially so that the object 5 is located therebetween, and the microbubble dispersion liquid 41 taken in from the intake port 34 is returned to the microbubble generator 31 and circulated. Same as the embodiment.

  The shock wave in the liquid due to the pulse discharge interferes not only with the microbubbles attached to the surface of the object to be processed but also with the microbubbles floating in the liquid. Since the acoustic impedance of the gas is smaller than the acoustic impedance of the liquid, the pressure of the shock wave transmitted through the gas in the bubble is attenuated. Therefore, in the deburring apparatus of the first embodiment, the pressure of the shock wave in the liquid that interferes with the microbubbles attached to the surface of the object to be processed is reduced by the pressure damping effect of the microbubbles floating between the electrode and the object. It will be weak.

  On the other hand, the deburring apparatus of the second embodiment is characterized in that the number of microbubbles floating between the electrode and the object to be treated is small, and the attenuation of the shock wave in the liquid is small, so that the shock wave in the liquid is efficiently transferred to the surface of the object to be treated. Can be caused to interfere with the microbubbles attached to the surface. Therefore, the deburring apparatus of the second embodiment can generate a rebound shock wave having the same pressure as that of the first embodiment with a lower energy amount.

"Third embodiment"
FIG. 3 shows a deburring apparatus according to a third embodiment. In FIG. 3, the same members as those in the first embodiment are denoted by the same reference numerals.
The deburring apparatus according to the third embodiment supplies tap water, industrial water, and the like to the microbubble generator 31 from the outside, and circulates the microbubble dispersion liquid taken in from the inlet port 34 of the processing tank 1 without circulating. This is the same as the second embodiment except that the water is drained out.

Since the discharge electrode is eluted and ionized little by little during arc discharge, the conductivity of the liquid increases when the arc discharge is repeated. When the conductivity of the liquid increases, the discharge voltage at which the arc discharge is induced decreases, so that the pressure of the shock wave in the liquid caused by the arc discharge decreases.
In the third embodiment, by discharging the liquid from the vicinity of the discharge electrode, ions generated by elution of the discharge electrode are removed from the processing tank, and an increase in the conductivity of the liquid can be suppressed. The pressure of the generated shock wave in the liquid can be strongly maintained.

"Other embodiments"
The deburring device of the present invention is not limited to the first to third embodiments.
For example, in the deburring apparatus of the second embodiment, the microbubble dispersion liquid 41 taken in from the intake port 34 is branched, one of which is circulated to the microbubble generator 31, and the other is drained out of the processing tank 1. You can also. At this time, the same amount of liquid as the drained liquid is supplied to the processing tank 1 or the microbubble generator 31.

"Example 1"
Using the deburring apparatus according to the first embodiment, a medical implant as an object to be processed was deburred.
The implant to be processed is a SUS cylinder having a diameter of 2.1 mm and a length of 120 mm, and the tip is a triangular pyramid. Along with turning the SUS round bar into a triangular pyramid shape, burrs having a maximum height (Hz) of about 20 μm adhere to the triangular pyramid portion.

  A treatment tank (made of acrylic, inner size: 300 × 300 × 300 mm) is filled with purified water, and the diameter is 40 μm using a microbubble generator (manufactured by Kansai Automated Equipment Co., Ltd., device name: MBLL-102V-S). Was generated, and the microbubble dispersion was circulated between the processing tank and the microbubble generator.

Using a pulse power supply (Suematsu Electronics Co., Ltd., device name: CUS3010S-5J), the average voltage of the power supply output was 35.6 kV, the capacitor capacity was 11.56 nF, the theoretical output discharge energy was 7.32 J / pulse, and the pulse was used. The width was 5.6 μsec, the frequency was 10 Hz, and the distance between the discharge electrodes was 1.5 mm.
In the case of a discharge voltage of 35 kV, a single bubble having a diameter of about 9 mm is generated when water is used as the liquid. For this reason, the implant, which is the object to be treated, was placed so that the tip of the implant is downward, and the distance between the tip of the object to be treated and the discharge electrode was 9.0 mm.

  While measuring the cumulative number of discharges (Nc) using a pulse counter, pulse discharges of Nc = 0, 68, 2951, and 3985 shot were performed.

"Comparative Example 1"
A pulse discharge of Nc = 0, 102, 2844, 3994 shot was performed in the same manner as in Example 1 except that microbubbles were not generated.

-Deburring evaluation Using a three-dimensional digital microscope (manufactured by KEYENCE CORPORATION, device name: VHX-2000), an area where burrs were present (480 x 120 µm) before and after each discharge of the workpiece. Was observed, and the maximum height (Hz) of the burr was measured.
FIG. 4 shows the relationship between the cumulative number of discharges and the maximum height of burrs Hz in Example 1 and Comparative Example 1.

In Example 1 of the present invention, the burr having a maximum height (Hz) of 18.51 μm was reduced to a maximum height of 12.40 μm and 6.11 μm after approximately 4000 pulse discharges. Also, the surface area of the burr was reduced.
On the other hand, in Comparative Example 1 using only the shock wave in liquid and a single bubble without using microbubbles, the burr whose maximum height (Hz) was 19.57 μm was reduced after approximately 4000 pulse discharges. The maximum height was 16.80 μm, only 2.77 μm.

Reference Signs List 1 processing tank 2 pulse discharge device 21 pulse power supply 22 discharge electrode 23 lead wire 3 microbubble generator 31 microbubble generator 32 pump 33 supply port 34 intake port 4 liquid 41 microbubble dispersion liquid 5

Claims (5)

A processing tank for storing the liquid,
In the treatment tank, a pulse discharge device that generates a shock wave in the liquid by pulse discharge,
A microbubble generating device that makes at least a part of the liquid a microbubble dispersion,
Has,
A deburring device, wherein the microbubble is attached to an object to be processed, which is a metal workpiece, and the shock wave in the liquid is generated, and the burr of the object is removed by a rebound shock wave of the microbubble. .   The deburring apparatus according to claim 1, wherein the diameter of the microbubble is 5 µm or more and 45 µm or less.   A supply port for supplying the microbubble dispersion from the microbubble generator and an intake for transferring the microbubble dispersion out of the processing tank are coaxial so that the object to be processed is located therebetween. The deburring apparatus according to claim 1, wherein the deburring apparatus is disposed on the top. In the state where microbubbles are adhered to the object to be processed which is a metal processed product, a shock wave in the liquid due to pulse discharge is generated,
Causing the microbubbles to interfere with the shock wave in the liquid to generate a rebound shockwave of the microbubbles;
A deburring method, comprising: removing burrs on the object to be processed by the rebound shock wave.   The deburring method according to claim 4, wherein the diameter of the microbubbles is 5 μm or more and 45 μm or less.