JP4178536B2 - Cleaning method for male screw tip - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for cleaning the tip of a male screw of a member (hereinafter simply referred to as a screw or bolt) that is joined by screwing such as a screw, bolt, or screw, and more specifically, a self-locking agent applied to them is removed. It is related with the method of cleaning.
[0002]
[Prior art]
The self-locking agent is applied in advance to a screw portion such as a screw or a bolt to improve the fastening force at the time of use, ie, fastening. The self-locking agent is a chemical-reactive sealing agent or adhesive such as epoxy or anaerobic curing. Most of the self-locking agent is a dry film, and is applied to the thread groove of the thread portion.
[0003]
In the past, liquid locking agents have been applied before screws and bolts are tightened. Since the manual application is complicated and the cost is high, more efficient work is possible if the self-locking agent is applied to fastening members such as screws and bolts in advance. Therefore, fastening members already coated with a self-locking agent have been sold.
[0004]
As a method of applying a self-locking agent to the screw part of a bolt or screw, the head of a fastening member such as a bolt is supported and fixed by a fastening tool such as a clamp, or the head of a metal bolt is held using a magnet. The bolt and the screw are supported by the above, and the threaded portion of the male screw is applied by dipping directly into the self-locking agent from the tip.
[0005]
In this method, as a matter of course, the self-locking agent is applied to all the portions immersed in the self-locking agent layer. That is, the self-locking agent is also applied to the tip portion of the screw portion of the male screw such as a bolt or a screw. When the self-locking agent is applied to the tip of the male screw, when trying to insert the male screw into the female screw, such as a screw hole, the male screw thread and female screw thread do not mesh with each other due to the coating thickness of the self-locking agent. There is a drawback that it is difficult to insert into. Therefore, it was inappropriate for automation by robots. Another drawback is that when a self-locking agent is applied to the tip of the bolt, it reacts in the temporary tightening process and the screw is cured. In order to avoid these drawbacks, it is necessary not to apply a self-locking agent to the tip portion of the male screw. That is, it is desired that the self-locking agent is applied only to an intermediate portion between the head and the tip of the male screw and does not exist at the tip.
[0006]
For example, a coating method using an apparatus disclosed in Japanese Utility Model Publication No. 62-23568 is known as a method for achieving the above-described coating form. This device includes a rail supported in an inclined direction and a pair of upper and lower rolls supported rotatably in the middle of the rail, and a part of the roll disposed below is immersed in a self-locking agent and the roll The material can be attached to the outer peripheral surface of the bolt and the bolt passes between the rolls while rolling, so that the material can be applied to the screw region of the bolt.
[0007]
Japanese Patent Laid-Open No. 8-131917 discloses that first and second rotating bodies are provided so that bolts can be sequentially supplied along rails extending in an inclined direction, and the bolts can be sandwiched from above and below in the middle of the rails. Is arranged. The bolt that has entered between the first and second rotating bodies is such that the liquid material attached to the outer peripheral surface of the second rotating body is applied to the outer peripheral surface of the bolt. These coating devices transfer and apply the self-locking agent directly to the middle part of the male screw while rotating the bolt in the circumferential direction. The application width of the self-locking agent can be adjusted by changing the width of the roll for transfer. Further, the position of transfer to the bolt can be adjusted by changing the position of the roll.
[0008]
[Problems to be solved by the invention]
However, the above applicator is not only complicated, but it is efficient when applying many fastening members of the same type, but it is suitable for the production of a small variety of products depending on the type of screw and the shape of the screw head. It is necessary to replace and adjust parts each time. In particular, it is necessary to adjust the speed and tension of the rotating body in accordance with the pitch of the thread, and skill is required for the adjustment operation.
[0009]
The most effective method for producing small quantities of various types of screws and bolts is the dipping method, which is a direct coating method by dipping in a self-locking agent. Since this coating method is also applied to the tip portion of the male screw, only the tip portion may be removed. The self-locking agent can be removed by wiping when the self-locking agent is in liquid form, but it is not easy to wipe the inside of the thread groove (the valley between the threads). Even after wiping off, it is difficult to remove completely from the tip end part by flowing down the thread groove. Further, as another method for removing the self-locking agent, the tip portion is removed and cleaned by immersing only the tip portion in a cleaning liquid such as an organic solvent.
[0010]
However, before the self-locking agent is dried, it can be easily removed by immersing it in a cleaning solution. However, when the self-locking agent is dried and solidified, it is difficult to remove it completely by the above method. In particular, the self-locking agent that has entered the thread groove cannot be completely removed. It becomes difficult to remove the portion closer to the liquid level. For example, if you try to remove and clean the 10mm part from the tip of the screw, you can remove the thread and the groove on the part 3mm from the tip, but the remaining 7mm part can remove the thread part, but the screw groove is completely Cannot be removed.
[0011]
The cleaning efficiency can be improved to some extent by adding means such as ultrasonic vibration when immersed in the cleaning liquid. However, if the ultrasonic vibration is increased, the surface of the cleaning liquid undulates or waves splash from the liquid surface, and the cleaning liquid surface does not reach a constant water level, and the removal surface and the non-removal surface of the self-locking agent are linear. It is not uniform. If the self-locking agent is applied in a narrow width to a small male screw or other small thread when the cleaning liquid undulates and splashes, the cleaning liquid will adhere to areas that you do not want to remove and remove the self-locking agent. Resulting in. The application width of the self-locking agent is not constant, and it is impossible to control the application width of the specified dimension of the product, which causes the product to vary. Moreover, even if it is not a small screw, since what was apply | coated is not constant, an external appearance is bad and a commercial value may be worsened. Therefore, the ultrasonic vibration cannot be made stronger than a certain value, and there is a limit to improving the cleaning power using ultrasonic waves.
[0012]
Further, since the cleaning liquid dissolves or decomposes and removes the self-locking agent, the cleaning liquid becomes dirty when the cleaning is repeated. If a contaminated cleaning solution is used, it will reattach to the cleaning surface of the bolts and screws and cannot be cleaned or removed completely. Therefore, it is possible to avoid the cleaning of the fastening member with the contaminated solvent by continuously circulating the cleaning liquid and keeping the cleaning liquid contaminated by filtration or adsorption in a clean state or by exchanging with a new cleaning liquid in a batch type. . However, since it is impossible to always wash with a solvent that is not contaminated at all, when the fastening member after washing is closely observed, there is a case where a self-locking agent component adheres. In particular, many self-locking agents contain microcapsules, and the microcapsules tend to reattach to the cleaning part.
[0013]
The cleaning liquid can recover the cleanliness to some extent by filtration or adsorption, but a special treatment such as distillation or electrical treatment is required to obtain a completely clean state. In the conventional fastening member removing method, the cleaning liquid must always be cleaned by the special treatment as described above.
[0014]
[Means for Solving the Problems]
As a result of intensive investigations to improve such defects, the conventional defects can be overcome by cleaning the screw by the cleaning method of the present invention. The method is a cleaning method in which the tip of the male screw is coated with a self-locking agent and the tip of the male screw is immersed in the cleaning agent. In this cleaning method, ultrasonic vibration is applied to the cleaning liquid and fine vibration is applied to the male screw. A method for cleaning an article, wherein the article is immersed in a cleaning liquid.
[0015]
The cleaning liquid is selected according to the material of the substance to be cleaned and the type of substance to be removed. For example, an organic solvent such as a hydrocarbon solvent, a chlorine solvent, or an ester solvent is preferably used. Examples of the organic solvent include toluene, xylene, methanol, ethanol, acetone, methyl ethyl ketone, methylene chloride, ethyl acetate, methyl amyl acetate, methyl cellosolve, carbitol, hexane and the like. In addition, when the substance to be removed by washing is a water-soluble substance or a liquid hydrophobic substance, water to which a surfactant, an acidic substance or a basic substance is added can be used.
[0016]
It is preferable that the cleaning liquid filled in the cleaning tank always has a constant water level. To keep the water level constant, a sensor may be provided in the water tank, or the cleaning liquid may be circulated so as to overflow from the water level hole.
[0017]
A means for applying ultrasonic vibration to the cleaning liquid stored in the cleaning tank can be achieved by disposing an ultrasonic vibrator at the bottom of the cleaning tank. Known ultrasonic transducers are used. The frequency of ultrasonic vibration is preferably 25 to 40 kHz. The output of the ultrasonic vibration cannot be determined unconditionally depending on the shape, capacity, distance to the liquid surface, etc. of the cleaning tank, but it must be determined so that the liquid surface of the cleaning liquid does not wave. The higher the output of the ultrasonic wave, the better the cleaning power. However, if the output is increased too much, the liquid surface of the cleaning liquid vibrates and waves and the cleaning liquid splashes, which is not preferable.
[0018]
The following means can be mentioned as a method of immersing the tip of the screw or bolt in the cleaning liquid. With the head of the screw or bolt held by a holding jig such as an electromagnet or a clamp, the holding jig is moved downward and immersed in the cleaning liquid. By adjusting the downward moving distance, only the tip portion can be immersed in the cleaning liquid. Another method for holding screws and bolts is called the punch panel method. By drilling holes in the panel that are approximately the same size as the screw and bolt diameter, the screws and bolts are passed through the holes from above. It can also be held. If a plurality of screws and bolts can be held simultaneously as means for holding the screws and bolts, the plurality of screws and bolts can be processed in a single cleaning step.
[0019]
The above-mentioned holding means can also be used in the process of applying a self-locking agent for screws and bolts. That is, the self-locking agent is applied in a state where the screws and bolts are held, and then the cleaning process can be performed as described above without removing from the holding jig.
[0020]
As a method of giving a fine vibration to a male screw such as a screw or a bolt, there is a method of giving a fine vibration to the above-mentioned holding jig and indirectly giving a fine vibration to the screw or bolt. The frequency of fine vibration is preferably 5 to 100 Hz. If it is 5 Hz or less, the cleaning effect is not improved, and if it is 100 Hz or more, the cleaning liquid undulates. The amplitude of the fine vibration must be such that the surface of the cleaning liquid does not wave. In addition, when ultrasonic cleaning is performed on the cleaning liquid, the vibrations may interfere with each other and the cleaning liquid may generate a wave. Therefore, the frequency and amplitude must be selected to avoid this.
[0021]
Here, the self-locking agent as used in the present invention is preliminarily applied to screwed portions such as screws and bolts, and achieves effects such as screw loosening prevention. The principle of the self-locking agent is that the substance that polymerizes and hardens due to the chemical reaction by mixing is present inside and outside the microcapsule, and the microcapsule is destroyed by the frictional pressure of the screwing part when tightening the screw and bolt, These polymerize. Self-locking agents are known in the art such as those diluted with organic solvents and applied to screws and bolts and dried, and water-based ones. For example, they are described in JP-A-2-248485 and JP-A-5-17723. ing.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
【Example】
Example 1: A total of nine ultrasonic transducers 3 × 3 are installed at the bottom of a stainless steel cleaning container (inner diameter 200 × 200 × height 95 mm). The vessel was filled with 3.6 liters of ethyl methyl ketone as a cleaning liquid. The ultrasonic transducer is connected to a transmission circuit and a power amplification circuit, and transmits and outputs a signal having a frequency of about several tens of kHz. The signal output from the transmission circuit is input to the power amplification circuit and amplified. The signal amplified in the power amplifier circuit is applied to the ultrasonic transducer, thereby vibrating the ultrasonic transducer.
[0023]
The bolt to be cleaned was a M10 screw with a length of 30 mm. An acrylic self-locking agent containing microcapsules (ThreeBond 2406 manufactured by ThreeBond Co., Ltd.) is applied to the bolt by 13 mm in the seating surface direction from the tip of the threaded portion, and is solidified by drying. The bolt is formed with a hole of about 11 mm in an aluminum panel having a thickness of 5 mm, and the bolt is inserted downward from the upper surface of the panel. The panel was moved downward from the upper part of the cleaning tank, and the screw part of the bolt was immersed in the cleaning liquid. The panel was held so that a 4 mm portion from the tip of the bolt was immersed in the cleaning solution.
[0024]
A micro vibration generator is attached to the panel holding the bolt via a panel fixture. BF-100P (made by IDEX Co., Ltd.) was used for the fine vibration generator. In the fine vibration generator, a vibration head is attached to a panel fixture, and the fine vibration is transmitted to the panel, and the fine vibration is transmitted to the bolt.
[0025]
The micro vibration of the bolt was set to 50 Hz and the amplitude was set to 2 mm PP, and the ultrasonic wave of the cleaning liquid was set to the highest output in a range where the cleaning liquid did not wave. The tip of the bolt was cleaned by immersing the tip of the bolt in a cleaning solution for 30 seconds. In these settings, even when both vibrations were combined, the liquid level of the cleaning liquid did not wave or splash.
[0026]
The fixing panel was taken out from the cleaning liquid, and the bolt was removed from the cleaning machine after the cleaning liquid dried from the bolt. When the removal of the self-locking agent on the bolt and the cleaning condition were confirmed, the cleaning part at the tip of all of the 20 bolts was cleanly cleaned without any trace of the self-locking agent. The boundary between the self-locking agent and the removed part was straight.
[0027]
Example 2: M2 screws (screw length 10 mm) were used in the same manner as in the above example. A self-locking agent is applied to the screw at a length of 5 mm from the tip. The distance immersed in the cleaning solution was 2 mm from the tip of the screw. The washing conditions were the same as in Example 1. As a result, the cleaning part at the tip of all the 50 parts was cleanly cleaned with no trace of the self-locking agent. The boundary between the self-locking agent and the removed part was straight. Even when the application width of the self-locking agent was compared, all the screws were uniform.
[0028]
Example 3: Washing was performed 10 times under the same conditions as in Example 1 without replacing the washing solution. The cleaning liquid turned red, which is the color of the self-locking agent. Even in the 10th cleaning step, the cleaning portion at the tip of all 50 was cleaned with no self-locking agent traces.
[0029]
Comparative Example 1: Using the same screw as in Example 2, the remaining conditions were cleaned in the same manner as in Example 2 without applying ultrasonic vibration to the purified liquid. As a result, it was confirmed by visual observation that 48 out of 50 were not removed in a part of the thread groove in the cleaning portion of the screw tip and the self-locking agent remained.
[0030]
Comparative Example 2: Using the same screw as in Example 2, the remaining conditions were cleaned in the same manner as in Example 2 without subjecting the screw to slight vibration. As a result, it was confirmed by eye that 44 out of 50 were not removed in some thread grooves in the cleaning portion at the tip of the screw and the self-locking agent remained.
[0031]
Comparative Example 3: The same screw as in Example 2 was used, the screw was not subjected to slight vibration, the output of ultrasonic vibration was doubled as in Example 2, and the remaining conditions were as in Example 2. Washing was performed in the same manner. The liquid level of the cleaning liquid was vibrating and splashed. As a result, it was confirmed by visual observation that 14 out of 50 screws were not removed in some thread grooves in the cleaning portion of the screw tip and the self-locking agent remained. Further, the boundary between the self-locking agent and the removed part was jagged in all 50 pieces. For this reason, when comparing the application width of the self-locking agent, it was confirmed that the application width was uneven.
[0032]
Comparative Example 4: Washing was performed 9 times under the same conditions as in Example 1 without replacing the clean solution. The cleaning liquid turned red, which is the color of the self-locking agent. Thereafter, the tenth cleaning was performed without applying slight vibration to the bolt. As a result, adhesion of foreign matters such as microcapsules was observed in all 50 pieces.
[0033]
【The invention's effect】
According to the configuration of the present invention, it is possible to increase the cleaning power without making the liquid surface of the cleaning liquid wave. Thereby, even the screw or bolt in which the self-locking agent has solidified can be removed even if it enters the groove portion of the screw. Furthermore, since the cleaning liquid does not wave and the cleaning effect is exerted up to the surface of the cleaning liquid, it is possible to accurately determine a location to be cleaned and removed. Therefore, since the boundary between the removed part and the part that has not been removed is clear, not only the appearance of the product is good, but even if the application width of the self-locking agent such as machine screws is small, the self-locking agent can be applied. The amount can be accurately controlled and the product can be stabilized.
[0034]
For this reason, the bolt and screw from which the self-locking agent is removed in the present invention are easy to tighten when tightened to the female screw, and the tightening force is stable without variation. Moreover, if this invention is used, the screw and bolt which apply | coated the self-locking agent at low cost and high productivity can be produced compared with the conventional method of apply | coating directly to a screw and a bolt one by one.
[0035]
Further, normally, when the cleaning liquid becomes contaminated, dirt from the cleaning agent is reattached to the cleaned part. However, when cleaning is performed by the cleaning method of the present invention, dirt is less likely to be reattached as compared with the conventional cleaning method. For this reason, it is possible to reduce the burden of replacing the cleaning liquid or filtering the cleaning liquid.

Claims (2)

In a cleaning method in which the tip of the male screw coated with a self-locking agent is immersed in the cleaning agent, the ultrasonic cleaning is applied to the cleaning liquid, and the male screw is immersed in the cleaning liquid while giving a slight vibration. A method for cleaning the tip of a male screw. The method for cleaning the tip of a male screw according to claim 1, wherein the cleaning agent is an organic solvent.