JP4076354B2 - Manufacturing method of hollow float body with built-in magnet - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a hollow float body with a built-in magnet used for a storage battery.
[0002]
[Prior art]
In order to monitor the electrolyte surface level and specific gravity of the storage battery, a hollow float body with a magnet covered with a resin covering the entire surface of the hollow cylindrical magnet was passed through a cylinder equipped with a magnetically sensitive switch at the bottom of the plug, and this was electrolyzed. The hollow float body is floated and lowered by changing the electrolyte surface level or the specific gravity of the electrolyte, and the magnetic sensitive switch is turned on and off by a magnet approaching by the hollow float body floating and sinking. It is known to detect the specific gravity of the electrolyte (Japanese Utility Model Laid-Open Nos. 55-14050 and 57-138272).
[0003]
Detecting the electrolyte solution surface level and specific gravity of these storage batteries is useful for clarifying the replacement time and charging time for the storage battery. In particular, for the purpose of environmental protection, an idling stop function has been recently added to automobiles such as trucks and buses to stop the idling engine while the vehicle is stopped. At this time, the liquid level and specific gravity are within a predetermined range. If the engine is stopped when it is not the value, troubles such as the inability to restart the automobile engine may occur, so detection of the electrolyte level and specific gravity is becoming more and more important.
[0004]
[Problems to be solved by the invention]
However, since these hollow float bodies with built-in magnets smoothly float and sink along the penetrating cylinder, the center of the hollow cylindrical magnet and the center of the hollow float body are the same so that the float body is not eccentric. However, in the conventional method, an eccentricity is often seen, and when this eccentric hollow float body is used, the hollow float body is inclined and caught by a cylindrical body penetrating the hollow float body. There is a case where the floating or sinking does not occur with the change of the position or specific gravity, and as a result, accurate detection cannot be performed.
[0005]
[Means for Solving the Problems]
The present invention solves the above-mentioned problem, and in embedding a hollow magnet in a hollow resin float body, preferably three locations on the outer peripheral surface in a state where a part of the hollow magnet is gripped in the first stage of molding. Hold the above firmly and place it on the molding machine, mold the synthetic resin to cover the hollow inner peripheral surface and outer peripheral surface other than the part where the magnet is gripped, and separate it from the outer surface of the magnet The ring surrounding the outer peripheral surface is molded integrally with the resin covering the outer peripheral surface of the magnet via a bridge to form a hollow float body, which is taken out from the mold of the molding machine, and then as the second stage, A protruding mold is inserted into the hollow portion of the in-process hollow float body molded in the first stage and placed in a molding mold having a recess to cover the magnet peripheral surface of the portion gripped in the first stage. , Molded into a hollow float body of a predetermined appearance That.
[0006]
At this time, in the first stage molding, if a ring surrounding the magnet is formed outside the outer peripheral surface of the magnet, it is possible to prevent generation of bubbles during the subsequent second stage molding. Furthermore, the bridge formed between the ring and the resin covering the outer peripheral surface of the magnet is projected so as to form a part of the outer surface of the predetermined appearance shape, so that the bridge is formed on the side surface of the mold during the second stage molding. It is more preferable that it can be molded by contact.
[0007]
[Action]
As a result, the center of the magnet and the center of the float body can be matched, and eccentricity can be eliminated.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
An example as an embodiment will be described with reference to the drawings.
[0009]
FIG. 1 is a perspective view showing an in-process hollow float body formed by the first stage of the first embodiment of the present invention, where (A) shows the front surface and (B) shows the back surface.
[0010]
As shown in the drawing, the hollow cylindrical magnet 1 is covered with a polypropylene resin 2 except for a part of the outer peripheral surface.
[0011]
The magnet 1 is coated with the resin 2 by a conventional method using an injection molding machine. However, one part of the outer peripheral surface of the magnet 1, that is, three places in the illustrated example, is held and fixed by a chuck and placed in a mold of the molding machine. It is done. Therefore, the inner peripheral surface of the hollow portion 3 and the outer peripheral surface of the magnet 1 other than the portion where the background of the magnet 1 is shown are spaces in the molding machine mold, and the resin is injected into the space. It is molded.
[0012]
In this example, not only the surface of the magnet 1 but also the ring 4 surrounding the outer peripheral surface is formed outside the outer peripheral surface, and the resin layer 5 on the surface of the magnet 1 is connected by a bridge 6 and formed integrally. ing. The bridge 4 is protruded so that a part of the outer surface having a predetermined external shape can be formed. The bridge 6 was formed at the portion where the background of the magnet is visible, that is, at the center between the positions where the magnets adjacent to each other are gripped, that is, in the middle in the embodiment. This makes it possible to increase the distance that the electrolyte solution penetrates into the slight gap that may occur between the resin 2 at the time of the first stage molding and the resin 2 at the time of the second stage molding. Corrosion due to the electrolyte can be prevented for a long time. In FIG. 1A, the resin of the portion covering the inner peripheral surface of the hollow portion 3 is also protruded at the same height as the bridge 6.
[0013]
Further, the back surface shown in FIG. 2B was made to protrude the resin of the portion covering the inner peripheral surface of the hollow portion 3.
[0014]
Thus, since the magnet 1 is firmly fixed in the mold by the chuck, it can be fixed at a predetermined position without moving in the mold, and accurate centering can be performed.
[0015]
After finishing the first stage molding, the second stage molding was performed.
[0016]
FIG. 2 is a perspective view of a magnet built-in hollow float body formed into a predetermined external shape by second-stage molding.
[0017]
As shown in the figure, it has a substantially cylindrical flat shape having a hollow portion 3. As indicated by the dotted line on the surface of the drawing, the protruding resin covering the inner peripheral surface of the bridge 6 and the hollow portion 3 was made visible so that a part of the outer surface having a predetermined external shape was formed. This is because this part was placed in contact with the side surface of the mold at the time of the second stage molding, so that the in-process hollow float body molded at the first stage in the mold of the molding machine It does not move while being firmly fixed together with the protruding mold that penetrates through the hollow portion 3. In addition, the back surface of this magnet built-in hollow float body is formed in the taper surface from which the hollow part 3 protrudes somewhat as shown by the alternate long and short dash line, and is used by penetrating through the cylinder body provided with the magnetically sensitive switch with the taper surface downward. It is.
[0018]
Also, the built-in magnet has a lower center position than the center position of the float body, rather than having the center position in the thickness direction of the float body and the center position in the thickness direction of the magnet be the same. It is more preferable to move it to the lower part of the float body because the operation is stable.
[0019]
In the above embodiment, since the ring was formed at the first stage, bubbles could be generated in the molding resin during the second stage molding, and the specific gravity of the float body could be manufactured more stably.
[0020]
FIG. 3 is a cross-sectional view of an example molding die for forming the in-process hollow float body, and is a cross-section of the portion corresponding to the AA line of the in-process hollow float body described in FIG. FIG.
[0021]
As shown in the figure, the movable mold 7 and the fixed mold 8 are combined to form a desired space 9 and resin is injected into the space 9 to be molded. In the figure, reference numeral 10 denotes a chuck for gripping the magnet 1, which comprises an L-shaped gripping part 11 for gripping the magnet 1 and a mounting part 12 for attaching the gripping part 11. The gripping part 11 is pivotally attached to the mounting part 12. Then, a tapered surface 14 is formed on the connecting rod 13 with the mounting portion 12, and when the mounting portion is moved back and forth by a cylinder (not shown), the gripping portion 11 moves forward from the fixed mold 8 to release the gripping and moves backward. And grip it. Reference numeral 15 denotes a projecting die that is inserted into the hollow portion 3 of the magnet 1 and is integrally attached to the fixed die 8. Reference numeral 16 denotes a projecting type for securing a space formed between the magnet 1 and the outer ring, and is formed in a hollow cylindrical shape integrally with the movable die 7 so as to form a space for forming a bridge. It has three notches.
[0022]
The in-process hollow float body formed in the first stage is a combination of a fixed mold having a protruding mold inserted into the hollow portion 3 and a movable mold having a concave portion having a predetermined external shape. Is performed to form a magnetically incorporated hollow float body having a predetermined external shape.
[0023]
In addition, although the example which gripped the outer peripheral surface of the magnet 1 was shown in the said Example, you may hold | grip a hollow inner peripheral surface and an inner peripheral surface, an outer peripheral surface, or an outer surface.
[0024]
【The invention's effect】
As described above, according to the present invention, the center of the magnet and the hollow float body can be matched, there is no eccentricity, and therefore the electrolyte solution can be accurately obtained without being caught by the cylindrical body penetrating the hollow float body. In this way, it floats and sinks following changes in the liquid level and specific gravity of the liquid, and has the effect of enabling accurate detection.
[Brief description of the drawings]
FIG. 1 is a perspective view of an in-process hollow float body, in which (a) shows the front surface (b) and the back surface.
FIG. 2 is a perspective view of a hollow float body with a magnet having a predetermined shape.
FIG. 3 is a partial sectional view of a molding die of an in-process hollow float body.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Magnet 2 ... Resin 3 ... Hollow part 4 ... Ring 6 ... Bridge 7 ... Moving type | mold 8 ... Fixed type | mold 10 ... Chuck

Claims (5)

State a hollow cylindrical magnet float body made of synthetic resin, in the manufacturing method of hollow section formed by burying as exists a built-in magnet hollow float body, which holds the part of the hollow magnet first stage of the molding was And forming a synthetic resin to cover the hollow inner peripheral surface and the outer peripheral surface other than the portion where the magnet is gripped, and a ring surrounding the outer peripheral surface and spaced apart from the outer surface of the magnet. The resin to be covered is molded integrally through a bridge to form an in-process hollow float body, which is taken out of the mold of the molding machine, and then the in-process hollow float body formed in the first stage as the second stage. Insert a projecting die into the hollow part and place it in a molding die with a recess to cover the magnet peripheral surface of the part gripped in the first stage and mold it into a hollow float body with a predetermined appearance Of hollow float bodies with built-in magnets Law.   The method of manufacturing a hollow float body with built-in magnet according to claim 1, wherein the magnet is gripped at at least three locations.   2. The method of manufacturing a hollow float body with built-in magnet according to claim 1, wherein the bridge is formed at a center position between positions where magnets adjacent to each other are gripped.   The method for manufacturing a hollow float body with built-in magnet according to claim 1 or 3, wherein the bridge is formed so as to protrude so as to form a part of an outer surface having a predetermined appearance shape at the time of the second stage molding.   The method for producing a magnet built-in hollow float body according to any one of claims 1 to 4, wherein the built-in magnet is housed in a lower position of the hollow float body formed in a predetermined external shape.

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