JP2597371B2 - Ceramic coil spring forming equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for forming a ceramic coil spring.

[Conventional technology]

Coil springs are used as an important part for various machines. Although such coil springs have been manufactured from metal materials, metal coil springs have inferior properties such as heat resistance, corrosion resistance, and wear resistance. In recent years, the manufacture of ceramic coil springs capable of improving these properties has been increasing. Attempted.

As a method of manufacturing a ceramic coil spring, an organic material imparting moldability to a ceramic powder raw material and a solvent thereof are kneaded, and a coil spring having a desired coil shape is formed using a ceramic wire obtained by extruding the kneaded material. The method of obtaining is performed.

When a water-soluble organic material that imparts moldability is used to manufacture a coil spring using water as the solvent,
The following problems arise.

When the wire contains a large amount of water (a wire having a high water content) The coiling itself is easy, but when wound around a core rod for coiling, the inside (inner diameter) is easily crushed during coiling. In addition, if drying is performed in this state, wire breakage due to drying shrinkage due to evaporation of water and further collapse of the inner diameter of the coil occur. In the case of coiling using a wire rod having a high water content, if the molded body is removed from the core rod immediately after coiling, there is no shape retention and the coil shape is not maintained.

If the water content in the opposite wire is small, reduce the amount of water added during kneading of the ceramic extrusion raw material, or dry the extruded wire to reduce the water content, and try to minimize the drying shrinkage after coiling, The wire becomes hard, and subsequent coiling work is difficult, and wire breakage occurs during coiling. Further, since the coiling state is greatly affected by the atmosphere (temperature, humidity, etc.), the conditions under which coiling is possible are limited. In addition, variation in the shape after drying is large due to a slight change in the amount of water. Therefore, it is difficult to coil a fine wire having a wire diameter of 1 mm or less and a coil having a small D / d (D: average coil diameter, d: wire diameter).

Therefore, as a generally considered method for manufacturing a ceramic coil spring, for example, the following method is known.

The ceramic powder raw material, methyl cellulose, surfactant, polyhydric alcohol and water are kneaded, extruded to obtain a wire, coiled on a core rod, pre-sintered as it is, and then the core rod is removed. Main sintering method
-7659).

In order to improve the above method and obtain a coil spring having the same pitch, the water content of an extruded wire made of ceramic powder as a main material is adjusted, and the interval is maintained on a core rod having the same heat shrinkage property as the wire. And sintering by embedding it in alumina powder, pre-sintering the wire, removing the pre-sintered wire from the core rod and performing main sintering (Japanese Patent Laid-Open No.
No. 3).

FIG. 6 shows these methods in a block diagram. As shown in FIG. 6, in these methods, after extruding a kneaded material of a raw material to obtain a wire, the wire is dried and reduced to a predetermined moisture content, generally to a value of about 3% or less. The plasticity of the wire is adjusted so that the ceramic coil spring can be formed. In addition, a surfactant and a polyhydric alcohol are added in a large amount so that the plasticity of the wire can be advantageously maintained even after drying (after moisture adjustment).

[Problems to be solved by the invention]

 However, the conventional method has the following problems.

In order to obtain a wire that does not cause wire breakage or the like after coiling, delicate control of moisture control by drying is required.

Since the plasticity of the wire can be advantageously maintained even after drying, the shape retention after coiling is poor. Therefore, it is necessary to perform sintering while being wound on a core rod having the same heat shrinkage characteristic as the wire.

Since a core rod having the same heat shrinkage property as the wire is used, wire breakage and deformation inside the coil can be prevented to some extent, but it cannot be reused because pre-sintering is performed. The cost required for the core bar increases.

Since it is necessary to use a core rod having a heat shrinkage characteristic similar to that of a wire rod, it cannot be coiled by a method similar to a metal spring using a coiling machine, and there is no mass productivity.

As described above, the conventional method has poor mass productivity from the viewpoint of cost, yield, and the like.

The present invention solves the above problems, and performs coiling of fine lines and D /
An object of the present invention is to provide a mass-produced ceramic coil spring forming apparatus capable of performing coiling with a small d, preventing breakage or deformation of a wire, and reducing shape variation.

[Means and actions for solving the problems]

The ceramic coil spring forming apparatus of the present invention is for immersing a dry wire mainly composed of ceramic powder, alcohol, ester, ketone, aromatic hydrocarbon, aliphatic hydrocarbon, alicyclic hydrocarbon, A solvent tank containing a single solvent or a mixed solvent of two or more selected from the group of chlorinated hydrocarbons, or a mixed solvent of alcohol and a small amount of water, and a core for coiling disposed after the solvent tank; A bar or an automatic coiling machine is provided.

In the present invention, in order to form a wire rod, an extruder for forming a kneaded material containing ceramic powder as a main component into a wire rod and a drying furnace for drying the wire rod may be provided in a stage preceding the solvent tank.

In the present invention, the ceramic powder as a raw material may be an oxide ceramic or a non-oxide ceramic. Examples of the oxide ceramics include alumina, mullite, partially stabilized zirconia, and the like. The non-oxide ceramics include, for example, silicon nitride, silicon carbide, sialon, and the like.

In the present invention, the organic material to be added (generally also called a binder) imparts plasticity and shape retention in the molding of a non-plastic raw material such as ceramic powder, and is decomposed and dispersed by sintering to form a sintered body. It has the advantage of not leaving residues such as impurities.

Organic materials used include binders, plasticizers, dispersants and the like. These are generally known to have the following functions.

The binder functions to maintain the strength of the green molded body. If the amount of the binder is too small, the obtained kneaded material becomes brittle, and it becomes difficult to perform extrusion molding or processing into a coil shape. On the other hand, if the compounding amount is too large, problems such as difficulty in extrusion molding from a die (nozzle) occur.

The plasticizer has a function of giving plasticity and flexibility, and gives good flexibility to extrusion molding or a wire obtained by extrusion molding. If the compounding amount is too small, the viscosity of the kneaded material increases, causing a problem that extrusion becomes difficult.If the compounding amount is too large, the strength of the kneaded material decreases, and the shape of the coil shape is maintained. Problems such as loss of performance occur.

The dispersant has a function of uniformly dispersing the ceramic powder and the organic material when kneaded and reducing the amount of the organic material solvent added.

When a water-soluble binder is used, a binder that is difficult to dissolve in a solvent contained in a solvent tank, for example, methylcellulose is used. As the plasticizer, a plasticizer which is water-soluble and easily soluble in a solvent in a solvent tank (amphiphilic) is selected. Examples of such a plasticizer include polyethylene glycol. Further, one or both ends of polyethylene glycol may be substituted with various hydrophilic groups. Each of the above-mentioned raw materials is blended at an appropriate blending ratio, kneaded, and then formed into a wire by, for example, an extruder, and further dried to a state where most of the water is removed and the dry shrinkage is sufficiently obtained.

In the present invention, the solvent contained in the solvent tank has an action of imparting plasticity to the dried wire (hereinafter, this solvent is referred to as a coiling solvent). Such a coiling solvent easily penetrates between ceramic powder particles,
What softens an organic material and provides plasticity is used. That is, a binder that softens but hardly dissolves a water-soluble binder (eg, methylcellulose) and has a function of dissolving a plastic component is used. Specifically, alcohols, esters, ketones, aromatic hydrocarbons, and aliphatic hydrocarbons are used. , Alicyclic hydrocarbons, chlorinated hydrocarbons, a single solvent or a mixed solvent of two or more, or a mixed solvent of an alcohol and a small amount of water. In particular, a mixed solvent of an ester, a ketone and a chlorinated hydrocarbon, a mixed solvent of an alcohol and a chlorinated hydrocarbon, and the like are desirable. Since the mixed solvent as described above has a small surface tension and easily penetrates between the ceramic powder particles through pores or the like on the surface of the wire agent, it is advantageous for imparting plasticity to the wire by a plasticizing effect and by softening the organic material. It is. When a mixed solvent is used as the coiling solvent, the organic material (the solubility of the binder and the plasticizer) can be adjusted according to the composition ratio, and the evaporation rate of the solvent during drying can be adjusted. Becomes wider.

In the molding apparatus of the present invention, the wire rod immersed in the coiling solvent in the solvent tank and given plasticity is wound around a core rod of a lathe type coiling machine, or is coiled by an automatic coiling machine. Thereafter, the coil-shaped formed body is dried, debindered, and sintered to produce a ceramic coil spring.

In the molding device of the present invention, when the wire that has been dried and shrunk after removing water is immersed in a coiling solvent, the wire absorbs the coiling solvent and is given the plasticity required for coiling. After the wire is dried, the plastic component (eg, polyethylene glycol) is eluted by the coiling solvent, and the binder (methylcellulose) is only softened by the coiling solvent and hardly dissolves or swells. Is obtained. Therefore, unlike the conventional case where the moisture and organic materials (binders, plasticizers, etc.) contained in the wire material impart the plasticity required for coiling the wire material, there is no need for moisture adjustment and good shape retention. It is not necessary to perform sintering while being wound on a core rod having the same heat-shrinking property as a wire rod, and a coiling machine can be used similarly to a conventional metal spring. In addition, wire breakage of the wire can be prevented, coiling of a fine wire and coiling with a small D / d can be performed, and variation in the shape of a formed body can be reduced.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 4 is a configuration diagram showing a wire rod forming apparatus. As shown in FIG. 4, the wire rod forming apparatus includes an extruder 1, a drying furnace 11, and a winding drum 12. First and second screws 2, 3 are provided inside the extruder 1. The first screw 2 is rotated by a main motor 4 and a vibration motor 5, and the second screw 3 is rotated by a motor 6. It has become. The inside of the extruder 1 is evacuated by a vacuum pump 7. From the hopper 8 of the extruder 1, a raw material adjusted by mixing ceramic powder, an organic material for imparting moldability and water as a solvent thereof at a predetermined mixing ratio is supplied. And
The raw material is kneaded by first and second screws 2 and 3 and extruded through a die 9 to form a wire 10 and a drying furnace.
After being dried to the state where it has shrunk and dried in 11, it is wound on a winding drum 12 having a large diameter. The cross-sectional shape of the wire is not limited to a perfect circle, but may be an ellipse or a square.

Coiling of the wire in a dry state produced as described above is performed by the apparatus shown in FIG. 1 or FIG.

The apparatus shown in FIG. 1 has a solvent tank 22 containing a coiling solvent 21 for imparting plasticity to a wire, and a lathe type coiling machine (only the core bar 23 is shown). In FIG. 1, a wire 10 is immersed in a coiling solvent 21 in a solvent tank 22, and this wire 10 is wound around a core rod 23 of a lathe type coiling machine in a state where sufficient plasticity is imparted by the coiling solvent 21. It is coiled. Wire rod to core rod 23
As shown in FIGS. 2 (a) and (b), the fixing of the wire 10 is performed by providing a hole 23a in the core rod 23 and inserting the end of the wire 10 into the hole 23a. Note that the end of the wire 10 may be fixed by a core bar 23 with an adhesive tape. Thereafter, the core bar 23 on which the wire 10 is coiled is placed in an oven (not shown).
Dry by inserting into and evaporating the coiling solvent.

Further, after the end of the wire 10 is cut, the wire 10 is removed from the core rod 23 and sintered in a sintering furnace, whereby a coil spring made of a ceramic sintered body is manufactured.

The apparatus shown in FIG. 3 has a solvent tank 22 containing a coiling solvent 21 for imparting plasticity to a wire, and an automatic coiling machine 31. In FIG. 3, the wire 10 is wound on a rotatable support table 24, and is immersed in a coiling solvent 21 in a solvent tank 22 and coiled by an automatic coiling machine 31 in a state where sufficient plasticity is imparted. You. In the automatic coiling machine 31, the wire 10 is fed by the straightening roller 32 and the feed roller 33, passes through the guide 34, along the core rod 35, the curvature set by the coiling pins 36, 37, and the pitch set by the pitch tool 38. And then cut with a cutting tool 39. Also,
Drying is performed in the dryer 40.

Further, the wire rod 10 is removed from the core rod 35 and sintered in a sintering furnace, whereby a coil spring made of a ceramic sintered body is manufactured.

Hereinafter, using the apparatus shown in FIGS. 1, 3 and 4,
An example in which a ceramic coil spring is manufactured according to the method shown in the block diagram of FIG. 5 will be described.

Production Example 1 100 parts by weight of partially stabilized zirconia, 4 parts by weight of methylcellulose, 4 parts by weight of polyethylene glycol, 4 parts by weight of glycerin, 0.5 parts by weight of ammonium polycarboxylate and 16 parts by weight of water were mixed to prepare a raw material. 4 Feeding to the extruder 1 shown in FIG.
After extruding the wire 10, the wire 10 was passed through a drying furnace 11 set at 60 to 120 ° C., dried, and wound up on a winding drum 12 having a diameter of 550 mm. The wire diameter of this wire 10 was 0.52 mm.

Next, a mixed solvent of 50% by volume of ethyl alcohol + 50% by volume of isopropyl alcohol is contained as a coiling solvent 21 in a solvent tank 22, and the wire 10 removed from the winding drum 12 is immersed for 1 minute or more, and FIG. 1 and FIG. (A) As shown in (b), the core rod 23 of the lathe type coiling machine was coiled.

Subsequently, after heating in an oven at 70 ° C. for 1 minute or more to volatilize the coiling solvent, both ends of the wire 10 were cut off, and the coil-shaped formed body was removed from the core rod 23. The shape of the obtained coil-shaped formed body has a wire diameter of 0.52 mm and a coil average diameter of 10.0.
mm, the number of effective turns was 6, the total number of turns was 8, and the free length was 11 mm.

Next, this coiled compact was sintered to produce a ceramic coil spring. The shape of the obtained coil spring had a wire diameter of 0.40 mm, an average coil diameter of 8.1 mm, an effective number of turns of 6, a total of 8 turns, and a free length of 10.0 mm.

Production Example 2 A wire rod 10 molded using the apparatus shown in FIG. 4 in the same manner as in Production Example 1 was coiled using the apparatus shown in FIG. In this case, the wire 10 is immersed in the coiling solvent 21 for 1 minute or more, and the coiling pins 36 and 37 and the pitch tool 38 of the automatic coiling machine 31 are arranged and coiled so as to have the same shape as in the above-mentioned Production Example 1, At the same time, the coiling solvent was volatilized by the dryer 40. Then, the end was cut with a cutting tool 39 to obtain a coil-shaped molded body. Then
When this coil-shaped formed body was sintered, a ceramic coil spring having substantially the same shape as that of Production Example 1 could be produced.

〔The invention's effect〕

According to the ceramic coil spring forming apparatus of the present invention, coiling of a thin wire having a wire diameter of 1 mm or less and coiling with a small D / d are possible, and wire breakage, deformation of the coil inside is eliminated, and shape variation is reduced, The yield is improved. Further, as with the metal spring, molding by an automatic coiling machine becomes possible, and the molding speed is greatly improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an apparatus for forming a ceramic coil spring in an embodiment of the present invention, FIG. 2 (a) is a front view showing a state in which a wire is fixed to a core rod of the apparatus, and FIG. FIG. 3 is a structural view showing a ceramic coil spring forming apparatus according to another embodiment of the present invention. FIG. 4 is a structural view showing a wire forming apparatus used in the embodiment of the present invention. FIG. 5 is a block diagram showing a method for manufacturing a ceramic coil spring in an embodiment of the present invention, and FIG. 6 is a block diagram showing a conventional method for manufacturing a ceramic coil spring. 10 ... wire, 21 ... coiling solvent, 22 ... solvent tank, 31
…… Automatic coiling machine, 32… Straightening roll, 33 ……
Feed roll, 34… Guide, 35… Core rod, 36, 37… Coiling pin, 38… Pitch tool, 39… Cutting tool, 40… Dryer.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hide Nomura 1 Shinisogocho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Inside the Nikka Group Central Research Laboratories Co., Ltd. (72) Inventor Ryusuke Adachi 1 Shinisogocho, Isogo-ku, Yokohama-shi, Kanagawa Address: Nikkatsu Group Central Research Laboratory Co., Ltd. (56) References JP-A-62-7659 (JP, A) JP-A-60-52309 (JP, A) 1-1110908 (JP, A) JP-A-1-110909 (JP, A)

Claims (2)

(57) [Claims] 1. A group of alcohols, esters, ketones, aromatic hydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons, and chlorinated hydrocarbons for immersing a dried wire mainly composed of ceramic powder. A solvent tank containing a single solvent or a mixed solvent of two or more solvents selected from, or a mixed solvent of alcohol and a small amount of water, and a core rod or an automatic coiling machine for coiling disposed at a subsequent stage of the solvent tank. An apparatus for forming a ceramic coil spring, comprising: 2. An extruder for forming a kneaded material mainly composed of ceramic powder into a wire rod and a drying furnace for drying the wire rod are provided at a stage preceding the solvent tank. 2. The apparatus for forming a ceramic coil spring according to claim 1.