JP2832934B2 - Method of manufacturing telescopic shaft - Google Patents

Description

Description: Object of the Invention (Industrial application field) The present invention relates to a telescopic shaft having an inner shaft slidably disposed in an outer shaft, and more particularly to a play between the shafts. In order to eliminate the problem, a resin layer is formed between the outer shaft and the inner shaft by a monomer casting method, and is used as a method for manufacturing the stretchable shaft. (Prior Art) The prior art according to the present invention is disclosed in JP-A-60-178013, JP-A-60-188613, and JP-A-61-184222.
Is described in Japanese Patent Application Publication No. Above, those described in JP-A-60-178013,
In a sliding component and its manufacturing method by a monomer casting method,
The shaft is fitted to the bearing so that it can rotate or reciprocate freely, and a low-viscosity monomer or prepolymer is polymerized and cured to the clearance between the bearing surface of the bearing and the shaft, and a resin lining is molded on the bearing surface. It slides on the resin lining. Also, those described in JP-A-60-188613,
A telescopic shaft in which a synthetic resin is filled and formed between an inner peripheral surface of an outer shaft and an outer peripheral surface of an inner shaft that constitute the telescopic shaft, and the synthetic resin layer is fixed to one of the shafts. It is. Also, those described in JP-A-61-184222,
In the slide spline device and the method for manufacturing the same, a release agent is applied to the inner peripheral surface of the bottomed cylindrical outer spline member on which the spline is formed, then a monomer is injected into the outer spline member, and then the outer spline member is The inner spline member having a spline formed on the outer peripheral surface corresponding to the outer spline is inserted into the outer spline member, and the liquid level of the monomer is adjusted through the clearance between the outer spline member and the inner spline member to the opening side of the outer spline member. , And then the monomer is polymerized and cured. (Problems to be Solved by the Invention) However, in Japanese Patent Application Laid-Open No. 60-178013, since a resin layer is formed by applying an adhesive to the bearing side, etc. It is considered that a large shrinkage occurs at the time), which causes a problem that a large residual stress remains and a crack is generated. Also, JP-A-60-188613 and JP-A-61-184222
The gazette described in Japanese Patent Application Laid-Open Publication No. H10-15064 is to prevent backlash between the outer shaft and the inner shaft and maintain good sliding feeling, but the pulling force exerting this characteristic is based on the relationship between the resin layer and the inner shaft or the shaft. It greatly depends on the state of adhesion, and when the adhesive is applied, slight relaxation of the adhesion of the adhesive layer over time greatly affects the pull-out force,
Further, when the adhesive is not applied, there is a problem that a large relaxation of the adhesion occurs over time, and the pulling force changes tightly. In addition, JP-A-60-178013, JP-A-60-1886
No. 13, Japanese Patent Application Laid-Open No. 61-184222 discloses a sliding part having a resin layer, while having good sliding characteristics attributable to its minute clearance, but having an outer shaft or a bearing part. Since the resin layer is minute, there is a problem that grease retention as a lubricant during actual use is poor. In view of the above, it is an object of the present invention to improve the sliding characteristics of a telescopic shaft, in particular, to maintain stable pulling force for a long time and to improve grease retention. [Means for Solving the Problems] The technical means taken to solve the above technical problem is to form a groove perpendicular to the axial direction on the outer peripheral surface of the inner shaft, A mold release agent is applied to the outer peripheral surface of the shaft, then the bottom of the outer shaft is closed, the monomer is injected into the outer shaft, the inner shaft is inserted therein, and then heated to complete the polymerization reaction of the monomer. Thus, the resin layer is formed on the outer peripheral surface of the inner shaft to which the release agent is applied so as to be engaged with the groove, and the sink portion is formed on the surface of the resin layer along the groove. (Function) According to the above technical means, the change in adhesion between the inner shaft and the resin layer can be made almost zero by applying a release agent to the outer peripheral surface of the inner shaft, and the sliding characteristics are stable over a long period of time. (Pulling force) can be ensured. In addition, by applying groove processing to the inner shaft, the fixing force of the resin layer can be improved, and the pulling force can be easily controlled by adjusting the number of grooves. The sink part due to the thickness is used as a grease reservoir,
Since the grease retention can be improved, the conventional problem can be solved. (Example) Hereinafter, an example of the present invention will be described with reference to the drawings. 1 to 4, the telescopic shaft 10 comprises an outer shaft 1 and an outer shaft 2. The outer shaft 1 is formed in a cylindrical shape and has a plurality of splines 1a formed along the axial direction on the entire inner peripheral surface thereof.
On the inner peripheral portion, a plurality of splines 2a are formed along the axial direction on the outer peripheral surface in a columnar shape, and a plurality of grooves 2b provided in a direction perpendicular to the axis are formed, and on the splines 2a, the grooves 2b are formed. Resin layer 3
The inner shaft 2 on which the is fixed is inserted. The inner shaft 2 expands and contracts without backlash due to the minute clearance 3a generated between the resin layer 3 and the outer shaft 1 and the sink portion 3b of the resin layer 3 formed by the plurality of grooves 2b. This is to maintain a constant pulling force without change. The method of manufacturing the telescopic shaft 10 is as follows. First, a release agent such as silicon oil or dry fluorine is applied to the entire inner peripheral surface of the outer shaft 1 and the outer peripheral surface of the inner shaft 2, and then the spline shape of the outer shaft 1 is formed. The fitted bottom plug 4 is fitted and fixed to the bottom 1b of the outer shaft 1, and the inner shaft 2 is inserted into the outer shaft 1, and a coil 22 is wound around a furnace core tube 21 as shown in FIG. It is placed in the induction heating device 20 and preheated in the device 20 until it reaches about 180 ° C. Next, the preheated inner shaft 2 is drawn out over the entire length, and 5 undiluted solutions in which ε-caprolactam as a monomer of the nylon 6 resin, a catalyst and a polymerization initiator are sufficiently mixed are injected into the outer shaft 1, and then the inner shaft 2 is drawn out.
Is inserted over the entire length, and then the high-frequency induction heating device
When the temperature is maintained at about 160 ° C to 165 ° C within 20 minutes and the temperature is maintained for 5 minutes, the polymerization reaction is completed, and nylon 6 is added to the clearance 3a with the outer shaft 1 so as to be fixed to the inner shaft 2.
Is formed. The resin layer 3 forms a minute clearance between itself and the outer shaft 1 due to molding shrinkage, and particularly, a sink portion 3b having an sink amount t is formed around the groove portion 2b. Since the sink portion 3b of the resin layer 3 formed by the plurality of grooves 2b formed in the inner shaft 2 is thicker than other places, the molding shrinkage around the groove 2b is smaller than that of the other portions. The difference t has the effect of reducing the pulling force. Thus, the pulling force can be controlled by the number of grooves. On the other hand, in the conventional telescopic shaft manufactured by forming a resin layer by the monomer casting method, the clearance between the outer shaft and the resin layer generated by molding shrinkage is extremely small, so lubrication during actual use is not possible. Grease retention as an agent is poor, but as in the present invention, the telescopic shaft is grooved at right angles to the axis of the inner shaft 2.
In the case of 10, the sink amount t of the resin layer 3 over the groove 2b becomes a grease pool, which has an effect of retaining grease. The telescopic shaft 10 obtained as described above has sliding characteristics with good pull-out force due to the minute clearance generated between the shaft 10 and the nylon 6 resin layer 3. C. × 500 hours or more), and almost no change in the drawing force with time was observed. The following table shows the data of the test results according to the above example, and also shows comparison data with comparative examples 1 and 2 manufactured by another different method. In Comparative Example 1 in the above table, aminosilane coupling (A1100, 1 wt% aqueous solution, manufactured by Nippon Unicar) was used as an adhesive for the inner shaft 2 in the same configuration as in Example 1.
The stretchable shaft obtained by this method showed good sliding characteristics (pulling force) at the initial stage, except that a high temperature of 80 ° C. ×
The 500 hour test showed a tendency for the pull-out force to increase. Comparative Example 2 has the same configuration as Comparative Example 1,
The inner shaft 2 is directly coated with a resin layer without applying a release agent or an adhesive to the inner shaft 2,
Immediately after the completion of the polymerization reaction, good sliding properties were exhibited, but a tendency was observed that the pulling force significantly increased with time. From the above results, the telescopic shaft 10 obtained by the manufacturing method of the present invention has good sliding characteristics (pulling force) with almost no change over time. [Effects of the Invention] According to the present invention, since the release agent is applied to the outer peripheral surface of the inner shaft on which the resin layer is formed (a groove perpendicular to the axial direction), the inner layer and the resin layer The adhesion becomes zero, and as a result, the adhesion becomes constant over a long period of time. Therefore, the sliding characteristics (pulling force) of the inner shaft can be stabilized for a long time. In addition, since a groove perpendicular to the axial direction is formed on the outer peripheral surface of the inner shaft, a fixing force of the resin layer to the inner shaft can be secured. Further, since the sink portion is formed in the resin layer around the groove, the grease retention is improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a shrinkable shaft according to an embodiment of the present invention, FIG. 2 is an enlarged view of a portion A in FIG. 1, and FIG. 3 is B in FIG.
FIG. 4 is a sectional view taken along the line B, and FIG. 1 ... outer shaft, 1a ... outer shaft spline, 2 ... inner shaft, 2a ... inner shaft spline, 2b ... inner shaft groove, 3 ... resin layer, 3a ... clearance, 3b ... resin layer Sink mark, 20 …… High frequency induction heating device.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-188613 (JP, A) JP-A-61-184222 (JP, A) JP-A-56-59030 (JP, A) JP-A 63-184 60713 (JP, A) JP-A-62-9027 (JP, A) JP-A-61-123223 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16C 3/03

Claims (1)

(57) [Claims] An outer shaft with a spline formed on the inner peripheral surface,
An expansion / contraction having an inner shaft formed with a spline on an outer peripheral surface corresponding to a spline of the outer shaft and arranged coaxially and extendably in the outer shaft, and a resin layer formed on an outer peripheral surface of the inner shaft. In the method for manufacturing a universal shaft, a groove perpendicular to the axial direction is formed on the outer peripheral surface of the inner shaft, then a mold release agent is applied to the outer peripheral surface of the inner shaft, and then the bottom of the outer shaft is closed, After injecting the monomer into the outer shaft and inserting the inner shaft therein, heating is performed to complete the polymerization reaction of the monomer, and the groove is formed on the outer peripheral surface of the inner shaft coated with the release agent. A method of manufacturing a telescopic shaft, wherein the resin layer is formed so as to engage with the resin layer and a sink portion is formed on the surface of the resin layer along the groove.