JPH09314582A - Mounting structure of plastic roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mounting structure of a plastic roll capable of preventing the decrease of a life due to the stress generated by the temperature difference of a rolling bearing and its housing even in the case of using under wide temper ature conditions by preventing the looseness of the bearing and the housing without considering the thermal expansion difference between the bearing and the housing in the roll used at the high temperature of 100 to 250 deg.C. SOLUTION: The mounting structure of a plastic roll 1 of a hollow cylindrical shape rotatably supports the roll 1 via a rolling bearing 6 to a fixed shaft 5 inserted into the central hole 2 of the roll, and a cylindrical housing 3 having larger diameter than the hole 2 coaxial with the hole 2 at both ends of the inner periphery of the hole 2, a taper formed at a boundary A between the hole 2 and the housing 3 in such a manner that the bearing 6 is mounted in the housing and the roll 1 is supported via shaft retainer 4 of the shaft 5 and urging means 7.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet-like material processing step such as calendar rolling, T-die extrusion or casting for molding a thermoplastic resin under high temperature conditions. Plastic rolls used in contact with thermoplastics,
In particular, it relates to a mounting structure for a roll made of polytetrafluoroethylene. Polytetrafluoroethylene is used as a material for a plastic roll which comes into contact with a thermoplastic resin at high temperature because of its excellent heat resistance, non-adhesiveness and chemical resistance. Conventionally, as a mounting structure of a plastic roll which is rotatably supported on a fixed shaft through a rolling bearing without being driven, those shown in FIGS. 4A and 4B are generally known. In this mounting structure, a cylindrical housing 13 having a diameter larger than that of the central hole 12 is provided at both ends of the inner peripheral surface of the central hole 12 of the cylindrical plastic roll 11, and the fixed shaft 15 is provided in the central hole 12. Is inserted, and an annular rolling bearing 16 is mounted between the housing 13 and the fixed shaft 15, and both ends of the fixed shaft 15 are fixed by the shaft retainers 14, and further on the outside of the rolling bearing 16. Along the groove 17 provided on the fixed shaft 15 along the retaining ring 1
8 is attached so that the axial displacement of the fixed shaft 15 can be prevented. With such a mounting structure, the inner ring of the rolling bearing 16 on the fixed shaft 15 stands still, the outer ring rotates, and the plastic roll 11 rotates on the fixed shaft 15. In the conventional plastic roll 11 described above, a difference in thermal expansion occurs due to the difference in material between the metal forming the rolling bearing 16 and the plastic forming the plastic roll 11. For example, in the case of polytetrafluoroethylene, which is a typical product of the fluorine resin used for plastic rolls, its linear expansion coefficient is about 10 × 10 ⁻⁵ / ° C., while that for general rolling bearings. The linear expansion coefficient of the steel used is 1.25 x 1
Since they are 0 ⁻⁵ / ° C., when both have the same size, due to the difference in thermal expansion, when the temperature change reaches 200 ° C., the polytetrafluoroethylene becomes large with a size difference of about 1.75%. Therefore, 100 plastic rolls 11
When used at a high temperature of up to 250 ° C., when there is a difference in thermal expansion compared with that at room temperature, the rolling bearing 16
Housing 1 for a rolling bearing 16 that has a proper fit dimension at room temperature to transmit the rotational movement of the outer ring of the bearing
The rolling bearing is loosened by the expansion of the portion 3 and the rolling bearing 1
There was a problem that the normal rotation of 6 was not transmitted to the plastic roll 11. In order to solve this, conventionally,
The inner diameter of the housing 13 during processing (at room temperature) should be small so that the difference between the outer diameter of the rolling bearing 16 and the inner diameter of the housing 13 due to thermal expansion under the operating temperature conditions calculated is zero. It was open. In this method, however, the rolling bearing 16 and the housing 1 are not under the operating temperature conditions, for example, at room temperature.
3 has a large amount of contraction, and the stress due to the difference in thermal expansion with the housing 13 caused by the temperature difference is applied to the contacted portion, and there is a problem that the life of the plastic roll 11 is shortened, and particularly the temperature difference repeatedly occurs. In such places, the decrease in life was remarkable. The present invention solves the above-mentioned conventional problems, and in a plastic roll used at a high temperature of 100 to 250 ° C., the rolling bearing does not consider the difference in thermal expansion between the rolling bearing and its housing portion. It is an object of the present invention to provide a plastic roll mounting structure capable of preventing loosening between a housing and a housing portion, and even when used in a wide range of temperature conditions, preventing a decrease in life due to stress caused by the temperature difference. To do. In the structure for mounting a plastic roll of the present invention, a rolling roll having a diameter larger than that of the central hole through which the fixed shaft is inserted is coaxial with the central hole. Providing a cylindrical housing for bearings,
A taper is formed at the boundary between the center hole and the housing. The boundary portion forming this taper is a portion for receiving the rolling bearing pressed by the urging means in the operating temperature condition range, and the taper angle θ is the heat between the plastic roll surface length and the inner diameter of the housing. Expansion difference is ΔL
And ΔDi, tan θ> ΔDi / ΔL is preferable. This is because when the temperature is evenly transmitted to the plastic roll and the rolling bearing, the thermal expansion differences ΔL and ΔDi at that temperature are determined by the linear expansion coefficient of the material. Further, in the plastic roll mounting structure of the present invention, rolling bearings are attached to each housing having a diameter larger than that of the central holes provided at both ends of the inner peripheral surface of the central hole,
The plastic roll is supported via the shaft retainer of the fixed shaft and the biasing means. As the biasing means, a compression spring, a metal spring, a fluid pressurizing means, or the like is usually used, but the biasing means is not limited to these as long as it has a biasing function. An example of the compression spring is a disc-shaped one as shown in FIG. With such a compression spring, the rolling bearing is pressed to the boundary side where the taper is formed.At that time, the rolling bearing is made of a ring-shaped metal having an inner diameter larger than the outer diameter of the fixed shaft and having an appropriate thickness. It is advisable to use a collar having an outer diameter that does not hinder the rotation of the outer ring of the rolling bearing. The assembly of the plastic roll, the fixed shaft, the rolling bearing, the collar and the urging means is carried out under a normal temperature by applying an appropriate preload of about twice the weight of the plastic roll. The biasing means considers the amount of contraction of the spring due to the thermal expansion of the plastic roll in the axial direction at the operating temperature, and the pressing force at that time does not exceed the allowable value of the axial load of the rolling bearing. It is better to select a bearing, and it is preferable that the rolling bearing be capable of bearing both radial pressure load and axial load. [Operation] The plastic roll expands not only in the radial direction but also in the axial direction of the fixed shaft when used at a high temperature. Due to the expansion in the radial direction, the outer ring of the rolling bearing in each housing becomes loose, so that the normal rolling motion of the rolling bearing cannot be transmitted to the plastic roll, but due to the axial expansion of the plastic roll,
Since the rolling bearing whose axial movement is restricted by the shaft retainer and the biasing means is pressed and locked to the boundary portion where the taper is formed by an appropriate force, the plastic roll can perform a normal rotational movement. . Therefore, even if the temperature changes over a wide range, the normal rotational movement can be performed, and the stress generated by the thermal expansion change can be interfered with, and the life can be extended. The plastic used for the mounting structure of the plastic roll of the present invention is a fluorine resin having excellent heat resistance, particularly PTFE (polytetrafluoroethylene) or PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer). However, other polyimide resins, PEEK (polyether ether ketone), etc. can also be used. BEST MODE FOR CARRYING OUT THE INVENTION An example of a plastic roll mounting structure of the present invention will be described below with reference to FIGS. FIG. 1 (a) shows a cross-sectional view of this plastic roll according to the plastic roll mounting structure of the present invention, and FIG.
A sectional view of a mounting structure of the present invention in which a rolling bearing and the like are mounted is shown. Further, FIG. 2 is a partially enlarged cross-sectional view of a mounting portion of the Teflon roll and the fixed shaft of FIG. 1 (b). As shown in the figure, the plastic roll 1
Is a hollow cylinder, and a central hole 2 for inserting the fixed shaft 5 is provided on the central axis thereof. Further, both ends of the inner peripheral surface of the central hole 2 are coaxial with the central hole 2 and A cylindrical housing 3 having a diameter larger than the diameter is provided. A taper is formed at the boundary A between the housing 3 and the center hole 2 toward the inside of the plastic roll 1.
A rolling bearing 6 is arranged in the housing 3, and a compression spring 7 serving as a biasing means is provided between the shaft retainer 4 of the fixed shaft 5 and the rolling bearing 6 and has a circular diameter larger than the outer diameter of the fixed shaft 5. Is mounted via a ring-shaped metal collar 8 having an appropriate thickness, and the compression spring 7 presses the rolling bearing 6 inward. With such an attachment structure, the plastic roll 1 is rotatably supported by the fixed shaft 5 via the rolling bearing 6. EXAMPLE An example was carried out using the plastic roll mounting structure of the present invention shown in FIG. [Example 1] The plastic roll 1 used was made of hard P
It was used as a press roll for preventing neck-in in the roll portion used in the take-up device of the calendering machine for VC. The maximum temperature of the plastic roll during use was 200 ° C. The plastic roll 1 is made of PTFE and has an outer diameter of 60 mm and a width of 100 mm, and the taper angle θ of the boundary A is 30 °.
And Further, the rolling bearing 6 is a deep groove ball bearing in the classification of JIS B 1513-1987 and uses 6802ZZ manufactured by NTN. ), And for color 8, JIS G 3101
1987 SS400, outer diameter φ18 mm, inner diameter φ15.1
A ring-shaped member having a thickness of 3 mm and a thickness of 3 mm was used. Using the above-mentioned mounting structure, the rotation state of the plastic roll was measured on the take-off roll after 24 hours of continuous operation at each temperature of 100 ° C, 150 ° C, and 200 ° C. As a result, the plastic roll is
Under both temperature conditions of 150 ° C. and 200 ° C., normal rotation was obtained, and the rolling bearing portion 6 of the housing 3 was not loosened. Comparative Example 1 For comparison, a plastic roll having the conventional mounting structure shown in FIG. 4 was used, the same PTFE plastic roll as in Example 1 was used, and the same conditions as in Example 1 were used. went. As a result, 100 ℃
Normal rotation was obtained, but at 150 ° C. and 200 ° C., the rolling bearing 6 of the housing 3 was loosened, and normal rotation was not obtained. According to the plastic roll mounting structure of the present invention, in a plastic roll used at a high temperature of 100 to 250 ° C., without considering the difference in thermal expansion between the rolling bearing and the housing portion thereof. In addition, the rolling bearing can be prevented from loosening, and even when the rolling bearing is used in a wide range of temperature conditions, it is possible to prevent the life from being shortened due to the stress caused by the temperature difference.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 (a) is a sectional view of a plastic roll used in the mounting structure of the present invention, and FIG. 1 (b) is a sectional view showing the mounting structure of the plastic roll of the present invention. Is. FIG. 2 is a partially enlarged cross-sectional view of an attachment portion between a plastic roll and a fixed shaft of the attachment structure of the present invention. FIG. 3 is a plan view showing an example of a biasing means used in the mounting structure of the present invention. FIG. 4 is a view showing a conventional plastic roll mounting structure, in which (a) is a sectional view of the plastic roll;
(B) is sectional drawing which shows the attachment structure. [Explanation of symbols] 1,11 Plastic roll 2,12 Center hole 3,13 Rolling bearing housing 4,14 Shaft retainer 5,15 Fixed shaft 6,16 Rolling bearing 7 Biasing means 8 Collar 18 Stop ring

Claims (1)

Claim: What is claimed is: 1. A hollow cylindrical plastic roll mounting structure rotatably supported via a rolling bearing on a fixed shaft inserted through a center hole of the plastic roll, wherein A cylindrical housing coaxial with the center hole and having a larger diameter than that of the center hole is provided at both ends of the inner peripheral surface of the hole, and a taper is formed at the boundary between the center hole and this housing to allow rolling in each housing. Install bearings,
A plastic roll mounting structure characterized in that a plastic roll is supported via a shaft retainer of a fixed shaft and a biasing means.