JPH0742705Y2 - Insulation bush - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a heat insulating bush used in a heat roll supporting device and a molding die thereof.

[Conventional technology]

As shown in FIG. 7, in the bearing portion 3 that rotatably supports the shaft portion 2a of the heat roll 2 heated by the heat source 1, the grease of the bearing 4 is prevented from being deteriorated due to heat and the hardness of the bearing inner ring being reduced. Therefore, the heat insulating bush 5 is provided between the shaft portion 2a and the bearing 4.
Is provided. Generally, the heat insulating bush 5 is made of a heat-resistant synthetic resin material and has a sleeve portion 5a and a flange portion 5b to thermally isolate the bearing 4 from the heat roll 2. However, in the heat insulating bush 5, the thermal expansion amount is different between the sleeve portion 5a which is constrained by the bearing 4 in the radial direction and the flange portion 5b which is not constrained in the radial direction, and thermal distortion occurs, so that the sleeve portion 5a and the flange portion 5a. Cracks are likely to occur at the boundary with 5b.

Therefore, a heat insulating bush for a heat roller, which prevents such a problem, is proposed in JP-A-54-59549. This is a cylindrical heat insulating sleeve in which the heat insulating bush is equal to or smaller than the width of the bearing, and between the side end surface of the heat roller and the bearing is a separate body from this cylindrical heat insulating sleeve. A heat insulating ring is inserted to prevent the occurrence of cracks due to thermal strain (first conventional example).

Alternatively, the heat insulating bush 5 is provided with an axial slit having a width of about 1 mm and split to absorb the thermal strain and prevent the occurrence of cracks (second conventional example).

[Problems to be solved by the invention]

However, in the case of the first conventional example, the strength of the weld line portion that is inevitably formed when the cylindrical heat insulating sleeve is injection-molded is weak, and the outer diameter surface of the heat insulating sleeve is press-fitted into the inner diameter surface of the bearing. Therefore, there was a problem that the embeddability was poor.

Further, in the case of the second conventional example, since there is a slit, it is projected from the mold and the inner diameter shrinks more in the direction of the slit during cooling to form an elliptical shape as a whole, making it difficult to obtain a perfect circular product. Therefore, there is a problem that the shape needs to be heat-corrected after molding, a perfect circle is difficult to obtain even if the shape is corrected, and the contact when assembled is not uniform.

Therefore, the present invention has been made by paying attention to the above-mentioned conventional problems, and the purpose thereof is not to be damaged by thermal strain, and the molding accuracy is good, and the need for correction or partial contact etc. It is to provide a heat insulating bushing which is free from the above problems and which can be easily assembled.

[Means for solving problems]

The present invention that achieves the above object is one in which the cross-sectional area of the weld line portion of the heat insulating bush formed by injection molding is made smaller than the cross-sectional area of other portions.

The present invention is a heat insulating bush formed of a resin, and is characterized by having a narrow cross-sectional area where a cross-sectional area of a weld line portion is smaller than a cross-sectional area of another portion. Further, here, the heat insulating bush has a body portion and a flange that rises radially outward from the body portion and is integral with the body portion, and the narrow cross-section portion is provided in at least one weld line portion of the body portion and the flange. It may be given.

[Action]

When the heat insulating bush is injection-molded using the above mold, the resin flow merges in the cavity on the side opposite to the gate to form a weld line. The portion of the weld line is a protrusion protruding into the cavity and has a very small cavity cross-sectional area, whereby a heat insulating bush molded product having a cross-sectional area of the weld line portion smaller than that of the other portion can be obtained.

This heat insulating bush is continuous with a perfect circle in cross section, and excellent molding accuracy can be obtained. Therefore, an extra step such as heat-correction treatment of the shape after molding is not required. In addition, since the cross-sectional area of the weld line portion where the mechanical strength against external force such as pulling becomes weak or weak, the narrow cross-sectional portion is easily broken when incorporating it into the bearing part of the heat insulating roll, and this break point is slightly The diameter of the heat insulating bush can be freely reduced or expanded by stacking or expanding. Therefore, the installation of the insulating sleeve is extremely easy.

Thus, the heat insulating bush assembled to the bearing portion has a perfect circular cross section, so that the contact does not become uneven. In addition, the thermal expansion of the heat insulating bush due to the temperature of the heat roll is absorbed up to the slit-shaped clearance in the weld line portion, and defects such as cracking due to thermal strain are prevented.

In addition, when the body of the heat insulating bush is provided with a flange that rises outward in the radial direction, and the narrow cross-section is provided in at least one of the body and the weld line portion of the flange, the above action is not achieved. In addition, the positioning of the bearing end face with respect to the heat roll can be adjusted by the thickness dimension of the flange to facilitate the mounting of the bearing, and it is also possible to insulate the heat roll from the bearing end face.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. First
FIG. 1 is a front view of one embodiment, FIG. 2 is a side view of the same, and FIG. 3 is an enlarged view of a main part of FIG. This heat insulating bush 10 is made of polyphenylene sulfide (PP
S) Injection molded using resin. The PPS resin may be a branched PPS resin or a linear PPS resin, and other synthetic resin such as polyamide resin or polyimide resin having excellent lubricity and wear resistance may be used.

While having a flange portion 12 at one end of the cylindrical body portion 11,
The cross-sectional area of the weld line portion 13 is made smaller than the cross-sectional area of the other portion to form a narrow cross-section portion 14. In the case of the heat insulating bush 10 of this embodiment, the cross-sectional area of the narrow cross-section 14 is about 0.5 mm ^{2 with} respect to the outer diameter 39 mm of the flange portion 12, the outer diameter 35 mm of the body portion 11, the inner diameter 30 mm, and the length 11 mm. . The narrow cross section 14 may be at an intermediate position of the thickness of the body 11 as shown in FIG. Alternatively, it may be located at the outer surface of the body 11 as shown in FIG. 4 or at the inner surface of the body 11 as shown in FIG.

FIG. 6 shows an example of an injection molding die for the heat insulating bush 10 shown in FIGS. 1 to 3, where 20 is a fixed die to which the sprue bush 21 is attached, and 22 is a movable die having a cavity 23. Is. Cavity 23 is the outer mold that forms the outer shape
22A and an inner die 22B forming an inner shape.
The molten resin pressed into the mold from the injection nozzle 25 of the injection molding machine passes through the sprue 26 and runner 27, and the submarine gate 2
The resin flow sent from 8 to the cavity 23 and split into right and left flows together on the opposite side of the gate 28 to form a weld line. In part 13 of this weld line,
The inner surface of the outer mold 22A and the outer surface of the inner mold 22B are formed into a cavity 23 having a triangular cross section with a base width of about 1 mm and an acute tip.
By projecting inward, a protrusion 22Aa is provided on the inner surface of the outer mold 22A, and a protrusion 22B is formed on the outer surface of the inner mold 22B.
b is provided. The tip ends of the two protrusions 22Aa and 22Bb are closely opposed to each other leaving a slight clearance (for forming the narrow cross section 14). However, the narrow cross section 14 is
When the heat insulating bush 10 is provided at a position closer to the outer surface of the body 11 as shown in the figure, the protrusion 22Aa on the inner surface of the outer die 22A is not provided. In addition, as shown in FIG.
If you want to place it on the inner surface of the body 11 of the
The protrusion 22Bb on the outer surface of 22B is not provided.

Weld line part 13 of flange part 12 of insulating bush 10
Is divided into slits by inserting the mold 22C.

In FIG. 6, PL is a parting line, 30 is a receiving plate, 31 is an upper ejector plate, 32 is a lower ejector plate, and 33.
Is a sprue protruding pin, and 34 is a product protruding pin.

Next, the operation will be described.

When the heat insulating bush 10 is injection molded using the above mold,
The resin that has flown into the cavity 23 from the gate 28 splits into a half circle in the cavity 23 in the clockwise and counterclockwise directions, and then joins on the opposite side of the gate 28 to form the weld line portion.
Form 13. The weld line portion 13 is continuous with a very small cavity cross-sectional area. The heat-insulated bush 10 that has been molded and stamped out and radiates heat naturally and cools, but the whole is a torus that is continuous in the narrow cross-section portion 14 and has a perfect circular cross-section. Therefore, unlike a conventional heat insulating bush with slits, the inner diameter does not shrink more in the direction of the slits during cooling to form an elliptical shape as a whole, and excellent molding accuracy can be obtained. Of course, it is not necessary to heat-correct the shape after molding.

Further, since the inner and outer diameter dimensions do not change as in the case of a heat insulating bush with slits, the dimension inspection can be performed easily and quality control can be performed easily.

Furthermore, since the narrow cross section 14 is formed in the weld line portion where the mechanical strength against external force such as pulling is weak, the narrow cross section 14 can be easily installed in the bearing portion of the heat insulating roll without applying a large external force. Break. This breakage may be slightly overlapped or expanded to expand the insulation bush.
Since the diameter of 10 can be freely reduced or expanded,
Assembling the heat insulating sleeve 10 is extremely easy.

The heat insulating bush 10 assembled to the bearing has a perfect circular cross section, so that the contact does not become uneven.

Moreover, the flange portion 12 of the heat insulating bush 10 is broken like a slit at the position of the weld line portion 13,
The thermal expansion of 12 is absorbed by this slit, and defects such as cracking due to thermal strain are prevented.

[Effect of device]

As described above, according to the present invention, the cross-sectional area of the weld line of the heat insulating bush formed by injection molding is set to be smaller than the cross-sectional area of other parts, so that it is not damaged by thermal strain. Further, there is an effect that it is possible to provide a heat insulating bush which has a good molding precision and does not have a problem such as need for correction and one-sided contact and which can be easily incorporated. Further, when the body of the heat insulating bush is provided with a flange that rises outward in the radial direction, and the weld line portion of at least one of the body and the flange is provided with a narrow cross-section, the positioning of the bearing end surface with respect to the heat roll is further performed. It is possible to adjust the thickness of the flange by the thickness dimension of the flange to facilitate the mounting of the bearing, and it is also possible to insulate the heat roll from the bearing end surface.

[Brief description of drawings]

FIG. 1 is a front view of an embodiment of the present invention, FIG. 2 is a side view of the same, FIG. 3 is an enlarged view of a main part of FIG. 1, and FIGS. 4 and 5 are main views shown in FIG. The figure which shows the other modification of the part, FIG. 6 is a longitudinal cross-sectional view of the main part of the mold for the heat insulating bush shown in FIG.
FIG. 7 is a vertical cross-sectional view of a heat roll bearing portion showing a usage state of a conventional heat insulating bush. In the figure, 10 is an insulating bush, 13 is a weld line portion, 14
Is a narrow cross section, 22A is an outer mold, 22B is an inner mold, 22Aa is a protrusion on the inner surface of the outer mold, and 22Bb is a protrusion on the outer surface of the inner mold.

Claims (2)

[Scope of utility model registration request] 1. A heat insulating bush formed of a resin, wherein the heat insulating bush has a narrow cross section having a cross sectional area at a weld line portion smaller than that of other portions. 2. The heat insulating bush has a body portion and a flange that rises radially outward from the body portion and is integral with the body portion, and the narrow cross-section portion is provided in at least one weld line portion of the body portion and the flange. The heat insulating bush according to claim 1.