JP2849667B2 - Plastic pulley and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulley used for cranes, elevators and the like, and more particularly to a pulley made of reinforced plastic and a method of manufacturing the same.

[0002]

2. Description of the Related Art In general, cast or forged products are used as pulleys for cranes, elevators, and the like, and a small portion of them is, for example, a plastic (nylon 66) pulley used for a ski lift. Have been done.

[0003]

In the conventional pulleys, metal pulleys have problems such as being heavy and easily rusting.
Further, in the case of plastic, the abutment surface of the rope, that is, the annular groove of the rim portion is easily worn, and thus the use is limited to extremely limited applications (specifically, ski lifts). This is based on the premise that conventional pulleys should be replaced if they are worn or rusted. In fact, whether they are made of metal or plastic, conventional pulleys have been replaced by wires or manila hemp. It can be said that it was more tolerant of the pulley wear than the rope wear.

[0004] In particular, for very large cranes,
Since the pulley used has a very large size exceeding 1000 mm in diameter and is heavy, the replacement operation itself involves difficulties. In addition, since it is made of metal, i.e., has electrical conductivity, an insulator must be separately provided between the crane main body and the vehicle to ensure safety.

[0005] By the way, in the recent environment, the price of ropes has been greatly reduced in relation to imported goods, and it is considered that replacing ropes is more cost-effective than replacing pulleys. Awareness is emerging. Based on such recognition, even if an attempt is made to apply a conventional plastic pulley as a substitute, there is a problem in durability and abrasion resistance, and it cannot be easily replaced.

Accordingly, an object of the present invention is to provide a plastic pulley having excellent wear resistance which can be applied to a large pulley. Another object of the present invention is to provide a plastic pulley which is more excellent in rust resistance.
A further object of the present invention is to provide a method of manufacturing a plastic pulley having excellent wear resistance.

[0007]

In order to achieve the above technical object, a pulley according to the present invention has a U-shaped cross section which is formed entirely of reinforced plastic and forms an annular groove of a rim portion. Among them, at least the bottom is formed of a C-shaped ring-shaped insert material, and the insert material is formed of a wear-resistant metal.

There are a number of advantages of making the pulley out of reinforced plastic. First, the weight can be significantly reduced as compared with a metal pulley, and the lifting efficiency of a crane or the like can be increased. In addition, the problem of rust of the pulley body is eliminated, and when the pulley is colored, an arbitrary color can be given to the pulley simply by mixing a coloring agent into the molding material at the time of molding. In addition, since plastic is generally insulative, the pulley itself becomes an insulator, and there is no need to provide a separate insulator for a crane or the like.

As the applicable reinforced plastic, a specific molding material may be selected in relation to the required mechanical strength, that is, the diameter of the pulley, but in the case of a large pulley, the mechanical strength is low. Preferably, the polyester is an unsaturated polyester containing glass fibers because of its superiority.

Similarly, as the insert material, a specific wear-resistant material may be selected according to the relationship between the suspension load, that is, the diameter of the pulley, and the type of rope, but it is used for ropes such as Manila hemp. In the case of a pulley, a rust-resistant metal such as stainless steel having excellent wear resistance and rust resistance may be selected.
In the case of a large pulley used for a wire rope, it is preferable to select carbon steel because of its excellent abrasion resistance, and if necessary, the contact surface with the wire rope is preferably selected. You only have to quench. Further, when it is necessary to consider the separation between the insert material and the resin in relation to the suspension load, that is, the diameter of the pulley, the back surface of the insert material may be formed with an uneven surface.

The overall shape of the insert has the shape of a C-ring with two end faces adjacent to each other. By adopting the C-shaped ring-shaped insert material, the dimensions of the insert material are automatically optimized by clamping the mold when molding the pulley, and therefore, the insert material is When manufacturing itself, there is no need to worry about the accuracy of the diameter of the insert material.

Further, according to the C-shaped ring-shaped insert material, idling of the insert material can be prevented by resin that has entered between both end surfaces of the insert material during molding,
This is effective in preventing separation between the insert material and the resin.

As described above, the weight reduction of the pulley also contributes to increasing the lifting efficiency of a crane or the like. By integrally molding the pulley with reinforced plastic, it is possible to significantly reduce the weight compared to the conventional metal pulley, but in order to promote the weight reduction, the boss and rim must be connected. What is necessary is just to make a connection part into plate shape, and to provide an appropriate rib in this plate-shaped connection part. In order to further reduce the weight, holes may be formed in the plate-shaped connecting portion, and the holes and ribs for reducing the weight may be arranged in the circumferential direction to balance the pulley in the circumferential direction. It is better to arrange them evenly.

As a specific method of manufacturing the above-described reinforced plastic pulley, a radial direction for forming an annular groove in a rim portion of the pulley by forming a cavity with an upper die, a lower die, and a split die is described above. A method for manufacturing a reinforced plastic pulley using a mold having a convex portion projecting inward, comprising an insert made of a wear-resistant material having a U-shaped cross section and a C-shaped ring as a whole. It is preferable that the method includes a step of mounting a material on the convex portion of the split mold, a step of filling the cavity with a reinforced plastic material, and a step of clamping the mold.

By forming the annular groove of the rim portion with a split mold as described above, it becomes easy to attach the insert material to the mold and take out the molded product after molding. In addition, by adopting the C-shaped ring-shaped insert material, the dimensions of the insert material can be automatically optimized by clamping the mold as described above.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a front view of a plastic pulley according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line II-II of FIG. Pulley 2 is generally
It is integrally molded with reinforced plastic. The pulley 2 has a rim portion 4 and a boss portion 6 into which a bearing (not shown) is press-fitted, as in the related art, and the rim portion 4 and the boss portion 6 are connected by a plate-shaped connecting portion 8. I have. A plurality of ribs 10 are provided on both plate surfaces of the connecting portion 8 at equal intervals in the circumferential direction. Each rib 10 extends in the radial direction, and its outer end is connected to the rim portion 4. The inner end is connected to the boss 6.
In the plate-like connecting portion 8, a circular hole 12 is formed between the adjacent ribs 10 to reduce the weight.

The reinforced plastic constituting the pulley 2 is specifically an unsaturated polyester containing glass fiber, and more specifically, a molding material sold by Takeda Pharmaceutical Co., Ltd. under the trade name "HSMC". It is preferred that
A colorant such as a suitable pigment may be mixed with such a molding material and used. According to this, the pulley 2 of an appropriate color can be produced.

As shown in FIG. 2, an insert material 16 which substantially forms the annular groove 14 is inserted into the rim portion 4. The insert material 16 has a ring-like overall shape extending in the circumferential direction along the annular groove 14, and is shown in FIG.
As shown in the figure, the outer shape has a U-shaped cross-sectional shape. Such an insert material 16 has a shape in which both end faces of a C-shaped ring having two ends facing each other are slightly separated.

The insert 16 is preferably made of stainless steel having excellent abrasion and rust resistance for ropes such as manila hemp, while having excellent abrasion resistance for wire ropes. For this reason, it is preferable to make it from carbon steel, specifically, "S35C" (JIS standard). Further, in order to further enhance the wear resistance, the outer surface 16a of the insert material 16 may be quenched, and the quenching depth is limited to the value obtained when the diameter of the wire rope 20 to be applied is “16 mm”. `` 1.5mm or 2.0mm
Is enough. Therefore, the insert material 16
At least a thickness of about 2.0 mm is sufficient. By the way,
In this embodiment, the thickness of the insert material 16 is "2.8 mm
". In order to prevent the insert 16 from peeling off from the resin, it is preferable that the back surface 16b is formed into an uneven surface by, for example, a cut groove or the like.

An example of the specific dimensions of the above-described pulley 2 will be described below. Outer diameter: 354mm PCD size: 320mm Inner diameter of boss 6: 130mm Width of boss 6: 52mm Diameter of circular hole 12: 50mm Thickness of rib 10: 5mm

The pulley 2 of the above size weighs about one third of a conventional metal pulley of the same size. Of course,
The pulley 2 of the present invention is not limited to such a specific numerical value, for example, from a small PCD dimension of about 200 mm to a large one exceeding 1,000 mm. The thickness of the insert 16 and / or the necessity of quenching may be determined according to the magnitude of the applied hanging load.

FIG. 4 shows a mold 2 used for molding the pulley 2.
Indicates 0. The mold 20 includes an upper mold 22, a lower mold 24, and two split molds 26 facing each other (only one split mold is shown in the drawing).
A cavity 28 is formed at 4 and 26. The split mold 26 is
The protrusion 26a protrudes radially inward, and the contour of the annular groove 14 of the rim 4 is formed by the protrusion 26a. In the mold 20, as in the conventional case, the upper mold 22 is fixed to an upper mold mounting plate 30 that is a movable plate, and the lower mold 24 is fixed to a lower mold mounting plate 32 that is a fixed plate. Further, a ring-shaped frame die 34 that is continuous in the circumferential direction is attached to the upper die mounting plate 30 via a spring 36, and the split die 26 is clamped by the frame die 34. And
A taper is formed on the inner peripheral surface 34a of the frame mold 34 and the outer peripheral surface 26b of the split mold 26 slidably contacting the inner peripheral surface 34a.
Is lowered, the split mold 26 is gradually clamped by the frame mold 34.

The step of forming the pulley 2 will be described. First, while the two split dies 26 laterally separated from each other are moved close to each other manually or by driving means, the convex portions 26 of the split dies 26 are moved.
The insert material 16 is attached to a. Next, a molding material is put into the metal mold 20, and then the pulley 2 as a molded product is molded by clamping.

The dimensions of the C-shaped ring-shaped insert 16 are automatically optimized by clamping the mold 20.
It is no longer necessary to use nerves for the dimensional accuracy when manufacturing a.

In the pulley 2 after molding, since the resin has entered the gap between both ends of the C-shaped insert material 16,
The invading resin can prevent the insert member 16 from spinning. That is, the C-shaped insert 1
The resin that has entered between both ends of 6 functions as a stopper for insert material 16. In addition, in manufacturing the insert 16, it is not necessary to weld the ends of the C-shaped ring, so that the manufacturing cost of the insert 16 itself can be reduced.

[0026]

As is apparent from the above description, according to the plastic pulley of the present invention, since a reinforced plastic is employed as a molding material, the plastic pulley is insufficient in strength as compared with the conventional metal pulley. This makes it possible to significantly reduce the weight, improve the efficiency of lifting a crane or the like, and eliminate the problem of rust on the pulley body. In addition, since the wear-resistant insert material is provided, the wear of the rim portion can be reduced, and a plastic pulley excellent in wear resistance can be provided. Thus, it is possible to provide a lightweight pulley excellent in wear resistance that can be sufficiently applied.

According to the manufacturing method of the present invention, since the split mold is adopted, there is an advantage that the molded product can be easily taken out and the like.
Since the C-shaped ring-shaped insert material is adopted, the dimensional accuracy of the insert material can be optimized only by clamping the mold, and at the same time, between the opposed end faces of the C-shaped insert material. There is an advantage that the slippage of the insert material can be prevented by the penetrated resin.

[Brief description of the drawings]

FIG. 1 is a front view of a reinforced plastic pulley of an embodiment.

FIG. 2 is a sectional view taken along the line II-II of FIG. 1;

FIG. 3 is a sectional view of an insert material.

FIG. 4 is a partial cross-sectional view of a mold suitable for manufacturing the pulley of the embodiment.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // B29C 45/33 B29C 67/14 J B29K 67:00 67/18 105: 22 309: 08 B29L 31:32 (56) Reference Document JP-A-59-133866 (JP, A) JP-A-1-220769 (JP, A) JP-A-3-207816 (JP, A) Japanese Utility Model Application Sho 54-44851 (JP, U) Japanese Utility Model Application Sho 55- 38020 (JP, U) Japanese Utility Model Showa 58-187651 (JP, U) Japanese Utility Model Showa 61-55547 (JP, U) Japanese Utility Model Application Hei 5-92566 (JP, U) Japanese Translation of PCT Application No. Sho 56-500069 (JP, A) (58) Field surveyed (Int.Cl. ⁶ , DB name) F16H 55/48 B66B 7/06 B66D 1/36 B29C 67/14 B29C 67/19 B29L 31:32

Claims (12)

(57) [Claims] 1. A metal having a cavity formed by an upper mold, a lower mold and a split mold, and having a radially inwardly projecting convex portion for forming a contour of an annular groove of a rim portion of a pulley in the split mold. A method of manufacturing a reinforced plastic pulley using a mold, wherein the rim portion is formed of a wear-resistant material having a U-shaped cross section opened radially outward and having a C-shaped ring shape as a whole. A step of mounting the insert material constituting the annular groove so that a concave outer surface that opens radially outward is fitted to the convex portion of the split mold; and a step of filling the cavity with a reinforced plastic material. And a step of clamping the mold. 2. The method according to claim 1, wherein the reinforced plastic is made of an unsaturated polyester containing glass fibers. 3. The method according to claim 1, wherein the insert material is made of carbon steel. 4. The method according to claim 3, wherein the concave outer surface of the insert material is hardened. 5. The method according to claim 1, wherein the insert material is made of a rust-resistant metal. 6. The manufacturing method according to claim 1, wherein the back surface of the insert material is constituted by an uneven surface. 7. A movable plate having the upper die attached thereto, and a fixed plate having the lower die attached thereto, wherein the movable plate has an outer periphery of the split die in a step of clamping the die. A step of providing a circumferentially continuous ring-shaped frame die which is in sliding contact with a surface, wherein an inner peripheral surface of the frame die and an outer peripheral surface of the split die are formed as tapered surfaces, and a step of clamping the die; 2. The split mold is gradually clamped by the frame mold.
The method according to claim 6. 8. The manufacturing method according to claim 7, wherein a spring is interposed between the movable plate and the frame mold. 9. A plastic pulley manufactured by the method according to claim 1. 10. A plate-shaped connecting portion is provided between the rim portion and the boss portion, and a radially extending rib is formed on the connecting portion, and an outer end of the rib has the rim portion. 10. The plastic pulley according to claim 9, wherein the pulley is connected to the boss and an inner end is connected to the boss. 11. The plastic pulley according to claim 9, wherein the pulley is for a crane. 12. The method according to C. D. 12. The plastic pulley according to claim 11, having a diameter greater than 1,000 mm in size.