JP3955068B2 - Synthetic resin ladder - Google Patents

Description

  The present invention relates to a synthetic resin ladder, and more particularly to an inner ladder used for a tank or the like.

  Conventionally, the present applicant has developed and provided a large number of so-called inner ladders that are installed in the tanks to enter and exit from the manhole provided at the top of a tank such as a water tank installed on the roof of the building. And gained popularity.

  For example, as shown in Design Registration No. 1001417, according to the plan view (a) and side view (b) of FIG. 3, two parallel long elliptical pieces having a length of 1 to 5 m are seamless. PVC ladders 21 having a large number of rungs (also referred to as steps or steps) 23, 23,... In FIG. 4, an elliptical ring 25 that is fitted onto the elliptical pipe is integrally formed at both ends of the crosspiece 23 and is fitted onto the column 22, and FIG. 4 (sectional view taken along the line BB in FIG. 3). As shown in FIG. 3, the crosspiece 23 is attached to the pillar 22 so that the pillar 22 and the ring 25 are inserted into a hole opened in advance and sewed by a pin 26 in a space without the rib 24 on the lower surface side of the crosspiece 23. A PVC ladder 21 is provided.

  In the figure, reference numeral 27 denotes a U-shaped leg in which the lower ends of the columns 22 and 22 are bent.

  However, the proposed PVC ladder 21 has the following problems.

  (1) Since the pillar 22 is a ladder composed of one seamless elliptical pipe, the length of the tank, such as an aquarium to be used, especially if there is a change in depth, the length will be different. It is necessary to prepare various ladders 21 for the pillars 22 to be stocked, and inventory for that purpose increases.

  (2) Since the rung 23 is attached to the pillars 22 and 22 by sewing with one pin 26, if the ring 25 is loosely fitted, wobbling of the rung 23 is inevitable, and the ladder 21 is moved up and down. Anxious to workers.

  (3) The attachment of the rung 23 to the pillar 22 is accompanied by work in the production factory, and the logistics cost for transferring the completed ladder 21 to the tank installation site increases.

  On the other hand, there are known proposals for a septic tank ladder without the problems (1) and (2) (Japanese Utility Model Publication No. 50-21, Japanese Utility Model Publication No. 48-93224).

In other words, a large number of short rigid synthetic resin pipes are bonded and connected by the same material joints, and the same material crossbars are bonded and connected to the T-foot of the cheese joints. A septic tank ladder is proposed.
Design Registration No. 1001417 Japanese Utility Model Publication No. 50-21

  In the ladder of Patent Document 2, not only the finished product in the production factory is troublesome but also troublesome, and there is a problem of physical distribution due to the low productivity by the adhesive joining work. Because it is connected by adhesive bonding, the crossing and the crossing are made of hard PVC (PVC), for example, making it possible to use an adhesive, making it difficult to use inexpensive materials such as polyethylene (PE) or polypropylene (PP) The PP or the like having a substantially half value cannot be used, and as a result, it is not preferable for cost reduction of a ladder having a large number of rungs.

  The present invention has been created to solve such problems. The gist of the present invention is as follows. 1) In a ladder in which a large number of rungs are attached to two parallel pipe columns at regular intervals. In the synthetic resin ladder in which a ring is integrally formed at both ends of the cross, and the ring is externally fitted to the pillar, the pillar is configured by connecting a short pipe, and the ring is attached to the pipe. It is on a synthetic resin ladder characterized in that the ring is attached to the pipe by externally fitting in advance and blow-molding the pipe, and 2) the ring is regenerated into a crosspiece integrally molded by injection molding. The synthetic resin ladder according to claim 1, wherein the synthetic resin is used.

  Since the crosspieces are attached by blow molding of the pillars, it is possible to select a low-cost resin that does not use an adhesive, but it is possible to produce a single piece and firmly attach it. Can be a ladder.

  In addition, since a plurality of short pipes are connected to form a pillar, ladders of various lengths can be formed while reducing the size of the blow molding die.

  The invention will be described in more detail by means of an embodiment shown in the accompanying drawings.

  FIG. 1 is a plan view of an essential part of an embodiment of the present invention, FIG. 2 is a detailed cross-sectional view passing through the tube axis line A of FIG. 1, and FIG. ) Is a side view, and in FIG. 4, the same parts as those in FIG.

  This embodiment relates to a non-corrosive inner ladder 1 for the purpose of moving up and down for inspection and cleaning from a manhole provided on the top of a tank for tap water or the like installed on the roof of a building. 2 is a ladder 1 having a well-known overall shape, in which a large number of crosspieces 3, 3... Are attached at regular intervals, and this ladder 1 has its production cost (due to no production errors, reduction of material cost, etc.). In addition to reducing costs, the company aims to make parts common and to reduce logistics costs.

  In particular, we intend to contribute to recycling by using recycled synthetic resin that does not cause any problems in strength.

  Therefore, the crosspiece 3 is attached to the pillar 2 as follows.

  First, the crosspiece 3 has a structure similar to that of the ladder 21 of the conventional example by injection molding a recycled resin such as PP or PE.

  That is, the cross 3 is formed by a channel having a U-shaped vertical cross section, a reinforcing rib (not shown) is formed in a cross shape on the back surface inside the U-shape, and the upper surface is a foot surface, and an ellipse is formed at both ends thereof. The ring-shaped rings 4 and 4 are integrally injection-molded. The length of the ring 4 in the axial direction, that is, the width is set to be approximately the length of a U-shaped foot.

  On the other hand, the column 2 is constituted by connecting a plurality of elliptical pipes obtained by blow-molding short original pipes (elliptical pipes), that is, a plurality of short columns 2A. In addition, the pillar 2 is described according to the pillar of one side about two pillars of the same structure below.

  Therefore, the ring 4 of the shaped crosspiece 3 is externally fitted in advance to a heat-softened short original tube formed on the short column 2A, and the cold parison method (using a mass-produced PVC original tube) is used. A mold using a blow molding method in which this is softened by heating and set in a mold, and then a heated and pressurized fluid such as air is blown into the original pipe, and the original pipe is placed along the cavity of the mold. When set in a mold (not shown) and blow-molded, both ends of the ring 4 are sandwiched from both sides, and in close contact with the inner surface of the ring 4, the attachment portion 5 can be formed on the short column 2A. .

  That is, the mounting portion 5 of the short column 2A has a pair of ring frustoconical sandwiched portions 6 and 6 that bulge and come into contact with the expanded bottom side, and these sandwiched portions 6 and 6. Are connected to the short pillar 2A in a so-called Saddle-Gorge state.

  Then, in order to connect a plurality of short pillars 2A integrated with the crosspieces 3 so as to have the length of the predetermined pillar 2, connecting fitting portions 8 are formed at both ends of the short pillar 2A.

  That is, a cylindrical enlarged diameter stopper portion 9 and an outer fitting portion 10 are formed in the fitting portion 8 at one end of one short column 2A, and the fitting portion 8 at the other end of the other short column 2A. Is formed with a cylindrical diameter-expanding stopper portion 9 and an inner fitting portion 10A, which are pushed in until these fitting portions 8, 8 are fitted and abutted against the respective diameter-expanding stopper portions 9, 9. For example, the short pillars 2A will be connected.

  These inner and outer fitting portions 10 and 10A are formed with a slightly enlarged taper and a reduced diameter taper so as to perform so-called TS joining, and non-return saw teeth 11 and 11A are provided at the axial center portion thereof. It is provided so that it cannot be easily pulled out once fitted at the site of use.

  Of course, since this TS joint has the non-return saw blades 11 and 11A, it is not necessary to use an adhesive suitable for on-site assembly, but it may be further used.

  Therefore, it is possible to use PP or PE, in particular recycled resin, which is difficult to use an adhesive by blow molding attachment for the crosspiece 3, and this and two blow molded PVC pillars 2 can be satisfactorily used at the production plant. As a result, the base in the shape of 2H or 3H composed of the two short pillars 2A, 2A and the two to three-stage crosspieces 3, 3 is manufactured as an inventory, A plurality of these can be connected at the site of use to have a predetermined ladder 1 length.

  Moreover, when the tank is raised and lowered at the site of use, the horizontal ring 3 is firmly gripped by the blow molding of the pillar, so that the cross 3 is not wobbled and the user is not worried.

It is a principal part top view of the Example of this invention. FIG. 2 is a detailed cross-sectional view of a part A in FIG. 1. In the conventional example, (a) is a plan view and (b) is a side view. FIG. 4 is a detailed cross-sectional view taken along the line B-B in FIG. 3.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Ladder, 2 ... Pillar, 2A ... Short pillar, 3 ... Cross, 4 ... Ring, 5 ... Mounting part

Claims (2)

Synthetic resin made of two parallel pipe-like pillars on a ladder with a large number of rungs attached at regular intervals. In the ladder
A synthetic resin characterized in that the pillar is formed by connecting short pipes, the ring is pre-fitted onto the pipe, and the pipe is blow molded to attach the ring to the pipe. Ladder. The synthetic resin ladder according to claim 1, wherein a recycled synthetic resin is used for a crosspiece obtained by integrally injection-molding the ring.

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