JPS6157172B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a step forming device for climbing up and down by stepping on a foot.

Generally, the inner wall of a manhole, the inner surface of a pool,
A U-shaped protruding step is attached to chimneys, fences, etc., but it has come to be used where part of the core metal is coated with resin for rust prevention purposes. However, since the core metal is not fully covered, there is a drawback that rust occurs on the exposed portion of the core metal while it is stored in piles at a site exposed to the rain. The reason why the conventional step was not able to completely cover the core metal with a resin layer is that the heavy core metal is kept floating in the molding cavity of the mold and coated with resin during injection molding. This is because the portion that holds the core bar in a floating state must be left uncovered due to necessity.

The present invention is a completely new step forming device made in view of this point, and it does not rust at all during storage or after installation, and the tip of the U-shaped step can be formed without machining the threaded part or hexagonal head. To provide a step whose entire surface is coated with resin and which can be easily formed into parts, etc., and which can be inserted extremely efficiently and quickly, and at the center without eccentricity of the core metal.

Hereinafter, the present invention will be explained in detail based on illustrated embodiments. A manhole 1 is shown in FIG. 1, and steps 2 are provided on the inner circumferential surface of the manhole 1 in multiple stages upward and downward, allowing a person to step down or climb into the manhole 1. FIGS. 2 and 3 show a concrete example of step 2, and the entire structure is U-shaped.
The left and right proximal ends 3, 3 have bulged hexagonal heads 4, 4, and a U-shaped insert core 5 made of steel or the like,
It is composed of a resin entire coating layer 6 that completely covers the entire surface of the core metal 5, and no part of the core metal 5 is exposed to the outside. Further, a predetermined length A from the base end portion 3 is embedded in concrete 7. Step foot section 8
has a rectangular or square cross section so that it is easy to put on the foot, and an outer flange 9, which is to be used as a guide for the length A, is provided protruding from the covering layer 6. Further, in the head 4, the end of the core bar 5 is formed into a circular outer flange-like head that is easy to mold, and the covering layer 6 side is formed into a hexagonal head.

Next, in another specific example of step 2 shown in FIG. 4, a male thread 11 is formed extending from the middle part of the left and right leg parts 10, 10 to the base end part. The nut 13 is screwed onto the male screw 11 from the back side of the wall 12, but even in this specific example, the entire surface of the insert core 5 is completely covered with the resin coating layer 6. It will be covered. Further, thread processing is omitted on the core metal 5, and threads are formed only on the coating layer 6 to form the male thread 11.

Therefore, if the manufacturing method and manufacturing apparatus of Step 2 are explained based on FIGS. 5 to 9, 14 and 14 are a pair of molds,
U-shaped molding cavities 16, 16 corresponding to the above-mentioned FIGS. 2 and 3 are recessed in the respective crimping surfaces 15, 15. This space 16 has a semicircular or rectangular cross section. 17 is a guide pin, and 18 is a return pin. Holder pins 18, 19, . . . are slidably attached to the surfaces protruding into the molding spaces 16 of the respective molds 14. The holder pins 18 are arranged so as to correspond to the left and right legs 10, 10 near the proximal ends 3, 3 of the step 2, as shown in FIG. The holder pins 18 are slidably inserted into holes 20, 20 formed in the molds 14, 14 in a direction perpendicular to the axis, and
As shown in FIG. 6 or FIGS. 7 and 8 when viewed in vertical section, the holder pins 1 of the respective molds 14, 14
8 and 18 are attached vertically facing each other so as to be on the same axis, and are configured to clamp the insert core metal 5 from above and below as described later.

Further, four holder pins 19 are disposed on the foot part 8, and are slidably inserted into the holes 20, respectively, and the holder pins 19, 19 of the upper and lower molds 14, 14, respectively. are attached vertically facing each other so as to be on the same axis, and clamp the foot part 8 of the core bar 5 from above and below.

Reference numeral 21 denotes a cam rod having concave inclined cam surfaces 22, 22, which is operated by a hydraulic cylinder (not shown) in the directions of arrows A and B, and has outer spherical heads of the holder pins 18, 19 on the cam surface 22. 23 is in sliding contact with each other to cause the holder pins 18, 19 to project into the space 16 or to be housed flush with the inner surface of the space 16, or to operate.

Thus, a large rectangular recess 24 is formed on the outer surface of the mold 14 at a position corresponding to the hole 20, and a bullet receiving plate 25 is fitted into the recess 24 so as to be vertically slidable. At the same time, with a connecting tool such as a small pin 26,
The outer ends of the holder pins 18 and 19 inserted into the holes 27 of the bullet receiving board 25 and the bullet receiving board 25,
Connected to form an integral structure. Further, reference numeral 28 is a resilient member such as a coil spring, which resiliently biases the integrated resilient receiving plate 25 and the holder pins 18, 19 upward and downward. Therefore, holder pin 1
The ball heads 23 of 8 and 19 are always resiliently pressed against the cam rod 21, and as the cam rod 21 moves in the longitudinal direction, it resists the biasing force of the resilient member 28 and presses against the mold molding cavity 16. When the inner ends of the holder pins 18 and 19 protrude inward (FIG. 7), or when the ball head 23 comes to the concave cam surface 22, the holder pin 18 is pushed back by the elastic urging force of the elastic member 28. , 19 until their inner end surfaces are flush with the molding cavity 16 (the eighth
figure).

In addition, since the bullet receiving plate 25 slides up and down without rotating in the rectangular recess 24, the holder pins 18, 19
will not rotate. Therefore, as shown in FIGS. 7 and 8, the press-contact inner end surfaces 29 of the holder pins 18 and 19 can be made concave in one direction to match the radius of the inner surface of the cavity 16 having a semicircular cross section. .

30 is a channel through which the molten resin is sent, and two tunnel gates 31, 31 are formed in the center of the U-shaped molding cavity 16 at the position corresponding to the foot pedal as shown in FIG. It will be done.

Next, a method of manufacturing Step 2 having the entire surface coating layer 6 using the above-mentioned apparatus will be explained.
First, as shown in FIGS. 6, 7, and 5, the U-shaped insert core metal 5 is held in a floating state in the molding cavity 16 by holder pins 18, 19, etc., and the mold is clamped. At this time, the cam rods 21 move in the direction of arrow B, and the inner end surfaces 2 of the holder pins 18 and 19 are pressed against each other.
9 clamps the core metal 5 from above and below and holds it firmly.
If the press-contact inner end surface 29 is formed into a rounded concave surface as described above, the holder pins 18, 18 can reliably prevent the legs 10, 10 from wobbling from side to side, as shown in FIG. Holder pin 19,1
9 has the advantage of being able to reliably prevent back-and-forth wobbling and securely hold the core metal 5 in place.

After that, melted resin such as polypropylene is poured into the channel 3.
0 and gates 31, 31 (referred to as primary injection), the holder pin 1 holds the core metal 5 by pressure.
All the remaining parts except for parts 8 and 19 are coated with resin.
For example, in the case of polypropylene, the cylinder temperature may be approximately 200° C. at the nozzle portion, the injection pressure may be approximately 70 atmospheres, and the injection time may be approximately 5 seconds.

Next, after a short second during which the primary resin coating layer 32 does not harden, the cam rod 21 is moved in the direction of arrow A, and the deepest part of the concave inclined cam surface 22 is aligned with the holder pins 18, 19.
If it comes to the ball head 23, the elastic member 28
The holder pins 18, 19 are moved back by the spring force of
9... are released from the core metal 5 at appropriate intervals.
For example, they are separated at intervals corresponding to the desired thickness of the entire resin coating layer 6.

If the molten resin has a high viscosity and the above injection pressure is continuously applied and the secondary injection is performed from the same gates 31, 31, the core metal 5 will fall under its own weight and cause misalignment. Nothing at all. For example, in the case of polypropylene, the secondary injection is performed for about 25 seconds. As a result, the pin holes left by the holder pins 18 and 19 can be filled as shown in FIG.

After that, take a sufficient cooling time, for example, about 30 to 50 seconds if the polypropylene is used.
After cooling and hardening, the step 2 in which the entire surface of the core metal 5 is completely covered with the entire resin coating layer 6 may be taken out.

In addition, as shown in FIG. 9, if the two double tunnel gates 31, 31 are tilted almost parallel, the step 2 as a product and the waste material (solidified resin body) in the flow path 30 can be separated. , which has the advantage of being easily divisible. That is, if the waste material is pushed up in the direction of arrow C, the portions corresponding to the gates 31 and 31 will be easily cut off.

According to the effect of the above embodiment, the gates 31, 3
1 is placed at two locations away from the center of the core metal 5 so that the flow pressure during injection is evenly applied to the entire circumference of the core metal 5. Therefore, the resin flow is made to have an equal speed up and down, and the holder pins 18 and 19 are retracted. It has become easier to find the timing to do this, and this double gate 3
1 and 31, pressure in the eccentric direction is not applied to the core metal 5, and the holder pins 18,
It was possible to reduce the load applied to the coating layer 19 and to make the thickness of the coating layer 6 uniform.

In addition, the uses of Step 2 are extremely wide, such as manholes for water supply, sewerage, gas, etc., pools, chimneys, fences, etc., and its shape and structure can be varied depending on the use, and is not limited to the illustrated example. Of course.

As described in detail above, the present invention is such that the molding cavities 16, 16, each having a substantially semicircular cross section and a substantially U-shaped planar shape, in which the U-shaped insert core metal 5 is held in a floating state, are connected to the crimping surfaces 15, 15. The holes 20 are recessed in the molding space 16, are perpendicular to the axial direction of the core metal 5, and are vertically opposed to each other. A step molding device having injection molding molds 14, 14 disposed in a foot part 8, and a rotation stopper provided on the outer surface of the mold 14 at a position corresponding to the hole 20. A recess 24 formed in a non-circular cross-sectional shape...
and a bullet receiving plate 25 that is vertically and slidably fitted in the recess, and connected to or integrally formed with the bullet receiving plate 25 and slidably fitted into the hole 20. In addition, holder pins 18 and 19 are formed in which the press-contact inner end surface 29 of the tip is concave in one direction and is formed in a shape that matches the radius of the inner surface of the molding cavity 6 having the semicircular cross section. , a resilient member 28 that constantly biases the bullet receiving plate 25 and the holder pins 18, 19 upward and downward, and a cam surface that slides into contact with the outer end ball heads 23 of the holder pins 18, 19. 22, the holder pins 18, 19
The holder pin is a step molding device equipped with a cam rod 21 that can be controlled to protrude and retract freely with the tip end of the cam rod 21 in the molding cavity 16 at an operating distance equal to the thickness of the resin coating layer 6. 18, 19...
Since the thrust into and retreat from the molding cavity 16 is carried out by the resilient member 28 and cam rod 21, which constantly bias the bullet receiving plate 25 and the holder pins 18, 19 upward and downward. The operating mechanism for holding the core metal 5 during the primary injection and for projecting and retracting the holder pins 18 and 19, which are retracted after the primary injection, can be configured extremely simply.

Further, the holder pins 18 and 19 are arranged on the left and right leg parts 10 and 10 of the molding cavity 16 and the foot part 8, and the inner end surfaces 29 of the tip parts of the holder pins 18 and 19 are made concave in one direction. , and by forming a concave radius surface that matches the radius of the inner surface of the molding cavity 16, the approximately U-shaped insert core 5 is formed.
can be accurately and firmly held in the center of the cross section of the cavity 16, allowing the leg 1
It was possible to reliably prevent horizontal shake of 0.0 and 10 mm and overall longitudinal shake. Therefore, the core metal 5 can be precisely placed at the center of the entire surface coating layer 6, and a high-quality step coated with resin can be obtained with a uniform thickness of the coating layer 6. be effective.

[Brief explanation of the drawing]

Fig. 1 is a sectional perspective view showing an example of the use of the step, Fig. 2 is a perspective view of the step, Fig. 3 is a sectional plan view, Fig. 4 is a sectional plan view of another example of the step, and Fig. 5 is a main Plan view of a specific example for explaining the invention, No. 6
The figure is a sectional view taken along line EE in figure 5, and figure 7 is a cross-sectional view taken along line G in figure 5.
-G sectional view, FIG. 8 is the same sectional view showing a state in which the second injection molding is completed, and FIG. 9 is a sectional view showing another specific example of the main part. 2...Step, 5...Insert core bar, 6...Resin entire coating layer, 14...Mold, 16...Molding space, 1
8, 19... Holder pin, 29... Pressure-welding inner end surface, 3
2...Primary resin coating layer.

Claims (1)

[Claims] 1. Molding cavities 16, 16, each having a substantially semicircular cross section and a substantially U-shaped planar shape, in which the U-shaped insert core metal 5 is held in a floating state, are embedded in the crimping surfaces 15, 15. The holes 20, which are perpendicular to the axial direction of the core metal 5 and are vertically opposed, form the left and right legs 10, 10 of the molding space 16 and the step foot when viewed from above. Injection mold 14,1 arranged at 8
4, the step molding apparatus has a recess 24 formed in a non-circular cross-sectional shape for preventing rotation, provided on the outer surface side of the mold 14 at a position corresponding to the hole 20. , a bullet receiving board 25 that is vertically slidably fitted in the recess 24, and a bullet receiving board 25 that is connected to or integrally formed with the bullet receiving board 25 and that is slidably fitted into the hole 20. In addition, the pressing inner end surface 29 of the tip part is concave in one direction, and the molding cavity 1 has the semicircular cross section.
holder pins 18 and 19 formed in a shape that matches the radius of the inner surface of
and a resilient member 28 that constantly resiliently biases the holder pins 18 and 19 upward and downward; and an outer ball head 23 of the holder pins 18 and 19.
The holder pin 1 is provided with a cam surface 22 that comes into sliding contact with the holder pin 1.
8, 19 into the molding cavity 16,
Even with a working distance equal to the thickness of the resin coating layer 6,
A step forming device comprising: a cam rod 21 that can be controlled to protrude and retract freely.