JPS6352951B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reinforced porous screen for sieving.

Sieving screens are perforated screens made of lattice-shaped molded bodies of rubber or rubber-like elastic materials (hereinafter referred to as rubber-like materials) in place of conventional wire mesh for most of the wide range of uses, including steel mills. So-called rubber screens have become widely used because they are more advantageous in terms of durability and low noise.

This type of porous screen has lower rigidity than a wire mesh screen, so it is necessary to embed reinforcement such as a rigid bar such as a steel round bar substantially inside the rubber material. In the past, for fear of deteriorating durability such as peeling of the outer skin from the internal reinforcement, adhesive treatment was applied to the surface of the rigid bar, and during molding and vulcanization, the entire surface was bonded using so-called vulcanization adhesive. It was customary to fix it integrally with the square lattice unit.

However, this molded porous screen reinforced with vulcanization adhesive may be accompanied by twitching of the shape or deformation of the sieve holes, and some parts, especially the reinforced joining bars, may As the use of this type of rubber screen expanded, the problem that localized wear appeared quickly due to the strong residual internal stress gradually became clear.

The inventors studied this point and conducted repeated experiments, and found the following fact.

1 Rubber materials shrink by 1 to 3% during the cooling process after vulcanization during in-mold molding, but the steel round rods used for reinforcement by vulcanization bonding with this shrinkage shrinkage compared to rubber materials. Since the coefficient of thermal expansion is much smaller, the above-mentioned shrinkage around the vulcanization bond area is hindered, and the distortion due to the presence or absence of shrinkage restraint causes irregularities in the overall shape of the compact and also in the shape of the sieve holes.

2. Restriction of shrinkage causes residual internal stress, and in areas where this residual stress is large, premature wear occurs.

The purpose of this invention is to eliminate these drawbacks, and thereby provide a reinforced porous screen for sieves that is free from irregular shapes, has excellent abrasion resistance, and is thus highly durable. It is.

The present invention is characterized in that a plurality of rectangular lattice units having a large number of sieve holes are formed by segmental preforming of rubber or rubber-like elastic material so that the edges of each rectangular lattice unit are aligned and their mutual spacing is filled. A porous screen for sieving consisting of an assembly of materials connected to a desired size with a joining bar, wherein the joining bar has a coefficient of thermal expansion smaller than that of the material over the entire length of the joining bar during the forming stage. This porous screen with reinforcement for sieving is characterized in that internal reinforcement made of rigid bars with poor adhesiveness is embedded in the connecting bars.

According to the present invention, for internal reinforcement using rigid bars, the adhesive treatment that was conventionally considered indispensable is abolished, and the fact that the rigid bars originally have poor adhesiveness with rubber materials is used instead. By even taking measures to prevent adhesion, such as applying a mold release agent, the rigid material can be applied even when the coefficient of thermal expansion of the steel material, such as a steel round bar, which is commonly used as the rigid material is much smaller than that of the rubber material. The shrinkage along the steel round bar that occurs in the compact during the cooling process after sulfurization is not significantly restricted, and therefore, there is no significant residual internal stress, especially in the radial direction of the steel round bar. This method was developed to ensure that the sieve was properly tightened, and was based on the investigation of undesirable situations such as the steel round bar moving uncontrollably during use of the sieve, which could lead to performance problems or accidents such as breakage. .

Now, the reinforced porous screen of this invention is the first
As shown in Fig. a, a lattice unit 1 having a large number of sieve holes 2 formed by segmented preforming is aligned with the four circumferential edges 3 in the width direction or even in the direction perpendicular to this, and the mutual spacing 4 thereof is filled with a rubber material. An assembly as shown in FIG. 1b is used, which is connected to a desired size using connecting bars 5 formed from a material (see FIG. 1b).
Additional internal reinforcement is provided as described above.

By extending the rigid bar 6 over the entire length of the joining bar 5 during molding and vulcanization, contraction of the joining bar 5 along the longitudinal direction of the rigid bar 6 is guided.

At this time, the rigid bar 6 protruding from the end of the cooled molded body may be cut and removed. In addition, if the processing is troublesome, prepare the rigid bar 6 in advance in a short shape so that it will align with the connecting bar 5 after hardening and shrinking.
By connecting a tough piece 6a as shown in FIG. 2 during the molding process, unsightly problems such as protruding ends of the rigid bar 6 can be avoided by simply removing the piece 6a after shrinkage. It disappears.

Although the main points of this invention have been mainly described above regarding the internal reinforcement of the connecting crosspiece 5, this does not exclude the use of other necessary fiber reinforcements for each part of the porous lattice unit 1.
In addition to general rubber, the materials include urethane resin, which has similar physical properties and is particularly advantageous in terms of wear resistance, and the cross-sectional shape and material of the rigid bar 6 used for internal reinforcement are also This does not limit the selection regarding the identification of

Hereinafter, embodiments of the present invention will be described in detail, particularly an example in which rectangular lattice units 1 are connected in series by segmental preforming of urethane using injection molding of urethane.

A required number of rectangular lattice units 1 made of thermoplastic urethane resin having a large number of sieve holes 2 as shown in FIGS. 1a and 1b are arranged side by side on a thermal surface plate.

It is preferable that this rectangular lattice unit 1 has protrusions 7 on the side surfaces of the four peripheral edges 3 as shown in FIG. The adjacent edges 3,
It is possible to form an arrangement in which three comrades are spaced apart from each other by a constant distance 4.

On the protrusions 2 alternately located in the gaps 4, rigid bars 6, which are optimally steel round bars as shown in FIG. Apply mold release agent and place.

Thereafter, the mutual spacing 4 is filled with a thermosetting resin by injection molding to form a reinforcing connecting bar 5.

At this time, the amount of resin to be injected can be adjusted by adjusting the height of the outer frame that surrounds the area directly above the mutual interval 4, and by changing the thickness of this outer frame, the connecting crosspiece 5
It is possible to create products with various heights.

After the thermoplastic resin is sufficiently cured, it is removed from the hot surface plate and subjected to secondary vulcanization if necessary.

Thereafter, as shown in FIG. 1b, the projections 7 that are no longer needed at the periphery of the porous screen 5 may be cut and removed.

The urethane resin shrinks during curing or vulcanization or during subsequent cooling, but the bonding crosspiece 5
Since no adhesive treatment is applied to the surface of the rigid rod 6 buried inside the rod 6, the shrinkage of the resin molded body forming the connecting beam 5 is not hindered. Therefore, the resin molded body as a whole or the sieve holes 2 will not be deformed.

After this, if necessary, cut it to the appropriate size.
In most cases, by appropriate selection of the number of rectangular grid units 1, the dimensions are adapted and they can be conventionally mounted on a sieving machine and put into use.

Note that both ends of the rigid bar 6 left behind by the shrinkage of the urethane resin protrude from the entire length of the connecting bar.

Although cutting this protruding end is troublesome, as shown in Fig. 2, the rigid bar 6 is removably attached to both ends of the main body part buried in the connecting bar 5 so that the rigid bar 6 is somewhat longer than the product width as a whole. The length of the main body part is equal to or slightly shorter than the width of the product after cooling, and the rigid bar 6 with such a narrow piece is connected to the connecting crosspiece 5 as described above. Figure 1b
When the reinforced porous screen S shown in is molded,
As mentioned above, the urethane resin contracts during curing and the tough piece 6a protrudes from the cured product, so cutting is not necessary by removing only the tough piece 6a.

It goes without saying that the cross-sectional shape and number of rigid bars 6 to be used can be appropriately selected depending on the degree of increase in rigidity of the crosspiece that is expected.

Next, we will discuss the results of experiments conducted to confirm the abrasion resistance of the reinforced porous screen according to the present invention.

In other words, the processed material is iron ore, and the processing amount is 400 tons/
As a result of measuring the amount of abrasion loss under the conditions of 1 hour, the average amount of abrasion loss per month was measured by inserting a reinforced porous screen that had been adhesively treated in the conventional manner and a reinforced porous screen according to the present invention. was 2.4 mm/month, whereas the result of this invention was 1.9 mm/month.

This clearly shows that the porous screen with internal reinforcement without adhesive treatment has better abrasion resistance.

As described above, according to the present invention, by embedding reinforcement inside the rigid bar material, which is conventionally considered indispensable, without any particular adhesive treatment, contraction during vulcanization of the rectangular lattice unit connected assembly can be smoothly performed. Therefore, there is no deformation of the sieve holes due to this, and it is possible to advantageously improve the abrasion resistance of the porous screen.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a rectangular lattice unit constituting a perforated screen according to the present invention and the main parts of the perforated screen, and FIG. 2 is a front view showing an example of a rigid bar. 1...Square grid unit, 2...Sieve hole, 3
...Four edges, 4... Mutual spacing, 5... Connecting bars, 6... Rigid bars.

Claims (1)

[Scope of Claims] 1. A rectangular lattice unit 1 having a large number of sieve holes 2 formed by section preforming of rubber or rubber-like elastic material.
A porous screen for sieving, consisting of an assembly in which a plurality of rectangular lattice units 1 are connected to a desired size with connecting bars 5 made of rubber or rubber-like elastic material that align the edges of each rectangular lattice unit 1 and fill the mutual spacing 4 between them. In this case, internal reinforcement made of a rigid bar material 6 having a smaller coefficient of thermal expansion and poor adhesiveness than that of the material is provided in the joining bar 5 over the entire length of the joining bar 5 during the forming stage. A reinforced porous screen for sieves characterized by being buried.