JP6230850B2 - Grating - Google Patents

Description

  The present invention relates to a grating used for a side groove or the like.

  Metal gratings are widely used as groove covers for road side grooves and the like. Many of these types of gratings use two side bars to fix both ends of a plurality of bearing bars (also called main bars) provided at regular intervals, and a cross bar is provided in parallel to the side bars. It has a structure in which a plurality of bearing bars are joined by pressure welding or the like. For joining the bearing bar and the side bar, welding or fitting is used.

  As the shape of the bearing bar, a T bar having a T-shaped cross section, a flat bar having a vertically long rectangular cross section, or an I bar having a I-shaped cross section (for example, Patent Document 1, particularly FIG. 3). The optimum bearing bar shape is selected according to the location where the groove lid is used.

JP 2010-229695 A

  The T-bar has a configuration in which the width of the upper portion that is the surface portion of the grating is widened, and the width of the other portions is narrowed. Therefore, the T-bar is lighter than other bearing bars. Since the bearing bar occupies a considerable volume among the components of the grating, the weight of the entire grating can be significantly reduced by using a lightweight T-bar. Therefore, there is an advantage that the installation of the grating and the maintenance in the groove can be easily performed by reducing the material cost as well as reducing the material cost.

On the other hand, the T bar itself is weak in strength, and the bonding area with the side bar is small, and the bonding portion is biased upward, so that the strength of the entire grating is reduced. Thus, in order to sufficiently secure the bonding strength, it is necessary to devise a special method such as using a special method for bonding to the side bar, resulting in a problem that the manufacturing cost increases.
Furthermore, since the upper width of the T bar is wide, when a heavy load such as an automobile passes through, if a load is applied to the upper end of the T bar, a large torque that rotates the entire T bar is generated. There was a fear that the joint with the bar was destroyed. For example, when a stone or the like is in the gap between adjacent T-bars and the car tires step over the stone or the like, the load of the automobile is applied to the upper end of the T-bar. A large rotational torque is generated. Therefore, the grating using the T-bar is not suitable for the gutter for the side groove installed on the side of the road through which the automobile passes, and there is a problem that the application is remarkably limited.
In the case of a flat bar or I-bar, the cross bar can be joined by pressure welding. However, since the T bar has a large upper surface area, it is difficult to join the cross bar by pressure welding. For this reason, an extra manufacturing process is required in which a hole is formed in the lower part of the T bar and joined through the cross bar, and there is a problem that the manufacturing cost is further increased.

A flat bar with a vertically long rectangular cross section has the same width in the upper part and other parts as the surface part of the grating, so that there is a problem that the cross-sectional area becomes large and the weight is considerably heavier than the T bar. .
There is also a drawback that stones or the like are easily clogged between two adjacent flat bars. If stones get stuck between the flat bars, not only the drainage performance of the grating will deteriorate, but also the appearance will be lacking.

  An I-bar having an I-shaped cross section has a smaller cross-sectional area than a flat bar, and can obtain the same strength as a flat bar. However, since the central portion between two adjacent I bars is widened, there is a problem that stones and the like are more easily clogged than a flat bar. Moreover, it is more difficult to remove clogged stones than a flat bar.

  The present invention has been made to solve the above various problems, and proposes a new grating configuration.

The grating according to the present invention includes a plurality of bearing bars arranged substantially parallel to each other at a predetermined interval, two side bars joined to both side ends of the plurality of bearing bars,
A cross bar arranged in parallel with the two side bars and joined to the plurality of bearing bars, and a cross section perpendicular to the longitudinal direction of the uppermost portion of the bearing bar has a long side located above The section perpendicular to the longitudinal direction of the lower part of the bearing bar is substantially rectangular, and the width of the upper end of the bearing bar is larger than the width of the lower part of the bearing bar. The width of the central portion is smaller than the width of the lower portion of the bearing bar.

  Since the grating according to the present invention is configured as described above, stones and the like are not easily clogged between the bearing bars, and can be easily removed even if they are clogged. Further, the weight of the grating can be reduced without losing the strength.

It is a top view of the groove cover which concerns on this invention. It is a fragmentary perspective view of the groove cover which concerns on this invention. It is a fragmentary perspective view of the bearing bar which concerns on this invention. It is explanatory drawing of the force of the perpendicular direction added to the bearing bar which concerns on this invention. It is explanatory drawing of the force which produces the rotation added to the bearing bar which concerns on this invention.

Embodiment.
Hereinafter, embodiments relating to grating according to the present invention will be described with reference to the drawings. The following embodiment is an example of the present invention, and the present invention is not particularly limited to this example. For example, the shape and specific dimensions shown in the present embodiment are good examples, and the present invention is not limited to these. Further, in the present embodiment, the configuration and the like will be described by taking fine grating as an example, but the concept of the invention described below can be similarly applied to even coarse grating.

First, the construction of the grating according to the present invention will be described with reference to FIGS.
FIG. 1 is a top view of the grating 1. The grating 1 is provided in parallel with a plurality of bearing bars 2 arranged in parallel at substantially regular intervals, two side bars 3 joined to both ends of the bearing bar 2, and the side bars 3. And a plurality of cross bars 4 joined together.

FIG. 2 is a partial perspective view of the grating 1 as viewed from the upper side. In this figure, the side bar 3 is not shown in order to clearly show the cross-sectional shape of the bearing bar 2. However, the vertical position of the side bar 3 is indicated by two dotted lines. That is, the side bar 3 is a plate having substantially the same height as the bearing bar 2 and is joined to the side surface of each bearing bar 2 by welding.
The side bars 3 and the side surfaces of the bearing bars 2 are not limited to welding but may be joined by other methods. For example, a hole that matches the shape of the bearing bar 2 may be provided in the side bar 3 and joined by fitting.

  The cross bar 4 is joined to the upper part of each bearing bar 2 by pressure contact. Regarding this joining, other methods may be used without being limited to the pressure welding.

As shown in FIG. 2, the bearing bars 2 are usually arranged in parallel at a constant interval P. In the present embodiment, the bearing bars 2 are arranged at intervals of 15 mm.
The shape of the bearing bar 2 will be further described with reference to FIG.
The shape of the bearing bar can be roughly divided into three parts. As shown in FIG. 3, the upper part 21, the central part 22, and the lower part 23.

The upper portion 21 has a trapezoidal cross section perpendicular to the longitudinal direction, and the upper surface thereof is subjected to uneven processing for the purpose of preventing slipping. The width A of the upper surface is about 5 mm.
The central portion 22 has a vertically rectangular cross section and a width B of about 2.3 mm.
The lower part 23 is a house-shaped hexagon whose cross section extends from the central part 22, and the width C of the bottom part is about 3.5 mm.

  The specific shape of each part of these bearing bars 2 is not limited to the above, but points to be particularly noted will be described below.

First, the most important thing is the width A, B, C of each part,

A>C> B ――― (Formula 1)

To satisfy the relationship. By satisfying this relationship, an object such as a stone entering the grating from the gap between the upper portions 21 between the adjacent bearing bars 2 falls into the groove with a high probability without stopping between the adjacent bearing bars 2. Since the width of the gap generated between the adjacent bearing bars 2 is the smallest in the upper portion 21, an object entering from the narrow gap is likely to fall into the groove through the gaps in the wider central portion 22 and the lower portion 23. .

  However, the possibility that an object stays in the lower part 23 is not zero. For example, a stone having a flat shape with a thickness smaller than A enters the grating 1 through the gap between the upper parts 21 between the adjacent bearing bars 2, rotates to reach the lower part 23, changes its posture, and changes to the lower part 23. It can get stuck and stop. However, in such a case, it is possible to easily drop the stone into the groove by poking the stone with a stick from above the grating. Alternatively, it is also conceivable that the stone falls into the groove due to vibration when the automobile or the like passes over the grating 1. In any case, even if an object may temporarily stay in the grating, it will not be clogged.

Further, by satisfying the relationship of Formula 1, even if the cross-sectional area of the bearing bar 2 is small, the rigidity of the bearing bar 2 itself can be increased and the strength of the grating 1 as a whole can be improved. That is, weight reduction and high rigidity of the bearing bar 2 and strength improvement of the entire grating 1 can be achieved at the same time.
Hereinafter, this reason will be described.

  The force generated in the bearing bar 2 when a heavy object such as a truck passes over the grating 1 is a force in a direction directly below the vertical direction shown in FIG. 4 and a force in the direction of rotating the bearing bar 2 shown in FIG.

  First, when the heavy object is on the grating 1, the load acts as a force for vertically pushing down the bearing bar 2 as shown in FIG. 4. This force is a force that causes the bearing bar 2 to bend in a bow shape. When the bearing bar 2 is bowed, the upper part 21 of the bearing bar 2 receives a large compressive stress and the lower part 23 receives a large tensile stress.

  Therefore, by making the width of the upper part 21 and the lower part 23 of the bearing bar 2 wider than the central part 22, it is possible to suppress deformation due to these large stresses as small as possible. In this way, by reducing the width of the central portion 22 where only a relatively small stress is generated by increasing the width of the portion where particularly large stress is generated by the load of the heavy object, the bearing bar 2 can be reduced in weight and rigidity. realizable.

  It should be noted that the section modulus that determines the maximum bending stress of the bearing bar 2 according to the present invention can be made larger than that of the flat bar when the cross-sectional area is the same, but can be made larger than that of the I bar. This is because the cross section secondary moment can be increased because the width of the upper portion 21 is larger than the width of the lower portion 23. Therefore, since the cross-sectional area of the bearing bar 2 according to the present invention having the same maximum bending stress as that of the conventional I-bar can be made smaller than that of the conventional I-bar, further weight reduction and material cost reduction are possible. It is.

  Next, the case where the force of the direction which rotates the bearing bar 2 generate | occur | produces notably is demonstrated using FIG. When a stone 5 larger than the gap between adjacent bearing bars 2 rides on the gap, when a tire such as a truck steps on the stone 5, the end of the upper part 21 of the bearing bar 2 is Load concentrates. In FIG. 5, a load is applied to the right end portion of the upper portion 21 of the left bearing bar 2 in the direction indicated by the arrow E. Similarly, a load is applied to the left end portion of the upper portion 21 of the right bearing bar 2 in the direction indicated by the arrow F. These loads are torques for rotating the respective bearing bars 2. This rotational torque is a magnitude obtained by multiplying the load applied to each of them by half of the width A of the upper portion 21.

  Since both side end portions of the bearing bar 2 are joined and fixed to the side bar 3, this fixing force counters the above-described rotational torque and prevents the bearing bar 2 from rotating. In particular, since the joining force between the side bars 3 and the side bars 3 of the upper portion 21 and the lower portion 23 far from the center of the bearing bar 2 becomes a large torque against the rotational torque, the upper portion 21 and the lower portion 23 The structure with a larger width is a structure that is strong against rotational torque.

That is, compared to a flat bar, the structure can withstand the same rotational torque with a smaller cross-sectional area.
In the case of a T-bar, the width of the upper part is very wide, so that the rotational torque proportional to half of that is very large. Furthermore, the joint area between the both side ends of the T-bar and the side bar 3 is small, and the structure is very weak to the rotational torque generated in the case shown in FIG.

  The case of FIG. 5 described above is a case where the rotational torque is remarkably generated. In other cases, for example, when the tire such as a truck passes through the end of the bearing bar, the rotational torque is also the same. Occur.

  Furthermore, by increasing the width A of the upper portion 21 of the bearing bar 2, it is possible to reduce the number of bearing bars 2 used for the grating 1 as compared with the conventional flat bar and I bar, and further reduce the weight. Material costs and assembly costs can be reduced. In general, the width of the gap between the bearing bars 2 is determined by the type and application of the grating. For example, in the case of fine lines, the width of the gap is a width that does not allow the tip of a high-heeled heel or wand to enter, and is about 10 mm. Therefore, the arrangement pitch of the bearing bars 2 is a length obtained by adding the upper surface width of the bearing bars to 10 mm, and is 15 mm in the case of grating in the present embodiment. On the other hand, in order to obtain the same rigidity as the bearing bar 2 and the strength of the entire grating using a flat bar as the bearing bar, the arrangement pitch of the bearing bars is about 12 to 13 mm. Further, even when an I bar is used as a bearing bar, it is about 13 to 14 mm, which is a narrower pitch than in the case of the grating in the present embodiment, and therefore, a large number of bearing bars are required.

The next important point is that the cross-sectional shape perpendicular to the longitudinal direction of the upper part 21 is a trapezoidal shape with the upper surface having a long side. By doing in this way, it can prevent as much as possible that a stone etc. are pinched | interposed into the clearance gap which each upper part 21 which opposes between the adjacent bearing bars 2 forms. Further, since the uppermost surface where the maximum compressive stress is generated is made the longest, even a small cross-sectional area can provide even greater rigidity as a bearing bar.
That is, since the uppermost surface farthest from the center is the portion most contributing to the sectional moment of inertia, the width of the portion is made the longest, so that the section modulus can be maximized with the same sectional area.

  Further, by making the upper surface the longest, the bonding area with the cross bar 4 increases, and there is an advantage that the strength of the entire grating can be further improved. Further, since it is not extremely wide like a T-bar, low-cost pressure welding can be used as a joining method with a cross bar.

The reason why the cross-sectional shape perpendicular to the longitudinal direction of the upper portion 21 is a trapezoidal shape is that it is easy to manufacture in terms of manufacturing, but is not necessarily limited to this shape. What is necessary for the cross-sectional shape perpendicular to the longitudinal direction of the upper portion 21 is that the uppermost surface is the longest. Furthermore, an acute angle is formed at the vertices at both ends of the uppermost surface. By doing so, since the uppermost surfaces of the adjacent bearing bars 2 are opposed to each other by a line, stones and the like are less likely to be clogged as compared to the case where the surfaces are opposed to each other.
This is important from the viewpoint of durability of the grating. This is because when a stone or the like is clogged near the uppermost surface of the bearing bar 2, when a truck or the like passes over it, the stone or the like is forcibly pushed deeper between the adjacent bearing bars 2 and the bearing bar 2 is deformed. This is because the joint between the bearing bar 2 and the side bar 3 may be damaged.

The features of the grating according to the present invention will be summarized below.
First, there is no clogging of objects such as stones between adjacent crossbars, so that the drainage performance and the beauty of the appearance can be maintained. In particular, in the cross-sectional shape perpendicular to the longitudinal direction of the upper portion 21, the uppermost surface is the longest and acute angles are formed at the apexes at both ends of the uppermost surface. 2 can be deformed, or damage to the joint between the bearing bar 2 and the side bar 3 can be prevented.

  Secondly, even if the cross-sectional area of the bearing bar is small, the rigidity of the bearing bar can be increased and the strength of the grating as a whole can be increased. Accordingly, the weight of the grating can be reduced and the cost can be reduced, and it can also be used in places where automobiles and the like frequently pass, and there is no limitation on the application.

  Thirdly, since the installation pitch of the bearing bars can be increased, the number of bearing bars to be used can be reduced. Therefore, further weight reduction and cost reduction of the grating can be achieved.

  Fourthly, the appearance seen from the grating surface is powerful and gives a strong image. Compared to gratings that use a flat bar or I-bar as the bearing bar, the bearing bar is wider, so it has a strong appearance when viewed during installation, and gives a good impression as a grating design. Can do.

Fifth, the bearing bar according to the present invention is not greatly different in shape from the I-bar that has been used for many years and can be made of the same material, so that it can be manufactured by a manufacturing process that has been proven for many years. For example, the bonding method with the side bar or the cross bar may be the same, and if the materials are the same, long-term reliability of the bonding is also guaranteed.
In addition, a special joining method with the side bar as in the case of the T-bar is not necessary, and pressure welding can be used for joining with the cross bar, so that the manufacturing cost is low.

  Note that SS400 (iron) has been widely used as a material constituting the bearing bar. Instead, it may be possible to use a harder metal. By using a hard metal, the strength can be increased and the thickness of the bearing bar can be reduced. However, in this case, the above-described problems such as the reliability of the bonding occur, and even if the yield point can be increased by increasing the material strength, the amount of strain becomes large, and when the track or the like passes. A more complicated design that takes into account the jumping of the grating is required.

Finally, consider the specific location where the grating will be installed.
One of the places where grating is most commonly used is on the side of the road. Since the center of the road is raised on the ridge, stones etc. bounced by tires such as cars tend to gather on the side of the road. Therefore, a grating using a T-bar that is less likely to be clogged with stones or the like is preferable. However, although less frequent than the center of the road, since tires such as trucks pass along the road, it is not appropriate to use a T-bar in terms of strength. In such places, the grating according to the present invention is most suitable for handling heavy loads and not causing clogging.

  In addition, gravel roads such as shrine shrines can be considered as places where stones are most likely to clog. Since many worshipers walk on the approach, fine gratings are used so that the heel of a high heel or the tip of a cane is not caught. Since fine gratings are very easily clogged with pebbles, a grating that does not cause clogging is desired. Furthermore, since the truck for carrying in also passes along a approach road, the high intensity | strength grating which can respond to a heavy load is required. Therefore, the grating according to the present invention is also optimal for the grating installed on the gravel road like the shrine approach.

1 grating 2 bearing bar 3 side plate 4 cross bar 21 upper part 22 central part 23 lower part

Claims (1)

A plurality of bearing bars arranged substantially parallel to each other at a predetermined interval;
Two side bars joined to both end portions of the plurality of bearing bars;
A cross bar disposed in parallel with the two side bars and joined to the plurality of bearing bars;
With
The cross section perpendicular to the longitudinal direction of the uppermost portion of the bearing bar has a substantially trapezoidal shape with the long side located on the top.
The cross section perpendicular to the longitudinal direction of the lower portion of the bearing bar is substantially rectangular,
The width of the upper end portion of the bearing bar is larger than the width of the lower portion of the bearing bar,
The grating characterized in that the width of the center part of the bearing bar is smaller than the width of the lower part of the bearing bar.