JP7340966B2 - dust remover - Google Patents

Description

The present invention relates to a dust remover.

Japanese Patent Publication No. 52-89221 (Patent Document 1) states, ``A dust remover installed in a waterway has wheels installed above the waterway and at the bottom of the waterway on the upstream side of a grid provided across the waterway. ``The chain is suspended, and rakes are attached to the chain at approximately equal intervals.'' Further, Patent Document 1 states, "Wheels are rotatably provided on the left and right sides of the upstream waterway bottom and above the waterway of the dust removal grid. (Omitted) The wheels on the waterway bottom are supported by wall shafts." has been done.

Special Publication No. 52-89221

A dust remover is used, for example, as a pretreatment for water treatment, for the purpose of removing impurities contained in water flowing into a waterway. The automatic dust remover includes a screen that is inserted into a waterway and traps foreign matter, and a rake that scrapes up and removes the foreign matter accumulated on the screen. Impurities contained in the water accumulate on the screen, but are automatically scraped up by the rake and discharged to the outside of the waterway.

For example, the rake is attached to an endless chain and is moved along the extending direction of the screen by a driving force applied to the endless chain. In the case of a structure where sprockets are attached to both sides of the upper folded part and the lower folded part of the endless chain, it is necessary to have a structure that rotatably supports both sprockets, which makes processing and installation of the sprockets complicated. Alternatively, an endless chain is engaged under tension with sprockets at both ends. For this reason, replacement work when replacing sprockets or chains periodically is complicated.

A brief overview of typical embodiments of the invention disclosed in this application is as follows.

That is, a dust remover according to one embodiment includes a screen having a plurality of slits, a rake having a plurality of teeth arranged along the width direction of the screen, and positions facing each other through the rake. a pair of endless chains that are driven in circulation between an upper folded part and a lower folded part along the extending direction of the screen; and a pair of endless chains that are engaged with the upper folded parts of the pair of endless chains; A sprocket that rotates to drive the pair of endless chains from the ascending side to the descending side of the endless chain, and a sprocket that is attached to the lower folded part of the pair of endless chains so that the pair of endless chains ascends from the descending side. a pair of lower chain guides that contact the pair of endless chains when folded back toward the side. The rake is driven in circulation via the pair of endless chains. The first lower chain guide, which is one of the pair of lower chain guides, has a chain contact portion that is formed in an arc shape and is arranged to face either one of the pair of endless chains, and the first lower chain. and a frame mounting portion for bolting to a frame supporting the guide. The first lower chain guide is a plate-like member in which the chain contact portion and the frame portion are integrally formed.

A dust remover according to another embodiment includes a screen provided with a plurality of slits, a rake provided with a plurality of teeth arranged along the width direction of the screen, and arranged at positions facing each other via the rake. , a pair of endless chains that are driven in circulation between an upper folded part and a lower folded part along the extending direction of the screen; and a pair of endless chains that are engaged with the upper folded parts of the pair of endless chains; a sprocket that rotates so as to drive the pair of endless chains from the ascending side of the chain toward the descending side; and a sprocket that is attached to the lower folded portion of the pair of endless chains, and the sprocket rotates so as to drive the pair of endless chains from the ascending side of the chain to the descending side; a pair of lower chain guides that come into contact with the pair of endless chains when folded back toward the chain. The rake is driven in circulation via the pair of endless chains. The first lower chain guide, which is one of the pair of lower chain guides, has a chain contact portion that is formed in an arc shape and is arranged to face either one of the pair of endless chains, and the first lower chain. and a frame mounting portion for bolting to a frame supporting the guide. The first lower chain guide has a first portion and a second portion that are independently attached to the frame. Each of the first part and the second part has the chain contact part and the frame attachment part, and are attached to positions adjacent to each other.

Among the inventions disclosed in this application, the effects obtained by typical inventions are briefly explained below.

That is, it is possible to efficiently manufacture or replace replacement parts for the dust remover.

Problems, configurations, and effects other than those described above will be made clear by the following description of the embodiments.

FIG. 2 is a front view of the dust remover according to one embodiment, viewed from the upstream side of a waterway. FIG. 2 is a side view of one side of the waterway viewed from the AA line shown in FIG. 1. FIG. FIG. 2 is an enlarged front view of section B in FIG. 1. FIG. FIG. 4 is a plan view of the rake shown in FIG. 3 viewed from above. FIG. 3 is an enlarged plan view of the vicinity of the lower folded portion of the chain shown in FIG. 2; 6 is an enlarged plan view showing the positional relationship of the chain guide shown in FIG. 5 when viewed from the front shown in FIG. 1. FIG. 6 is a perspective view of the chain guide shown in FIG. 5. FIG. 8 is a perspective view of a chain guide that is a modification of FIG. 7. FIG. FIG. 9 is a plan view of the chain guide shown in FIG. 8 after it is attached to the dust remover, viewed from the direction of line AA shown in FIG. 1; 9 is a plan view of the chain guide shown in FIG. 9, viewed from the direction of line AA in FIG. 9. FIG. FIG. 8 is a plan view of a chain guide that is another modification of the chain guide shown in FIG. 7, as seen from the direction of line AA shown in FIG. 1, after it is attached to a dust remover. 12 is a plan view of the chain guide shown in FIG. 11 viewed from the direction of line AA in FIG. 11. FIG. 9 is an assembled perspective view of a chain guide that is a modification of the chain guide shown in FIG. 8. FIG. 14 is a plan view of the chain guide shown in FIG. 13 after it is attached to the dust remover, viewed from the direction of line AA shown in FIG. 1. FIG. 15 is a plan view of the chain guide shown in FIG. 14, viewed from the direction of line AA in FIG. 14. FIG.

In each of the drawings for explaining the embodiments below, the same members are designated by the same reference numerals in principle, and repeated explanations thereof will be omitted. Note that, in order to make the drawings easier to understand, hatching may be added even in a plan view.

<Overview of dust remover>
FIG. 1 is a front view of a dust remover according to the present embodiment, viewed from the upstream side of a waterway. Further, FIG. 2 is a side view of one side of the waterway viewed from the position of line AA shown in FIG. FIG. 3 is an enlarged front view of section B in FIG. FIG. 4 is a plan view of the rake shown in FIG. 3 viewed from above. In FIGS. 1 to 4, some of the parts included in the dust remover 10 are omitted for ease of viewing. For example, in FIG. 1, among the plurality of rakes 30 shown in FIG. 2, the rakes 30 on the descending side and near the bottom of the water are not shown. For example, in FIGS. 1 and 2, parts of the chain 40 that conveys the rake 30 are not shown, and the circulation orbit of the chain 40 is shown by a chain double-dashed line. Further, in FIG. 1, a guide rail that guides the chain 40 in the traveling direction is not illustrated.

The dust remover 10 of this embodiment is installed in a waterway W1 upstream of a pretreatment facility such as a settling basin in a water treatment facility such as a sewage treatment plant, for example. The dust remover 10 includes a screen 20 inserted into the waterway W1, a rake 30 that scrapes up foreign matter blocked by the screen 20, and a rake drive unit that circulates and drives the rake 30 along the extending direction of the screen 20. It has a chain 40.

The screen 20 is a component that dams up impurities contained in sewage and wastewater flowing through the waterway W1 and separates water and impurities. The screen 20 includes a plurality of slits 21 (see FIGS. 3 and 4) extending in the longitudinal direction. In other words, the screen 20 includes a plurality of bar screens (plate-like members) 22 that extend in the longitudinal direction and are arranged in the width direction so as to be spaced apart from each other. As schematically shown by arrow WF1 in FIG. 2, water flowing from the upstream side passes through the slits 21 of the screen 20 and flows into the downstream side. At this time, contaminants larger than the width of the slits 21 are blocked by the screen 20 and remain on the upstream side of the screen 20. In this way, the screen 20 has the function of capturing impurities and separating them from water flowing downstream.

In this embodiment, each of the plurality of bar screens 22 shown in FIGS. 3 and 4 has the same shape and is arranged at regular intervals. However, the shape and arrangement interval of the bar screen (in other words, the width of the slit 21) are not limited to the example of this embodiment. For example, a plurality of bar screens may be arranged at different intervals. Alternatively, a plurality of types of bar screens (not shown) having different thicknesses and sizes may be arranged alternately or every plurality in the width direction.

As shown in FIG. 2, the screen 20 is fixed in the waterway W1 so as to be inclined at an angle that is not perpendicular to the water surface Wt or the bottom surface Wb of the waterway W1. The screen 20 is inclined so that the upper end is located downstream of the lower end. One longitudinal end of the screen 20 is disposed on the bottom side of the waterway W1, and the other end is disposed near the upper end of the waterway W1.

The rake 30 shown in FIGS. 1 to 4 is a member that scrapes up impurities that have been dammed up on the screen 20 and removes them to the outside of the screen 20. As shown in FIG. 3, the rake 30 includes a comb-teeth member 31 having a plurality of teeth arranged along the width direction of the screen 20, and a support member 32 that supports the comb-teeth member 31. Both ends of the support member 32 extending in the width direction of the screen 20 are fixed to rake fixing portions 74 of an arm 70, which will be described later. The comb tooth member 31 is a plate-shaped member, and has a plurality of teeth formed on one long side. The support member 32 is a reinforcing member that reinforces the mechanical strength of the rake 30, and includes a fixing surface that fixes parts of the comb tooth member 31 other than the plurality of teeth. Note that the shape of the support member 32 is not limited to the embodiments shown in FIGS. 1 to 4 as long as it can improve the mechanical strength of the rake 30 and has a fixing surface for fixing the comb tooth member 31. . For example, it may be a rod-shaped member extending along the width direction of the screen, or it may be a pipe-shaped member. However, from the viewpoint of reducing the weight of the support member 32 or making it easier to fix the comb tooth member 31, the support member 32 is preferably a member without a core, such as a groove shape or a pipe shape.

As shown in FIG. 1, the chains 40 are provided outside both ends of the screen 20 in the width direction of the screen 20. As shown in FIG. 2, each of the pair of chains 40 is an endless chain that is formed in an annular shape and circulates between an upper folded part 41 and a lower folded part 42 along the extending direction of the screen 20. . Note that the upper folded portion 41 is defined as an arcuate portion including the upper end of the annular chain. Similarly, the lower fold 42 is defined as an arcuate portion including the lower end of the annular chain. Each of the pair of chains 40 is arranged on the upstream side of the screen 20. The upper folded portion 41 is located above the upper end of the screen 20. In the example of this embodiment, the chain 40 and the rake 30 rise between the upper folded part 41 and the lower folded part 42 and the screen 20. Therefore, the portion between the upper folded portion 41 and lower folded portion 42 of the chain 40 and the screen 20 is referred to as the rising side. On the other hand, on the opposite side to the rising side, the chain 40 and rake 30 descend. Therefore, the portion of the chain 40 opposite to the ascending side is called the descending side.

As shown in FIG. 2, each of the pair of chains 40 is driven in circulation by the driving force of a motor 50 fixed on the waterway. Specifically, each of the pair of chains 40 is stretched between a sprocket 52 disposed on the upper folded portion 41 and a chain guide (lower chain guide) 60 disposed on the lower folded portion 42 . The driving force of the motor 50 is transmitted to a sprocket (gear) 52 via a chain 51. The teeth of sprocket 52 are engaged with chain 40. A plurality of rakes 30 are attached to the chain 40, and the rakes 30 move along guide rails 43 provided to sandwich the chain 40. Rake 30 is connected to chain 40. Each of the plurality of rakes 30 is driven to circulate between an upper folded portion 41 and a lower folded portion 42 via a chain 40.

As shown in FIG. 4, on the ascending side of the chain 40, each of the plurality of teeth of the comb tooth member 31 of the rake 30 is inserted into the slit 21 of the screen 20. Further, the rake 30 rises along the extending direction of the screen 20 with a plurality of teeth inserted into the slits 21. Thereby, the impurities dammed up by the screen 20 are scraped up by the rake 30.

As shown in FIG. 2, the chain 40 and the rake 30 are covered by the housing 11 on the waterway W1. The screen 20 terminates near the upper end of the waterway W1, and an apron portion 12, which is a part of the casing 11, is arranged above the waterway W1. The apron portion 12 extends along the extension line of the screen 20 in the extending direction and is connected to the chute 13. The foreign matter raked up by the rake 30 is raked up along the screen 20 and the apron section 12, and is thrown into the recovery device 14 via the chute 13.

Further, the rake 30 rises to the upper folded portion 41 of the chain 40, and is reversed at the upper folded portion 41. On the descending side of the chain 40, the rake 30 descends toward the lower folded portion 42 in a state that is reversed from the ascending side. The rake 30 is reversed again at the lower fold 42 of the chain 40 and ascends along the screen 20. Each of the plurality of rakes 30 attached to the chain 40 sequentially repeats the above-described cycle as the motor 50 rotates. Thereby, the impurities staying on the screen 20 are intermittently scraped up by the rake 30 and thrown into the recovery device 14. As a result, the screen 20 is maintained in a state where there is little accumulation of impurities, and the dust remover 10 is able to stably remove impurities contained in water without reducing the separation performance between impurities and water. can.

Furthermore, although the rake 30 scrapes up the above-mentioned impurities, for example, during heavy rain, coarse items etc. that are difficult to scrape up with the rake 30 may accumulate on the screen 2. In this case, the rake 30 automatically rotates to avoid the large object, thereby preventing damage to the rake 30 itself. Note that, as an example, an embodiment in which the rake 30 automatically rotates to avoid large objects will be described below. However, as a modification, the rake 30 may be driven in circulation while being fixed to the chain 40 without rotating to avoid large objects.

As shown in FIG. 1, the dust remover 10 of this embodiment includes a pair of arms 70 that rotatably support the rake 30. Specifically, one end of the rake 30 is fixed to an arm (first arm) 70A attached to one of the pair of chains 40 (chain 40A). The other end of the rake 30 is fixed to an arm (second arm) 70B attached to the other of the pair of chains 40 (chain 40B). Each of the pair of arms 70 is connected to each of the pair of chains 40. Each of the pair of arms 70 is connected to each of the pair of chains 40 via a pin 71 (see FIG. 3), and is rotatable with respect to the chain 40 about the center line (imaginary line) of the pin 71 as the rotation axis. is attached to. When coarse materials accumulate on the screen 20 and a large load is applied to the rake 30, the arm 70 automatically rotates due to the load. This rotational movement allows the rake 30 to automatically avoid large objects.

<Details of the lower folded part of the chain>
Next, details of the structure around the lower folded portion of the chain shown in FIG. 2 will be described. FIG. 5 is an enlarged plan view of the lower folded portion of the chain shown in FIG. 2 and its vicinity. 6 is an enlarged plan view showing the positional relationship of the chain guide shown in FIG. 5 when viewed from the front shown in FIG. 1. FIG. FIG. 7 is a perspective view of the chain guide 60 shown in FIG. 5. As shown in FIG. 6, the dust remover 10 includes a pair of chain guides (first lower chain guide) 60A and a chain guide (second lower chain guide) 60B that face each other. Chain guides 60A and 60B have similar structures. In the following description, when chain guides 60A and 60B are simply described as chain guide 60 without distinguishing them, this is a common description for chain guides 60A and 60B shown in FIG. Further, although FIG. 7 is a perspective view, in order to clearly distinguish between the chain contact portion 61 and the frame attachment portion 62, the portion corresponding to the chain contact portion 61 is shown with hatching.

As shown in FIG. 2, a sprocket 52 that rotates to drive the pair of chains 40 from the ascending side to the descending side of the pair of chains 40 is engaged with the upper folded portion 41 of the chain 40. Sprocket 52 is a gear that transmits the driving force of motor 50 to chain 40.

As shown in FIGS. 2 and 5, the guide rail 43 that guides the chain 40 in the traveling direction includes a guide rail 43a that guides the outer circumferential side of the chain 40 and a guide rail 43a that guides the outer circumferential side of the chain 40 on the ascending side of the chain 40, and a guide rail 43 that guides the inner circumferential side of the chain 40. It includes a guide rail 43b for guiding. Further, the guide rail 43 includes, on the ascending side of the chain 40, a guide rail 43c that guides the outer circumferential side of the chain 40, and a guide rail 43d that guides the inner circumferential side of the chain 40. Further, the guide rail 43 includes a guide rail 43e that guides the outer peripheral side of the chain 40 at the lower folded portion 42 of the chain 40. At the lower folded portion 42 of the chain 40, the inner peripheral side of the chain 40 is guided by a chain guide 60.

As an example of consideration for this embodiment, a method may be considered in which a sprocket (not shown) is engaged with the lower folded portion 42 of the chain 40. However, when providing a sprocket to be engaged with the lower folded portion 42, it is necessary to provide a rotation mechanism underwater. If the rotational operation of the sprocket becomes unstable underwater, the operation of the chain 40 will stop due to this. For this reason, there are problems such as the structure of the sprocket placed underwater becoming complicated or the maintenance of the sprocket becoming complicated.

On the other hand, in the case of the present embodiment, the inner peripheral side of the chain 40 is guided by a chain guide 60 at the lower folded portion 42 of the chain 40 . In this case, the chain guide 60 itself does not rotate, and the chain 40, which circulates due to the rotation of the sprocket 52 (see FIG. 2) provided above the water, turns back along the chain guide 60 from the descending side to the ascending side. Therefore, the chain guide 60 does not require a complicated structure, and the chain guide 60 is easy to manufacture or maintain.

However, while the chain 40 is being driven in circulation, the chain 40 comes into contact with the chain guide 60, so the chain guide 60 is likely to wear out due to friction. Each portion of the chain 40 contacts the chain guide 60 once during the cycle of the chain 40 for one week. On the other hand, the chain guide 60 is always rubbed against some part of the chain 40 while the chain 40 is in operation. Therefore, the chain guide 60 is subject to greater wear and tear over time than the chain 40. As a result, the chain guide 60 may need to be replaced before other parts. Therefore, it is preferable that the chain guide 60 has a structure that takes into consideration ease of parts replacement.

As shown in FIG. 7, the chain guide 60 of this embodiment includes a chain contact portion 61 disposed to face either one of a pair of chains 40A and 40B (see FIG. 1), and a chain guide 60. It has a frame attachment part 62 for fixing to the supporting frame 15 (see FIG. 5) with bolts 16 (see FIG. 5). The chain guide 60 is a plate-like member in which a chain contact portion 61 and a frame attachment portion 62 are integrally formed.

As shown in FIG. 5, the chain contact portion 61 is a portion facing the chain 40 (side surfaces 63s1 and 64s1 shown in FIG. 7). Although the chain contact portion 61 is a portion that may come into contact with the chain 40, the chain contact portion 61 may include a portion that does not come into contact with the chain 40. Although details will be described later, a specific portion of the chain contact portion 61 (the portion facing the ascending side of the chain 40) frequently contacts the chain 40, but other portions do not contact the chain 40. Often not.

The frame attachment portion 62 corresponds to the through hole into which the bolt 16 (see FIG. 5) is inserted and its surrounding area. The through hole of the frame attachment portion 62 passes through the chain guide 60 in the thickness direction. In the example shown in FIG. 7, the side surface of the through hole of the frame attaching portion 62 is a smooth surface with no threads formed thereon. However, as a modified example, the side surface of the through hole of the frame attaching portion 62 may have an unevenness that can be used as a screw thread.

When the chain guide 60 is a plate-like member as in this embodiment, the structure is simple. Therefore, when manufacturing replacement parts for the chain guide 60, manufacturing efficiency can be improved. In the case of this embodiment, as will be described later, the chain guide 60 includes a portion (first portion) 63 and a portion (second portion) 64 that are separable from each other. However, as a modification, the chain guide 60 may not be divided into a plurality of parts, but may be a single plate-like member. In this case, the structure is even simpler than the example of this embodiment. In this case, the effect of improving the manufacturing efficiency of replacement parts described above can be obtained.

The chain guide 60 of this embodiment includes a portion (first portion) 63 and a portion (second portion) 64 that are independently attached to the frame 15 (see FIG. 5). Each of the sections 63 and 64 has a chain contact section 61 and a frame attachment section 62, and are attached at positions adjacent to each other. In FIG. 7, the portion 63 and the portion 64 included in the chain guide 60 are shown separated from each other in order to clearly show that the portion 63 and the portion 64 are separable from each other. However, when the chain guide 60 is attached to the dust remover 10 shown in FIG. 5, the side surface 63s2 of the portion 63 and the side surface 64s2 of the portion 64 face each other and are in contact with each other.

Specifically, the portion 63 of the chain guide 60A has a main surface 63t facing the chain guide 60B, and a main surface 63b located on the opposite side of the main surface 63t. The chain guide 60A has a side surface 63s1 having a curved surface portion that intersects the main surface 63t and the main surface 63b and forms the chain contact portion 61. The chain guide 60A has a side surface 63s2 that intersects the main surface 63t and the main surface 63b and faces the portion 64. Furthermore, the chain guide 60A intersects each of the main surface 63t, the main surface 63b, the side surface 63s1, and the side surface 63s2, and in the extending direction of the chain 40A (see FIG. 1), the chain guide 60A intersects with the upper folded portion 41 (see FIG. 2). It has opposing side surfaces 63s3.

The portion 64 of the chain guide 60A has a main surface 64t facing the chain guide 60B, and a main surface 64b located on the opposite side of the main surface 64t. The chain guide 60A has a side surface 64s1 having a curved surface portion that intersects the main surface 64t and the main surface 64b and forms the chain contact portion 61. The chain guide 60A has a side surface 64s2 that intersects the main surface 64t and the main surface 64b and faces the portion 63. Furthermore, the chain guide 60A intersects each of the main surface 64t, the main surface 64b, the side surface 64s1, and the side surface 64s2, and intersects with the upper folded portion 41 (see FIG. 2) in the extending direction of the chain 40A (see FIG. 1). It has opposing side surfaces 64s3.

Similarly, the portion 63 of the chain guide 60B has a main surface 63t facing the chain guide 60A, and a main surface 63b located on the opposite side of the main surface 63t. The chain guide 60B has a side surface 63s1 that intersects the main surface 63t and the main surface 63b and has a curved surface portion that forms the chain contact portion 61. Chain guide 60B has a side surface 63s2 that intersects main surface 63t and main surface 63b and faces portion 64. Furthermore, the chain guide 60B intersects each of the main surface 63t, the main surface 63b, the side surface 63s1, and the side surface 63s2, and the upper folded portion 41 (see FIG. 2) in the extending direction of the chain 40B (see FIG. 1). It has opposing side surfaces 63s3.

The portion 64 of the chain guide 60B has a main surface 64t facing the chain guide 60A, and a main surface 64b located on the opposite side of the main surface 64t. The chain guide 60B has a side surface 64s1 that intersects the main surface 64t and the main surface 64b and has a curved surface portion that forms the chain contact portion 61. Chain guide 60B has a side surface 64s2 that intersects main surface 64t and main surface 64b and faces portion 63. Furthermore, the chain guide 60B intersects each of the main surface 64t, the main surface 64b, the side surface 64s1, and the side surface 64s2, and the upper folded portion 41 (see FIG. 2) in the extending direction of the chain 40B (see FIG. 1). It has opposing side surfaces 64s3.

A side surface (first opposing surface) 63s2 of the portion 63 and a side surface (second opposing surface) 64s2 of the portion 64 of each of the chain guides 60A and 60B face each other and are in contact with each other in the dust remover 10 (Fig. 5) with bolts 16.

If the chain guide 60 is an integral piece, it is necessary to replace each pair of chain guides 60 when replacing the chain guide 60. At this time, the chain guide 60, which is an integral part, weighs about 20 to 30 kg, making the replacement work complicated.

On the other hand, when the chain guide 60 includes a plurality of separable parts 63 and 64 as in this embodiment, the weight of the replacement parts can be reduced by replacing each part individually. Therefore, it becomes possible to perform the replacement work easily. Further, according to studies conducted by the inventor of the present application, it has been found that wear of the chain guide 60 occurs at a specific portion of the chain contact portion 61. Specifically, in the chain guide 60 shown in FIG. 5, the ascending side of the chain 40 (screen 20 side) is likely to wear out. Therefore, when comparing parts 63 and 64 of the chain guide 60 shown in FIG. 7, part 63 has a greater degree of wear than part 64. This difference in the degree of wear is significant, and even when it is time to replace the portion 63, there is often no need to replace the portion 64.

In the case of this embodiment, the portion 63 is located closer to the screen 20 than the portion 64. In other words, since the portion 64 is less prone to wear than the portion 63, there is almost no need for replacement. Therefore, in the case of this embodiment, only the portion 63 needs to be replaced, so the portion 64 does not need to be replaced. In this case, the efficiency of the replacement work can be further improved compared to the case where the parts 63 and 64 are replaced respectively.

Furthermore, in the case of this embodiment, the volume of portion 63 is smaller than the volume of portion 64. Since portions 63 and 64 are manufactured from the same material, the mass of portion 63 is less than the mass of portion 64. In this way, by making the mass of the portion 63 that requires replacement smaller than the mass of the portion 64 that does not require replacement, replacement work can be facilitated. Moreover, the materials required for replacement parts can be reduced. However, the relationship between the sizes of the portion 63 and the portion 64 can be changed depending on the position where wear is likely to occur. For example, if wear occurs over a wide range of the chain contact portion 61, the mass of the portion 63 may exceed the mass of the portion 64.

As described above, in this embodiment, chain guides 60A and 60B shown in FIG. 6 have similar structures. Therefore, each of the pair of chain guides 60A and 60B shown in FIG. 6 has the portions 63 and 64 described using FIG. 7. However, if at least one of the chain guides 60A and 60B is divided into a plurality of separable parts 63 and 64, it is possible to make the replacement work of the divided chain guide 60 more efficient. can. However, it is preferred that chain guides 60A and 60B each include portions 63 and 64.

5 and 7 exemplarily show the structure of the chain guide 60A shown in FIG. 6 as the structure of the chain guide 60. Although not shown, the structure of the chain guide 60B is symmetrical to the structure of the chain guide 60A shown in FIG. 7 with respect to the main surface 63t or 64t.

<Modification 1>
Below, a modification of the chain guide 60 described using FIGS. 1 to 7 will be described. FIG. 8 is a perspective view of a chain guide that is a modification of FIG. 7. FIG. 9 is a plan view of the chain guide shown in FIG. 8 after it is attached to the dust remover, as seen from the direction of line AA shown in FIG. FIG. 10 is a plan view of the chain guide shown in FIG. 9, viewed from the direction of line AA in FIG. In addition, in the following description, in principle, redundant description will be omitted for parts of the structure of the chain guide 60C that are not different from the chain guide 60 shown in FIG. 7. Further, parts that are not different from the chain guide 60 are denoted by the same reference numerals as those described in FIGS. 1 to 7, and may be described with reference to FIGS. 1 to 7 as necessary.

The chain guide 60C shown in FIGS. 8 to 10 differs from the chain guide 60 shown in FIG. 7 in the shapes of portions 63 and 64. Details of the differences will be described later, but first, a method for removing and replacing the portion 63 of the chain guide 60 shown in FIG. 5 will be described. In the case of the chain guide 60 shown in FIG. 7, the side surface 63s2 is perpendicular to the main surface 63t, and the side surface 64s2 is perpendicular to the main surface 64t. Further, as shown in FIG. 5, the portions 63 and 64 are attached to the dust remover 10 in close contact with each other, and the chain 40 is in contact with a portion of the chain guide 60.

As shown in FIG. 5, the portion 63 is sandwiched between the chain 40, the guide rail 43b, and the portion 64, so even if the bolt 16 fixing the portion 63 of the chain guide 60 is removed, the portion 63 cannot be immediately removed. I can't. Therefore, when replacing the portion 63, the tension on the chain 40 is released and then the bolts 16 that secure the portion 63 are removed. This allows the position of the portion 63 to be shifted in the direction of the chain 40, so that the portion 63 can be removed without loosening the bolt 16 that fixes the portion 64. Moreover, when attaching the replacement part 63, the above-mentioned operation is performed in reverse. That is, the replacement part 63 is placed next to the portion 64 with the tension on the chain 40 relaxed and is fixed by the bolt 16. Thereafter, the replacement work is completed by tensioning the chain 40.

On the other hand, the chain guide 60C shown in FIGS. 8 to 10 differs from the chain guide 60 shown in FIG. 7 in the following points. In the case of the chain guide 60C shown in FIGS. 8 to 10, if the direction from the main surface 63t of the portion 63 toward the main surface 63b (Z1 direction shown in FIG. 10) is the thickness direction of the chain guide 60, the side surface 63s2 and the side surface 64s2 are provided so as to be inclined with respect to the thickness direction of the chain guide 60. Further, in a plan view from the main surface 63t side of the portion 63, at least a portion of the side surface 64s2 is covered by the side surface 63s2.

The structure of the chain guide 60C shown in FIGS. 8 to 10 can also be expressed as follows. That is, the portion 63 is located closer to the screen 20 (see FIG. 2) than the portion 64. The portion 63 has a side surface (first opposing surface) 63s2 that faces the portion 64. The portion 64 has a side surface (second opposing surface) 64s2 that faces the side surface 63s2 of the portion 63. If the direction from the chain guide 60B to the chain guide 60A shown in FIG. 6 of the pair of chain guides 60C (Z1 direction shown in FIG. It is provided so as to be inclined in one direction. Further, in a plan view of the chain guide 60A from the chain guide 60B side shown in FIG. 6, at least a portion of the side surface 64s2 is covered by the side surface 63s2.

Each of the side surfaces 63s2 and 64s2 of the chain guide 60C of this modification is a tapered surface that is inclined with respect to the thickness direction of the chain guide 60C. Further, in the Z1 direction, which is the mounting direction of the chain guide 60C, the side surface 63s2 of the portion 63, which is more easily worn than the portion 64, covers the side surface 64s2 of the portion 64. In this case, when the bolt 16 fixing the part 63 shown in FIG. be able to. Therefore, the component 63 can be replaced without loosening the tension on the chain 40.

Specifically, when replacing the portion 63 of the chain guide 60C of this modification, the bolts 16 fixing the portion 63 are removed without loosening the tension on the chain 40. This allows the position of the portion 63 to be shifted in the direction of the portion 64, so that the portion 63 can be removed without loosening the bolt 16 that fixes the portion 64. Moreover, when attaching the replacement part 63, the above-mentioned operation is reversed. That is, the replacement part 63 is pushed in so as to be shifted from the part 64 side toward the chain 40 while the chain 40 is under tension. When the side surface 63s2 of the portion 63 and the side surface 64s2 of the portion 64 are placed in positions facing each other, the portion 63 is fixed with the bolt 16, and the replacement work is completed.

As described above, according to this modification, the work of loosening the tension on the chain 40 and the work of tensioning it again can be omitted, so that the work of replacing the parts 63 can be made more efficient. Note that in FIGS. 8 to 10, the structure of the chain guide 60A shown in FIG. 6 is illustrated as an example. Although not shown, the structure of the chain guide 60B is symmetrical to the structure of the chain guide 60A shown in FIGS. 8 to 10 with respect to the main surface 63t or 64t. In other words, each of the pair of chain guides 60A and 60B shown in FIG. 6 has the structure of the chain guide 60C described using FIGS. 8 to 10. However, if at least one of the pair of chain guides 60A and 60B has the structure of the chain guide 60C described above, the replacement work of the part 63 having the structure of the chain guide 60C becomes more efficient. be able to.

<Modification 2>
FIG. 11 is a plan view of a chain guide that is another modified example of the chain guide shown in FIG. 7, as viewed from the direction of the line AA shown in FIG. 1, after the chain guide is attached to the dust remover. 12 is a plan view of the chain guide shown in FIG. 11, viewed from the direction of line AA in FIG. 11. In addition, in the following description, in principle, redundant description will be omitted for parts of the structure of the chain guide 60C that are not different from the chain guide 60 shown in FIG. 7. Further, parts that are not different from the chain guide 60 are denoted by the same reference numerals as those described in FIGS. 1 to 7, and may be described with reference to FIGS. 1 to 7 as necessary.

The chain guide 60D shown in FIGS. 11 and 12 is different from the chain guide 60 shown in FIG. 7 in the angle of inclination of the side surface 63s3 of the portion 63 and the angle of inclination of the side surface 64s3 of the portion 64. Specifically, a side surface (fifth side surface) 63s3 of the portion 63 included in the chain guide 60D is provided so as to be inclined with respect to the thickness direction (Z1 direction shown in FIGS. 11 and 12) of the chain guide 60D. In a plan view viewed from the main surface 63t side of the portion 63, the side surface 63s3 is not visible.

A side surface 63s3 of the chain guide 60D of this modification is a tapered surface that is inclined with respect to the thickness direction of the chain guide 60D. Furthermore, in the Z1 direction, which is the mounting direction of the chain guide 60C, the side surface 63s2 of the portion 63, which is more easily worn than the portion 64, is provided at a position that cannot be visually recognized from the main surface 63t side. In this case, when the bolts 16 fixing the part 63 shown in FIG. It can be shifted. Therefore, the component 63 can be replaced without loosening the tension on the chain 40.

Specifically, when replacing the portion 63 of the chain guide 60C of this modification, the bolts 16 fixing the portion 63 are removed without loosening the tension on the chain 40. As a result, the position of the portion 63 can be shifted in the direction of the guide rail 43b, so the portion 63 can be removed without loosening the bolt 16 that fixes the portion 64. Moreover, when attaching the replacement part 63, the above-mentioned operation is performed in reverse. That is, the replacement part 63 is pushed in so as to be shifted from the guide rail 43b side toward the chain 40 while the chain 40 is under tension. When the side surface 63s2 of the portion 63 and the side surface 64s2 of the portion 64 are placed in positions facing each other, the portion 63 is fixed with the bolt 16, and the replacement work is completed.

As described above, according to this modification, the work of loosening the tension on the chain 40 and the work of tensioning it again can be omitted, so that the work of replacing the parts 63 can be made more efficient. Note that in FIGS. 11 and 12, the structure of the chain guide 60A shown in FIG. 6 is illustrated as an example. Although not shown, the structure of the chain guide 60B is plane symmetrical to the structure of the chain guide 60A shown in FIGS. 11 and 12 with respect to the main surface 63t or 64t. In other words, each of the pair of chain guides 60A and 60B shown in FIG. 6 has the structure of the chain guide 60D described using FIGS. 11 and 12. However, if at least one of the pair of chain guides 60A and 60B has the structure of the chain guide 60D described above, the replacement work of the part 63 having the structure of the chain guide 60D becomes more efficient. be able to.

<Modification 3>
FIG. 13 is an assembled perspective view of a chain guide that is a modification of the chain guide shown in FIG. 8. FIG. 14 is a plan view of the chain guide shown in FIG. 13 after it is attached to the dust remover, as seen from the direction of line AA shown in FIG. 15 is a plan view of the chain guide shown in FIG. 14, viewed from the direction of line AA in FIG. 14. In addition, in the following description, in principle, redundant description of parts of the structure of the chain guide 60E that are not different from the chain guide 60C shown in FIG. 8 will be omitted. Further, the same reference numerals as those described in FIGS. 1 to 10 are used for parts that are not different from the chain guide 60C, and the description may be made with reference to FIGS. 1 to 10 as necessary.

The chain guide 60E shown in FIGS. 13 and 14 differs from the chain guide 60C shown in FIG. 8 in that each of the portions 63 and 64 is a composite member in which a plurality of members are joined by welding or the like. Specifically, the chain guide 60E is similar to the chain guide 60C in that it has a separable portion 63 and a portion 64. However, each of the portions 63 and 64 includes the following members joined by welding. That is, each of the portions 63 and 64 includes a chain contact member (chain contact portion) 61E that is formed in an arc shape and is arranged to face either one of the pair of chains 40A and 40B (see FIG. 1). have Each of the portions 63 and 64 has a frame attachment member (frame attachment portion) 62E for fixing the chain guide 60E to the frame 15 (see FIG. 6) with a bolt 16 (see FIG. 14). Further, each of the portions 63 and 64 has a support member 65E to which a chain contact member 61E and a frame attachment portion 62E are joined and supports these members.

The support member 65E is a member formed to bend a plate-like member, and includes a curved surface 65s1 and a curved surface 65s2 located on the opposite side of the curved surface 65s1. The chain contact member 61E is joined to the curved surface 65s1 of the support member 65E by, for example, welding. The frame attachment portion 62E is joined to the curved surface 65s2 of the support member 65E by, for example, welding.

The chain guide 60E has a more complex structure than the chain guide 60 shown in FIG. 7, the chain guide 60C shown in FIG. 8, or the chain guide 60D shown in FIG. Therefore, when manufacturing replacement parts for chain guide 60E, the manufacturing process becomes more complicated than when manufacturing chain guides 60, 60C, or 60D.

However, the chain guide 60E also has a portion 63 and a portion 64 that are independently attached to the frame 15 (see FIG. 6), similarly to the chain guide 60 and the like described above. As described above, the portion 63 is located closer to the screen 20 (see FIG. 5) than the portion 64. In other words, since the portion 64 is less prone to wear than the portion 63, there is almost no need for replacement. Therefore, in the case of this modification, only the portion 63 needs to be replaced, so the portion 64 does not need to be replaced. In this case, the efficiency of the replacement work can be further improved compared to the case where the parts 63 and 64 are replaced respectively.

Further, as shown in FIG. 15, the portion 63 has a side surface 63s2 facing the portion 64, and the portion 64 has a side surface 64s2 facing the side surface 63s2 of the portion 63. Assuming that the Z1 direction from the chain guide 60B to the chain guide 60A of the pair of chain guides 60 shown in FIG. 6 is the first direction, as shown in FIG. Each is provided so as to be inclined with respect to the first direction. Furthermore, in a plan view of the chain guide 60A from the chain guide 60B side shown in FIG. 6, as shown in FIG. 15, at least a portion of the side surface 64s2 is covered by the side surface 63s2.

Note that in FIGS. 11 and 12, the structure of the chain guide 60A shown in FIG. 6 is illustrated as an example. Although not shown, the structure of the chain guide 60B is plane symmetrical to the structure of the chain guide 60A shown in FIGS. 13 to 15 with respect to the main surface 63t or 64t. In other words, each of the pair of chain guides 60A and 60B shown in FIG. 6 has the structure of the chain guide 60E described using FIGS. 13 to 15. However, if at least one of the pair of chain guides 60A and 60B has the structure of the chain guide 60E described above, the replacement work of the part 63 having the structure of the chain guide 60E becomes more efficient. be able to.

<Other variations>
Although several modified examples have been representatively described above, there are various other modified examples in addition to the above. For example, in the chain guide 60 shown in FIG. 7, the arc shape of the chain contact portion 61 (the combination of the line where the main surface 63t and the side surface 63s1 intersect, and the line where the main surface 64t and the side surface 64s1 intersect) is a semicircle. However, the chain contact portion 61 has various modifications as long as it has at least an arcuate portion. For example, the example shown in FIG. 11 has a semicircular part and a straight part connected to the short arc of the semicircular part. Further, although not shown, it may be an arcuate shape that does not reach a semicircle (in other words, the center angle is less than 180 degrees). However, in consideration of continuity in the portion where the guide rails 43b and 43d and the chain guide 60 shown in FIG. 5 face each other, it is preferable that at least a semicircular portion is provided.

For example, in the case of the embodiment described above, the guide rail 43e that guides the outer peripheral side of the chain 40 at the lower folded portion 42 of the chain 40 is not divided into a plurality of members, as shown in FIG. 5, for example. As a modification, the guide rail 43e may be divided into a plurality of members. In this case, when replacing the guide rail 43e, the replacement work can be made more efficient. However, as described above, since the chain 40 is driven in circulation while contacting a portion of the chain guide 60, there are very few opportunities for the guide rail 43e to come into contact with the chain 40. Therefore, it is unlikely that the guide rail 43e will need to be replaced due to wear and tear. Therefore, from the viewpoint of making it easier to replace only the parts that are likely to need replacement, it is preferable that the guide rail 43e is not divided into a plurality of parts.

For example, each of the chain guides 60, 60C, 60D, and 60E described above is divided into two parts 63 and 64. However, the number of divisions is not limited to two, and may be three or more. However, as the number of divisions of the chain guide 60 increases, the number of bolts 16 for fixing each divided part increases. Therefore, as described above, it is particularly preferable to divide into two parts, the part 63 that includes a relatively easily worn part and the part 64 that does not include a relatively easily worn part.

Further, for example, the layout of the bolts 16 for fixing the chain guide 60 is not limited to the example shown in FIG. 5 etc., and there are various modifications.

For example, the example shown in FIG. 2 shows an embodiment in which each of the chain 40 and the rake 30 is disposed upstream of the screen 20. However, as a modification, the rake 30 and chain 40 may be arranged downstream of the screen 20. Also in this modification, the chain 40 circulates between the upper folded part 41 and the lower folded part 42 along the extending direction of the screen 20, as in the example shown in FIG. 2. 2, the rake 30 rises along the screen 20 at a position relatively close to the screen 20, and descends at a position away from the screen 20. Therefore, the above-described chain guide 60, 60B, 60C, 60D, or 60E can be applied to this modification as well.

Although typical modifications of the present embodiment have been described above, the present invention is not limited to the above-described embodiments and typical modifications, and various modifications can be made without departing from the spirit of the invention. Applicable.

Moreover, although various modified examples have been described above, each modified example can be appropriately combined and applied.

INDUSTRIAL APPLICATION This invention can be utilized for the dust remover which removes the impurities contained in sewage and wastewater.

10 Dust remover 11 Housing 12 Apron part 13 Chute 14 Collection device 15 Frame 20 Screen 21 Slit 22 Bar screen 30 Rake 31 Comb tooth member 32 Support member 40, 40A, 40B Chain (endless chain)
41 Upper folded part 42 Lower folded part 43, 43a, 43b, 43c, 43d, 43e Guide rail 50 Motor 51 Chain 52 Sprocket (gear)
60, 60A, 60B, 60C, 60D, 60E Chain guide 61 Chain contact part 61E Chain contact member 62 Frame attachment part 62E Frame attachment member 63, 64 Part (first part, second part)
63b, 63t, 64b, 64t Main surface 63s1, 63s2, 63s3, 64s1, 64s2, 64s3 Side surface 65E Support member 65s1, 65s2 Curved surface 70, 70A, 70B Arm 71 Pin (connection part)
72, 73 Roller 74 Rake fixing part W1 Waterway Wb Bottom surface Wt Water surface

Claims (9)

a screen with multiple slits;
a rake including a plurality of teeth arranged along the width direction of the screen;
a pair of endless chains disposed at positions facing each other via the rake and driven in circulation between an upper folded portion and a lower folded portion along the extending direction of the screen;
a sprocket that is engaged with the upper folded portions of the pair of endless chains and rotates to drive the pair of endless chains from a rising side to a falling side of the pair of endless chains;
a pair of lower chain guides that are attached to the lower folded portions of the pair of endless chains and come into contact with the pair of endless chains when the pair of endless chains are folded back from the descending side toward the ascending side;
has
The rake is driven in circulation via the pair of endless chains,
The first lower chain guide, which is one of the pair of lower chain guides,
a chain contact portion formed in an arc shape and arranged to face either one of the pair of endless chains;
a frame attachment portion for bolting to a frame supporting the first lower chain guide;
has
The first lower chain guide is a plate-like member in which the chain contact part and the frame attachment part are integrally formed,
The first lower chain guide has a first part and a second part independently attached to the frame. The dust remover according to claim 1,
The dust remover, wherein each of the first part and the second part has the chain contact part and the frame attachment part, and is attached to positions adjacent to each other. The dust remover according to claim 2,
the first part is located closer to the screen than the second part,
The first part is
a first main surface facing a second lower chain guide that is the other of the pair of lower chain guides;
a second main surface located on the opposite side of the first main surface;
a first side surface having a curved surface portion that intersects the first main surface and the second main surface and forms the chain contact portion;
a second side surface that intersects the first main surface and the second main surface and faces the second portion;
has
The second part is
a third main surface facing the second lower chain guide;
a fourth main surface located on the opposite side of the third main surface;
a third side surface having a curved surface portion that intersects the third main surface and the fourth main surface and forms the chain contact portion;
a fourth side surface that intersects the third main surface and the fourth main surface and faces the second side surface of the first portion;
has
If the direction from the first main surface to the second main surface of the first portion is the thickness direction of the first lower chain guide,
Each of the second side surface and the fourth side surface is provided to be inclined with respect to the thickness direction of the first lower chain guide,
The dust remover, wherein at least a portion of the fourth side surface is covered by the second side surface in a plan view from the first main surface side of the first portion. The dust remover according to claim 2,
the first part is located closer to the screen than the second part,
The first portion has a first opposing surface facing the second portion,
The second portion has a second opposing surface that faces the first opposing surface of the first portion,
When a direction from the second lower chain guide, which is the other of the pair of lower chain guides, toward the first lower chain guide is defined as a first direction,
In the first direction,
Each of the first opposing surface and the second opposing surface is provided to be inclined with respect to the first direction,
In a plan view of the first lower chain guide from the second lower chain guide side, at least a portion of the second opposing surface is covered by the first opposing surface. The dust remover according to claim 2,
the first part is located closer to the screen than the second part,
The first part is
a first main surface facing a second lower chain guide that is the other of the pair of lower chain guides;
a second main surface located on the opposite side of the first main surface;
a first side surface having a curved surface portion that intersects the first main surface and the second main surface and forms the chain contact portion;
a second side surface that intersects the first main surface and the second main surface and faces the second portion;
a fifth side surface that intersects each of the first main surface, the second main surface, the first side surface, and the second side surface and faces the upper folded part in the extending direction of the pair of endless chains; ,
has
The second part is
a third main surface facing the second lower chain guide;
a fourth main surface located on the opposite side of the third main surface;
a third side surface having a curved surface portion that intersects the third main surface and the fourth main surface and forms the chain contact portion;
a fourth side surface that intersects the third main surface and the fourth main surface and faces the second side surface of the first portion;
has
If the direction from the first main surface to the second main surface of the first portion is the thickness direction of the first lower chain guide,
The fifth side surface is provided so as to be inclined with respect to the thickness direction of the first lower chain guide,
The dust remover, wherein the fifth side surface is not visible in a plan view from the first main surface side of the first portion. a screen with multiple slits;
a rake including a plurality of teeth arranged along the width direction of the screen;
a pair of endless chains disposed at positions facing each other via the rake and driven in circulation between an upper folded portion and a lower folded portion along the extending direction of the screen;
a sprocket that is engaged with the upper folded portions of the pair of endless chains and rotates to drive the pair of endless chains from a rising side to a falling side of the pair of endless chains;
a pair of lower chain guides that are attached to the lower folded portions of the pair of endless chains and come into contact with the pair of endless chains when the pair of endless chains are folded back from the descending side toward the ascending side;
has
The rake is driven in circulation via the pair of endless chains,
Each of the pair of lower chain guides is
a chain contact portion formed in an arc shape and arranged to face either one of the pair of endless chains;
a frame mounting portion for bolting to a frame supporting each of the pair of lower chain guides;
has
Each of the pair of lower chain guides is a plate-like member in which the chain contact part and the frame attachment part are integrally formed,
Each of the pair of lower chain guides has a first portion and a second portion independently attached to the frame,
The dust remover, wherein each of the first part and the second part has the chain contact part and the frame attachment part, and is attached to positions adjacent to each other. The dust remover according to claim 6,
Each of the pair of first portions is located closer to the screen than each of the pair of second portions,
Each of the pair of first portions has a first opposing surface that faces either of the pair of second portions,
Each of the pair of second portions has a second opposing surface opposite to the first opposing surface,
If the direction from the second lower chain guide, which is the other of the pair of lower chain guides, to the first lower chain guide, which is one of the pair of lower chain guides, is defined as a first direction,
In the first direction,
Each of the pair of first opposing surfaces and the pair of second opposing surfaces are provided to be inclined with respect to the first direction,
In a plan view of the first lower chain guide from the second lower chain guide side,
At least a portion of the second opposing surface of the first lower chain guide is covered by the first opposing surface of the first lower chain guide,
At least a portion of the second opposing surface of the second lower chain guide is covered by the first opposing surface of the second lower chain guide. a screen with multiple slits;
a rake including a plurality of teeth arranged along the width direction of the screen;
a pair of endless chains disposed at positions facing each other via the rake and driven in circulation between an upper folded portion and a lower folded portion along the extending direction of the screen;
a sprocket that is engaged with the upper folded portions of the pair of endless chains and rotates to drive the pair of endless chains from a rising side to a falling side of the pair of endless chains;
a pair of lower chain guides that are attached to the lower folded portions of the pair of endless chains and come into contact with the pair of endless chains when the pair of endless chains are folded back from the descending side toward the ascending side;
has
The rake is driven in circulation via the pair of endless chains,
The first lower chain guide, which is one of the pair of lower chain guides,
a chain contact portion formed in an arc shape and arranged to face either one of the pair of endless chains;
a frame attachment portion for bolting to a frame supporting the first lower chain guide;
has
The first lower chain guide has a first portion and a second portion attached to the frame independently of each other;
The dust remover, wherein each of the first part and the second part has the chain contact part and the frame attachment part, and is attached to positions adjacent to each other. The dust remover according to claim 8,
the first part is located closer to the screen than the second part,
The first portion has a first opposing surface facing the second portion,
The second portion has a second opposing surface that faces the first opposing surface of the first portion,
When a direction from the second lower chain guide, which is the other of the pair of lower chain guides, toward the first lower chain guide is defined as a first direction,
In the first direction,
Each of the first opposing surface and the second opposing surface is provided to be inclined with respect to the first direction,
In a plan view of the first lower chain guide from the second lower chain guide side, at least a portion of the second opposing surface is covered by the first opposing surface.

Images