KR101037761B1 - forming device for manufacturing a grid of a battery - Google Patents

Abstract

The present invention allows the manufacture of a grid of a battery manufactured by a roll forming method to be manufactured by a press mold operation, which is easy to maintain, enables mass production, and improves precision. The present invention relates to a mold apparatus for manufacturing a grid of a battery.

To this end, the present invention is disposed on the material input side, the pilot-hole piercing part (pilot-hole piercing part) for forming a pilot hole for the penetration of the pilot pin in the material received from the feeder; A plurality of main peircing parts which are sequentially disposed on the material ejecting side of the pilot hole piercing part and are provided such that a plurality of punches for forming a plurality of perforation holes are formed in a plurality of rows and rows; In addition, the main die piercing portion is disposed on the material carrying side, and a main notching part (main notching part): to remove the unnecessary portion of the material is provided, characterized in that the press mold apparatus for manufacturing a battery grid is provided.

Battery Grid, Press Molding Equipment, Side Notching, Main Piercing, Main Notching

Description

Forming device for manufacturing a grid of batteries

The present invention relates to a manufacturing apparatus, and more specifically, to manufacture a grid of a battery manufactured by a roll forming method (roll forming) method to be manufactured by a press mold operation, the maintenance is convenient and mass production is possible The present invention relates to a mold apparatus for manufacturing a grid of a battery of a new type, which can improve precision.

In general, fabrication of a battery grid is performed by a roll forming method.

In this case, the roll forming method refers to a plurality of perforation holes forming various shapes in the material by the protrusions formed on the surface of the pair of rolls in the process of passing the material between the pair of rolls corresponding to each other. It is a molding method to make it possible.

However, the manufacturing method of the battery grid using the above-mentioned roll forming method has a problem that the defective rate is high because the accurate speed can be produced only when the rotational speed at which the pair of rolls is rotated and the inflow rate of the material match each other.

In addition, since the roll to be a tool (Tool) is composed of a curved surface it is difficult to mechanically give a contour shape on the surface of the roll for forming the perforated hole, it is difficult to precise position machining.

In particular, the manufacturing method of the battery grid using the roll forming method has a problem in that maintenance is difficult, such as replacing the entire roll due to difficulty in repairing only a corresponding part when wear or breakage occurs on a specific part of the roll.

Of course, the above-mentioned various problems can also be solved by constructing a manufacturing apparatus for manufacturing a battery grid with a conventional press mold apparatus.

However, the above-described battery grid is not only difficult to form the installation site for the installation of each punch, because each punch must be located very close to the formation of each hole, considering that the perforations are located very close to each other Since they are located adjacent to each other, the durability of the mold is reduced, so there is a high risk of breakage, and thus development into a press die apparatus has not been achieved.

The present invention has been made to solve the various problems of the prior art described above, the object of the present invention is to configure a battery grid manufacturing apparatus of a press mold while the various problems that can be caused due to the proximity between the punches The present invention provides a mold apparatus for manufacturing a grid of a battery of a new type, which can be easily maintained, mass-produced, and improved in precision by preventing it.

According to the press mold apparatus for manufacturing a battery grid of the present invention for achieving the above object, a pilot hole piercing part disposed on a material input side and forming a pilot hole for penetration of a pilot pin in a material provided from a feeder ( pilot-hole piercing part; A plurality of main peircing parts which are sequentially disposed on the material ejecting side of the pilot hole piercing part and are provided such that a plurality of punches for forming a plurality of perforation holes are formed in a plurality of rows and rows; In addition, the main notching part disposed on the material carrying side of each of the main piercing parts and removing unnecessary parts of the material is characterized in that it is provided in sequence.

Here, each of the main piercing unit is arranged so that the front and rear and left and right positions are different from each other when the rows and columns of punches provided in each of the main piercing units are different from each other based on the entry direction of the material. It is characterized in that the perforated holes to be perforated do not overlap with each other and can be sequentially formed for each part.

At this time, each of the main piercing portion is composed of four, the row and column of the punch provided in any one of the main piercing portion of the four main piercing parts are located to the left rearward side when viewed relative to the entry direction of the material, Rows and columns of punches provided in the other main piercing part are located to the right rearward with respect to the entry direction of the workpiece, and rows and columns of punches provided in the main piercing part of the other It is characterized by being positioned forward left as a reference, and the rows and columns of punches provided in another main piercing part are biased forward right when viewed from the entry direction of the material.

In addition, each of the main piercing unit is characterized in that the left and right reconstruction based on the entry direction of the material.

In addition, a side notching part is disposed at a part provided with a pilot hole piercing part, which is a material importing side, and notches and removes both parts of the material according to a set width from a feeder. It is characterized by being further included.

In addition, the outer portion of each of the main piercing portion guides the movement of the material and is characterized in that it further comprises a plurality of guide portion for blocking the rise of the material with the punch or the pilot pin of each main piercing portion, Each of the guides has a fixed shaft, a rolling member installed on the circumferential surface of the fixed shaft to guide rolling of the material, and a cover formed to cover a part of the upper end of the rolling member while being fixed to the upper end of the fixed shaft. It is characterized by consisting of members.

In addition, the front part and the rear part of each main piercing part when viewed based on the entry direction of the material is characterized in that it is configured to further include an idle part (idle part) to secure a clearance gap between each other.

According to the press mold apparatus for manufacturing a battery grid according to the present invention as described above, by changing the apparatus for manufacturing a battery grid into a press forming method instead of a roll forming method, various problems of the roll forming method device can be solved. Has an effect.

That is, the difficulty in the work for manufacturing the roll forming apparatus and the work for the maintenance of the roll forming apparatus can be solved as the press mold apparatus is changed.

In particular, the press mold apparatus for manufacturing a battery grid of the present invention allows the structure for forming the perforated holes of the battery grid to be sequentially formed by a plurality of main piercing parts, and the positions of the perforated holes formed by the respective main piercing parts are By configuring the parts to be different parts, the spacing between the punches can be sufficiently relaxed. As a result, the punches can be prevented from interfering with each other in operation.

In addition, the press mold apparatus for manufacturing a battery grid of the present invention enables stable conveyance of the material by the configuration of the guide part, and prevents the material from being moved upward with the respective punches or the pilot pin during the punching process. Due to the configuration of the cover member of the guide portion has the effect that can prevent the problem that the material is caught in the gap between the cloud member and the cover member.

Hereinafter, a preferred embodiment of the press mold apparatus for manufacturing a battery grid of the present invention will be described with reference to FIGS. 1 to 12.

1 to 3, the press mold apparatus for manufacturing a battery grid according to an exemplary embodiment of the present invention (hereinafter, referred to as a “molding apparatus”) includes an upper mold 110 and a lower mold 120 corresponding to each other. In the above two molds 110 and 120, the pilot hole piercing unit 300, the main piercing unit 410, 420, 430, 440, and the main notching unit 500 are sequentially arranged along the entry direction of the material 130. do.

This will be described in more detail below for each configuration.

First, the pilot-hole piercing part 300 may include a pilot hole 302 through which a pilot pin 301 may be penetrated to prevent the flow of the material 130 during a subsequent process. A series of sites configured to be molded into the material 130.

The pilot hole piercing unit 300 is provided to form a pilot hole 302 in the material 130 received from the feeder (feeder) is disposed on the material input side, as shown in Figure 1 to 4 attached It is configured to include a pilot hole forming punch 310 and the through hole 320.

At this time, the pilot hole forming punch 310 is a punch for forming the pilot hole 302 in the material 130, it can be lifted to the center side of the material loading side of the bottom surface of the upper mold (110). It is provided.

In addition, the through hole 320 is a hole formed to allow the pilot hole forming punch 310 to penetrate into a corresponding portion of the upper surface of the lower mold 120 with the pilot hole forming punch 310. Each is formed.

On the other hand, the material loading side of the mold apparatus according to an embodiment of the present invention suggests that the side notching portion 200 is further included.

The side notching part 200 may remove the material 130 provided from the feeder (not shown) by notching both sides of the material 130 to a predetermined width. It is a set of sites.

The side notching portion 200 is configured to be placed on the material loading side between the respective molds 110 and 120, as shown in Figures 1 to 3 attached, and the side notching punch as shown in Figures 3 and 4 attached ( 210 and a through hole 220 is configured.

In this case, the side notching punch 210 is a punch for notching both side portions of the material 130, and is provided to be liftable on both sides of the material loading side of the bottom surface of the upper mold 110.

In addition, the through hole 220 is a hole formed to penetrate the side notching punch 210, and is formed in a corresponding portion of the upper surface of the lower mold 120 with the side notching punch 210, respectively. do.

Particularly, in the embodiment of the present invention, the pilot hole piercing part 300 is disposed to be provided at a portion between the two side notching punches (or through holes) 210 of the side notching part 200. do.

That is, a side notching process for both side portions of the material 130 and a pilot hole 302 in the material 130 by one operation (side notching process or operation in which the upper mold is moved downward for the pilot hole piercing process). ), And the pilot hole forming process for molding) can be performed at the same time.

This is because the work area by the pilot hole piercing part 300 and the side notching part 200 is a very local part compared to the overall size of the material 130, so that the simultaneous arrangement between the two configurations is possible.

Of course, the side notching portion 200 may be configured to be disposed on the material carrying side of each of the main piercing portion 410, 420, 430, 440 described later according to the design of the mold apparatus.

Next, the main piercing part 410, 420, 430, 440 is a series of configurations for forming a plurality of perforation holes 131, 132, 133, 134 in the material 130, and the side notching part 200 and the pilot hole piercing part 300. ) Is provided on the raw material carrying side.

The main piercing parts 410, 420, 430, and 440 are installed such that a plurality of punches 411, 421, 431, 441 for forming the perforation holes 131, 132, 133, 134 (see FIGS. 8 to 11) formed in the battery grid form a plurality of rows and rows. This is as shown in Figure 4 attached.

In particular, the embodiment of the present invention suggests that the main piercing unit 410, 420, 430, 440 is configured in plurality along the conveying direction of the material.

That is, the number of processes may be variously determined such that the number of the main piercing portions may be three or less or four or more depending on the size and spacing of the perforation holes 131, 132, 133, and 134 of the battery grid or the shape of the battery grid.

In the embodiment of the present invention, four main piercing parts 410, 420, 430 and 440 are configured as four, and the four main piercing parts 410, 420, 430 and 440 may be arranged in order from the material importing side.

In addition, in the embodiment of the present invention, the front and rear and left and right positions when the rows and columns of the punches 411, 421, 431, 441 provided in each of the main piercing parts 410, 420, 430, and 440 are respectively relative to the entry direction of the material 130. Are arranged so as to be different from each other, so that the perforation holes 131, 132, 133, and 134 perforated in the material 130 in the main piercing parts 410, 420, 430, and 440 are sequentially formed by portions without overlapping each other.

For example, the rows and columns of the punches 411 forming the first main piercing portion (hereinafter referred to as “primary main piercing portion” 410) 410 on the basis of the material importing side are mutually biased to the rear of the left side. The rows and columns of the punches 421 constituting the main piercing portion (hereinafter referred to as “secondary main piercing portion” 420) of the portion 420 are spaced apart from each other while shifting to the rear of the right side. And the rows and columns of the punches 431 constituting the main piercing portion (hereinafter referred to as “third main piercing portion” 430) 430 of the portion are configured to be spaced apart from each other while being biased forward of the left side. Thereafter, the rows and columns of the punches 441 constituting the main piercing portion (hereinafter, referred to as “fourth main piercing portion”) 440 are configured to be spaced apart from each other while being biased forward of the right side.

Accordingly, the punch 411 of the primary main piercing unit 410 and the punch 421 of the secondary main piercing unit 420 and the punch 431 and the fourth main piercing unit of the tertiary main piercing unit 430 ( The punching holes 131, 132, 133, and 134 formed in the material 130 by the punch 441 of 440 are not overlapped with each other, so that the separation distance between the punches 411, 421, 431, 441 can be sufficiently secured. In addition to improving the reliability of the site is installed, it is also possible to form a more compact perforated holes (131, 132, 133, 134).

In addition, in the embodiment of the present invention, each of the main piercing parts 410, 420, 430, 440 is characterized in that it is configured in a double row based on the entry direction of the material (130).

In other words, by allowing a single material 130 to simultaneously manufacture the two battery grids to enable mass production.

Particularly, it is more preferable that the punches 411, 421, 431, and 441 are arranged between the main piercing parts 410, 420, 430, and 440 in the above-described array so that the punches 411, 421, 431, 441 are arranged opposite to each other.

This is to minimize waste of the material 130 that is unnecessary to be removed by allowing the lug (current collector) 135 of the battery grid to be formed at the central side portion of the material 130. In this case, the pilot hole 302 formed by the pilot hole piercing unit 300 is formed between the lug (current collector) 135 of the material 130 and the portion where the lug 135 is to be formed. .

In addition, a plurality of pilot pins 301 are provided between the rows of the main piercing parts 410, 420, 430, and 440, and the pilot pins 301 are pierced by the corresponding main piercing parts 410, 420, 430, and 440. It is inserted into the pilot hole 302 formed in the material 130 serves to determine the position of the material 130.

Next, the main notching part 500 is a series of components for removing unnecessary portions of the material 130 for which molding of the perforation holes 131, 132, 133, and 134 is completed. Likewise, the main piercing parts 410, 420, 430, and 440 are disposed on the material carrying side.

At this time, the main notching part 500 is composed of a punch 510 is formed on the upper mold 110 and the punch hole 520 formed on the upper surface of the lower mold 120, for the material 130 The unnecessary portion may be, for example, a portion between each lug (current collector) 135 in which the pilot hole 302 is formed among the central portions of the material 130.

On the other hand, the mold apparatus according to an embodiment of the present invention proposes that the idle unit (Idle Parts) (610,620) for further securing the clearance between the components for each part is further configured.

In this case, the idle parts 610 and 620 are the primary idle parts 610 disposed in front of the primary main piercing parts 410 among the main piercing parts 410, 420, 430 and 440 based on the entry direction of the material 130. ) And a secondary idle part 620 disposed at a rear side portion of the fourth main piercing part 440. This is the same as in Figures 1 to 4 attached.

As described above, the configuration of the idle parts 610 and 620 may include the configuration of each part such as between the main piercing parts 410 and 440 and the punches 210, 411 and 510 of the side notching part 200 and the main notching part 500. By providing a free space to prevent interference between the punches (210, 411, 510), and also to prevent the problem that the overlap between the punch plate (220, 412, 520) can be weakened in advance.

In addition, the mold apparatus according to an embodiment of the present invention suggests that a plurality of guide portion 700 is further included as shown in Figure 1 to 3 attached.

At this time, the guide portion 700 guides the movement of the material 130 to the outer portions of the main piercing parts 410, 420, 430, and 440, and the material 130 punches the main piercing parts 410, 420, 430, and 440. 411, 421, 431, 441, or a series of configurations to block rising with the pilot pin 301.

The guide part 700 has a fixed shaft 710 fixedly installed on the upper surface of the lower mold 120 and the rotation of the material 130 while being rotatably installed on the circumferential surface of the fixed shaft 710. Consists of guiding rolling member 720 and the cover member 730 is fixed to the upper end of the fixed shaft 710.

That is, the guide unit 700 is not only a configuration for guiding the movement of the material 130 by simply coupling the rolling member 720 to the circumferential surface of the fixed shaft 710, the material 130 is each main The punches 411, 421, 431, 441 of the piercing parts 410, 420, 430, 440, or the pilot pins 301 block the upward movement of the material 130 when raised together with the pilot pins 301. It is configured to perform the function of the ejector to allow the smooth departure from 301).

In particular, the circumferential side portion of the cover member 730 is formed so as to surround a part of the upper end of the cloud member 720 as a gap that may occur in the laminated portion between the cover member 730 and the cloud member 720. It is configured to prevent the problem that the jamming phenomenon of the material 130 occurs in advance.

In this case, the rolling member 720 may be any one of a conventional bush, a roller, or a needle bearing.

Of course, the guide portion 700 as described above is not only provided in each of the main piercing portion (410, 420, 430, 440), but also more preferably installed in the side notching portion 200 and the main notching portion 500, which is attached to Figure 3 and same.

In the following, a battery grid manufacturing process using a mold apparatus according to an embodiment of the present invention described above will be described with reference to FIGS. 5 to 12.

First, the battery 130 manufacturing material 130 is conveyed by a feeder (not shown).

At this time, the material 130 is wound in a roll shape, and the conveyance is sequentially performed by the separation distance between components of the material 130 forming the mold apparatus by driving the feeder. You lose.

In addition, the material 130 sequentially conveyed as described above is provided to the site where the side notching part 200 and the pilot hole piercing part 300 are disposed through the material loading side of the mold apparatus.

In this state, notching of both sides of the material 130 is performed by the progress of the molding operation according to the downward movement of the upper mold 110, and a pilot hole 302 is formed at the center side of the material 130. Is formed. This is as shown in Figure 5 attached.

When the side notching and pilot hole piercing is completed, the upward movement of the upper mold 110 is performed and the feeder is operated, and the material 130 is transferred to the portion where the primary idle part 610 is disposed. .

In this case, a portion where the side notching and pilot hole piercing is not formed among the portions of the material 130 is located at the portion where the side notching portion 200 and the pilot hole piercing portion 300 are disposed.

Then, when the transfer of the material 130 is completed, the downward movement of the upper mold 110 is made, but no operation is performed in the primary idle part 610, and each part of the material 130 is simply performed. Side notching and pilot hole piercing is performed for the rear side portion in which side notching and pilot hole piercing are not made. This is as shown in Figure 6 attached.

In addition, when the work on the primary idle unit 610 is completed, the upward movement of the upper mold 110 is performed and the feeder is operated, and the material 130 is the primary main piercing unit 410. Is transported to the place where it is placed.

In this case, a portion where the side notching and pilot hole piercing is not formed among the portions of the material 130 is located at the portion where the side notching portion 200 and the pilot hole piercing portion 300 are disposed.

When the transfer of the material 130 is completed, the downward movement of the upper mold 110 is performed, and a first piercing process is performed in which a plurality of perforation holes 131 are formed in a specific portion of the material 130. .

In this case, the perforated holes 131 are formed to have a plurality of rows and columns, and are formed to be spaced apart from each other with a sufficient interval. This is as shown in Figure 7 attached.

Subsequently, when the primary piercing process is completed, the upward movement of the upper mold 110 is performed, and at the same time, the material 130 is transferred to the portion where the secondary main piercing unit 420 is disposed by driving the feeder. do.

When the transfer of the material 130 is completed, the second piercing process is performed in which a plurality of perforation holes 132 are formed in a specific portion of the material 130 while descending movement of the upper mold 110 is performed. .

In this case, the plurality of perforation holes 132 formed in the secondary piercing process are formed at different portions from the positions of the plurality of perforation holes 131 formed in the primary piercing process. For example, the plurality of perforation holes 132 formed in the secondary piercing process are formed between rows and rows of the plurality of perforation holes 131 formed in the primary piercing process. This is as shown in Figure 8 attached.

Subsequently, when the secondary piercing process is completed, the upward movement of the upper mold 110 is performed, and at the same time, the material 130 is transferred to the portion where the tertiary main piercing unit 430 is disposed by driving the feeder. do.

When the transfer of the material 130 is completed, the lowering movement of the upper mold 110 is performed, and the third piercing process of forming the plurality of perforation holes 133 in a specific portion of the material 130 is performed. .

In this case, the plurality of perforated holes 133 formed in the third piercing process are located in the plurality of perforated holes 131 formed in the first piercing process and the plurality of perforated holes 132 formed in the second piercing process. And are formed in different parts. For example, the plurality of perforation holes 133 formed in the third piercing process are formed between rows and rows formed by the plurality of perforation holes 131 formed in the first piercing process. This is the same as in FIG. 9.

Subsequently, when the tertiary piercing process is completed, the upward movement of the upper mold 110 is performed, and at the same time, the material 130 is transferred to the portion where the fourth main piercing unit 440 is disposed by driving the feeder. do.

When the transfer of the material 130 is completed, the fourth piercing process is performed in which a plurality of perforation holes 134 are formed in a specific portion of the material 130 while descending movement of the upper mold 110 is performed. .

In this case, the plurality of perforated holes 134 formed in the fourth piercing process are a plurality of perforated holes 131 formed in the first piercing process and a plurality of perforated holes 132 formed in the second piercing process and In the third piercing process, a plurality of perforated holes 133 formed at different positions are formed. For example, the plurality of perforation holes 134 formed in the fourth piercing process are formed between rows and rows formed by the plurality of perforation holes 132 formed in the second piercing process. This is the same as in FIG. 10.

As a result, as described above, the plurality of perforation holes 131, 132, 133, and 134 may be densely formed while the material 130 sequentially passes through the four main piercing parts 410, 420, 430, and 440.

In addition, when the above-described fourth piercing process is completed, the upward movement of the upper mold 110 is performed, and at the same time, the material 130 is provided to a portion where the secondary idle part 620 is disposed by driving the feeder. Subsequently, after the downward movement and the upward movement of the upper mold 110 are performed, the raw material 130 is provided to a portion where the main notching part 500 is disposed by driving the feeder.

Subsequently, removal of unnecessary portions of the material 130 is performed by the punch 510 constituting the main notching part 500 by the downward movement of the upper mold 110.

In this case, the unnecessary portion may be, for example, a portion excluding the lug (current collector) 135 portion of the central portion of the material 130.

As a result, while the above-described series of processes are sequentially and repeatedly made, the battery grid is continuously manufactured.

1 and 2 are a front sectional view showing a press mold apparatus for manufacturing a battery grid according to a preferred embodiment of the present invention.

3 is a plan view showing the lower mold of the press mold apparatus for manufacturing a battery grid according to a preferred embodiment of the present invention.

Figure 4 is a schematic state diagram showing the arrangement structure for the punch of the components of each part of the press mold apparatus for manufacturing a battery grid according to an embodiment of the present invention

5 to 12 are state diagrams shown for explaining a battery grid manufacturing process using a press mold apparatus for manufacturing a battery grid according to an embodiment of the present invention.

Explanation of symbols for main parts of the drawings

110. Upper mold 120. Lower mold

130. Material 131,132,133,134. Perforation Hall

135.Lug 200.Side notching

210. Side notch punch 300. Pilot hole piercing part

301. Pilot Pins 302. Pilot Holes

310. Punch for forming pilot hole 320. Through hole

410,420,430,440. Main piercing parts 411,421,431,441. punch

412,422,432,442. Punch plate 500. Main notch

510. Notching Punch 520. Punching Plate

610,620. Idle part 700.Guide part

710. Fixed shaft 720. Rolling member

730. Cover member

Claims (8)

A pilot-hole piercing part disposed on a work-loading side and forming a pilot hole for penetration of the pilot pin in the work received from the feeder; A plurality of main peircing parts which are sequentially disposed on the material ejecting side of the pilot hole piercing part and are provided such that a plurality of punches for forming a plurality of perforation holes are formed in a plurality of rows and rows; And, And a main notching part disposed on the material carrying side of each main piercing part and removing an unnecessary portion of the material. The method of claim 1, Each of the main piercing parts The rows and columns of punches provided in each of them are arranged so that the front, rear, and left and right positions are different from each other based on the entry direction of the material. Press mold apparatus for manufacturing a battery grid, characterized in that the sequential molding can be made by each. The method of claim 2, Each of the main piercing portion is composed of four, The rows and columns of the punches provided in any one of the four main piercing parts are oriented to the left rearward with respect to the entry direction of the material. The rows and columns of punches provided in the other main piercing part are located to the right rearward with respect to the entry direction of the material, Rows and columns of punches provided in another main piercing part are located to the left forward side with reference to the entry direction of the material, Rows and columns of punches provided in another main piercing part is positioned to be rightward forward when viewed based on the entry direction of the material. The method of claim 1, Each of the main piercing unit is a press mold device for manufacturing a battery grid, characterized in that it consists of a left and right double row based on the entry direction of the material. The method of claim 1, It is disposed on a portion provided with a pilot hole piercing portion that is a material import side, and further comprises a side notching part (notch) to remove the material provided from the feeder (feeder) by notching both sides of the material in accordance with a set width Press mold apparatus for manufacturing a battery grid, characterized in that the configuration. The method of claim 1, The outer side of the main piercing portion of the battery grid further comprises a plurality of guides for guiding the movement of the material and blocking the rise of the material with the punches or the pilot pin of each main piercing portion Press mold apparatus for manufacturing. The method of claim 6, Each guide part Fixed shaft, And rolling member installed on the circumferential surface of the fixed shaft and the rolling member for guiding the movement of the material, The press mold device for manufacturing a battery grid, characterized in that the cover member is fixed to the upper end of the fixed shaft formed to cover a portion of the upper end of the rolling member. 8. The method according to any one of claims 1 to 7, Pressing apparatus for manufacturing a battery grid, characterized in that the front part and the rear part of the main piercing part based on the entry direction of the material further comprises an idle part (idle part) for securing a clearance between each other .

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