Perforated plate conveying mechanism

Abstract

To provide a perforated panel conveying mechanism that can prevent a perforated panel from being deformed due to forward and backward movements of a conveying pin, by restricting the conveying pin from wobbling when moving the conveying pin up and down to and from a transparent hole formed in the perforated panel.SOLUTION: A hitch feeding mechanism 24, as a perforated panel conveying mechanism, is provided with: a reciprocating body 25 having a concave hole 25A formed on an upper surface thereof, which is arranged in a conveying direction of a metal belt-like body 81; a conveying pin 27 in which an energizing member 27C whose upper end part contacts an inner surface of an upper bottomed-part of an upper bottomed-cylindrical body and whose lower end part contacts the concave hole 25A is stored and which intrudes into a transparent hole 89 of the metal belt-like body 81; and an upper surface plate 28 mounted on an upper surface of the reciprocating body 25, which has an insertion hole 28A through which the conveying pin 27 is inserted. In the conveying pin 27, plane parts 27A are formed in a required range in a circumferential direction on a side peripheral surface thereof. A flange part 27B is formed at a lower end part of the plane part 27A. An opening part at a lower surface side of the insertion hole 28A is formed in a turning restriction hole, and the conveying pin 27 is retained by the flange part 27A.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a perforated plate body conveying mechanism.

Background Art

[0002] As a perforated plate body conveying mechanism for conveying a perforated plate body in which through holes are formed, there is a configuration disclosed in Patent Document 1 (Japanese Patent No. 5505911).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The perforated plate body conveying mechanism disclosed in Patent Document 1 intermittently conveys the perforated plate body by reciprocating a inserted conveying pin that is biased upward by a biasing member in the through holes formed in the perforated plate body in the conveying direction of the perforated plate body. The conveying pin that has conveyed the perforated plate body to a predetermined position returns in the direction opposite to the conveying direction while潜入 the conveying surface against the biasing force of the biasing member, thereby preventing deformation of the perforated plate body by the conveying pin. However, there is no disclosure regarding a configuration for restricting the rotation of the conveying pin around the horizontal plane, and there is a possibility that rotation (play during lifting and lowering) of the conveying pin around the horizontal plane may occur. Therefore, when play occurs during the lifting and lowering of the conveying pin in the conveyance of a perforated plate body with a thin plate thickness, there is a problem that the perforated plate body is deformed by the inertial force of the conveying pin.

Means for Solving the Problems

[0005] It should be noted that the part "潜入" in the original text seems to be an incorrect or unclear expression. I translated it as "潜入" as it is, but it might need to be further clarified in the original context.Therefore, the present invention aims to solve the above problems, and its objective is as follows: Specifically, it aims to provide a perforated plate conveying mechanism that can prevent deformation of the perforated plate due to the movement of the conveying pins, by restricting the rotation (wobble during upward and downward movement) of the conveying pins around the horizontal plane when the conveying pins move up and down to the through holes formed in the perforated plate.

[0006] In order to solve the above problems, the inventor diligently conducted research and arrived at the following configuration. That is, the present invention is a perforated plate conveying mechanism for conveying a perforated plate having a through hole formed therein, comprising: a reciprocating body that moves back and forth along the conveying direction of the perforated plate and has a recessed hole formed on its upper surface; an upper bottomed cylindrical body in which the upper end of a biasing member abuts against the inner surface of the upper bottomed portion of the upper bottomed cylindrical body, and the lower end of the biasing member abuts against the inner bottom surface of the recessed hole, and the conveying pin which is supported by the biasing member and is movable up and down and enters the through hole when raised; and an upper plate attached to the upper surface of the reciprocating body and having an insertion hole through which the conveying pin is inserted, wherein the conveying pin has a flat portion formed from the upper end to a required height range in the portion corresponding to the chord in the circumferential direction of the side surface, and a flange portion formed at the lower end of the flat portion by a portion without a flat portion, and the insertion hole This has a shape that restricts the rotation of the transport pin around the insertion hole, This perforated plate transport mechanism is characterized in that the transport pin is prevented from coming loose by the flange portion.

[0007] This restricts the rotation (wobble during vertical movement) of the transport pins in the perforated plate when they move up and down through holes formed in the perforated plate, thereby preventing deformation of the perforated plate due to the movement of the transport pins.

[0008] Furthermore, a perforated plate transport mechanism for transporting a perforated plate having through holes formed therein, comprising: a reciprocating body that moves back and forth along the transport direction of the perforated plate; a base attached to the upper surface of the reciprocating body and having a recessed hole formed on its upper surface; an upper bottomed cylindrical body, in which the biasing member is housed such that the upper end of the biasing member abuts against the inner surface of the upper bottomed portion of the upper bottomed cylindrical body and the lower end of the biasing member abuts against the inner bottom surface of the recessed hole, and supported by the biasing member, a transport pin that is movable up and down and enters the through hole when raised, and attached to the upper surface of the base There is also an invention of a perforated plate transport mechanism comprising: an upper plate attached to which an insertion hole for the transport pin is drilled; wherein the transport pin has a flat portion formed on the part corresponding to the chord in a required circumferential range on its side surface, extending from the upper end to a required height range, and a flange portion formed at the lower end of the flat portion by a portion not formed with a flat portion; and at least the opening on the lower side of the upper plate of the insertion hole is formed as a rotation restricting hole that restricts the rotation of the transport pin around the insertion hole, and the transport pin is prevented from coming out by the flange portion.

[0009] This restricts the rotation (wobble during vertical movement) of the conveying pins around the horizontal plane when they move up and down to the through-holes formed in the perforated plate, thereby preventing deformation of the perforated plate due to the movement of the conveying pins. Furthermore, the perforated plate conveying mechanism of the present invention can be modified simply by replacing a part of the existing perforated plate conveying mechanism. Moreover, the replacement of consumable parts such as the conveying pins and biasing members can be easily performed.

[0010] Furthermore, it is preferable that a bush is embedded in the upper opening of the insertion hole to allow the arc-shaped portion of the side circumferential surface of the transport pin to slide.

[0011] This allows the lifting and lowering motion of the transport pins to be smoother.

[0012] Furthermore, it is preferable that the planar portion is formed with the same dimensions at opposing positions on the side circumferential surface, and that the rotation restricting hole is racetrack shaped.

[0013] This makes it easier to machine the transport pins and rotation-restricting holes. [Effects of the Invention]

[0014] According to the configuration of the present invention, by restricting the rotation (wobble during vertical movement) of the conveying pins to the through holes formed in the perforated plate body around the horizontal plane during vertical movement, it is possible to prevent deformation of the perforated plate body due to the movement of the conveying pins. Furthermore, the perforated plate body conveying mechanism according to the present invention can be modified simply by replacing a part of the existing perforated plate body conveying mechanism. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic diagram of a heat exchange fin manufacturing apparatus having a perforated plate transport mechanism according to the present invention. [Figure 2] This is a plan view of the heat exchange fins. [Figure 3] This is a plan view showing a portion of a metal strip (perforated plate). [Figure 4] This is a plan view showing a portion of a perforated metal strip. [Figure 5] This is a plan view of a portion of the width of the product, which is a metal strip. [Figure 6] This is a plan view of the hitch feeding mechanism in the first embodiment. [Figure 7] This is a cross-sectional view along the line VII-VII in Figure 6. [Figure 8] This is a cross-sectional view along the line VIII-VIII in Figure 6. [Figure 9] (A) Plan view of the transport pin, (B) Front view of the transport pin, (C) Side view of the transport pin. [Figure 10] This is a diagram corresponding to Figure 7 of the hitch feeding mechanism in the second embodiment. [Figure 11] This is a diagram corresponding to Figure 8 of the hitch feeding mechanism in the second embodiment. [Figure 12] (A) A plan view and (B) A cross-sectional view along line BB in the plan view, showing a modified example of the insertion hole in the first embodiment. (C) A cross-sectional view along line CC in the plan view.

Best Mode for Carrying Out the Invention

[0016] FIG. 1 is a schematic configuration diagram of a fin manufacturing apparatus 100 for heat exchange having a perforated plate body conveying mechanism according to the present invention. The fin manufacturing apparatus 100 for heat exchange in the present embodiment includes an uncoiler 10, a press forming unit 20, a buffer unit 30, a perforation slit forming machine 40, a cutoff machine 50, a suction unit 60, a stack unit 70, and an operation control unit 200. The operation control unit 200 controls the operations of the uncoiler 10, the press forming unit 20, the perforation slit forming machine 40, the cutoff machine 50, and the suction unit 60. The operation control unit 200 can adopt a known configuration having an operation control program stored in a storage unit not shown and an arithmetic unit represented by a CPU that operates based on the operation control program.

[0017] The uncoiler 10 unwinds an aluminum sheet 80, which is a material for the fins 88 for heat exchange, from a coil 11 wound around a bobbin not shown, and a known configuration can be adopted. The press forming unit 20 has an oil supply unit 21, a press die 22, a press mechanism 23, and a hitch feed mechanism 24 as a perforated plate body conveying mechanism. The aluminum sheet 80 coated with processing oil by the oil supply unit 21 is processed into a metal strip 81 as a perforated plate body having a predetermined shape by the press die 22 that contacts and separates by the press mechanism 23. The metal strip 81 is intermittently sent out from the press forming unit 20 in synchronization with the operation of the press mechanism 23 by the hitch feed mechanism 24. The buffer unit 30 in the present embodiment is a space for allowing the metal strip 81 sent out from the press forming unit 20 to sag downward, and buffers the difference in the forming length and the cutting length per stroke by the press forming unit 20 and the cutoff machine 50 described later. The buffer unit 30 can also be configured by guiding means or the like for making the metal strip 81 have a predetermined sagging shape.

[0018] The perforation slit forming machine 40 has an upper rotating blade 41 and a lower rotating blade 42 that faces the upper rotating blade 41 at a position below the upper rotating blade 41 and clamps the metal strip 81. The perforation slit forming machine 40 forms perforation slits 90 to easily divide the metal strip 81, which is formed as a long body with multiple rows of heat exchange fins 88, the final product shown in Figure 2, in the width direction (a direction perpendicular to the same plane as the feeding direction), into product widths. Figure 3 is a plan view showing a part of the length of the metal strip 81. At least one perforation slit 90 is formed on the metal strip 81 in the product width direction, and cutting lines 91, which are cutting portions, and connecting portions 92, which are non-cutting portions, are formed at required intervals in the product length direction. The perforated metal strip 82 (see Figure 4), which has perforated slits 90 formed by the perforation slit forming machine 40, is intermittently fed in the length of the product by a conveying device 51 installed on the cutoff machine 50 and is held by suction on the suction surface 61 of a suction section 60 installed downstream of the cutoff machine 50. At this time, the length of the perforated metal strip 82 that protrudes from the cutoff blade 52 of the cutoff machine 50 is equal to the length of the product.

[0019] In this manner, the perforated metal strip 82 is cut to product length by the cut-off blade 52 while the product length portion at the tip is adsorbed to the suction surface 61. As shown in Figure 5, the product-length metal strip 83 cut to product length by the cut-off machine 50 has multiple heat exchange fins 88 connected by connecting parts 92 in the product width direction. Below the suction surface 61 in the suction section 60, a stack section 70 is provided, which has a stack base 72 on which a stack pin 71 is erected, aligned with the position of a through hole 89 for insertion formed in the product-length metal strip 83 while it is adsorbed and held by the suction surface 61. When the operation control unit 200 temporarily stops the suction device (not shown) of the suction section 60, the product-length metal strip 83 falls from the suction surface 61 and is stacked on the stack base 72 in the thickness direction with the stack pin 71 inserted through the through hole 89. When a predetermined number of product-length metal strips 83 are stacked in the stacking section 70, the stacking section 70 is transported to the next process by an operator or the like. Alternatively, a blank stacking section 70 is positioned in the suction section 60, and the above operations are repeated.

[0020] Next, a first embodiment of the hitch feeding mechanism 24 as a perforated plate transport mechanism in the present invention will be described in detail. In this embodiment, the hitch feeding mechanism 24 is arranged on the transport path of the metal strip 81 along the width direction of the metal strip 81, as shown in Figures 1 and 6 to 8. The hitch feeding mechanism 24 comprises a reciprocating body 25 that moves back and forth in the transport direction of the metal strip 81 and has a recessed hole 25A formed on its upper surface, a transport pin 27 that moves back and forth in a through hole 89 of the metal strip 81, and an upper plate 28 through which the transport pin 27 is inserted and has an insertion hole 28A formed therein.

[0021] The reciprocating body 25 intermittently transports the metal strip 81 in the transport direction by a so-called hitch operation, which involves reciprocating along the transport direction of the metal strip 81. Multiple recessed holes 25A are formed on the upper surface of the reciprocating body 25 for erecting (housing) the transport pins 27. Since a known configuration can be used for such a reciprocating body 25, a detailed explanation is omitted here.

[0022] As shown in Figure 9, the transport pin 27 is formed as an upper bottomed cylindrical body. On the side surface of the transport pin 27, a flat portion 27A is formed in the portion corresponding to two chords that are in opposing positions within a required range in the circumferential direction, extending from the upper end of the transport pin 27 to a required height range, and a flange portion 27B is formed at the lower end of the flat portion 27A by a portion where the flat portion is not formed. A biasing member 27C is housed in the internal space of the transport pin 27. The upper end of the biasing member 27C abuts against the inner surface of the upper bottomed portion (ceiling portion) of the transport pin 27, and the lower end abuts against the inner bottom surface of the recessed hole 25A of the reciprocating moving body 25. Furthermore, in this embodiment, it is preferable that the upper end surface 27D of the transport pin 27 is formed as an inclined surface that gradually decreases as it approaches the upstream side in the transport direction of the metal strip 81, as shown in Figure 9.

[0023] The through-hole 28A formed in the top plate 28 is for inserting the transport pin 27. The top plate 28 is fixed to the upper surface of the reciprocating body 25 by a known method with the transport pin 27, which is erected together with the biasing member 27C in the recessed hole 25A of the reciprocating body 25, inserted through the through-hole 28A. In this embodiment, the plan view shape of the through-hole 28A is formed in the shape of a racetrack, which is the cross-sectional shape of the portion where the planar portion 27A of the transport pin 27 is formed. As shown in Figures 6 to 8, the inner periphery of the insertion-hole 28A in this embodiment abuts the side surface of the transport pin 27, but it is not limited to this form. The inner periphery of the insertion-hole 28A can also be formed to be outside the side surface of the upper end of the transport pin 27 and inside the flange portion 27B. The top plate 28 prevents the transport pin 27 from coming out of the top plate 28, restricting the rotation (wobble) of the transport pin 27 around the horizontal plane (around the insertion hole) and guiding the upward and downward movement of the transport pin 27.

[0024] Furthermore, since the flange portion 27B, which serves as a retaining portion for the transport pin 27, is formed by the flat portion 27A, which is a so-called D-cut, the transport pin 27 can be made smaller and lighter, and consequently the biasing force of the biasing member 27C housed in the transport pin 27 can also be weakened. This is advantageous because it can significantly reduce damage to the metal strip 81 caused by inertial force and biasing force during the lifting and lowering operation of the transport pin 27.

[0025] As described above, the hitch feeding mechanism 24 in this embodiment restricts the rotation (wobble) of the transport pin 27 around the horizontal plane when it is raised or lowered, so that the transport pin 27 can always enter and exit the through-hole 89 of the metal strip 81 in the same orientation. Therefore, it is advantageous that damage to the metal strip 81 (especially the part with the through-hole 89) by the transport pin 27 can be prevented, which improves the product yield. It is also advantageous that the hitch feeding mechanism 24 of the present invention can be modified by replacing only the transport pin 27 and the top plate 28 of an existing hitch feeding mechanism 24.

[0026] Next, the hitch feeding mechanism 324 in the second embodiment will be described with reference to Figures 10 and 11. The hitch feeding mechanism 324 in this embodiment comprises a reciprocating body 325 that moves back and forth in the conveying direction of the metal strip 81, a conveying pin 327, a base 328 attached to the upper surface of the reciprocating body 325, and an upper plate 329 attached to the upper surface of the base 328.

[0027] In this embodiment, the reciprocating body 325 is formed in a known shape such as a block, plate, or frame. Similar to the first embodiment, this reciprocating body 325 reciprocates along the conveying direction of the metal strip 81.

[0028] The transport pin 327 performs a vertical movement, entering and exiting the through-hole 89 of the metal strip 81, due to the reciprocating motion of the reciprocating body 325 and the biasing force of the biasing member 327C housed in the internal space of the transport pin 327. In this embodiment, the transport pin 327 can be formed in the same shape as the first embodiment. That is, it has two flat portions 327A and two flange portions 327B, and the biasing member 327C is housed in the internal space.

[0029] In this embodiment, the upper surface of the base 328 has multiple recessed holes 328A that can accommodate the flange portion 327B of the transport pin 327. An upper plate 329 is attached to the upper surface of the base 328, having through holes 329A drilled to align with the planar position of the recessed holes 328A. In this embodiment, the through holes 329A are formed as circular holes 329B in the required depth range on the upper side of the upper plate 329, and as racetrack-shaped rotation restricting holes 329C in the required depth range on the lower side of the upper plate 329 (lower side opening). Furthermore, according to this embodiment, the biasing member 327C of the transport pin 327 can be easily replaced, and the manufacturing efficiency of the heat exchange fins 88 is improved.

[0030] By employing the through-hole 329A in this embodiment, a bush B1 that slides the arc-shaped portion of the transport pin 327 can be housed in the circular hole 329B, which is the upper opening of the top plate 329, thereby enabling smooth up and down movement of the transport pin 327. Furthermore, since the lower opening of the top plate 329 is formed as a rotation restricting hole 329C, the rotation of the transport pin 327, which is erected together with the biasing member 327C in the recessed hole 328A of the base 328, around the through-hole can be restricted. This combination of the base 328 and top plate 329 is advantageous in that it prevents damage to the metal strip 81 during transport due to the up and down movement of the transport pin 327.

[0031] Furthermore, by reducing the thickness of the top plate 28 in the first embodiment and the base portion 328 and top plate 329 in the second embodiment, the height dimension of the transport pin 27(327) can be reduced. In addition, the miniaturization and weight reduction of the transport pin 27(327) can significantly reduce the inertial force of the transport pin 27(327), and furthermore, the biasing force by the biasing member 27C(327C) can be weakened in conjunction with the miniaturization and weight reduction of the transport pin 27(327). This is advantageous in that it is possible to significantly reduce damage to the metal strip 81 (especially the through-hole 89) when the transport pin 27(327) enters and exits the through-hole 89 of the metal strip 81.

[0032] In the first embodiment, the through-hole 28A drilled in the top plate 28 is shown as having the same cross-sectional shape in the depth direction, but the embodiment is not limited to this form. As shown in Figure 12, the shape of the through-hole 28A can also be such that the required depth range 28X on the upper side of the top plate 28 is a circular hole in plan view, and the required depth range 28Y on the lower side of the top plate 28 is a racetrack-shaped hole in plan view to restrict the rotation of the transport pin (not shown in Figure 12). When this form is adopted, the bush B1 is housed in the required depth range 28X on the upper side of the top plate 28 of the through-hole 28A, which improves the sliding properties of the arc-shaped portion of the transport pin 27 and is advantageous in that it allows for smoother vertical movement of the transport pin 27.

[0033] Furthermore, while the second embodiment illustrates a configuration in which the bush B1 is housed in an insertion hole 329A drilled in the top plate 329, the present invention is not limited to this configuration. The insertion hole 329A of the top plate 329 is formed with the same cross-sectional shape in the depth direction, similar to the insertion hole 28A in the first embodiment, and a configuration in which the bush B1 is omitted can also be adopted.

[0034] Furthermore, in the above embodiments, the plan view shapes of the transport pin 27(327) and the insertion hole 28A(329A) are exemplified as being formed in a racetrack shape, but the embodiment is not limited to this form. It is also possible to adopt an embodiment in which a flat portion 27A(327A) is formed in only one or three or more locations within the required circumferential range on the side surface of the transport pin 27(327). The plan view shape of the insertion hole 28A(329A) can be a shape that matches the plan view shape of the transport pin 27(327), or a plan view shape that allows the rotation of the transport pin 27(327) around the hole of the insertion hole 28A(329A) to be restricted by utilizing the flat portion 27A(127A).

[0035] Furthermore, while this embodiment illustrates a configuration in which a perforation slit forming machine 40 is positioned between the press forming section 20 and the cut-off machine 50, the apparatus is not limited to this configuration. A configuration in which an inter-row slitting device is positioned instead of the perforation slit forming machine 40 can also be adopted. Since the configuration of the inter-row slitting device is well known, a detailed explanation is omitted here.

[0036] In addition to the modifications described above, it is also possible to adopt forms that appropriately combine the modifications described in the embodiments. [Explanation of symbols]

[0037] 10: Ancoira 11: Coil 20: Press molding section 21: Lubrication section, 22: Press die, 23: Press mechanism, 24: Hitch feed mechanism, 25: Reciprocating moving body, 25A: Recessed hole, 27: Conveyor pin, 27A: Flat surface, 27B: Flange portion, 27C: Biasing member, 27D: Upper end surface, 28: Top plate, 28A: Through hole, 28X: Required depth range on the upper side, 28Y: Required depth range on the lower side 30: Buffer section 40: Perforation slit forming machine 41: Upper rotating blade, 42: Lower rotating blade 50: Cut-off machine 51: Conveying device, 52: Cut-off blade 60: Suction section 61: Adsorption surface 70: Stack section 71: Stacking pin, 72: Stacking base 80: Aluminum sheet 81: Metal strip, 82: Perforated metal strip, 83: Product length metal strip 88: Heat exchange fins, 89: Through holes 90: Perforated slit 91: Cutting line, 92: Connecting part 100: Heat exchange fin manufacturing equipment 200: Operation Control Unit 324: Hitch feed mechanism, 325: Reciprocating body, 327: Conveyor pin, 327A: Flat part, 327B: Flange part, 327C: Biasing member, 328: Base part, 328A: Recessed hole, 329: Top plate, 329A: Through hole, 329B: Circular hole, 329C: Rotation restricting hole B1: Bush

Claims

1. A perforated plate transport mechanism for transporting perforated plates with through holes formed therein, A reciprocating body moves back and forth along the transport direction of the perforated plate body, and has a recessed hole formed on its upper surface, An upper bottomed cylindrical body, wherein the biasing member is housed such that the upper end of the biasing member abuts against the inner surface of the upper bottomed portion of the upper bottomed cylindrical body, and the lower end of the biasing member abuts against the inner bottom surface of the recessed hole, and is supported by the biasing member, and is vertically movable, and enters the through hole when raised, The system comprises an upper plate attached to the upper surface of the reciprocating body, and having an insertion hole through which the transport pin is inserted, The transport pin has a flat portion formed on the side surface in a required area in the circumferential direction corresponding to the chord, extending from the upper end to a required height range, and a flange portion is formed at the lower end of the flat portion by a portion without a flat portion. The perforated plate conveying mechanism is characterized in that the insertion hole is shaped to restrict the rotation of the conveying pin around the insertion hole, and the conveying pin is prevented from coming out by the flange portion.

2. A perforated plate transport mechanism for transporting perforated plates with through holes formed therein, A reciprocating body that moves back and forth along the transport direction of the perforated plate body, A base attached to the upper surface of the reciprocating body, with a recessed hole formed on its upper surface, An upper bottomed cylindrical body, wherein the biasing member is housed such that the upper end of the biasing member abuts against the inner surface of the upper bottomed portion of the upper bottomed cylindrical body, and the lower end of the biasing member abuts against the inner bottom surface of the recessed hole, and is supported by the biasing member, and is vertically movable, and enters the through hole when raised, The system comprises an upper plate attached to the upper surface of the base, through which the transport pin is inserted, and an insertion hole for the transport pin is drilled. The transport pin has a flat portion formed on the side surface in a required area in the circumferential direction corresponding to the chord, extending from the upper end to a required height range, and a flange portion is formed at the lower end of the flat portion by a portion without a flat portion. A perforated plate conveying mechanism characterized in that at least the opening on the lower side of the upper plate of the insertion hole is formed as a rotation restricting hole that restricts the rotation of the conveying pin around the insertion hole, and the conveying pin is prevented from coming out by the flange portion.

3. The perforated plate conveying mechanism according to claim 1 or 2, characterized in that a bush is embedded in the upper opening of the insertion hole, which slides the arc-shaped portion of the side circumferential surface of the conveying pin.

4. The perforated plate transport mechanism according to claim 2, characterized in that the planar portion is formed with the same dimensions at opposing positions on the side circumferential surface, and the rotation restricting hole is racetrack shaped.

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