Automatic film pressing equipment

Abstract

The utility model relates to the technical field of carbon fiber product manufacturing, in particular to automatic film pressing equipment which comprises an annular conveying track, a film pressing device and a film pressing device. The loading and unloading track is connected with the annular conveying track; the hot press unit comprises a plurality of hot presses; the cold press unit comprises a plurality of cold presses; the material taking and placing mechanisms are arranged between the hot pressing unit and the annular conveying rail and between the cold pressing unit and the annular conveying rail correspondingly, and each material taking and placing mechanism comprises a first linear guide rail and a conveying assembly. The conveying assembly is installed at the output end of the first linear guide rail and used for conveying the molds on the annular conveying rail into the hot presses or the cold presses, and the first linear guide rail is used for driving the conveying assembly to move from the position of one hot press or the position of the next hot press or the position of the next cold press. According to the feeding mechanism, feeding can be conducted on the multiple hot presses through the single feeding mechanism, and the manufacturing cost is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of carbon fiber product manufacturing, and in particular to an automatic film pressing device. Background Art

[0002] Carbon fiber is a material with excellent performance and is widely used in the fields of aircraft, aerospace equipment, sporting goods and industrial equipment parts. In the process of manufacturing carbon fiber products, multiple layers of carbon fiber materials are usually stacked and formed. In the process of manufacturing carbon fiber products, there are a series of processes such as prepreg preparation, lamination, molding, curing, and post-processing. In the molding process, molding equipment is usually used to hot press the laminated carbon fiber material. At present, the molding equipment usually includes multiple hot presses, a transmission track and multiple feeding mechanisms. The multiple feeding mechanisms are set in a one-to-one correspondence with the multiple hot presses. When in use, the carbon fiber material after lamination is placed in the mold, and the mold is transferred to the hot press position through the transmission track. The mold is transported to the hot press through the feeding mechanism for hot pressing to complete the molding process.

[0003] When the number of hot presses is large, the number of feeding mechanisms is also large, which leads to a problem of high production cost. Utility Model Content

[0004] The purpose of this application is to provide an automatic film pressing device that can load multiple hot presses through a single loading mechanism, thereby reducing production costs.

[0005] The automatic lamination equipment provided in this application adopts the following technical solution:

[0006] An automatic film pressing device, comprising:

[0007] Circular conveyor track;

[0008] A loading and unloading track connected to the annular conveying track for conveying the mold onto the annular conveying track;

[0009] A hot pressing unit, comprising a plurality of hot pressing machines, wherein the plurality of hot pressing machines are all located on one side of the annular conveying track;

[0010] A cold press unit, comprising a plurality of cold presses, wherein the plurality of cold presses are all located on one side of the annular conveying track;

[0011] A material picking and unloading mechanism is provided between the hot press unit and the annular conveying track, and between the cold press unit and the annular conveying track. The material picking and unloading mechanism includes a first linear guide rail and a transmission component. The transmission component is installed at the output end of the first linear guide rail and is used to transport the mold on the annular conveying track into the hot press or the cold press. The first linear guide rail is used to drive the transmission component to move from one hot press or the cold press position to the next hot press or the cold press position.

[0012] Optionally, the transmission component includes:

[0013] A frame fixedly connected to the output end of the first linear guide rail;

[0014] A second linear guide rail is fixedly connected to the side wall of the frame and arranged along the Z-axis direction;

[0015] A third linear guide rail, fixedly connected to the output end of the second linear guide rail and arranged along the Y axis;

[0016] A driving frame, fixedly connected to the output end of the third linear guide rail;

[0017] A clamping claw, fixedly connected to the driving frame and used for clamping the mold;

[0018] A fourth linear guide rail, fixedly connected to the side wall of the frame and arranged along the Z-axis direction;

[0019] The supporting frame is fixedly connected to the output end of the fourth linear guide rail and is used to support the mold.

[0020] Optionally, the supporting frame includes a first mounting rod, a second mounting rod and rollers, the first mounting rod and the second mounting rod are symmetrically arranged and fixedly mounted on the frame, and a plurality of rollers are installed on the first mounting rod and the second mounting rod.

[0021] Optionally, a plurality of the carriers are arranged at intervals along the Z-axis direction, and the plurality of the carriers are fixedly connected to the output end of the third linear guide rail.

[0022] Optionally, a limit assembly is also included, which includes a mounting plate, a clamping plate and an elastic member. The first mounting rod and the second mounting rod are fixedly connected to one mounting plate on one side away from each other, and each mounting plate is slidably connected to one clamping plate. The two clamping plates can slide toward or away from each other, and the elastic member is arranged between each clamping plate and the mounting plate, and one end of the elastic member acts on the clamping plate and the other end acts on the mounting plate.

[0023] Optionally, an inclined surface is provided at one end of the clamping plate close to the annular conveying track.

[0024] Optionally, a baffle is fixedly connected to the top of each mounting plate.

[0025] Optionally, also include:

[0026] A pre-pressing mechanism is provided corresponding to each loading and unloading track position. The pre-pressing mechanism includes a telescopic member, an upper top plate, a lower top plate and a machine platform. A pre-pressing cavity for pre-pressing is provided on the machine platform. The lower top plate is fixedly connected to the bottom wall of the pre-pressing cavity. The telescopic member is fixed to the top wall of the pre-pressing cavity and is arranged downward. The upper top plate is fixedly connected to the output end of the telescopic member.

[0027] A positive pressure pipe, fixedly connected to the machine platform and used to provide positive pressure air;

[0028] The negative pressure pipe is fixedly connected to the machine platform and is used to provide negative pressure air.

[0029] The present application drives the frame to slide through the first track, so that one transmission component can correspond to multiple hot presses at the same time, and one transmission component can transport multiple molds to different hot presses in turn, thereby reducing production costs, and by arranging a clamping plate on the carrier, the two clamping plates clamp the mold, thereby reducing the sliding of the mold on the carrier during the movement of the frame, and increasing the stability of the mold during the transmission process. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the overall structure of an automatic film pressing device in an embodiment of the present application.

[0031] Figure 2 It is a structural diagram of the pre-pressing mechanism in an embodiment of the present application.

[0032] Figure 3 yes Figure 1 A partial enlarged schematic diagram of part A.

[0033] Figure 4 This is a structural diagram of an embodiment of the present application in which a transmission component hides a limiting component.

[0034] Figure 5 It is a structural diagram of the limiting component of an embodiment of the present application.

[0035] In the figure, 1, annular conveyor track; 11, frame; 12, roller; 121, first roller; 122, second roller; 13, reversing assembly; 131, mounting frame; 132, reversing wheel; 2, loading and unloading track; 3, hot press unit; 31, hot press; 4, cold press unit; 41, cold press; 5, material loading and unloading mechanism; 51, first linear guide; 52, transmission assembly; 521, frame; 522, second linear guide; 523, third linear guide; 524, Drive frame; 525, clamping claw; 526, fourth linear guide rail; 527, supporting frame; 5271, first mounting rod; 5272, second mounting rod; 5273, roller; 6, limit assembly; 61, mounting plate; 611, sliding hole; 62, clamping plate; 621, inclined plane; 63, elastic member; 64, baffle; 7, preloading mechanism; 71, telescopic member; 72, upper top plate; 73, lower top plate; 74, machine table; 741, preloading cavity; 8, positive pressure tube; 9, negative pressure tube. DETAILED DESCRIPTION

[0036] The following is combined with Figure 1 -Attached Figure 5 , further details of this application are given.

[0037] An automatic laminating device, referring to Figure 1 , including a circular conveying track 1, a loading and unloading track 2, a hot pressing unit 3, a cold pressing unit 4 and a material taking and unloading mechanism 5. There are several loading and unloading tracks 2. Several loading and unloading tracks 2 are connected to one side of the circular conveying track 1 for conveying the mold to the circular conveying track 1. The hot pressing unit 3 and the cold pressing unit 4 are both arranged on the other side of the circular conveying track 1. The above-mentioned material taking and unloading mechanism 5 is set between the hot pressing unit 3 and the circular conveying track 1, and between the cold pressing unit 4 and the circular conveying track 1.

[0038] When lamination is required, the multi-layer carbon fiber material to be pressed is first placed in the mold, and the mold is placed on the loading and unloading track 2. The mold is transported to the circular conveying track 1 through the loading and unloading track 2. When the mold is transported to the vicinity of the hot pressing unit 3, the material picking and unloading mechanism 5 corresponding to the hot pressing unit 3 transports the mold to the hot pressing unit 3 for hot pressing treatment. The mold after the hot pressing treatment is completed is placed back on the circular conveying track 1 through the material picking and unloading mechanism 5, and is transported to the vicinity of the cold pressing unit 4 through the circular conveying track 1.

[0039] The picking and unloading mechanism 5 corresponding to the cold pressing unit 4 transports the hot-pressed mold to the cold pressing unit 4 for cold pressing treatment. The mold that has completed the cold pressing treatment is placed back in the annular conveying track 1 through the picking and unloading mechanism 5, and is transported to the loading and unloading track 2 through the annular conveying track 1, and the mold is unloaded on the loading and unloading track 2.

[0040] The annular conveyor track 1 comprises a frame 11, rollers 12, and a reversing assembly 13. The frame 11 is annular, and a plurality of rollers 12 are evenly spaced around the circumference of the frame 11 and rotatably connected to the frame 11. A reversing assembly 13 is provided at each corner of the frame 11, and the rollers 12 are driven by a motor. In other embodiments, a gear set or other transmission assembly can be provided to enable a single motor to drive multiple rollers 12, thereby reducing the number of motors and achieving cost savings.

[0041] Reference Figure 2 Furthermore, an automatic film pressing device also includes a pre-pressing mechanism 7, which pre-presses the mold before placing it on the loading and unloading track 2. The pre-pressed mold is transported to the loading and unloading track 2 by a robot (not shown in the figure).

[0042] Specifically, a cavity is provided in the mold, and an air bag is provided in the cavity. The product to be formed is placed between the air bag and the inner wall of the cavity. A positive pressure tube 8 and a negative pressure tube 9 are provided on the pre-pressing mechanism 7. The positive pressure tube 8 is connected to the air bag, and the negative pressure tube 9 is connected to the cavity. During the pre-pressing process, the positive pressure tube 8 ventilates the air bag to make the air bag bulge, thereby avoiding wrinkles on the inner wall of the product; the negative pressure tube 9 vacuums the cavity to avoid bubbles and air holes in the product.

[0043] The pre-pressing mechanism 7 includes a telescopic member 71, an upper top plate 72, a lower top plate 73, and a machine platform 74. The positive pressure tube 8 and the negative pressure tube 9 are both fixed to the machine platform 74. A pre-pressing cavity 741 for pre-pressing is provided on the machine platform 74. The lower top plate 73 is fixed to the bottom wall of the pre-pressing cavity 741. The telescopic member 71 is fixed to the top wall of the pre-pressing cavity 741 and is arranged downward. The upper top plate 72 is fixedly connected to the output end of the telescopic member 71. The telescopic member 71 drives the upper top plate 72 to move closer to the lower top plate 73, so that the upper top plate 72 and the lower top plate 73 pre-press the mold. In this embodiment, the telescopic member 71 adopts a telescopic oil cylinder.

[0044] By pre-pressing, vacuuming and inflating, and setting a pressure gauge to detect the pressure inside the mold, the mold's sealing can be tested. If the pressure gauge value is within the predetermined range, it proves that the mold is not leaking. If the pressure gauge value is outside the predetermined range, it proves that there is a leak.

[0045] Reference Figure 3 The reversing assembly 13 includes an electric telescopic rod (not shown in the figure), a mounting frame 131 and a reversing wheel 132. The reversing wheel 132 is fixedly mounted on the mounting frame 131 and is rotated by a motor. The electric telescopic rod is fixedly connected to the frame body 11 and the output end of the electric telescopic rod is fixedly connected to the mounting frame 131.

[0046] Taking one corner of the frame 11 as an example, the structures of the remaining corners are the same as this corner.

[0047] The axes of the rollers 12 arranged at intervals along the Y-axis direction are named first rollers 121, and the axes of the rollers 12 arranged at intervals along the X-axis direction are named second rollers 122. The reversing assembly 13 is arranged below the first roller 121, and the reversing wheel 132 is located between adjacent first rollers 121, and the axis of the reversing wheel 132 is perpendicular to the axis of the first roller 121. When the mold is transported to the top of the reversing assembly 13, the electric telescopic rod extends, so that the reversing wheel 132 is inserted into the gap between the adjacent first rollers 121, and the top of the reversing wheel 132 is higher than the first roller 121. At this time, the reversing wheel 132 is driven to drive the mold from the first roller 121 to the second roller 122, thereby realizing the change of the mold movement direction.

[0048] The above-mentioned reversing assembly 13 is provided at the connection between each loading and unloading track 2 and the frame 11, so as to realize the movement of the mold from the annular conveying track 1 to the loading and unloading track 2.

[0049] Reference Figure 1 The hot pressing group 3 is composed of multiple hot pressing groups 3, and the cold pressing group 4 is composed of multiple cold pressing groups 4. In this embodiment, the number of hot presses 31 is greater than the number of cold presses 41. Since the hot pressing time is higher than the cold pressing time, the number of hot presses 31 is greater than the number of cold presses 41 to achieve reasonable operation.

[0050] The following takes the material taking and unloading mechanism 5 between the hot pressing unit 3 and the circular track as an example to introduce the structure of the material taking and unloading mechanism 5. The structure of the material taking and unloading mechanism 5 between the cold pressing unit 4 and the circular track is consistent with that of the material taking and unloading mechanism 5 between the hot pressing unit 3 and the circular track, and no unnecessary details are given in this embodiment.

[0051] Reference Figure 1 and Figure 4 The material taking and unloading mechanism 5 includes a first linear guide rail 51 and a transmission assembly 52. The first linear guide rail 51 is fixedly set on the ground and is located between the hot press unit 3 and the circular track. The transmission assembly 52 is fixedly connected to the output end of the first linear guide rail 51. The transmission assembly 52 is driven to move by the first linear guide rail 51 so that the transmission assembly 52 corresponds to the position of each hot press 31 in turn, thereby enabling the transmission assembly 52 to transport the mold on the circular conveyor track 1 to the hot press 31. In other embodiments, in order to ensure the stable operation of the transmission assembly 52, a guide frame can be set on the top of the transmission assembly 52. The top of the transmission assembly 52 is slidably connected to the guide frame, and the guide frame is fixed to the ground or wall. The setting of the guide frame increases the sliding stability of the transmission assembly 52.

[0052] The transmission assembly 52 includes a frame 521, a second linear guide 522, a third linear guide 523, a drive frame 524, a clamp 525, a fourth linear guide 526, and a carrier frame 527. The frame 521 is fixedly connected to the output end of the first linear guide 51, the second linear guide 522 is fixedly connected to the side wall of the frame 521 and is arranged along the Z-axis, the third linear guide 523 is fixedly connected to the output end of the second linear guide 522 and is arranged along the Y-axis, the drive frame 524 is fixedly connected to the output end of the third linear guide 523, and the clamp 525 is fixedly connected to the side of the drive frame 524 away from the annular conveyor track 1. In this embodiment, the clamp 525 is an electric clamp 525.

[0053] When the circular conveyor track 1 transports the mold to the vicinity of the transmission component 52, the third linear guide rail 523 drives the driving frame 524 to move to the end of the mold away from the frame 521, and then drives the third linear guide rail 523 downward through the second linear guide rail 522, so that the side wall of the lower end of the driving frame 524 abuts against the side wall of the mold away from the frame 521, and then drives the supporting frame 527 to move through the fourth linear guide rail 526, so that the position of the supporting frame 527 corresponds to the position of the mold, and finally drives the driving frame 524 to move by the third linear guide rail 523, so that the driving frame 524 pushes the mold to move onto the supporting frame 527, so that the mold moves from the circular conveyor track 1 to the supporting frame 527, and then The frame 521 is driven to move to the position of the hot press 31 by the first linear guide 51, and the carrier frame 527 is driven to move to the position corresponding to the cavity of the hot press 31 by the fourth linear guide 526. The position of the driving frame 524 is adjusted by the operation of the second linear guide 522 so that the clamping jaws 525 correspond to the position of the mold. The driving frame 524 is driven to move toward the direction close to the hot press 31 by the operation of the third linear guide 523, so that the clamping jaws 525 push the mold into the cavity of the hot press 31, thereby hot pressing the mold. At this time, the first linear guide 51 drives the transmission component 52 to reset, and through the above steps, the next mold is moved to the cavity of the next hot press 31 for hot pressing.

[0054] After the hot pressing is completed, the driving frame 524 is driven to move to the predetermined position through the operation of the first linear guide 51, the second linear guide 522, and the third linear guide 523, so that the clamping jaws 525 correspond to the position of the mold in the hot press cavity 31 after hot pressing. The fourth linear guide 526 is operated to drive the supporting frame 527 to move to the position corresponding to the position of the hot press cavity 31. At this time, the mold is clamped out of the hot press cavity 31 and placed in the supporting frame 527 through the cooperation of the third linear guide 523 and the clamping jaws 525. On the carrier 527, the fourth linear guide rail 526 is operated to drive the carrier 527 to move to the position corresponding to the circular conveyor track 1, and then the mold is moved to the circular conveyor track 1 through the driving frame 524 and the clamp 525, and is transported to the position of the cold press 41 through the circular conveyor track 1. Through the material taking and unloading mechanism 5 corresponding to the cold press 41, the hot-pressed mold is transported into the cavity of the cold press 41 for cold pressing, and the cold-pressed mold is placed on the circular conveyor track 1.

[0055] Furthermore, a number of carriers 527 are evenly spaced along the Z-axis direction, and the carriers 527 are all fixedly connected to the output end of the third linear guide 523. Each carrier 527 can hold a mold, so the transmission assembly 52 can transport multiple molds at a time to increase efficiency. Correspondingly, multiple cavities are set in the hot press 31 and the cold press 41, so that the hot press 31 and the cold press 41 can perform hot pressing or cold pressing on multiple molds at a time. Correspondingly, a plurality of clamps 525 are provided, and the plurality of clamps 525 are arranged along the Z-axis direction and are all fixedly connected to the drive frame 524. The plurality of clamps 525 can correspond to the positions of the plurality of carriers 527, so that multiple molds can be pushed into the corresponding cavities at one time.

[0056] The supporting frame 527 includes a first mounting rod 5271, a second mounting rod 5272 and a roller 5273. The first mounting rod 5271 and the second mounting rod 5272 are symmetrically arranged and fixedly mounted on the frame 521. The first mounting rod 5271 and the second mounting rod 5272 are both fixedly mounted with a plurality of the above-mentioned rollers 5273 along the Y-axis direction. After being pushed by the driving frame 524, the mold slides onto the rollers 5273. The two sides of the mold are respectively supported by the rollers 5273 on the first mounting rod 5271 and the rollers 5273 on the second mounting rod 5272. Through the arrangement of the rollers 5273, the friction force on the mold during sliding is reduced, thereby reducing the difficulty of sliding the mold.

[0057] Reference Figure 5The automatic die pressing device also includes a limit assembly 6, which is used to limit the movement of the mold on the carrier 527. The limit assembly 6 includes a mounting plate 61, a clamping plate 62, and an elastic member 63. The first mounting rod 5271 and the second mounting rod 5272 are fixedly connected to the mounting plate 61 on their sides facing away from each other. The mounting plate 61 has a sliding hole 611 along the X-axis direction. The clamping plate 62 is slidably arranged in the sliding hole 611. The elastic member 63 is arranged between the clamping plate 62 and the mounting plate 61. One end of the elastic member 63 acts on the mounting plate 61, and the other end acts on the clamping plate 62. In this embodiment, the elastic member 63 is a spring, and its two ends are fixedly connected to the clamping plate 62 and the mounting plate 61 respectively. The two clamping plates 62 clamp the mold, reducing the sliding of the clamp on the carrier 527 during the movement of the frame 521.

[0058] Furthermore, a slope 621 is provided at one end of the clamping plate 62 close to the annular conveying track 1. After the mold is pushed onto the roller 5273, the mold abuts against the slope 621, and the clamping plate 62 slides away from the mold under the guidance of the slope 621, thereby achieving the two clamping plates 62 clamping the mold.

[0059] Furthermore, a baffle 64 is fixedly connected to the top surface of each mounting plate 61. The baffle 64 limits the movement of the mold in the Z-axis direction, thereby further ensuring the operational stability of the mold.

[0060] The examples of this specific embodiment are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, any equivalent changes made based on the structure, shape, and principle of this application should be included in the scope of protection of this application.

Claims

1. An automatic film pressing device, characterized in that: include: Annular conveying track (1); A loading and unloading track (2) connected to the annular conveying track (1) for conveying the mold onto the annular conveying track (1); A hot press unit (3), comprising a plurality of hot presses (31), wherein the plurality of hot presses (31) are all located on one side of the annular conveying track (1); A cold press unit (4), comprising a plurality of cold presses (41), wherein the plurality of cold presses (41) are all located on one side of the annular conveying track (1); A material taking and discharging mechanism (5) is provided between the hot press unit (3) and the annular conveying track (1), and between the cold press unit (4) and the annular conveying track (1). The material taking and discharging mechanism (5) comprises a first linear guide rail (51) and a transmission component (52). The transmission component (52) is installed at the output end of the first linear guide rail (51) and is used to transport the mold on the annular conveying track (1) into the hot press (31) or the cold press (41). The first linear guide rail (51) is used to drive the transmission component to move from one hot press (31) or the cold press (41) position to the next hot press (31) or the cold press (41) position.

2. The automatic lamination device according to claim 1, characterized in that: The transmission component (52) includes: A frame (521) is fixedly connected to the output end of the first linear guide rail (51); A second linear guide rail (522) is fixedly connected to the side wall of the frame (521) and is arranged along the Z-axis direction; A third linear guide rail (523) is fixedly connected to the output end of the second linear guide rail (522) and is arranged along the Y axis; A driving frame (524) is fixedly connected to the output end of the third linear guide rail (523); A clamping claw (525) is fixedly connected to the driving frame (524) and is used for clamping the mold; a fourth linear guide rail (526) fixedly connected to the side wall of the frame (521) and arranged along the Z-axis direction; The supporting frame (527) is fixedly connected to the output end of the fourth linear guide rail (526) and is used to support the mold.

3. The automatic lamination device according to claim 2, characterized in that: The carrier frame (527) includes a first mounting rod (5271), a second mounting rod (5272) and a roller (5273). The first mounting rod (5271) and the second mounting rod (5272) are symmetrically arranged and fixedly mounted on the frame (521). A plurality of rollers (5273) are mounted on the first mounting rod (5271) and the second mounting rod (5272).

4. An automatic film pressing device according to claim 2 or 3, characterized in that: A plurality of the carriers (527) are arranged at intervals along the Z-axis direction, and the plurality of carriers (527) are all fixedly connected to the output end of the third linear guide rail (523).

5. The automatic lamination equipment according to claim 3, characterized in that: The invention also includes a limiting component (6), wherein the limiting component (6) includes a mounting plate (61), a clamping plate (62) and an elastic member (63), wherein the first mounting rod (5271) and the second mounting rod (5272) are fixedly connected to one mounting plate (61) on their sides away from each other, and each mounting plate (61) is slidably connected to one clamping plate (62), and the two clamping plates (62) can slide in a direction toward or away from each other, and the elastic member (63) is arranged between each clamping plate (62) and the mounting plate (61), and one end of the elastic member (63) acts on the clamping plate (62) and the other end acts on the mounting plate (61).

6. The automatic lamination equipment according to claim 5, characterized in that: An inclined surface (621) is provided at one end of the clamping plate (62) close to the annular conveying track.

7. An automatic film pressing device according to any one of claims 5-6, characterized in that: A baffle (64) is fixedly connected to the top of each mounting plate (61).

8. The automatic lamination equipment according to claim 1, characterized in that: Also includes: A pre-pressing mechanism (7), wherein each position of the loading and unloading rails (2) is provided with a corresponding pre-pressing mechanism (7), the pre-pressing mechanism (7) comprises a telescopic member (71), an upper top plate (72), a lower top plate (73) and a machine platform (74), a pre-pressing cavity (741) for pre-pressing is provided on the machine platform (74), the lower top plate (73) is fixedly connected to the inner bottom wall of the pre-pressing cavity (741), the telescopic member (71) is fixed to the top wall of the pre-pressing cavity (741) and is arranged downward, and the upper top plate (72) is fixedly connected to the output end of the telescopic member (71); A positive pressure pipe (8) is fixedly connected to the machine (74) and is used to provide positive pressure air; A negative pressure pipe (9) is fixedly connected to the machine platform (74) and is used to provide negative pressure air.

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