A material adsorption structure for a feeding device of a laser cutting machine

Abstract

The utility model discloses a material adsorption structure for a feeding device of a laser cutting machine, and relates to the technical field of laser cutting machines. The utility model includes a placement frame, a placement component is arranged inside the placement frame, a connecting frame in the placement component is arranged below the placement frame, a forward air box and a reverse air box are arranged inside the connecting frame, guide blocks are symmetrically fixed on both sides of the forward air box and the reverse air box, and the guide blocks are slidably connected to guide grooves provided on the side walls of the connecting frame; adsorption components are arranged at equal intervals on the lower surfaces of the forward air box and the reverse air box. The utility model is provided with a placement component, which is convenient for adjusting the spacing between the forward air box and the reverse air box, thereby making the material adsorption structure suitable for sheets of different sizes, improving practicality, and effectively preventing the adsorption cover from being arranged too much, and providing an adsorption component, which effectively buffers the impact force between the adsorption cover and the sheet, thereby improving the protection effect on the sheet.

Description

Technical Field

[0001] The utility model belongs to the technical field of laser cutting machines, and in particular relates to a material adsorption structure used for a feeding device of a laser cutting machine. Background Art

[0002] Laser cutting machine refers to a mechanical cutting device used to cut materials. Compared with manual cutting, laser cutting machine has the advantages of high cutting efficiency, high cutting accuracy and low workload. In order to facilitate the transportation of sheet materials when the laser cutting machine is started, a corresponding feeding device is configured on the laser cutting machine, and the staff operates the material adsorption structure to absorb the sheet materials onto the feeding device, thereby greatly reducing the workload during sheet material transportation. The material adsorption structure is mainly composed of a vacuum pump, a connecting pipe, an adsorption hood and a lifting component.

[0003] After searching, a patent document with patent announcement number CN214109259U discloses a laser processing device with an adsorption structure, including a processing table, a laser cutting head and a first driving mechanism for driving the laser cutting head to rotate are arranged in the central area of ​​the worktable, the first driving mechanism is fixedly connected to the processing table, the first adsorption holes and the second adsorption holes are symmetrically opened on both sides of the processing table, a first cavity is opened inside the processing table, the first cavity side wall and the positions corresponding to the first adsorption holes and the second adsorption holes are respectively sealed with a first suction cup and a second suction cup, the first adsorption hole is connected to the first suction cup, the second adsorption hole is connected to the first suction cup, the first suction cup and the second suction cup are respectively connected to a first connecting pipe and a second connecting pipe, and the first connecting pipe and the second connecting pipe are connected to an exhaust pipe through a three-way solenoid valve. It improves the working efficiency of laser processing.

[0004] However, it still has the following disadvantages in actual use:

[0005] The existing material adsorption structure for the feeding device of the laser cutting machine, during use, evacuates the interior of the adsorption cover by starting the vacuum pump, and then makes the adsorption cover adsorb on the sheet material, thereby achieving the absorption of the sheet material, but it is not convenient to adjust the spacing between the adsorption covers, resulting in the existence of redundant adsorption covers when absorbing small-sized sheets, which will result in too many adsorption covers being set, thereby reducing the utilization rate of the adsorption covers;

[0006] 2. The existing laser cutting machine feeding device uses a material adsorption structure. During use, the sheet material is sucked up by the cooperation of a vacuum pump and an adsorption hood. However, in this process, since there is no buffer component in the adsorption hood, the impact force between the adsorption hood and the sheet material will be relatively large, which will have an adverse effect on the sheet material and reduce the quality of the sheet material when being adsorbed.

[0007] To this end, we provide a material adsorption structure for a feeding device of a laser cutting machine to solve the above-mentioned problems. Utility Model Content

[0008] The purpose of the utility model is to provide a material adsorption structure for a feeding device of a laser cutting machine. By arranging a placement component and an adsorption component, the utility model solves the problems of low utilization rate of the adsorption cover in the material adsorption structure for the feeding device of the laser cutting machine and poor quality when the sheet material is absorbed.

[0009] In order to solve the above technical problems, the utility model is achieved through the following technical solutions:

[0010] The utility model discloses a material adsorption structure for a feeding device of a laser cutting machine, comprising a placement frame, a placement assembly is arranged inside the placement frame, a connecting frame in the placement assembly is arranged below the placement frame, a forward air box and a reverse air box are arranged inside the connecting frame, guide blocks are symmetrically fixed on both sides of the forward air box and the reverse air box, the guide blocks are slidably connected to guide grooves opened on the side walls of the connecting frame, the end of the forward hydraulic cylinder connected to one side wall of the connecting frame is connected to a forward hydraulic rod, the end of the forward hydraulic rod is connected to a forward seat, the forward seat and the forward The guide block on the side wall of the air box is connected, the end of the reverse hydraulic cylinder connected to the other side wall of the connecting frame is connected to a reverse hydraulic rod, the end of the reverse hydraulic rod is connected to a reverse seat, and the reverse seat is connected to the guide block on the side wall of the reverse air box; the lower surfaces of the forward air box and the reverse air box are both provided with adsorption components at equal intervals, and the connecting tube in the adsorption component is connected with a limiting block, and the lower surface of the limiting block is in a rectangular array. The surrounding side wall of the damper is sleeved with a shock-absorbing spring, and the adsorption cover inserted into the connecting tube is connected to the lower end of the damper.

[0011] The utility model is further configured such that a fixed air box is also provided inside the connecting frame, the forward air box and the reverse air box are located on both sides of the fixed air box, the guide blocks connected on both sides of the fixed air box are locked inside the guide groove by bolts, and the lower surface of the fixed air box is provided with adsorption components in a rectangular array.

[0012] The utility model is further configured that the connecting frame is U-shaped, the guide block is T-shaped, the guide groove is T-shaped, and the opening end of the connecting frame is locked and connected with a limiting plate by bolts.

[0013] The utility model is further configured such that the mounting seat connected to the fixed air box is U-shaped, a vacuum pump is connected to the inner top of the mounting seat, a main pipe connected to the side wall of the vacuum pump is connected to the interior of the fixed air box, telescopic tubes are symmetrically connected on the peripheral side walls of the main pipe, and the two telescopic tubes are respectively connected to the interior of the forward air box and the reverse air box.

[0014] The utility model is further configured that a lifting hydraulic cylinder is connected to the lifting hydraulic rod connected to the placement seat, and a stabilizing rod connected to the peripheral side wall of the lifting hydraulic rod is connected to a connecting frame.

[0015] The utility model is further configured such that the connecting tube is connected to the lower surfaces of the fixed air box, the forward air box and the reverse air box, a sealing ring is provided on the inner wall of the connecting tube, a sealing gasket is provided on the connecting seat sleeved on the outer wall of the connecting tube, the connecting seat is locked and connected to the lower surfaces of the fixed air box, the forward air box and the reverse air box by bolts, and the connecting seat and the limit block are both in the shape of a U-shaped letter "U".

[0016] The utility model is further configured as follows: a translation assembly is provided inside the mounting frame, a lead screw in the translation assembly is rotatably connected to the inside of the mounting frame, a movable seat is sleeved on the circumferential side wall of a ball nut connected to the circumferential side wall of the lead screw, sliders are symmetrically connected to the two side walls of the movable seat, the two sliders are slidably connected to the sliding grooves opened on the two side walls of the mounting frame, the motor connected to the end of the lead screw is connected to the outer side wall of the mounting frame, and the movable seat is connected to the lifting hydraulic cylinder.

[0017] The utility model is further configured that a placement plate is symmetrically connected to the lower surface of the placement frame, a stabilizing frame symmetrically connected to the placement plate is connected to a side wall of the placement frame, the sliding block is U-shaped, and the sliding groove is U-shaped.

[0018] The utility model has the following beneficial effects:

[0019] The utility model sets a placement component, starts the forward hydraulic cylinder and the reverse hydraulic cylinder, and adjusts the distance between the forward air box and the reverse air box, so that the material adsorption structure is suitable for adsorbing sheet materials of different sizes, thereby improving the practicality of the material adsorption structure and effectively preventing the adsorption component from running dry, that is, preventing the number of adsorption components from being set too much, so that the adsorption components in the material adsorption structure can be fully utilized.

[0020] The utility model provides an adsorption component. When the adsorption cover contacts the sheet material, the damper cooperates with the shock-absorbing spring to effectively buffer the impact force between the adsorption cover and the sheet material, thereby improving the protection effect of the sheet material, and effectively improving the quality of manipulating the material adsorption structure to transport the sheet material to the feeding device of the laser cutting machine.

[0021] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings required for describing the embodiments are briefly introduced below.

[0023] Figure 1 A three-dimensional diagram of a material adsorption structure used in a feeding device of a laser cutting machine Figure 1 ;

[0024] Figure 2 A three-dimensional diagram of a material adsorption structure used in a feeding device of a laser cutting machine Figure 2 ;

[0025] Figure 3 It is a connection diagram of the mounting seat and the vacuum pump;

[0026] Figure 4 for Figure 2 A schematic diagram of the structure enlargement in the middle;

[0027] Figure 5 Schematic diagram of the structural decomposition of the adsorption component.

[0028] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0029] 1-Placement frame, 101-Slide, 102-Placement plate, 102a-Stable frame, 2-Translation assembly, 201-Motor, 202-Screw, 202a-Ball nut, 203-Moving seat, 203a-Slider, 3-Placement assembly, 301-Connecting frame, 301a-Guide groove, 301b-Limiting plate, 302-Forward hydraulic cylinder, 302a-Forward hydraulic rod, 302b-Forward seat, 303-Placement seat, 303a-Vacuum pump, 303b-Main pipe, 304-Lifting hydraulic cylinder , 304a-lifting hydraulic rod, 304b-stabilizing rod, 305-reverse hydraulic cylinder, 305a-reverse hydraulic rod, 305b-reverse seat, 306-fixed air box, 306a-forward air box, 306b-telescopic tube, 306c-reverse air box, 306d-guide block, 4-adsorption assembly, 401-adsorption cover, 402-connecting cylinder, 402a-limiting block, 402b-sealing ring, 403-connecting seat, 403a-sealing pad, 404-damper, 404a-shock-absorbing spring. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0031] For specific embodiment 1, please refer to Figure 1 and Figure 3The utility model is a material adsorption structure for a feeding device of a laser cutting machine, comprising a placement frame 1, a placement assembly 3 is arranged inside the placement frame 1, and the placement assembly 3 includes a connecting frame 301, a forward hydraulic cylinder 302, a forward hydraulic rod 302a, a placement seat 303, a vacuum pump 303a, a lifting hydraulic cylinder 304, a lifting hydraulic rod 304a, a reverse hydraulic cylinder 305, a reverse hydraulic rod 305a, a fixed air box 306, a forward air box 306a and a reverse air box 306c. By cooperating with the forward hydraulic cylinder 302 and the reverse hydraulic cylinder 305, the distance between the forward air box 306a and the reverse air box 306c is adjusted, so that the material adsorption structure is suitable for adsorbing sheets of different lengths;

[0032] Specifically, the connecting frame 301 is arranged inside the placement frame 1, and the open end of the connecting frame 301 is connected to the limiting plate 301b by bolt locking, and the inner side wall of the connecting frame 301 is provided with a guide groove 301a, and the forward air box 306a, the fixed air box 306 and the reverse air box 306c are arranged inside the connecting frame 301 in sequence, and the guide blocks 306d fixed on the side walls of the forward air box 306a and the reverse air box 306c are slidably connected to the guide groove 301a, and the fixed air box 306a is provided with a guide block 306d fixed on the side walls of the forward air box 306a and the reverse air box 306c. The guide block 306d fixed on the side wall of the forward air box 306 is locked in the guide groove 301a by bolts, the forward hydraulic cylinder 302 is connected to an outer side wall of the connecting frame 301, the end of the forward hydraulic cylinder 302 is connected to the forward hydraulic rod 302a, the end of the forward hydraulic rod 302a is connected to the forward seat 302b, the forward seat 302b is connected to the guide block 306d on the side wall of the forward air box 306a, and the reverse hydraulic cylinder 305 is connected to the other outer side wall of the connecting frame 301. The end of the reverse hydraulic cylinder 305 is connected to a reverse hydraulic rod 305a, the end of the reverse hydraulic rod 305a is connected to a reverse seat 305b, the reverse seat 305b is connected to a guide block 306d on the side wall of the reverse air box 306c, the placement seat 303 is connected to the fixed air box 306, the inner top of the placement seat 303 is connected to a vacuum pump 303a, the side wall of the vacuum pump 303a is connected to a main pipe 303b, the lower end of the main pipe 303b is connected to the inner part of the fixed air box 306 The main pipe 303b is connected with a telescopic pipe 306b on its peripheral side wall, the telescopic pipe 306b is connected with the interior of the forward air box 306a, and the telescopic pipe 306b is connected with the interior of the reverse air box 306c, the lower end of the lifting hydraulic cylinder 304 is connected with a lifting hydraulic rod 304a, the lifting hydraulic rod 304a is connected to the placement seat 303, the lifting hydraulic rod 304a is connected with a stabilizing rod 304b on its peripheral side wall, and the stabilizing rod 304b is connected to the connecting frame 301;

[0033] Further, the connecting frame 301 is U-shaped, the placement frame 1 is U-shaped, the two guide grooves 301a are symmetrically opened, and the guide groove 301a is T-shaped, three groups of guide blocks 306d are provided, and each group of guide blocks 306d is provided with two, each group of guide blocks 306d is symmetrically arranged, the guide blocks 306d are T-shaped, the forward seat 302b is L-shaped, the reverse seat 305b is L-shaped, the two telescopic tubes 306b are symmetrically arranged, the placement seat 303 is U-shaped, and four stabilizing rods 304b are provided;

[0034] The operation process of this embodiment is as follows: after the staff starts the forward hydraulic cylinder 302 and the reverse hydraulic cylinder 305, when the forward hydraulic rod 302a and the reverse hydraulic rod 305a are both extended, the forward air box 306a and the reverse air box 306c move in opposite directions, that is, the distance between the forward air box 306a and the reverse air box 306c increases, which is suitable for the material adsorption structure to absorb longer sheets; conversely, when the forward hydraulic rod 302a and the reverse hydraulic rod 305a are both retracted, the distance between the forward air box 306a and the reverse air box 306c decreases, which is suitable for the material adsorption structure to absorb shorter sheets; after starting the lifting hydraulic cylinder 304, when the lifting hydraulic rod 304a is extended, the connecting frame 301 moves downward, and when the lifting hydraulic rod 304a is retracted, the connecting frame 301 moves upward.

[0035] For specific embodiment 2, please refer to Figure 2 , Figure 4 and Figure 5 On the basis of the specific embodiment 1, an adsorption assembly 4 is provided, which includes an adsorption cover 401, a connecting tube 402, a connecting seat 403 and a damper 404. The damper 404 cooperates with a shock absorbing spring 404a to effectively buffer the impact force caused by the contact between the adsorption cover 401 and the sheet material, thereby protecting the sheet material and improving the quality of the sheet material during adsorption;

[0036] Specifically, the connecting tube 402 is connected to the lower surfaces of the fixed air box 306, the forward air box 306a and the reverse air box 306c, the limiting block 402a is fixedly connected to the connecting tube 402, the lower surface of the limiting block 402a is connected to the damper 404, the peripheral side wall of the damper 404 is sleeved with a shock absorbing spring 404a, the adsorption cover 401 is plugged into the lower surface of the connecting tube 402, the inner side wall of the connecting tube 402 is provided with a sealing ring 402b, the outer side wall of the connecting tube 402 is sleeved with a connecting seat 403, the connecting seat 403 is locked and connected to the lower surfaces of the fixed air box 306, the forward air box 306a and the reverse air box 306c by bolts, and a sealing gasket 403a is provided on the connecting seat 403;

[0037] Further, three groups of adsorption components 4 are provided, and each group of adsorption components 4 is arranged in a rectangular array, the connecting tube 402 is a hollow structure, the limit block 402a is in a U-shaped shape, and the connecting seat 403 is in a U-shaped shape;

[0038] The operation process of this embodiment is as follows: when the lifting hydraulic rod 304a moves downward, the adsorption cover 401 contacts the sheet material downward. During the contact between the adsorption cover 401 and the sheet material, the damper 404 cooperates with the shock-absorbing spring 404a to reduce the impact force between the adsorption cover 401 and the sheet material. Then, the vacuum pump 303a is started, the interior of the symmetrical adsorption cover 401 is vacuumed, the adsorption cover 401 is adsorbed on the sheet material, and the lifting hydraulic cylinder 304 is controlled to drive the sheet material to move upward.

[0039] For specific embodiment 3, please refer to Figure 1 and Figure 2 On the basis of the specific embodiment 1 and the specific embodiment 2, a translation assembly 2 is provided, and the translation assembly 2 includes a motor 201, a lead screw 202 and a movable seat 203. By starting the motor 201, the sheet material adsorbed on the lower surface of the adsorption cover 401 is moved to the feeding device of the laser cutting machine, thereby realizing the plane movement of the sheet material;

[0040] Specifically, the lead screw 202 is rotatably connected to the inside of the mounting frame 1, the motor 201 is connected to the end of the lead screw 202, the peripheral side wall of the lead screw 202 is connected with a ball nut 202a, the movable seat 203 is sleeved on the peripheral side wall of the ball nut 202a, the side wall of the movable seat 203 is connected with a slider 203a, a slide groove 101 is opened on the side wall of the mounting frame 1, the slider 203a is slidably connected to the slide groove 101, the lower surface of the mounting frame 1 is connected with a mounting plate 102, the mounting plate 102 is connected with a stabilizing frame 102a, and the stabilizing frame 102a is connected to the side wall of the mounting frame 1;

[0041] Furthermore, the two sliders 203a are symmetrically arranged, and the sliders 203a are U-shaped, the two slide grooves 101 are symmetrically opened, and the slide grooves 101 are U-shaped, the two placement plates 102 are symmetrically arranged, and two groups of stabilizing frames 102a are arranged, and each group of stabilizing frames 102a is provided with two, and each group of stabilizing frames 102a is symmetrically arranged;

[0042] The operation process of this embodiment is: the staff starts the motor 201, the screw 202 rotates, the slider 203a slides along the slide groove 101, the movable seat 203 moves linearly along the screw 202, the connecting frame 301 moves toward the laser cutting machine feeding device, the adsorption cover 401 moves toward the laser cutting machine feeding device, and the sheet material moves toward the laser cutting machine feeding device.

[0043] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0044] The preferred embodiments of the utility model disclosed above are only used to help explain the utility model. The preferred embodiments do not describe all the details in detail, nor do they limit the utility model to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the utility model, so that technicians in the relevant technical field can well understand and use the utility model. The utility model is limited only by the claims and their full scope and equivalents.

Claims

1. A material adsorption structure for a feeding device of a laser cutting machine, comprising a mounting frame (1), characterized in that: The placement frame (1) is provided with a placement component (3) inside. The connection frame (301) in the placement component (3) is provided below the placement frame (1). The connection frame (301) is provided with a forward air box (306a) and a reverse air box (306c) inside. Guide blocks (306d) are symmetrically fixedly connected to both sides of the forward air box (306a) and the reverse air box (306c). The guide blocks (306d) are slidably connected to guide grooves (301a) provided on the side walls of the connection frame (301). The end of the forward hydraulic cylinder (302) connected to one side wall of the connection frame (301) is connected to the guide grooves (301a) provided on the side walls of the connection frame (301). The end of the connecting frame (301) is connected to a forward hydraulic rod (302a), the end of the forward hydraulic rod (302a) is connected to a forward seat (302b), the forward seat (302b) is connected to a guide block (306d) on the side wall of the forward air box (306a), the end of a reverse hydraulic cylinder (305) connected to the other side wall of the connecting frame (301) is connected to a reverse hydraulic rod (305a), the end of the reverse hydraulic rod (305a) is connected to a reverse seat (305b), the reverse seat (305b) is connected to a guide block (306d) on the side wall of the reverse air box (306c); Adsorption components (4) are arranged at equal intervals on the lower surfaces of the forward air box (306a) and the reverse air box (306c); a limit block (402a) is connected to the connecting tube (402) in the adsorption component (4); a damper (404) is connected to the lower surface of the limit block (402a) in a rectangular array; a shock absorbing spring (404a) is sleeved on the peripheral side wall of the damper (404); and an adsorption cover (401) inserted into the interior of the connecting tube (402) is connected to the lower end of the damper (404).

2. The material adsorption structure for a feeding device of a laser cutting machine according to claim 1, characterized in that: A fixed air box (306) is also provided inside the connecting frame (301), the forward air box (306a) and the reverse air box (306c) are located on both sides of the fixed air box (306), the guide blocks (306d) connected to both sides of the fixed air box (306) are locked inside the guide groove (301a) by means of bolts, and the lower surface of the fixed air box (306) is provided with adsorption components (4) in a rectangular array.

3. The material adsorption structure for a feeding device of a laser cutting machine according to claim 2, characterized in that: The connecting frame (301) is U-shaped, the guide block (306d) is T-shaped, the guide groove (301a) is T-shaped, and the open end of the connecting frame (301) is locked and connected to a limiting plate (301b) via bolts.

4. The material adsorption structure for a feeding device of a laser cutting machine according to claim 2, characterized in that: The mounting seat (303) connected to the fixed air box (306) is U-shaped, and the inner top of the mounting seat (303) is connected to a vacuum pump (303a). The main pipe (303b) connected to the side wall of the vacuum pump (303a) is connected to the interior of the fixed air box (306). The peripheral side wall of the main pipe (303b) is symmetrically connected to telescopic pipes (306b), and the two telescopic pipes (306b) are respectively connected to the interior of the forward air box (306a) and the reverse air box (306c).

5. The material adsorption structure for a feeding device of a laser cutting machine according to claim 4, characterized in that: A lifting hydraulic cylinder (304) is connected to a lifting hydraulic rod (304a) connected to the placement seat (303); and a stabilizing rod (304b) connected to a peripheral side wall of the lifting hydraulic rod (304a) is connected to a connecting frame (301).

6. The material adsorption structure for a feeding device of a laser cutting machine according to claim 1, characterized in that: The connecting tube (402) is connected to the lower surfaces of the fixed air box (306), the forward air box (306a) and the reverse air box (306c); a sealing ring (402b) is provided on the inner wall of the connecting tube (402); a sealing gasket (403a) is provided on the connecting seat (403) sleeved on the outer wall of the connecting tube (402); the connecting seat (403) is connected to the lower surfaces of the fixed air box (306), the forward air box (306a) and the reverse air box (306c) by means of bolts; the connecting seat (403) and the limiting block (402a) are both in the shape of a Chinese character "Yu".

7. The material adsorption structure for a feeding device of a laser cutting machine according to claim 1, characterized in that: A translation assembly (2) is arranged inside the mounting frame (1); a lead screw (202) in the translation assembly (2) is rotatably connected to the inside of the mounting frame (1); a movable seat (203) is sleeved on the circumferential side wall of a ball nut (202a) connected to the circumferential side wall of the lead screw (202); sliders (203a) are symmetrically connected to the two side walls of the movable seat (203); the two sliders (203a) are slidably connected to the slide grooves (101) provided on the two side walls of the mounting frame (1); the motor (201) connected to the end of the lead screw (202) is connected to the outer side wall of the mounting frame (1); and the movable seat (203) is connected to a lifting hydraulic cylinder (304).

8. The material adsorption structure for a feeding device of a laser cutting machine according to claim 7, characterized in that: The lower surface of the placement frame (1) is symmetrically connected to a placement plate (102); a stabilizing frame (102a) symmetrically connected to the placement plate (102) is connected to a side wall of the placement frame (1); the sliding block (203a) is U-shaped; and the sliding groove (101) is U-shaped.

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