Pressing machine for mobile phone screen production

Abstract

The invention relates to the technical field of screen pressing equipment, and discloses a pressing machine for mobile phone screen production, the pressing machine comprises a supporting table, a negative pressure pump and a jig, a conveying belt is arranged on the supporting table, the jig is placed on the conveying belt and moves along with the conveying belt, a vacuum box and the jig are matched and sealed to form an outer cavity and a pressing cavity, and the pressing cavity is located in the outer cavity. According to the pressing machine for mobile phone screen production, the pressing cavity is surrounded by the outer cavity, the external outer cavity is communicated with the normal negative pressure cavity, the relative size is large, slight leakage within a short time does not cause obvious change of the pressure in the normal negative pressure cavity and the outer cavity, the pressure between the outer cavity and the pressing cavity is equal or the pressure difference between the outer cavity and the pressing cavity is extremely small, and the pressing effect is good. The inner-layer sealing structure is not prone to leakage, meanwhile, the negative pressure pump is used for pumping air in the pressing cavity to complete early-stage air pumping, and when the pressure of the pressing cavity is lower than a first set value, the reduced negative pressure in the normal-state negative pressure cavity is used for pumping the pressing cavity to assist in completing later-stage air pumping.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of screen pressing equipment, in particular to a pressing machine for mobile phone screen production. BACKGROUND

[0002] In the large-scale production of mobile phone screens, the full-lamination process is a key link to ensure the display effect and structural stability of the screen. The core of the process is to realize the seamless lamination of the liquid crystal display (LCD / OLED) and the glass cover plate through OCA optical glue or UV glue, so as to eliminate the air layer in the traditional frame bonding process, improve the light transmittance, reduce the reflection, and enhance the waterproof and dustproof performance. The key execution equipment of the process is a vacuum pressing machine. Its working principle is as follows: first, a vacuum pump is used to perform vacuumizing treatment on the pressing space to build a closed vacuum environment free of air bubbles; after the vacuum degree reaches the process requirement, an air compressor drives the pressing component to move downward to apply uniform pressure to the screen assembly, so that the optical glue and the screen layers are tightly combined, and finally the lamination is completed.

[0003] To improve the beat efficiency of the production line, the existing technology generally adopts the design idea of "reducing the volume of the pressing space". Since the vacuumizing time and the time for destroying the vacuum (restoring normal pressure after lamination is completed) are both positively related to the space volume, reducing the space volume can directly shorten the auxiliary time of single lamination, thereby improving the production capacity per unit time. In actual production lines, this design is realized through the cooperation of a vacuum box and a jig: the jig carrying the screen assembly is conveyed along the production line, and when it moves to the pressing station, the vacuum box of the equipment is pressed downward and forms a sealed cooperation with the jig. The area enclosed by the two is the actual pressing space.

[0004] However, the above design has exposed two key technical defects in long-term production, which seriously restrict the stability of the lamination quality and production efficiency:

[0005] Firstly, as a recycled component, the jig needs to be frequently connected and separated with the vacuum box, and bears mechanical stress during the pressing process. After long-term use, the sealing surface is prone to structural deformation (such as local depression and warping), or the sealing performance of the sealing element (such as the rubber sealing ring) is reduced due to wear and aging, thereby causing vacuum leakage. Since the volume of the pressing space has been designed to be small, even slight leakage (such as the infiltration of atmospheric air through a small gap) will quickly affect the pressure in the pressing space. It is manifested that the vacuum degree cannot be maintained within the process requirement range, or the fluctuation amplitude of the vacuum degree exceeds the allowable threshold. The instability of the vacuum environment will directly lead to air residues during the lamination process, forming defects such as air bubbles and delamination, and ultimately affecting the display effect and service life of the screen, and even causing the scrap of finished products.

[0006] Second, the decay of the pumping efficiency of the vacuum pump restricts the improvement of production efficiency. Although reducing the volume of the lamination space can shorten the time taken for the initial vacuum pumping stage, as the vacuum pumping process progresses, the vacuum degree within the lamination space gradually increases (i.e., the absolute pressure decreases), and the vacuum pump has an inherent characteristic that its pumping efficiency "significantly decreases as the vacuum degree increases". When the vacuum degree approaches the high vacuum range required by the process, the amount of gas pumped out by the vacuum pump per unit time significantly decreases, resulting in a significant prolongation of the time taken for the later stage of vacuum pumping from "approaching the target vacuum degree" to "reaching the target vacuum degree". This problem is particularly prominent for the OLED screen lamination process with high requirements for vacuum degree, restricting the release of production capacity. Summary of the Invention

[0007] This application proposes a laminating machine for mobile phone screen production. The lamination chamber is surrounded by an outer cavity, and the external outer cavity is connected to a normal negative pressure chamber, which has a relatively large volume. A slight leakage within a short time will not cause significant changes in the pressures within the normal negative pressure chamber and the outer cavity. The pressure between the outer cavity and the lamination chamber is equal or has a very small pressure difference, and the inner sealing structure is not prone to leakage, thereby improving the reliability of sealing. At the same time, first use a negative pressure pump to pump the air in the lamination chamber to complete the initial vacuum pumping. When the pressure in the lamination chamber is lower than the set value one, then use the reduced negative pressure in the normal negative pressure chamber to suck the lamination chamber to assist in completing the later stage of vacuum pumping, and use the gap to suck the normal negative pressure chamber to keep the pressure in the normal negative pressure chamber relatively constant, improving the efficiency of vacuum pumping.

[0008] To achieve the above object, this application adopts the following technical solution: A laminating machine for mobile phone screen production, comprising a support table, a negative pressure pump, and a jig. A conveyor belt is provided on the support table. The support table is connected to a lifting cylinder through a support frame, and the lifting cylinder is connected to a vacuum box. The jig is placed on the conveyor belt and moves along with the conveyor belt. The vacuum box and the jig cooperate to form an outer cavity and a lamination chamber. The lamination chamber is located within the outer cavity. A normal negative pressure chamber is provided within the vacuum box. A pressing plate capable of moving up and down is provided in the lamination chamber. The volume of the normal negative pressure chamber is larger than that of the outer cavity and the lamination chamber. The normal negative pressure chamber is sealed and maintains a relatively constant negative pressure value. The negative pressure pump can be selectively connected to the normal negative pressure chamber, the outer cavity, or the lamination chamber through an air extraction valve. The outer cavity or the lamination chamber is connected to the atmosphere through an air intake valve. During lamination, the normal negative pressure chamber is connected to the outer cavity through a first air vent valve.

[0009] Further, two sets of recessed sealing structures are provided at the bottom of the vacuum box. The two sets of sealing structures form a "hui" character shape, and the two sets of sealing structures cooperate with the jig to form an outer cavity and a lamination chamber.

[0010] Further, the conveying belts are provided with two groups, the two groups of conveying belts are arranged on the two sides of the support table, the jig is placed on the two groups of conveying belts, and the two groups of conveying belts are arranged at one end and the other end, and the two groups of conveying belts are provided with positioning columns corresponding to the positions of the vacuum boxes, and the positioning columns are telescopic.

[0011] Further, the pressing plate is communicated with a pressing member, the pressing plate is arranged in the normal negative pressure cavity, the pressing member is connected with the pressing plate through a connecting rod, the connecting rod penetrates the top of the pressing cavity and is communicated with the pressing plate, and sealing is realized between the top of the pressing cavity and the connecting rod by an O-shaped ring. The pressing member for driving the pressing plate is arranged in the normal negative pressure cavity, thereby reducing the volume of the pressing cavity, and at the same time, although the pressing member is generally a gas bag or a gas cylinder, since the pressure difference between the normal negative pressure cavity and the pressing cavity is small, even if the pressing member leaks, the pressure in the pressing cavity will not be affected.

[0012] Further, as the vacuum degree increases, the pumping efficiency of the negative pressure pump will decrease, in order to reduce the time consumption of vacuumizing, the normal negative pressure cavity is communicated with the pressing cavity through a second air valve, the pressure in the normal negative pressure cavity is lower than the target value of the vacuumizing of the pressing cavity, when the pressure in the pressing cavity is lower than the set value, the second air valve is opened, the normal negative pressure cavity is communicated with the pressing cavity, and the second air valve is closed when the pressing cavity reaches the target value.

[0013] Further, the negative pressure pump is communicated with the normal negative pressure cavity after the pressure in the pressing cavity reaches the target value, so that the pressure in the normal negative pressure cavity is maintained relatively constant.

[0014] Further, the top of the jig is provided with a flat plate, and the flat plate is sealed in cooperation with the sealing structure at the bottom of the vacuum box. The relatively complex sealing structure is arranged on the vacuum box, and the flat plate is arranged on the jig, thereby reducing the manufacturing cost of the jig.

[0015] Further, since the conveying belt of the embodiment always keeps moving, the jig needs to be lifted when the pressing screen is pressed, the bottom of the jig is provided with a lifting plate, the lifting plate can be lifted, and the lifting plate lifts the jig away from the conveying belt.

[0016] The present application has the following advantages:

[0017] The mobile phone screen production press provided by the application has two groups of sealing structures between the jig and the vacuum box, and the sealing can be maintained as long as one group is intact. Even if both groups of sealing structures are damaged and there is leakage, the slight leakage in a short time will not cause obvious changes in the pressure in the normal negative pressure cavity and the outer cavity, because the press cavity is surrounded by the outer cavity, and the outer cavity is in communication with the normal negative pressure cavity. The pressure between the outer cavity and the press cavity is equal or the pressure difference is very small, and the inner layer sealing structure is not easy to leak, thereby improving the reliability of the sealing. At the same time, because the outer cavity does not need to accommodate any structure, its volume can be set to be very small, and the vacuum time is very short, which can be realized at the same time as the press plate is pressed down, and will not significantly increase the time required for vacuumizing and destroying the vacuum.

[0018] First, the negative pressure pump is used to pump air in the press cavity to complete the early stage of air pumping. When the pressure in the press cavity is lower than the set value, the reduced negative pressure in the normal negative pressure cavity is used to pump the press cavity to assist in completing the later stage of air pumping. The gap is used to pump the normal negative pressure cavity, so that the pressure in the normal negative pressure cavity is maintained relatively constant, and the press time is not additionally increased. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings:

[0020] Figure 1 The structural schematic diagram of the present application;

[0021] Figure 2 The schematic diagram of the bottom sealing structure of the vacuum box in the present application;

[0022] Figure 3 The front view of the present application; Figure 1

[0023] Figure 4 The side view of the present application; Figure 1

[0024] Figure 5 The schematic diagram of the jig in the present application.

[0025] ​​In the figure: 1, support table; 2, conveying belt; 3, jig; 4, flat plate; 5, vacuum box; 6, lifting cylinder; 7, support frame; 8, positioning column; 9, normal negative pressure cavity; 10, outer cavity; 11, pressing cavity; 12, pressing plate; 13, air inlet; 14, air outlet; 15, negative pressure pump; 16, air suction valve; 17, jacking plate; 18, air inlet valve; 19, pressing piece; 20, first air vent valve; 21, second air vent valve; 22, buffer table; 23, screen module. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0027] Embodiment one, please refer to Figure 1 A pressing machine for mobile phone screen production, comprising a jig 3 capable of moving laterally and a vacuum box 5 capable of moving up and down, the jig 3 is attached to the lower surface of the vacuum box 5 to form a sealed space, the jig 3 has a flat surface around it, the lower surface of the vacuum box 5 has a sealing structure, the structure for driving the jig 3 is two sets of conveying belts 2, the two sets of conveying belts 2 are respectively arranged on both sides of the support table 1, the support table 1 is used to support the conveying belts 2, the vacuum box 5 is connected with a lifting cylinder 6, the lifting cylinder 6 drives the vacuum box 5 to move up and down through extension and retraction, the lifting cylinder 6 is connected with the support table 1 through a support frame 7, the support frame 7 is composed of four support legs and a support flat plate, the cylinder body of the lifting cylinder 6 is fixedly connected with the support flat plate of the support frame 7, the support legs are located outside the two sets of conveying belts 2 and do not interfere with the lateral movement of the jig 3, in order to make the movement of the vacuum box 5 more stable, the vacuum box 5 is connected with guide columns, the guide columns penetrate through the support flat plate and are slidingly connected with the support flat plate, the ends of the multiple guide columns can be fixed together through a connecting plate to enhance stability, the jig 3 is placed on the conveying belt 2 and moves together with the conveying belt 2, in order to align the jig 3 with the vacuum box 5 when the jig 3 stops, a positioning column 8 is arranged between the two sets of conveying belts 2, in this embodiment, the conveying belt 2 is continuously operated by a motor, the jig 3 is put in from one side and moved out from the other side, in order not to interfere with the movement of the jig 3, the positioning column 8 can be extended and retracted, in other embodiments, the conveying belt 2 can also be arranged to reciprocate, carrying the jig 3 to move in from one side and move out from the same side, at this time, the positioning column 8 can be fixed.

[0028] Please refer to Figures 2-4, two sets of sealing structures are provided at the bottom of the vacuum chamber 5. The two sets of sealing structures form a "hui" character shape, forming two relatively enclosed and sunken spaces. That is, the sealing structure is composed of two "kou" character-shaped mounting grooves, and sealing strips are installed in the mounting grooves. The two sets of sealed spaces are respectively the outer cavity 10 on the outside and the pressing cavity 11 on the inside. A normal negative pressure cavity 9 is provided in the vacuum chamber 5. The normal negative pressure cavity 9 is sealed and maintains a constant negative pressure state. The volume of the normal negative pressure cavity 9 is much larger than that of the outer cavity 10 and the pressing cavity 11. A pressing plate 12 is provided in the pressing cavity 11. The pressing plate 12 can move up and down. The depth of the pressing cavity 11 is large enough to completely accommodate the pressing plate 12. Air inlets 13 are provided on the outer cavity 10 and the pressing cavity 11. Air extraction ports 14 are provided on the outer cavity 10, the pressing cavity 11 and the normal negative pressure cavity 9. The air inlet 13 is connected to the atmosphere through an air inlet valve 18. The air extraction port 14 is connected to a negative pressure pump 15 through an air extraction valve 16. When the air inlet valve 18 is opened, both the outer cavity 10 and the pressing cavity 11 are connected to the atmosphere, quickly destroying the vacuum environment in the outer cavity 10 and the pressing cavity 11. The air extraction valve 16 selectively connects the normal negative pressure cavity 9, the outer cavity 10 and the pressing cavity 11 to the negative pressure pump 15 to evacuate the normal negative pressure cavity 9, the outer cavity 10 and the pressing cavity 11. In the appendix Figure 4 In this case, the air extraction valve 16 is implemented in the form of a four-way valve, but other forms are not excluded, such as three sets of independent control valves. The normal negative pressure cavity 9 and the outer cavity 10 are connected through a first ventilation valve 20. When pressing the screen, the negative pressure pump 15 is first connected to the pressing cavity 11. When the vacuum degree of the pressing cavity 11 reaches the requirement, the negative pressure pump 15 is connected to the outer cavity 10. At the same time, the pressing plate 12 starts to move downward to apply pressure to the screen. When the outer cavity 10 finishes suction, the first ventilation valve 20 connects the normal negative pressure cavity 9 and the outer cavity 10. When neither the outer cavity 10 nor the pressing cavity 11 needs suction, that is, when the current screen pressing is completed and the next group has not started yet, the negative pressure pump 15 is connected to the normal negative pressure cavity 9 to adjust the pressure of the normal negative pressure cavity 9 to keep the pressure of the normal negative pressure cavity 9 constant. The negative pressure pump 15 is installed on the support frame 7 and is connected to the air extraction valve 16 through a hose.

[0029] The pressing plate 12 is connected to a pressing member 19. The pressing plate 12 is provided in the normal negative pressure cavity 9. The pressing member 19 is connected to the pressing plate 12 through a connecting rod. The connecting rod passes through the top of the pressing cavity 11 and is connected to the pressing plate 12. The top of the pressing cavity 11 and the connecting rod are sealed by an O-ring. The pressing member 19 that drives the pressing plate 12 is provided in the normal negative pressure cavity 9, reducing the volume of the pressing cavity 11. At the same time, although the pressing member 19 is generally an airbag or a cylinder, due to the small pressure difference between the normal negative pressure cavity 9 and the pressing cavity 11, even if the pressing member 19 leaks, it will not affect the pressure in the pressing cavity 11, ensuring the stability of the pressure in the pressing cavity 11 during pressing.

[0030] In order to reduce the time for vacuumizing, the normal negative pressure cavity 9 is communicated with the pressing cavity 11 through the second air valve 21, the pressure in the normal negative pressure cavity 9 is lower than the target value of the vacuumizing of the pressing cavity 11, when the pressure in the pressing cavity 11 is lower than the set value, the normal negative pressure cavity 9 is communicated with the pressing cavity 11, under the action of the negative pressure of the normal negative pressure cavity 9, the pressure in the pressing cavity 11 is rapidly reduced to or close to the target value, thereby reducing the time for vacuumizing. Although the volume of the normal negative pressure cavity 9 is large, the vacuumizing of the normal negative pressure cavity 9 can be realized in the interval of the pressure maintaining or the switching of the two groups of screens, and the time consumption does not affect the processing efficiency.

[0031] Please refer to Figure 4 and Figure 5 The top of the jig 3 is provided with a flat plate 4, the flat plate 4 is sealed with the sealing structure at the bottom of the vacuum box 5, the more complex sealing structure is arranged on the vacuum box 5, the flat plate 4 is arranged on the jig 3, thereby reducing the manufacturing cost of the jig 3, the middle part of the flat plate 4 is provided with a buffer table 22 corresponding to the pressing cavity 11, and the screen module 23 is arranged on the buffer table 22.

[0032] Since the conveying belt 2 is always kept moving, the jig 3 needs to be lifted up when pressing the screen, the bottom of the jig 3 is provided with a lifting plate 17, the bottom of the lifting plate 17 is provided with a pneumatic cylinder, and the lifting plate 17 can be lifted and lowered.

[0033] When the screen is pressed, the screen module 23 is placed on the buffer table 22, the jig 3 is placed on the conveying belt 2, the conveying belt 2 moves with the jig 3, the jig 3 stops moving when encountering the positioning column 8, the lifting plate 17 lifts the jig 3, and the jig 3 is separated from the conveying belt 2, then the lifting cylinder 6 drives the vacuum box 5 to descend, and the vacuum box 5 is close to the jig 3, the bottom sealing structure of the vacuum box 5 is close to the flat plate 4 to realize sealing, forming the sealed outer cavity 10 and the pressing cavity 11, when the pressure pump 15 is started, the gas in the pressing cavity 11 is sucked, when the pressure in the pressing cavity 11 reaches the set value one, the second air valve 21 makes the normal negative pressure cavity 9 communicate with the pressing cavity 11, the negative pressure in the normal negative pressure cavity 9 makes the pressure in the pressing cavity 11 rapidly decrease to reach or approach the target value, when the pressure in the pressing cavity 11 reaches the target value, the second air valve 21 is closed, the pressure pump 15 is switched to communicate with the outer cavity 10, and the first air valve 20 is opened to make the normal negative pressure cavity 9 communicate with the outer cavity 10, because the volume of the outer cavity 10 can be set to be very small, the outer cavity 10 is rapidly vacuumized by the pressure pump 15 or the normal negative pressure cavity 9, after the outer cavity 10 is vacuumized, the pressure pump 15 is switched to communicate with the normal negative pressure cavity 9, the normal negative pressure cavity 9, the outer cavity 10 and the pressing cavity 11 are all provided with pressure sensors to monitor the pressure change, while the outer cavity 10 is vacuumized, the pressing plate 12 descends to press the screen module 23 and keep pressure and temperature, when the screen pressing is completed, the first air valve 20 is closed, the air inlet valve 18 is opened to make the outer cavity 10 and the pressing cavity 11 communicate with the atmosphere, after the vacuum is destroyed, the vacuum box 5 is lifted to be separated from the jig 3, the lifting plate 17 is reset, the positioning column 8 is retracted, the pressure pump 15 sucks the air in the normal negative pressure cavity 9 to keep the pressure relatively constant, and the jig 3 moves to the outlet with the conveying belt 2.

[0034] The above description of disclosed embodiments enables one of ordinary skill in the art to make or use the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A laminating machine for mobile phone screen production, comprising a support table (1) and a fixture (3). A conveyor belt (2) is provided on the support table (1). The support table (1) is connected to a lifting cylinder (6) through a support frame (7). The lifting cylinder (6) is connected to a vacuum box (5). The fixture (3) is placed on the conveyor belt (2) and moves along with the conveyor belt (2). It is characterized in that: It further includes a negative pressure pump (15). The vacuum box (5) and the fixture (3) cooperate to form an outer cavity (10) and a lamination cavity (11) in a sealed manner. The lamination cavity (11) is located inside the outer cavity (10). A normal negative pressure cavity (9) is provided inside the vacuum box (5). A lamination plate (12) that can move up and down is provided in the lamination cavity (11). The volume of the normal negative pressure cavity (9) is larger than that of the outer cavity (10) and the lamination cavity (11). The normal negative pressure cavity (9) is sealed and maintains a relatively constant negative pressure value. The negative pressure pump (15) can be selectively connected to the normal negative pressure cavity (9), the outer cavity (10), or the lamination cavity (11) through an air extraction valve (16). The outer cavity (10) or the lamination cavity (11) is connected to the atmosphere through an air inlet valve (18). During lamination, the normal negative pressure cavity (9) is connected to the outer cavity (10) through a first ventilation valve (20).

2. The pressing machine for producing mobile phone screens according to claim 1, characterized in that, Two sets of concave sealing structures are provided at the bottom of the vacuum box (5). The two sets of sealing structures form a "hui" character shape. The two sets of sealing structures cooperate with the fixture (3) to form an outer cavity (10) and a lamination cavity (11).

3. A pressing machine for producing mobile phone screens according to claim 1, characterized in that, Two sets of conveyor belts (2) are provided. The two sets of conveyor belts (2) are respectively arranged on both sides of the support table (1). The fixture (3) is placed on the two sets of conveyor belts (2) and enters from one end and exits from the other end along with the conveyor belts (2). A positioning column (8) corresponding to the position of the vacuum box (5) is provided between the two sets of conveyor belts (2). The positioning column (8) can be telescopic.

4. A pressing machine for producing mobile phone screens according to claim 2, characterized in that, The lamination plate (12) is connected to a lamination component (19). The lamination plate (12) is arranged inside the normal negative pressure cavity (9). The lamination component (19) is connected to the lamination plate (12) through a connecting rod. The connecting rod penetrates through the top of the lamination cavity (11) and is connected to the lamination plate (12). The top of the lamination cavity (11) and the connecting rod are sealed by an O-ring.

5. A pressing machine for producing mobile phone screens according to claim 4, characterized in that, The normal negative pressure cavity (9) is connected to the lamination cavity (11) through a second ventilation valve (21). The pressure inside the normal negative pressure cavity (9) is lower than the target value for evacuating the lamination cavity (11). When the pressure inside the lamination cavity (11) is pumped lower than a set value one, the second ventilation valve (21) opens and closes when the lamination cavity (11) reaches the target value.

6. A pressing machine for producing mobile phone screens according to claim 5, characterized in that, After the pressure in the lamination cavity (11) reaches the target value, the negative pressure pump (15) is connected to the normal negative pressure cavity (9) to keep the pressure in the normal negative pressure cavity (9) relatively constant.

7. A pressing machine for producing mobile phone screens according to claim 2, characterized in that, A flat plate (4) is provided at the top of the fixture (3). The flat plate (4) cooperates with the sealing structure at the bottom of the vacuum box (5) to achieve sealing.

8. A pressing machine for producing mobile phone screens according to claim 1, characterized in that, A jacking plate (17) is provided at the bottom of the fixture (3). The jacking plate (17) can be lifted. When the jacking plate (17) rises, it jacks the fixture (3) away from the conveyor belt (2).

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