Contact lens uv light curing apparatus

Abstract

The utility model relates to contact lens automation production technical field, concretely is a kind of contact lens UV light solid equipment, including feeding station, light solid host computer and discharging station, its characterized in that, gas injection and exhaust mechanism is equipped on the light solid host computer, the feeding place and the discharge of light solid host computer are all provided with airtight mechanism, the curing conveying line that does not protrude light solid host computer is provided in the light solid host computer;The starting end of the curing conveying line is located at the feeding place of light solid host computer, and the termination of curing conveying line is located at the discharge of light solid host computer;The present contact lens UV light solid equipment improves the stability of light solid host computer internal environment, reduces oxygen content, reduces oxygen inhibition effect, reduces the influence of high temperature on curing operation, improves curing quality;Realize the light solid operation of automation, reduce the proportion of manual operation, improve curing efficiency, reduce artificial cost and the quality fluctuation caused by factor, ensure the quality high consistency of contact lens product.

Description

Technical Field

[0001] This utility model relates to the field of automated production technology of contact lenses, specifically a UV curing device for contact lenses. Background Technology

[0002] UV curing of contact lenses is a crucial step in the entire contact lens manufacturing process. Conventional curing methods are prone to oxygen inhibition, a phenomenon where oxygen suppresses the polymerization reaction during photocuring or free radical polymerization. Oxygen, acting as a free radical scavenger, hinders the reaction through three mechanisms: quenching excited-state photoinitiators, combining with active free radicals to form peroxides, and oxidizing already polymerized free radicals. This results in incomplete curing of the (contact lens) cured layer surface and a decline in performance.

[0003] Chinese invention patent document CN113968485B discloses an automatic loading and unloading curing device, comprising a loading module, a curing module, and an unloading module arranged sequentially. The loading module is equipped with a carrier for placing workpieces. A first XYZ axis conveying mechanism is provided between the loading module and the curing module. The curing module has a high-temperature channel and a downstream conveying component that passes through the high-temperature channel. A return conveying component is correspondingly provided below the downstream conveying component. The transport length of the return conveying component is greater than that of the downstream conveying component. A second XYZ axis conveying mechanism is provided between the curing module and the unloading module. This structure operates smoothly, has a high degree of automation, is easy to operate, saves labor and time costs, and is highly practical.

[0004] The existing technology involves baking and curing components, which has a certain degree of automation. However, for UV curing of contact lenses, this technology relies on temperature curing. The curing module of this technology is connected to the outside air, making it impossible to control the oxygen concentration. Furthermore, there are other transfer and handling devices between the feeding module and the curing module, resulting in a complex overall structure. Therefore, the existing technology and its specific structure cannot meet the UV curing requirements of the contact lens industry.

[0005] Therefore, in order to meet market demands, a solution is urgently needed. Utility Model Content

[0006] The purpose of this invention is to provide a UV curing device for contact lenses, which improves the stability of the internal environment of the curing host, reduces oxygen content, reduces oxygen inhibition effect, reduces the impact of high temperature on curing operation, and improves curing quality; realizes automated curing operation, reduces the proportion of manual operation, improves curing efficiency, reduces labor costs and factors causing quality fluctuations, and ensures a high degree of consistency in the quality of contact lens products.

[0007] To achieve the above objectives, the present invention provides the following technical solution.

[0008] A UV curing device for contact lenses includes a feeding station, a curing host, and an unloading station. The curing host is characterized by a gas injection and discharge mechanism, and both its inlet and outlet are equipped with sealing mechanisms. A curing conveyor line that does not extend beyond the curing host is installed inside the device. The starting end of the curing conveyor line is located at the inlet of the curing host, and the ending end is located at the outlet of the curing host.

[0009] During loading, the sealing mechanism opens, and the loading station drives the carrier to extend into the curing host and place the carrier at the curing conveyor line; during curing, the sealing mechanism closes, and the gas injection and discharge mechanism releases protective gas and low-temperature gas; during unloading, the sealing mechanism opens, and the unloading station removes the carrier containing the cured material from the curing conveyor line inside the curing host.

[0010] Furthermore, both the inlet and outlet of the optical curing host are provided with sealing guide grooves; the sealing mechanism includes a sealing plate driving device installed on the optical curing host and a sealing plate driven and connected to the execution end of the sealing plate driving device; the sealing plate is slidably assembled in the sealing guide groove.

[0011] Furthermore, the gas injection and discharge mechanism includes an air heat exchange component installed on the optical-solidification host, multiple gas injection components installed on the optical-solidification host and connected to the gas storage device, and a gas collection device installed inside the optical-solidification host and connected to the gas injection components.

[0012] When adding gas, the sealing mechanism closes, and the gas injection component introduces the protective gas from the gas storage device into the gas collection device. The gas collection device releases the protective gas into the UV curing host, and the air heat exchange component injects low-temperature gas into the UV curing host to control the curing temperature and cool the cured material.

[0013] Furthermore, the top of the optical curing host has an air passage hole, and the air heat exchange component is covered and installed at the air passage hole, and the air heat exchange component is connected to the interior of the optical curing host.

[0014] Furthermore, the feeding station includes a frame, on which a carrier transport mechanism and a carrier transfer mechanism are also installed. The carrier transport mechanism transports the carrier carrying the material to be cured to the carrier transfer mechanism, and the carrier transfer mechanism extends the carrier carrying the material to be cured into the feeding end of the light curing host and places it at the curing conveyor line.

[0015] Furthermore, the vehicle transport mechanism includes a transport lifting drive device and a transport horizontal drive device, and the execution end of the transport horizontal drive device is driven to be connected to a vehicle clamping device.

[0016] During loading, the transport lifting drive device drives the carrier to the loading point of the curing host, and the transport horizontal drive device drives the carrier clamping device to the transport lifting drive device. The carrier clamping device grabs the carrier carrying the material to be cured and places it at the carrier transfer mechanism.

[0017] Furthermore, the vehicle transfer mechanism includes an adjustment lateral movement drive device, an adjustment lifting drive device and a transfer lifting drive device that are driven and connected to the execution end of the adjustment lateral movement drive device, and a transfer lateral movement drive device that is driven and connected to the execution end of the transfer lifting drive device; the execution end of the adjustment lifting drive device is provided with an adjustment frame, and the execution end of the transfer lateral movement drive device is provided with a transfer seat.

[0018] During transfer, the adjustment lifting drive device adjusts the adjustment frame to the specified height, the carrier transport mechanism places the carrier at the adjustment frame, and the adjustment lateral drive device drives the adjustment lifting drive device and the transfer lifting drive device to extend into the light curing host; the transfer lifting drive device and the transfer lateral drive device work together to drive the transfer seat, transferring the carrier from the point where the adjustment frame is raised to the curing conveyor line.

[0019] Furthermore, the curing host is also equipped with curing lamps located on both sides of the curing conveyor line.

[0020] Furthermore, both the loading and unloading stations are equipped with material handling devices for handling materials in the carrier.

[0021] Furthermore, a carrier return station is also installed between the loading station and the unloading station. The carrier return station is located outside the optical solidification host and is used to move the empty carrier at the unloading station to the loading station.

[0022] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0023] In practical use, the enclosed mechanism prevents dust, debris, temperature, and other gases from affecting the UV curing process, improving the stability of the internal environment of the UV curing unit. The gas injection and discharge mechanism connects to the external protective gas, injecting protective gas into the UV curing unit to reduce oxygen content and decrease oxygen inhibition. Furthermore, the gas injection and discharge mechanism can control the temperature, reducing the impact of high temperatures on the curing process and improving curing quality. The loading and unloading stations, combined with the curing conveyor line inside the UV curing unit, enable automated placement and retrieval of carriers, achieving automated UV curing, reducing the proportion of manual labor, and improving curing efficiency. Overall, this improves the efficiency of UV curing for contact lenses, reduces labor costs and quality fluctuations caused by factors, and ensures a high degree of consistency in the quality of contact lens products. Attached Figure Description

[0024] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0025] Figure 2 This is a three-dimensional structural diagram of the optical-solidification host in this utility model;

[0026] Figure 3 for Figure 2 Partial schematic diagram at point A in the middle;

[0027] Figure 4 for Figure 2 Partial schematic diagram at point B in the middle;

[0028] Figure 5 This is a three-dimensional structural diagram of the feeding station in this utility model;

[0029] Figure 6 This is a schematic diagram of the planar structure of the loading station in this utility model. Detailed Implementation

[0030] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0031] refer to Figure 1-6 As shown, a UV curing device for contact lenses includes a feeding station 1, a curing host 2, and a discharging station 7. The curing host 2 is characterized by having a gas injection and discharge mechanism 3, and both the inlet and outlet of the curing host 2 are equipped with sealing mechanisms 4. A curing conveyor line 21, which does not extend beyond the curing host 2, is installed inside the curing host 2. The starting end of the curing conveyor line 21 is located at the inlet of the curing host 2, and the ending end of the curing conveyor line 21 is located at the outlet of the curing host 2.

[0032] During loading, the sealing mechanism 4 opens, and the loading station 1 drives the carrier 5 to extend into the curing host 2 and place the carrier 5 on the curing conveyor line 21; during curing, the sealing mechanism 4 closes, and the gas injection and discharge mechanism 3 injects protective gas and low temperature gas; during unloading, the sealing mechanism 4 opens, and the unloading station 7 removes the carrier 5 carrying the cured material from the curing conveyor line 21 inside the curing host 2.

[0033] This UV curing equipment for contact lenses features a sealed mechanism 4 to prevent dust, debris, temperature, and other gases from affecting the curing process, thus improving the stability of the internal environment of the curing unit 2 during the curing process. A gas injection and discharge mechanism 3 connects to an external protective gas source, injecting protective gas into the curing unit 2 to reduce oxygen content and minimize oxygen inhibition. The gas injection and discharge mechanism 3 also controls the temperature, reducing the impact of high temperatures on the curing process and improving curing quality. The loading station 1 and unloading station 7, combined with the curing conveyor line 21 located inside the curing unit 2, enable automated placement and pickup of the carriers 5, achieving automated curing operations, reducing the proportion of manual labor, and improving curing efficiency. Overall, this improves the efficiency of UV curing operations for contact lenses, reduces labor costs and quality fluctuations caused by factors, and ensures a high degree of consistency in the quality of contact lens products.

[0034] In this embodiment, both the inlet and outlet of the optical curing host 2 are provided with sealing guide grooves 22; the sealing mechanism 4 includes a sealing plate driving device 41 installed on the optical curing host 2 and a sealing plate 42 drivenly connected to the execution end of the sealing plate driving device 41; the sealing plate 42 is slidably assembled in the sealing guide groove 22.

[0035] Specifically, the sealing plate drive device can be an electric cylinder. The sealing plate 42 and the sealing guide groove 22 can seal the inlet and outlet, avoid the exchange of air inside and outside the internal light curing host 2, reduce pollution and temperature difference caused by air flow, and improve the quality of contact lens light curing operation.

[0036] In this embodiment, the gas injection and discharge mechanism 3 includes an air heat exchange component 31 installed on the curing host 2, multiple gas injection components 32 installed on the curing host 2 and connected to the gas storage device, and a gas collection device 33 installed inside the curing host 2 and connected to the gas injection components 32. When injecting gas, the sealing mechanism 4 is closed, the gas injection component 32 introduces the protective gas in the gas storage device into the gas collection device 33, the gas collection device 33 releases the protective gas into the curing host 2, and the air heat exchange component 31 injects low-temperature gas into the curing host 2 to control the curing temperature and cool the cured material.

[0037] Specifically, the gas injection and discharge mechanism 3 regulates temperature by adjusting the flow rate ratio of inert gas and temperature-controlled gas. The air heat exchange component 31 can be a system including a condenser and a fan. The gas injection and discharge mechanism 3, in conjunction with the gas filling component 32, controls the oxygen concentration and temperature within the photocuring host 2. Nitrogen is preferably used as the protective gas to ensure that the oxygen concentration in the chamber is maintained at a low level (e.g., ≤50ppm) and the temperature is controlled at a low level (e.g., below 50℃) during photocuring. At the end of curing, rapid cooling can be performed to quickly lower the product temperature to a lower level (e.g., below 35℃).

[0038] Specifically, the four-stage gas circulation system (intake → distribution → monitoring → recovery) in the gas injection and discharge mechanism 3 dynamically adjusts the nitrogen concentration (fluctuation value ≤5ppm) through a PID algorithm, reducing energy consumption by 60% compared to the traditional replacement method; the cavity is protected by double-layer stainless steel sealing to prevent ultraviolet light penetration and nitrogen leakage. Internal cooling and intelligent real-time temperature control keep the temperature below 50℃.

[0039] In this embodiment, the top of the optical curing host 2 is provided with an air passage hole 23, and the air heat exchange component 31 is covered and installed at the air passage hole 23. The air heat exchange component 31 is connected to the interior of the optical curing host 2 through the air passage hole 23.

[0040] In this embodiment, the loading station 1 includes a frame 11, on which a carrier transport mechanism 12 and a carrier transfer mechanism are also installed. The carrier transport mechanism 12 transports the carrier 5 carrying the material to be cured to the carrier transfer mechanism. The carrier transfer mechanism extends the carrier 5 carrying the material to be cured into the feeding end of the light curing host 2 and places it at the curing conveyor line 21.

[0041] Specifically, the feeding action is broken down into the adjustment action in the preparation stage and the transfer action at the curing conveyor line 21; the carrier handling mechanism 12 is responsible for the adjustment action, so that the carrier can adapt to various feeding methods and scenarios, and the carrier transfer mechanism can make the carrier adapt to the optical curing host 2 and curing conveyor line 21 with different height specifications.

[0042] In this embodiment, the carrier transport mechanism 12 includes a transport lifting drive device 121 and a transport horizontal drive device 122. The execution end of the transport horizontal drive device 122 is driven to connect to the carrier clamping device 123. During loading, the transport lifting drive device 121 drives the carrier 5 to the loading point of the optical curing host 2, and the transport horizontal drive device 122 drives the carrier clamping device 123 to the transport lifting drive device 121. The carrier clamping device 123 grabs the carrier 5 and places it at the carrier transfer mechanism.

[0043] Specifically, both the lifting and conveying drive device 121 and the horizontal conveying drive device 122 can be linear motor modules, and the carrier clamping device 123 can be an electric cylinder driven gripper used to clamp the carrier 9. The carrier conveying mechanism 12 is used for the first positioning and assistance of the material to be solidified. Under the coordinated work of the lifting and conveying drive device 121 and the horizontal conveying drive device 122, the carrier clamping device 123 is driven to operate the carrier 5. The lifting and conveying drive device 121 can be adapted to various feeding methods, such as stacked carriers carried manually or mobile carriers in conjunction with automatic conveyor lines, which can transport the carrier 5 to the carrier transfer mechanism, improve the overall adaptability, and adapt to various production line scenarios.

[0044] In this embodiment, the vehicle transfer mechanism includes an adjustment lateral movement drive device 13, an adjustment lifting drive device 14 and a transfer lifting drive device 15 drivenly connected to the execution end of the adjustment lateral movement drive device 13, and a transfer lateral movement drive device 16 drivenly connected to the execution end of the transfer lifting drive device 15; the execution end of the adjustment lifting drive device 14 is provided with an adjustment frame 141, and the execution end of the transfer lateral movement drive device 16 is provided with a transfer seat 161;

[0045] During the transfer, after adjusting the lifting drive device 14 to adjust the adjustment frame 141 to the specified height, the carrier transport mechanism 12 places the carrier 5 at the adjustment frame 141. The adjusting lateral drive device 13 drives the adjusting lifting drive device 14 and the transfer lifting drive device 15 to extend into the light curing host 2. The transfer lifting drive device 15 and the transfer lateral drive device 16 work together to drive the transfer seat 161 to transfer the carrier 5 from the lifted position of the adjustment frame 141 to the curing conveyor line 21.

[0046] Specifically, the adjustment lateral drive device 13 can be a linear motor module, the adjustment lifting drive device 14 and the transfer lifting drive device 15 can be electric cylinders, and the transfer lateral drive device 16 can be a rodless cylinder; the carrier transfer mechanism is used to transfer the carrier 5 from outside the light-curing host 2 to the curing conveyor line 21 inside the light-curing host 2.

[0047] The process involves two adjustments. The first adjustment involves the adjustment lifting drive 14 moving the adjustment frame 141 to a designated position to receive the carrier 5 carrying the material to be cured, which is transported by the carrier transport mechanism 12. Then, the adjustment lifting drive 14 and the adjustment lateral drive 13 work together to move the carrier 5 into the curing host 2. This ensures that the loading station 1 can accommodate curing hosts 2 of various sizes and heights, improving compatibility. The second adjustment is the transfer process, where the transfer lifting drive 15 and the transfer lateral drive 16 work together to drive the transfer seat 161, transferring the carrier 5 to the curing conveyor line 21. This achieves precise transfer and placement of the carrier 5, allowing the loading station 1 to accommodate curing conveyor lines 21 of different heights.

[0048] In this embodiment, the unloading station 7 has the same structure as the loading station 1. The only difference is that the unloading station 7 takes out the carrier 5 from the optical curing host 2. Therefore, this application will not elaborate further.

[0049] In this embodiment, the curing host 2 is also equipped with curing lamp groups 24 located on the upper and lower sides of the curing conveyor line 21. Specifically, a double-layer optical path design is adopted, with two groups in one layer. Each group of single lamps consists of 8 groups of high-power UV-LED light area arrays, and the light intensity uniformity reaches more than 95%. Combined with the movement of the carrier (the rotation speed is adjustable from 5 to 30 rpm), the irradiance deviation of the lens surface is achieved to be <5%.

[0050] In this embodiment, both the loading station 1 and the unloading station 7 are equipped with material handling devices for handling materials in the carrier 5.

[0051] Specifically, the material handling device is used to pick up and place contact lens materials in carrier 5. It can employ devices including but not limited to suction cups or grippers to achieve the replenishment and collection of materials at the very end.

[0052] In this embodiment, a carrier return station 6 is also installed between the loading station 1 and the unloading station 7. The carrier return station 6 is located outside the photocuring host 2. The carrier return station 6 moves the photocured carrier 5 from the unloading station 7 to the loading station 1. Specifically, through the closed-loop system of "loading → curing → unloading → empty carrier return", a single machine's daily production capacity of over 100,000 pieces is achieved, which is twice that of traditional equipment.

[0053] The material handling device at the unloading station 7 takes the solidified material out of the carrier 5, and the unloading station 7 moves the empty carrier 5 to the carrier return station 6; the carrier return station 6 moves the empty carrier 5 to the loading station 1; after the loading station 1 picks up the empty carrier 5, the material handling device at the loading station 1 places the material to be solidified into the empty carrier 5 at the loading station 1.

[0054] Specifically, the carrier return station 6, in conjunction with the material handling device, enables the carrier 5 to move and rotate between the unloading station 7 and the loading station 1, thereby improving the utilization rate of the carrier 5, reducing the time cost of the carrier 5 under manual operation, and further enhancing the overall curing efficiency and automation level.

[0055] This equipment achieves a daily production capacity of 100,000 UV curing lenses per machine through the coordinated operation of five major modules, significantly reducing labor costs and quality fluctuations caused by human factors. Through intelligent control, it achieves a high degree of consistency in lens quality and is suitable for the production of UV curing sections for lenses made of various materials such as silicone hydrogel and hydrogel. It truly embodies green intelligent manufacturing, with technologies such as nitrogen circulation and LED energy saving, reducing the carbon footprint by 60% compared to traditional production lines.

[0056] The specific embodiments described herein are merely illustrative examples illustrating the spirit of this utility model. Those skilled in the art to which this utility model pertains may make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the scope defined by the spirit of this utility model.

Claims

1. A UV curing device for contact lenses, characterized in that, It includes a feeding station (1), a curing host (2) and a discharging station (7). The curing host (2) is equipped with a gas injection and discharge mechanism (3). The feeding port and the discharging port of the curing host (2) are both equipped with a sealing mechanism (4). The curing host (2) is equipped with a curing conveyor line (21) that does not extend out of the curing host (2). The starting end of the curing conveyor line (21) is located at the feeding port of the curing host (2), and the ending end of the curing conveyor line (21) is located at the discharging port of the curing host (2). When loading, the sealing mechanism (4) opens, and the loading station (1) drives the carrier (5) to extend into the curing host (2) and place the carrier (5) on the curing conveyor line (21); when curing, the sealing mechanism (4) closes, and the gas injection and discharge mechanism (3) injects protective gas and low temperature gas; when unloading, the sealing mechanism (4) opens, and the unloading station (7) takes the carrier (5) carrying the cured material out from the curing conveyor line (21) in the curing host (2).

2. The UV curing device for contact lenses according to claim 1, characterized in that, The light-curing host (2) is provided with sealing guide grooves (22) at both the inlet and outlet; the sealing mechanism (4) includes a sealing plate drive device (41) installed on the light-curing host (2) and a sealing plate (42) driven and connected to the execution end of the sealing plate drive device (41); the sealing plate (42) is slidably assembled in the sealing guide groove (22).

3. The UV curing device for contact lenses according to claim 1, characterized in that, The gas injection and discharge mechanism (3) includes an air heat exchange component (31) installed on the optical solid-state host (2), a plurality of gas injection components (32) installed on the optical solid-state host (2) and connected to the gas storage device, and a gas collection device (33) installed inside the optical solid-state host (2) and connected to the gas injection components (32). When adding gas, the sealing mechanism (4) is closed, the gas injection component (32) introduces the protective gas in the gas storage device into the gas collection device (33), the gas collection device (33) releases the protective gas into the light curing host (2), and the air heat exchange component (31) injects low temperature gas into the light curing host (2) to control the curing temperature and cool down the cured material.

4. The UV curing device for contact lenses according to claim 3, characterized in that, The top of the optical curing host (2) is provided with an air passage hole (23), and the air heat exchange component (31) is covered and installed at the air passage hole (23). The air heat exchange component (31) is connected to the interior of the optical curing host (2) through the air passage hole (23).

5. The UV curing device for contact lenses according to claim 1, characterized in that, The loading station (1) includes a frame (11), and a carrier transport mechanism (12) and a carrier transfer mechanism are also installed on the frame (11). The carrier transport mechanism (12) transports the carrier (5) carrying the material to be cured to the carrier transfer mechanism. The carrier transfer mechanism extends the carrier (5) carrying the material to be cured into the feeding end of the light curing host (2) and places it on the curing conveyor line (21).

6. The UV curing device for contact lenses according to claim 5, characterized in that, The vehicle transport mechanism (12) includes a transport lifting drive device (121) and a transport horizontal drive device (122), and the execution end of the transport horizontal drive device (122) is driven to be connected to a vehicle clamping device (123). During loading, the transport lifting drive device (121) drives the carrier (5) to the loading point of the light curing host (2), and the transport horizontal drive device (122) drives the carrier clamping device (123) to the transport lifting drive device (121). The carrier clamping device (123) grabs the carrier (5) carrying the material to be cured and places it at the carrier transfer mechanism.

7. The UV curing device for contact lenses according to claim 5, characterized in that, The vehicle transfer mechanism includes an adjustment lateral drive device (13), an adjustment lifting drive device (14) and a transfer lifting drive device (15) driven by the execution end of the adjustment lateral drive device (13), and a transfer lateral drive device (16) driven by the execution end of the transfer lifting drive device (15); the execution end of the adjustment lifting drive device (14) is provided with an adjustment frame (141), and the execution end of the transfer lateral drive device (16) is provided with a transfer seat (161). During the transfer, the lifting drive device (14) is adjusted to the height of the adjustment frame (141), the carrier transport mechanism (12) places the carrier (5) at the adjustment frame (141), and the lateral movement drive device (13) drives the lifting drive device (14) and the transfer lifting drive device (15) to extend into the light curing host (2); the transfer lifting drive device (15) and the transfer lateral movement drive device (16) work together to drive the transfer seat (161) to lift the carrier (5) from the adjustment frame (141) and transfer it to the curing conveyor line (21).

8. The UV curing device for contact lenses according to claim 1, characterized in that, The curing host (2) is also equipped with a curing lamp group (24).

9. A UV curing device for contact lenses according to claim 1, characterized in that, Both the loading station (1) and the unloading station (7) are equipped with material handling devices for handling contact lens materials in the carrier (5).

10. A UV curing device for contact lenses according to any one of claims 1-9, characterized in that, A carrier return station (6) is also provided between the loading station (1) and the unloading station (7). The carrier return station (6) is located outside the optical solidification host (2). The carrier return station (6) is used to move the empty carrier (5) at the unloading station (7) to the loading station (1).

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