A sheet material stacking and collecting device and method

Abstract

The application discloses a kind of sheet material stacking collection device and method, to solve the technical problems of low efficiency, labor intensity in prior art, and high cost, poor reliability of automated vision scheme.The device comprises: a plurality of stacking jigs are provided with work position switching mechanism;For pushing sheet material upward, stacking drive part;Stacking jig is provided with one-way stop structure, allow sheet material to pass in one direction and prevent it from falling to form material pile;Discharge stop mechanism;And control system.The control system when stacking jig is full, control discharge stop mechanism pauses feeding, and drive work position switching mechanism to switch empty stacking jig to stacking work position after restoring feeding, realize continuous operation without shutdown.Stacking jig includes substrate, one-way stop structure and opening for external push block to pass through.The application realizes the automatic, low-cost, high-reliability continuous collection of stamping sheet material by multi-station cycle and pure mechanical one-way stacking, significantly improves production efficiency.

Description

Technical Field

[0001] This invention relates to the field of metal stamping post-processing technology, specifically to a sheet material stacking and collecting device and method. Background Technology

[0002] In the metal stamping industry, sheet metal parts produced by high-speed stamping, i.e., sheet metal, typically need to be collected and sorted using a receiving device. Traditional collection methods rely mainly on manual labor, where workers manually pick up and stack the sheet metal at the end of the conveyor line. This method is not only inefficient and difficult to match the production rhythm of high-speed stamping presses, but also suffers from problems such as oil mist, dust, and noise in stamping workshops, resulting in a harsh working environment. This leads to high labor intensity, high safety hazards, and high employee fatigue and turnover rates for manual material handling.

[0003] To address these challenges, automation technology has been introduced into the material receiving process. A common automation solution is to use machine vision-based industrial robots (such as parallel robots) to replace manual labor for grasping and placing. However, this solution has inherent limitations. First, vision systems are extremely sensitive to environmental factors such as changes in lighting, oil mist interference, and equipment vibration, which can easily lead to recognition errors or positioning deviations, affecting the reliability of material receiving. Second, the robot's operation mode of grasping one piece at a time does not fundamentally solve the problem of batch processing and high-efficiency stacking.

[0004] Furthermore, automated solutions involving industrial robots and high-end vision systems have high equipment investment costs, long commissioning cycles, and require highly skilled maintenance personnel, making them unaffordable for many small and medium-sized stamping enterprises. Therefore, there is a significant market gap between existing technologies that offer high-cost, highly complex vision solutions and inefficient, high-intensity manual solutions. There is an urgent need for an innovative solution that is cost-effective, structurally reliable, easy to maintain, and capable of continuous, automated batch stacking. Summary of the Invention

[0005] To address the technical problems of low efficiency and high labor intensity of manual material collection in existing technologies, as well as high cost, poor reliability, and difficulty in achieving efficient batch stacking of automated vision solutions, this invention provides a sheet material stacking and collection device and method, aiming to achieve automated, continuous, low-cost, and highly reliable batch stacking and collection of stamped sheet materials.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A sheet material stacking and collecting device, comprising: A single-station switching mechanism is provided, which has multiple stations, each of which is equipped with a stacking fixture; A stacking drive is provided at a stacking station to push the sheet material into the stacking fixture located at the stacking station upward. The stacking fixture is provided with a one-way stop structure, which allows the sheet material being pushed upward to pass through and prevents the sheet material that has passed through from falling down, so as to form a stack. A material feeding stop mechanism is located upstream of the material stacking station; and A control system is configured to: when the stacking jig at the stacking station is detected to be full, control the feeding stop mechanism to temporarily block the entry of subsequent sheet materials, and control the station switching mechanism to switch an empty stacking jig to the stacking station, and then control the feeding stop mechanism to resume sheet material supply. This scheme achieves uninterrupted continuous material receiving operation through multi-station cycle and coordinated control.

[0007] Furthermore, the workstation switching mechanism is a rotary table with indexable rotation. Using a rotary table as the workstation switching mechanism results in a simple structure, reliable operation, and the ability to accurately switch different stacking fixtures to the designated stacking workstation.

[0008] In one embodiment, the one-way stop structure includes at least one stop block that can rotate about a pivot. The lower front side of the stop block has an inclined surface for the sheet material to push over, and the stop block is configured to automatically reset after the sheet material passes over it. This purely mechanical design uses the upward force of the sheet material itself to trigger the stop block to rotate, and automatically resets and locks itself by gravity or elastic force after passing over it. No additional drive is required, the operation is reliable, and the cost is low.

[0009] Optionally, the stacking fixture is detachably mounted on the workstation switching mechanism, and the stacking fixture is equipped with a handle. This modular design allows the fully loaded fixture to be easily removed and transported as a whole, while the empty fixture can be quickly replaced, greatly improving turnover efficiency and operational convenience.

[0010] Furthermore, the stacking fixture is equipped with a limiting rod extending along the stacking direction of the sheets to circumferentially limit the stacked sheets. By setting the limiting rod, the boundary of the stack can be effectively constrained, preventing the sheets from shifting horizontally or tipping over during the stacking process, thereby ensuring the neatness and stability of the final stack.

[0011] The present invention also provides a method for collecting stacked sheet materials, comprising the following steps: A piece of material is fed into a jig located at a stack of material station; A stacking drive pushes the sheet upward, causing it to pass over a one-way stop structure inside the stacking fixture, and the one-way stop structure prevents it from falling. Repeat the aforementioned steps to stack the sheet materials one by one in the stacking fixture to form a stack; When a full stacking jig is detected, a station switch is executed: the supply of subsequent sheet material is temporarily blocked, and an empty stacking jig is switched to the stacking station via a station switching mechanism. Then, the supply of sheet material to the empty stacking jig is resumed. This method defines the core workflow of automated continuous stacking.

[0012] Specifically, the step of pushing the sheet upwards involves: using a pusher block to move upwards and lift the sheet located within the stacking fixture; the step of detecting that the stacking fixture is full is achieved through sensor detection or a system counter. This provides a clear and feasible technical means for implementing the method.

[0013] In addition, the method includes: at non-stacking stations, removing the fully loaded stacking jig from the station switching mechanism and replacing it with another empty stacking jig. This step allows material transfer and equipment receiving processes to be carried out in parallel, further ensuring production continuity. Beneficial effects

[0014] This invention provides a sheet material stacking and collecting device, which has the following advantages compared with the prior art: This invention solves the problem of single-station equipment requiring downtime for material replacement by setting up a station switching mechanism with multiple workstations and cooperating with a control system to achieve automatic switching after full load. This achieves true continuous automated production and significantly improves the overall efficiency of the material receiving process. Simultaneously, the invention employs a purely mechanical unidirectional stop structure, replacing the expensive and environmentally sensitive vision robot solution, achieving highly reliable piece-by-piece stacking at extremely low cost. The structure is simple and easy to maintain. Furthermore, the detachable fixture design and circumferential limiting structure, all from a practical perspective, improve the ease of use and stacking quality of the device. In summary, this invention provides a complete automated stacking solution that combines economy and reliability. Attached Figure Description

[0015] Figure 1 This is a three-dimensional view of the overall structure of an embodiment of the present invention.

[0016] Figure 2 This is a side view of the overall structure of an embodiment of the present invention.

[0017] Figure 3 This is a three-dimensional structural diagram of the conveying and unloading section in an embodiment of the present invention.

[0018] Figure 4 This is a top view of the workstation switching mechanism and stacking fixture in an embodiment of the present invention.

[0019] Figure 5 This is a perspective view of the operating state of the workstation switching mechanism in an embodiment of the present invention.

[0020] Figure 6 This is a schematic diagram illustrating the installation relationship between the workstation switching mechanism and the stacking fixture in an embodiment of the present invention.

[0021] Figure 7 This is a three-dimensional structural diagram of the stacked jig in an unloaded state according to an embodiment of the present invention.

[0022] Figure 8 This is a three-dimensional structural diagram of the stacked jig in a fully loaded state according to an embodiment of the present invention.

[0023] Figure 9 This is a partially enlarged structural diagram of the sheet material being lifted in preparation for its placement in an embodiment of the present invention.

[0024] Figure 10 This is a partially enlarged structural diagram of the core stacking action of the stacking fixture in an embodiment of the present invention.

[0025] In the diagram: 1-Conveyor line; 11-Guide side guard; 12-Mounting block; 2-Stacking fixture; 21-Base plate; 211-Slotting; 22-One-way stop structure; 221-Side block; 222-Positioning block; 223-Stop block; 2231-Inclined surface; 224-Rotating shaft; 225-Fixing block; 23-Limiting rod; 24-Handle; 3-Stacking drive component; 31-Push block; 4-Rotating table; 41-Gutter; 42-Inclined block; 5-Rotating table drive component; 6-Discharge plate; 61-Linear conveyor trough; 7-Discharge stop mechanism; 71-Stop drive component; 72-Stop block; 8-Sheet material. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0027] Please see Figures 1 to 10 This invention provides a sheet material stacking and collecting device, which is particularly suitable for the automated and continuous collection and stacking of sheet materials 8 produced after the stamping process. In this embodiment, aluminum palladium sheet is used as an example for illustration, but the scope of protection of this invention is not limited to this, and it is also applicable to other metal stamping sheet materials such as connecting pieces and shielding covers. The core idea of ​​this device is to achieve uninterrupted material collection by combining multi-station cyclic switching with a purely mechanical unidirectional stacking structure, thereby significantly reducing automation costs while ensuring high reliability.

[0028] like Figure 1 and Figure 2As shown, the device mainly comprises an upstream feeding section and a downstream tower-type collection unit. The tower-type collection unit is the core for continuous collection, and it includes a station switching mechanism, multiple stacking fixtures 2 mounted on the station switching mechanism, a fixedly mounted stacking drive component 3, a discharge stop mechanism 7, and a control system for coordinating the actions of each component. In this embodiment, the control system can be a programmable logic controller (PLC). Specifically, the station switching mechanism is a rotatable rotary table 4 with multiple stations evenly distributed circumferentially, each station used to install a stacking fixture 2. The stacking drive component 3 is fixedly mounted below one of the stations (i.e., the stacking station), while the discharge stop mechanism 7 is located on the feeding path of the stacking station. This layout allows the rotary table 4 to quickly switch an empty stacking fixture 2 to the stacking station when one stacking fixture 2 is full, without stopping the upstream stamping and conveying, thus achieving seamless connection of the production process.

[0029] To achieve stable conveying and precise feeding of the sheet material, the feeding section of this invention has been specially designed. Please refer to... Figure 3 The feeding section includes a conveyor line 1 and a discharge plate 6 located at its output end. The conveyor line 1 can be a conventional belt conveyor or chain conveyor, its main function being to transport the sheet material 8 produced by the upstream stamping machine along a predetermined direction to the collection unit. To enhance the versatility of the device and accommodate sheet materials 8 of different sizes, guide rails 11 are provided on both sides of the conveyor line 1. These guide rails 11 are connected to the frame of the conveyor line 1 via mounting blocks 12, and the connection between them and the mounting blocks 12 is movable. By adjusting the spacing between the guide rails 11 on both sides, the width of the conveying channel can be flexibly changed, thereby ensuring that sheet materials 8 of different sizes maintain the correct posture and path during conveying, avoiding skewing or jamming. At the end of the conveyor line 1, the sheet material 8 needs to smoothly transition into the stacking fixture 2 below. For this purpose, a discharge plate 6 is provided. Figure 3 As shown, the feed plate 6 is inclined, forming an angle of 15° to 45° with the horizontal conveying surface of the conveyor line 1. This inclination angle utilizes gravity to assist the sheet material 8 in sliding smoothly, achieving a smooth transition from horizontal movement to inclined descent. More importantly, a straight conveying groove 61 is formed along the length of the feed plate 6, and the width of the groove is adapted to the width of the straight conveying channel on the conveyor line 1. When the sheet material 8 leaves the conveyor line 1, it immediately enters the straight conveying groove 61, where the groove wall continuously guides it laterally, ensuring that the sheet material 8 maintains an upright posture throughout its sliding towards the stacking fixture 2, laying a solid foundation for subsequent precise positioning and stacking.

[0030] In this embodiment, the workstation switching mechanism is specifically a rotary table 4, the structure of which is as follows: Figure 4 , Figure 5and Figure 6 As shown, the rotary table 4 is a circular turntable, with its central axis connected to the output shaft of a rotary table drive 5. The rotary table drive 5, such as a servo motor or stepper motor, is controlled by the control system and can drive the rotary table 4 to rotate precisely intermittently according to a preset indexing angle (e.g., 72 degrees if there are five workstations). Through this indexing rotation, different stacking fixtures 2 can be moved sequentially and precisely to fixed stacking workstations.

[0031] On the upper surface of the rotary table 4, multiple fixture mounting positions are evenly distributed circumferentially for detachably mounting the stacking fixture 2. In this embodiment, as... Figure 4 As shown, five fixture mounting positions are provided. The specific structure of each fixture mounting position is as follows: Figure 6 As shown, it includes a through slot 41 formed on the rotary table 4, and at least two inclined blocks 42 disposed outside the slot 41. The inclined surfaces of the inclined blocks 42 form an angle of 15° to 45° with the upper surface of the rotary table 4. The base plate 21 of the stacking fixture 2 is detachably fixedly mounted on the inclined surfaces of these inclined blocks 42. Multiple stacking fixtures 2 are mounted at an angle along the circumference of the rotary table 4. The stacking fixture 2 with its tilt setting can prevent the sheet material 8 from being thrown away by inertial force when the rotary table 4 rotates in increments, thus better limiting and fixing the stacked sheet material 8.

[0032] The stacking drive unit 3 is the power source for realizing the stacking action piece by piece. For example... Figure 5 and Figure 6 As shown, the stacking drive unit 3 (e.g., a cylinder or electric push rod) is fixedly mounted on the frame, located below the rotary table 4, and directly opposite the stacking station. Its output end is connected to a push block 31, which is vertically upward and positioned precisely within the slot 41 of the rotary table 4. When a stacking fixture 2 is rotated to the stacking station, its bottom slot 211 aligns with the slot 41 of the rotary table 4. At this time, under the command of the control system, the stacking drive unit 3 actuates, driving the push block 31 to reciprocate vertically. During upward movement, the push block 31 passes through the slot 41 and the slot 211 in sequence, lifting the sheet material 8 located within the stacking fixture 2 from below, providing the necessary vertical displacement for performing the unidirectional stacking action.

[0033] As a core component for carrying and stacking sheet metal, the structure of the stacking fixture 2 is crucial; its ingenious design is key to achieving low-cost, high-reliability stacking. Please refer to... Figures 7 to 10Let's understand. Each stacking fixture 2 is an independent module, mainly consisting of a base plate 21, a one-way stop structure 22, and multiple limiting rods 23. The base plate 21 is the base of the entire fixture, and its bottom has a slot 211 for the push block 31 to pass through. To facilitate manual operation, the base plate 21 is designed to be detachably mounted on the fixture mounting position of the rotary table 4, and handles 24 are specially provided on both sides of its upper part. This design allows the operator to easily grasp the handles 24 when the fixture is fully loaded, lift the entire fully loaded fixture, which weighs several kilograms, from the rotary table 4 and transport it to the next process, while quickly replacing it with an empty fixture. The entire process does not require any tools, greatly improving the convenience and safety of operation.

[0034] One of the core innovations of this invention lies in the one-way stop structure 22, which achieves one-way passage and self-locking of the sheet material in a purely mechanical manner. For example... Figure 7 and Figure 9 As shown, the one-way stop structure 22 is disposed on the substrate 21, located on both sides of the movement path through which the sheet material 8 is lifted. It includes two side stops 221 respectively disposed on the left and right sides of the substrate 21, a positioning block 222 disposed at the front end, and two rotatable stops 223. The two side stops 221 and the positioning block 222 together constitute a positioning part for initially receiving and positioning the sheet material 8. After the sheet material 8 slides from the unloading plate 6 into the positioning part, its left and right sides are limited by the two side stops 221, and its front is limited by the positioning block 222. The key lies in the design of the rotatable stops 223. Figure 9 and Figure 10 As shown, each stop 223 is rotatably connected to a fixed block 225 via a horizontally positioned pivot 224, and the fixed block 225 is fixed to the upper part of the side stop 221. The front end of the stop 223 can freely rotate around the pivot 224, and its front end facing the surface of the substrate 21 is designed as a slope 2231. When the sheet material 8 is pushed upward by the push block 31 below, its edge contacts and pushes this slope 2231, causing the stop 223 to rotate upward around the pivot 224, thereby clearing a path for the sheet material 8. After the sheet material 8 has completely passed the stop 223, the stop 223 will automatically rotate in the opposite direction around the pivot 224 and return to its initial horizontal blocking position under its own weight or under the action of a return spring (not shown). At this time, if the push block 31 descends to reset, the lifted sheet material 8 will be supported by the reset stop 223 and will not fall, thus remaining stably above the stop 223, completing the single-sheet stacking. This purely mechanical ratchet structure is simple and reliable in operation, requiring no additional sensors or actuators, which greatly reduces costs and failure rates.

[0035] To ensure the neatness and stability of the multi-layer sheet material 8 after stacking (forming a stack), such as Figure 7 and Figure 8As shown, multiple cylindrical limiting rods 23 are vertically fixed to the upper ends of the side blocks 221 and the positioning blocks 222. These limiting rods 23 together form a limiting space that matches the shape of the sheet material 8. During the stacking process, the circumferential edge of each sheet material 8 is constrained by these limiting rods 23, thereby effectively preventing the stack from shifting horizontally, misaligning, or tipping over during stacking, ensuring that the final collected stack is neat and uniform, facilitating subsequent packaging or processing.

[0036] To ensure that the continuously supplied sheet material 8 does not fall into the gap of the rotary table 4 or cause accumulation and disorder during the brief intervals between workstations, this device is also equipped with a feeding stop mechanism 7. For example... Figure 3 As shown, the mechanism is located above the feed plate 6 and includes a stop drive 71 (such as a small cylinder) and a stop block 72 connected to its output end. During normal stacking, the stop block 72 is in the retracted position and does not interfere with the downward movement of the sheet material 8. When the control system detects that the current station's stacking fixture 2 is full and is ready to perform a station switch, it first issues a command to the stop drive 71, causing it to drive the stop block 72 to extend and enter the linear conveyor trough 61, thereby temporarily blocking the subsequent downward movement of the sheet material 8. This action creates a safe time window during which the rotary table 4 can smoothly complete the rotation switch.

[0037] The following describes in detail the sheet material stacking and collection method provided by the present invention, based on the above structure. This method fully embodies the collaborative workflow of the various components of the device. The first step is the feeding and single-sheet stacking process. Initially, an unloaded stacking fixture 2 on the rotary table 4 is located at the stacking station, aligned with the output end of the conveyor line 1. The sheet material 8 produced by the upstream stamping machine falls into the conveyor line 1 and is conveyed to the end under the guidance of the guide flange 11. Then, it slides along the straight conveying groove 61 of the unloading plate 6 into the positioning part of the stacking fixture 2. When the photoelectric sensor (not shown) located in the positioning part detects that the sheet material 8 has arrived, it sends a signal to the control system (e.g., PLC). The control system then instructs the stacking drive 3 to start, driving the pusher block 31 to move rapidly upward. The pusher block 31 extends from the slot 211 of the substrate 21, lifting the sheet material 8 upward. During the upward movement, the edge of the sheet material 8 pushes the inclined surfaces 2231 of the side stops 223, causing the stops 223 to flip upward. Once the bottom surface of sheet 8 has completely passed the top of stop 223, stop 223 automatically resets. Immediately afterwards, the control system instructs the stacking drive 3 to move in the opposite direction, causing push block 31 to reset downwards. The lifted sheet 8 is then firmly held by the reset stop 223, suspended above the positioning section, completing the stacking of the first sheet. Subsequent sheets 8 repeat this process, being lifted and stacked sequentially on top of the previous sheet, thus continuously increasing the height of the stack.

[0038] When the stack reaches a preset height or quantity, it means that the current stacking fixture 2 is fully loaded. The full-load signal can be detected in several ways. For example, a photoelectric sensor can be installed on the top of the fixture, triggering a signal when the top of the stack blocks light; or, the control system can have a built-in counter that increments by one for each stacking operation, determining full load when the count reaches a preset value (e.g., 50 pieces). Both methods can reliably achieve full-load detection.

[0039] Once full load is detected, the control system immediately executes the station switching procedure. First, it controls the feeding stop mechanism 7 to extend its stop block 72, temporarily blocking the subsequent sheet material supply on the feeding plate 6 to prevent material spillage during the switching process. Second, after confirming that the material supply has stopped, the control system instructs the rotary table drive 5 to start, driving the rotary table 4 to rotate precisely by one indexing angle, accurately switching an empty stacking fixture 2 to the stacking station. Third, once the new empty fixture is in place, the control system immediately instructs the feeding stop mechanism 7 to reset, its stop block 72 retracts, restoring sheet material supply to the new fixture, and the device then begins a new round of stacking cycles in the new fixture.

[0040] While the device automatically switches workstations and continues production, the previously fully loaded stacking fixture 2 has been rotated to a non-working area. At this point, the operator can easily approach the equipment, disassemble the fully loaded fixture, grasp its handle 24, remove it from the rotary table 4, and place a new empty fixture into the vacant fixture mounting position. This manual material change is performed in parallel with the automated stacking and switching process of the equipment, without interference. Through the aforementioned cycle of "automatic stacking - full load detection - pause feeding - rotation switching - resume feeding - manual material change," this invention ultimately achieves a continuous and highly efficient automated sheet material stacking and collection operation that does not interrupt upstream production.

Claims

1. A sheet material stacking and collecting device, characterized in that, include: A workstation switching mechanism is provided, wherein the workstation switching mechanism is provided with multiple workstations, and each workstation is provided with a stacking fixture; A stacking drive is provided at a stacking station to push the sheet material entering the stacking fixture located at the stacking station upward; the stacking fixture is provided with a one-way stop structure, which allows the sheet material being pushed upward to pass through and prevents the sheet material that has passed through from falling down, so as to form a stack. A material feeding stop mechanism is located upstream of the material stacking station; and A control system is configured to: when it detects that the stacking fixture located at the stacking station is fully loaded, control the unloading stop mechanism to temporarily block the entry of subsequent sheet materials, and control the station switching mechanism to switch an empty stacking fixture to the stacking station, and then control the unloading stop mechanism to resume sheet material supply.

2. The sheet material stacking and collecting device according to claim 1, characterized in that, The workstation switching mechanism is a rotary table that can be indexed and rotated.

3. The sheet material stacking and collecting device according to claim 1, characterized in that, The one-way stop structure includes at least one stop block that can be rotated around a pivot. The lower front end of the stop block is provided with an inclined surface for the sheet material to be pushed, and the stop block is configured to automatically reset after the sheet material passes over it.

4. The sheet material stacking and collecting device according to claim 1, characterized in that, The stacking fixture is detachably mounted on the workstation switching mechanism.

5. The sheet material stacking and collecting device according to claim 4, characterized in that, The stacking fixture is equipped with a handle.

6. The sheet material stacking and collecting device according to claim 1, characterized in that, The stacking fixture is provided with a limiting rod extending along the stacking direction of the sheet materials, which is used to circumferentially limit the stacked sheet materials.

7. The sheet material stacking and collecting device according to claim 1, characterized in that, It also includes a feeding conveying system, which includes a conveyor line and a discharge plate; the conveyor line is used to convey the sheet material to the discharge plate, and the discharge plate is used to guide the sheet material to slide into the stacking fixture.

8. A method for collecting stacked sheet material according to any one of claims 1 to 7, characterized in that, Includes the following steps: A piece of material is fed into a jig located at a stack of material station; The sheet material is pushed upward by a stacking drive component, so that it passes through a one-way stop structure inside the stacking fixture, and the one-way stop structure prevents it from falling. Repeat the aforementioned steps to stack the sheet materials one by one in the stacking fixture to form a stack; When the stacking jig is detected to be full, a station switch is performed: the supply of subsequent sheet material is temporarily blocked, an empty stacking jig is switched to the stacking station through a station switch mechanism, and then the sheet material supply to the empty stacking jig is restored.

9. The method for collecting stacked sheet materials according to claim 8, characterized in that, The step of pushing the sheet material upwards specifically involves: using a pusher block to move upwards and lift the sheet material located inside the stacking fixture; the step of detecting that the stacking fixture is fully loaded is achieved by sensor detection or PLC counter counting.

10. The method for collecting stacked sheet materials according to claim 8, characterized in that, The method further includes: at a non-stacking station, removing the fully loaded stacking fixture from the station switching mechanism and replacing it with another empty stacking fixture.

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