A feeding device of a wood sander

Abstract

The application discloses a feeding device of a wood sander and relates to the technical field of wood processing automation equipment. The feeding device comprises a rack, a lifting mechanism arranged at the lower end of the inside of the rack, a middle layer plate fixedly arranged at the lower end of the inside of the rack, a supporting plate arranged above the lifting mechanism and used for stacking wood plates, a centering mechanism arranged at the top end of the middle layer plate, two centering push plates symmetrically arranged at the middle part of the upper end of the rack, a plurality of guide balls rotatably arranged on the opposite sides of the two centering push plates, a feeding mechanism arranged at one side of the top end of the rack, and a rubber-coated friction wheel arranged at the end of the feeding mechanism. The wood plate is lifted by the lifting mechanism, the friction wheel is constantly pushed by the cylinder linkage, the proportional valve is used for real-time pressure regulation and self-adapting thickness change, the centering push plate is synchronously clamped by the bidirectional ball screw drive, sliding friction is converted into rolling friction, and the three parts are cooperatively used to form a self-adapting channel, so that deviation and biting of the wood plate are eliminated.

Description

Technical Field

[0001] This application relates to the field of automated wood processing equipment, and in particular to a feeding device for a wood sander. Background Technology

[0002] Sanding and polishing are indispensable physical processing steps in wood surface treatment. They aim to remove uneven parts of the material surface through physical cutting, making it uniform in thickness and smooth in order to meet the requirements of subsequent high-precision processing processes such as veneering and painting.

[0003] Traditional wood sanders typically use a single-sided cylinder push plate for lateral positioning, with a spring-loaded rigid roller providing longitudinal driving force. Because the lateral clamping force and the longitudinal feeding force are physically coupled, the single-sided thrust acting on the side of the wood board will generate a yaw moment around the center of gravity of the wood board. This causes the wood board to rotate in the plane when it enters the sander, making it difficult to ensure that the longitudinal center line coincides with the sander's feed axis. This results in defects such as skewing, scratches, or even jamming of the spindle. Summary of the Invention

[0004] In order to improve the problem that the unilateral thrust in traditional devices causes the wood board to deflect or even jam the main shaft, this application provides a feeding device for a wood sander.

[0005] The feeding device for a wood sander provided in this application adopts the following technical solution:

[0006] A feeding device for a wood sander includes a frame and a lifting mechanism located at the lower end of the frame. A middle layer plate is fixed inside the lower end of the frame. The lifting mechanism is mounted on the top of the middle layer plate. A support plate for stacked wood boards is located above the lifting mechanism. A centering mechanism is also located at the top of the middle layer plate. Centering push plates are symmetrically slidably arranged in the middle of the upper end of the frame. Multiple guide balls are rotatably arranged on opposite sides of the two centering push plates. A feeding mechanism is located on one side of the top of the frame, and a rubber-coated friction element is provided at the end of the feeding mechanism. The frame has a gantry support fixed at the top near the feeding mechanism, a proportional valve fixed at the top of the gantry support, and a cylinder for driving the feeding mechanism fixed on the inner top surface of the gantry support. A sander body is provided at one end of the frame. A limit baffle is fixed in the middle of the side of the top of the frame near the sander body. A photoelectric sensor is embedded in the inner wall of the upper end of the frame near the feeding mechanism. A distance sensor is fixed at the bottom of the extension block of the gantry support near the sander body. The probe of the distance sensor is facing the surface of the top layer of the wooden board on the pallet.

[0007] By adopting the above technical solution, the frame serves as the load-bearing foundation for all mechanisms, the middle plate provides the installation benchmark for the lifting and centering mechanisms, the lifting mechanism raises the stacked wooden boards on the pallet layer by layer upwards, and the distance sensor provides real-time feedback on the height of the top layer of wooden board to control the lifting position in a closed loop, so that the wooden board is always kept at the benchmark working plane flush with the top of the limit baffle. The top of the limit baffle is coplanar and flush with the upper surface of the feed conveyor belt of the sander body to intercept the lower layer of wooden board and achieve layer-by-layer release; the centering mechanism forces two centering push plates to move in opposite directions at the same speed through a bidirectional ball screw, so that the longitudinal center line of the wooden board is physically forced to align with the feed center axis of the sander body, fundamentally eliminating the yaw moment generated by unilateral thrust, and the guide on the inner side of the centering push plate... When the ball bearings clamp the side of the wooden board, they convert sliding friction into rolling friction, so that the lateral clamping force no longer hinders the longitudinal feed. The rubber-coated friction wheel at the end of the feed mechanism is adjusted in real time by the proportional valve on the gantry bracket to generate a constant positive pressure that is independent of the thickness of the wooden board. This ensures that the rubber-coated friction wheel neither slips nor damages the board surface when pushing the board. The photoelectric sensor detects that the wooden board has entered the working area and starts pushing. The sander body completes the synchronous sanding and polishing of the upper and lower surfaces of the wooden board. The extension block provides fixed support for the distance sensor. The cooperation of all mechanisms ensures that the wooden board is in an adaptive dynamic channel with zero longitudinal resistance, absolute lateral centering, and constant vertical force suspension during high-speed movement. This effectively avoids the defects of traditional devices such as skewing, scratches, and even jamming of the spindle.

[0008] Preferably, the lifting mechanism includes four worm gear lifts and bevel gear steering gears disposed between adjacent worm gear lifts. The four worm gear lifts are respectively installed at the top four corners of the middle layer plate. A hexagonal drive shaft is disposed between two adjacent bevel gear steering gears. Both ends of the hexagonal drive shaft are movably fitted with hexagonal sliding sleeves. The hexagonal drive shaft is connected to the bevel gear steering gear through the hexagonal sliding sleeves. One end of the worm of one of the worm gear lifts is connected to a second drive motor, and the other end of the worm of the worm gear lift is connected to a transmission closed loop formed by the hexagonal drive shaft and the bevel gear steering gear.

[0009] By adopting the above technical solution, the second drive motor transmits power synchronously to the four worm gear lifters through a transmission closed loop consisting of a hexagonal drive shaft and a bevel gear steering gear. In conjunction with the axial sliding compensation of the hexagonal sliding sleeve for installation errors, the pallet remains horizontal during the lifting process.

[0010] Preferably, the centering mechanism includes a bidirectional ball screw and sliding seats threaded at both ends of the bidirectional ball screw. Both sides of the support plate are provided with clearance grooves. The upper ends of the two sliding seats pass through the clearance grooves on the corresponding sides and are fixedly connected to the lower end of the opposite side of the centering push plate. One end of the bidirectional ball screw is connected to a first drive motor. The top of the middle layer plate is fixedly provided with a slide rail. The sliding seats are slidably disposed on the slide rail. Both ends of the bidirectional ball screw are rotatably fitted with mounting seats. The bottom end of the mounting seat is fixed to the top end of the middle layer plate.

[0011] By adopting the above technical solution, the first drive motor drives the bidirectional ball screw to rotate, forcing the two sliding seats to move synchronously towards each other along the slide rail, thereby driving the two centering push plates to clamp synchronously by passing through the tray clearance groove, so that the longitudinal center line of the wooden board is always aligned with the center of the sander's feed inlet.

[0012] Preferably, the feeding mechanism includes a transmission plate and a connecting rod rotatably disposed at one end of the transmission plate. A connecting rod is rotatably disposed at the end of the connecting rod away from the transmission plate. The end of the connecting rod away from the connecting rod is fixedly connected to the piston rod end of the cylinder. Rotating rods are fixedly disposed at the middle of both sides of the transmission plate. A fixing block fixed to the frame is rotatably sleeved at the end of the rotating rod away from the transmission plate. Mounting brackets are fixedly disposed on both sides of the end of the transmission plate away from the connecting rod. The rubber-coated friction wheel is rotatably disposed between the two mounting brackets.

[0013] By adopting the above technical solution, the cylinder pushes the transmission plate to swing around the rotating rod through the connecting rod and the connecting rod, so that the mounting bracket at the front end of the transmission plate drives the rubber-coated friction wheel to float up and down. In conjunction with the proportional valve, the air pressure is adjusted in real time to generate a constant positive pressure that is independent of the thickness of the wood board, so that the rubber-coated friction wheel pushes the wood board with constant friction force, avoiding slippage and preventing damage to the board surface.

[0014] Preferably, an anti-adhesion mechanism is provided on the side of the frame near the limiting baffle. The anti-adhesion mechanism includes a pry bar and a first rotating shaft fixedly inserted through the middle of the pry bar. A transverse long groove is opened at the end of the limiting baffle near the rubber-coated friction wheel. The pry bar is rotatably disposed in the transverse long groove at the end of the limiting baffle. A connecting shaft is fixed at both ends of the pry bar. A first transmission rod is rotatably sleeved on the outer side of the connecting shaft. A second rotating shaft is rotatably disposed at the end of the first transmission rod away from the connecting shaft. A second transmission rod is rotatably sleeved on the outer side of the second rotating shaft. An L-shaped rod is fixed at the end of the second transmission rod away from the first transmission rod. The end of the L-shaped rod away from the second transmission rod is fixed to the transmission plate.

[0015] By adopting the above technical solution, the swinging motion of the transmission plate is transmitted to the connecting shaft through the L-shaped rod, the second transmission rod and the first transmission rod, which drives the pry bar to rotate around the first rotating shaft in the transverse long groove of the limiting baffle. When the transmission plate swings and lifts the rubber-coated friction wheel, the front end of the pry bar tilts upward from the long groove and extends out, thereby inserting into the gap between the second and third layers of wood boards at the moment of material change.

[0016] Preferably, the upper middle part of the frame is symmetrically provided with a first rectangular groove, and the two centering push plates are respectively slidably disposed in the corresponding first rectangular groove. Multiple spherical grooves are provided on the opposite side surface of the centering push plate, and the guide ball is rotatably disposed in the spherical groove. The groove opening diameter of the spherical groove is smaller than the spherical diameter of the guide ball, and the guide ball protrudes from the inner working surface of the centering push plate.

[0017] By adopting the above technical solution, the first rectangular groove provides sliding guidance for the centering push plate, and the guide ball embedded in the spherical groove is kept in a convex state by the limiting structure that the groove diameter is smaller than the ball diameter. When the centering push plate clamps the wooden board, the side sliding friction is converted into rolling friction, which ensures lateral centering and avoids scratching the board surface and hindering longitudinal feed.

[0018] Preferably, a sander body is fixed at one end of the frame, the upper surface of the feed conveyor belt of the sander body is flush with the top horizontal edge of the limiting baffle, and guide plates are fixed on both sides of the inner top surface of the frame.

[0019] By adopting the above technical solution, the upper surface of the feeding conveyor belt of the sander body is flush with the top horizontal edge of the limiting baffle, ensuring that the wooden board smoothly transitions from above the baffle to the sander conveyor belt, avoiding impact or jamming due to height difference; the guide plates on both sides of the inner top surface of the frame wedge-shaped the sides of the wooden board when the pallet rises, preventing the wooden board from shifting laterally during the lifting process and affecting the subsequent centering accuracy.

[0020] Preferably, a planetary reducer is provided at one end of the rubber-coated friction wheel, the housing of the planetary reducer is fixed to the side wall of the mounting bracket on the corresponding side, a third drive motor is provided at the end of the planetary reducer away from the rubber-coated friction wheel, the housing of the third drive motor is fixed to the housing of the planetary reducer, the output end of the third drive motor is fixed to the input end of the planetary reducer, and the output end of the planetary reducer is fixed to the end of the rubber-coated friction wheel.

[0021] By adopting the above technical solution, the third drive motor drives the rubber-coated friction wheel to rotate after being reduced in speed and increased in torque by the planetary reducer, so that the rubber-coated friction wheel presses the wooden board with a constant positive pressure and pushes it forward.

[0022] Preferably, a second rectangular groove is provided on both sides of the top of the frame and at the corresponding positions of the two ends of the transverse long groove of the limiting baffle, and the two ends of the first rotating shaft are respectively rotatably connected to the inner wall of the second rectangular groove.

[0023] By adopting the above technical solution, the second rectangular groove provides rotational support for the first rotating shaft, so that the warp can rotate stably in the transverse long groove of the limiting baffle, which facilitates the extension or retraction of the front end of the warp, ensuring that the warp can accurately insert into the board seam to separate the sticky wood board at the moment of material replacement, and avoiding double-layer feeding.

[0024] Preferably, the detection beam of the photoelectric sensor is horizontally positioned across the front edge of the vertical projection area directly below the rubber-coated friction wheel, and the height of the detection beam is flush with the top of the limiting baffle.

[0025] By adopting the above technical solution, the detection beam of the photoelectric sensor spans the front edge of the projection area directly below the rubber-coated friction wheel, and its height is level with the top of the limiting baffle. When the topmost wooden board is pushed under the friction wheel, its head just blocks the beam, and the controller then starts the friction wheel drive motor so that the pushing action and the wooden board reach a synchronous response.

[0026] In summary, this application includes at least one of the following beneficial technical effects:

[0027] 1. The second drive motor drives the lifting mechanism to lift the wooden boards layer by layer to the reference working plane. At the same time, the cylinder drives the rubber-coated friction wheel to float up and down through the connecting rod and transmission plate. The proportional valve dynamically adjusts the air pressure in real time, so that the rubber-coated friction wheel adapts to the change of the wooden board thickness and generates a constant positive pressure. Then, the first drive motor drives the bidirectional ball screw to make the two centering push plates move towards each other at the same speed, forcing the longitudinal center line of the wooden board to align with the center axis of the sander's feed. With the help of the guide ball, the sliding friction is converted into rolling friction, so that the lateral centering force and the longitudinal feed force are physically decoupled and coordinated in three-dimensional space. This allows the wood to be in an adaptive dynamic channel with zero longitudinal resistance, absolute lateral centering, and constant vertical force suspension during high-speed movement. This avoids the slippage, board biting, jamming, and skew problems of traditional devices, and achieves high-speed, non-destructive, continuous, and absolutely centered feeding.

[0028] 2. The piston rod of the cylinder extends and retracts, driving the connecting rod and transmission plate to move, causing the rubber-coated friction wheel to float up and down with the mounting frame. At the same time, the proportional valve dynamically adjusts the air pressure input to the cylinder in real time, so that the rubber-coated friction wheel adaptively generates a constant vertical positive pressure independent of the thickness of the wood board. This allows the rubber-coated friction wheel to drive the wood board forward with constant friction force, avoiding the problems of slippage of thin boards and jamming or indentation of thick boards caused by the thickness fluctuation of the wood board in the traditional spring clamping mechanism. It achieves zero slippage and zero damage constant pressure pushing under high-speed continuous feeding conditions.

[0029] 3. The first drive motor drives the bidirectional ball screw to rotate, causing the two sliding seats to move at the same speed towards each other along the slide rail. This forces the two centering push plates to move equidistantly in a mirror image at a physical level, so that the longitudinal center line of the wood board is forced to align with the feed center axis of the sander body. At the same time, the guide balls on the inner side of the centering push plate convert sliding friction into rolling friction, so that while the wood board is subjected to lateral clamping force for absolute centering, the longitudinal feed resistance does not increase but decreases, thus avoiding the problem of the wood board entering the sander at an angle, causing scratches or even jamming the main shaft.

[0030] 4. The transmission plate swings, driving the L-shaped rod and the second transmission rod in tandem. This, in turn, drives the first rotating shaft to rotate via the first transmission rod. When the top layer of wood is pushed away, the transmission plate swings in the opposite direction, lifting the rubber-coated friction wheel. As the lifting mechanism raises the pallet by one board thickness, the front end of the pry bar rises from the transverse groove and extends out, inserting into the gap between the second and third layers of wood. The pry bar separates the two layers of wood that are stuck together, preventing both layers from entering the sander body simultaneously. This avoids the problem of sanding belt breakage and spindle seizure caused by multiple layers of adhesion due to static electricity or glue residue. Attached Figure Description

[0031] Figure 1 This is an isometric view of the present application;

[0032] Figure 2 This is a schematic diagram of the left visual axis of this application;

[0033] Figure 3 This is a schematic diagram of the rear-view axis of this application;

[0034] Figure 4 This is a schematic diagram of the lifting mechanism and centering mechanism of this application;

[0035] Figure 5 This is an exploded view of the lifting mechanism and centering mechanism of this application;

[0036] Figure 6 This is an exploded view of the centering push plate and guide ball structure of this application;

[0037] Figure 7 This is a schematic diagram of the feed mechanism structure in this application;

[0038] Figure 8 This is a schematic diagram of the gantry support structure of this application;

[0039] Figure 9 This is a bottom view of the feed mechanism structure in this application;

[0040] Figure 10 This is an exploded view of the feeding mechanism and anti-adhesion mechanism of this application;

[0041] Figure 11This is an exploded view of the anti-adhesion mechanism of this application.

[0042] Reference numerals: 1. Frame; 2. Lifting mechanism; 3. Centering mechanism; 4. Feeding mechanism; 5. Anti-sticking mechanism; 6. Rubber-coated friction wheel; 7. Middle layer plate; 8. Support plate; 9. Centering push plate; 10. Guide ball bearings;

[0043] 11. Limit baffle; 12. Sander body; 13. Gantry support; 14. Cylinder; 15. Proportional valve; 16. Photoelectric sensor; 17. Distance sensor; 18. Guide plate; 19. First drive motor;

[0044] 20. Second drive motor; 21. Third drive motor; 22. Planetary reducer; 23. First rectangular slot; 24. Second rectangular slot; 25. Through hole; 26. Spherical slot;

[0045] 201. Worm gear jack; 202. Bevel gear steering gear; 203. Hexagonal drive shaft; 204. Hexagonal sliding sleeve; 205. Support base;

[0046] 301. Double-direction ball screw; 302. Sliding seat; 303. Slide rail; 304. Mounting base; 305. Double-direction threaded hole;

[0047] 401. Transmission plate; 402. Connecting rod; 403. Connecting rod; 404. Rotating rod; 405. Mounting bracket; 406. Fixing block; 407. First rotating hole; 408. Second rotating hole;

[0048] 409. Third rotating hole; 410. Fourth rotating hole;

[0049] 501, rocker arm; 502, first rotating shaft; 503, connecting shaft; 504, first transmission rod; 505, second transmission rod; 506, L-shaped rod; 507, rotating groove; 508, first circular hole;

[0050] 509. Second circular hole; 510. Second rotating shaft. Detailed Implementation

[0051] The following is in conjunction with the appendix Figure 1 - Figure 11 This application will be described in further detail.

[0052] This application discloses a feeding device for a wood sander.

[0053] Reference Figure 1 - Figure 11A feeding device for a wood sander includes a frame 1 and a lifting mechanism 2 installed at the lower end of the frame 1. A middle layer plate 7 is fixed inside the lower end of the frame 1. The lifting mechanism 2 is installed at the top of the middle layer plate 7. A support plate 8 is installed above the lifting mechanism 2. The support plate 8 is used to support stacked wooden boards. Both sides of the support plate 8 are provided with clearance grooves. A second drive motor 20 is installed on one side of the lifting mechanism 2. The second drive motor 20 is used to drive the lifting mechanism 2 to realize the vertical lifting of the support plate 8. The fixed end of the second drive motor 20 is fixed to the top of the middle layer plate 7. A centering mechanism 3 is installed at the top of the middle layer plate 7. The centering mechanism 3 spans the middle area of ​​the lifting mechanism 2. A first drive motor 19 is installed on one side of the centering mechanism 3. The fixed end of the first drive motor 19 is fixed to the top of the middle layer plate 7. The first drive motor 19 is used to drive the centering mechanism 3. A centering push plate 9 is symmetrically slidably arranged in the middle of the upper end of the frame 1. The first drive motor 19 is used to drive the centering mechanism 3 to realize the opposite or opposite movement of the two centering push plates 9. A first rectangular groove 23 is symmetrically opened in the middle of the top of the frame 1, and the two centering push plates 9 are respectively slidably arranged in the corresponding first rectangular groove 23.

[0054] This device is suitable for sanding and feeding operations of wood boards in the board processing industry. Before use, the frame 1 needs to be installed horizontally on the workshop foundation. The top plane of the frame 1 should be adjusted to be flush with the upper surface of the feed conveyor belt of the sander body 12. The lifting mechanism 2 should be installed on the middle plate 7. The second drive motor 20 should be fixed on the middle plate 7 and connected to the input end of the lifting mechanism 2. The support plate 8 should be fixed on the top of the lifting mechanism 2. Then, the centering mechanism 3 should be fixed on the middle plate 7. The first drive motor 19 should be installed on the middle plate 7 and connected to the end of the centering mechanism 3. The two centering push plates 9 should be fixed to the centering mechanism 3.

[0055] A gantry bracket 13 is installed on the rear top of the frame 1. The cylinder 14 and proportional valve 15 are mounted on the gantry bracket 13. The feeding mechanism 4 is installed on the top of the frame 1 and connected to the piston rod end of the cylinder 14. A limiting baffle 11 is welded and fixed to the inner side of the end of the frame 1 closest to the sander body 12, so that the top of the limiting baffle 11 is flush with the upper surface of the feed conveyor belt of the sander body 12. A photoelectric sensor 16 is embedded in the upper inner wall of the frame 1, and a distance sensor 17 is fixed to the bottom of the extension block and installed vertically downwards. Finally, the anti-adhesion mechanism 5 is installed in the transverse long groove of the limiting baffle 11 and connected to the feeding mechanism 4, thus completing the assembly of the entire machine.

[0056] The centering mechanism 3 is connected to the lower ends of the opposite sides of the two centering push plates 9, and is used to drive the two centering push plates 9 to move horizontally relative to or opposite to each other. Multiple spherical grooves 26 are formed on the opposite surfaces of the two centering push plates 9. Guide balls 10 are rotatably arranged inside the spherical grooves 26. The diameter of the groove opening of the spherical groove 26 is smaller than the diameter of the sphere. The guide balls 10 partially protrude from the inner working surface of the centering push plates 9, and are used to convert the sliding friction generated when the centering push plates 9 clamp the side of the wooden board into rolling friction, thereby reducing the resistance during the longitudinal feeding of the wooden board and preventing scratches on the side surface of the wooden board. The inner wall of the spherical groove 26 and the surface of the guide ball 10 are coated with a self-lubricating coating. The guide ball 10 is made of polyoxymethylene (POM) material. A feeding mechanism 4 is provided on one side of the top of the frame 1. A rubber-coated friction wheel 6 is provided at the end of the feeding mechanism 4. The rubber-coated friction wheel 6 is used to press the upper surface of the top layer of the wooden board and push the top layer of the wooden board forward by friction. A planetary reducer 22 is provided at one end of the rubber-coated friction wheel 6. A third drive motor 21 is provided at the end of the planetary reducer 22 away from the rubber-coated friction wheel 6. The third drive motor 21 is a servo motor.

[0057] In use, the operator places the stacked wooden boards on the pallet 8. The external controller drives the lifting mechanism 2 via the second drive motor 20 to push the pallet 8 upward. At the same time, the distance sensor 17 detects the height of the upper surface of the top wooden board in real time and feeds it back to the external controller. Through closed-loop control, the lower surface of the top wooden board is always kept at the top plane of the limit baffle 11. Then, the first drive motor 19 drives the centering mechanism 3 to move the two centering push plates 9 at the same speed towards each other. This causes the guide balls 10 on the inner working surface of the centering push plates 9 to contact and clamp the left and right sides of the top wooden board. Through the forced equidistant displacement of the centering push plates 9, the longitudinal center line of the wooden board is aligned with the feed center axis of the sander body 12.

[0058] A gantry support 13 is fixedly mounted on one side of the top of the frame 1. The gantry support 13 is in an inverted U-shape and spans across the upper part of the wooden board passage. The bottom two sides of the gantry support 13 are fixed to the top two sides of the frame 1, respectively. A proportional valve 15, which is a high-frequency electric proportional valve, is fixedly mounted on the top of the gantry support 13. A cylinder 14 is fixedly mounted on the inner top surface of the gantry support 13. The proportional valve 15 dynamically adjusts the air pressure input to the cylinder 14 in real time. The air inlet of the proportional valve 15 is connected to an external air source, and the air outlet of the proportional valve 15 is connected to an air pipe. The air inlet of the three-position five-way solenoid directional valve (not shown in the figure) has two working air ports that are connected to the rodless chamber and rod chamber air inlets of the cylinder 14 through air pipes, respectively. The exhaust port of the three-position five-way solenoid directional valve is open to the atmosphere. The external controller controls the reversal of the three-position five-way solenoid directional valve to realize the extension and retraction of the piston rod of the cylinder 14. The proportional valve 15 adjusts the air pressure input to the cylinder 14 to achieve precise control of the normal pressure applied to the surface of the wooden board by the rubber-coated friction wheel 6.

[0059] The cylinder 14 is a double-acting low-friction cylinder. The drive end of the cylinder 14 is connected to the feeding mechanism 4. An anti-adhesion mechanism 5 is provided on one side of the feeding mechanism 4. A limiting baffle 11 is fixed on one side of the upper end of the frame 1. The limiting baffle 11 is used to prevent the lower wooden boards on the pallet 8, except for the top layer, from moving forward under the action of friction, so as to realize the unidirectional release layer by layer. The upper edge of the limiting baffle 11 is processed with a rounded chamfer. A transverse long groove is opened at the end of the limiting baffle 11 near the rubber-coated friction wheel 6. The long groove extends along the width direction of the limiting baffle 11. A second rectangular groove 24 is opened on both sides of the top of the frame 1. The second rectangular groove 24 is located at the corresponding positions of the two long ends of the limiting baffle 11.

[0060] A sander body 12 is provided at one end of the frame 1. The sander body 12 is used to simultaneously sand the upper and lower surfaces of the wood board to remove surface knife marks and burrs and make the wood board thickness uniform. The upper surface of the feed conveyor belt of the sander body 12 is flush with the top horizontal edge of the limit baffle 11. A photoelectric sensor 16 is embedded in the upper inner wall of the frame 1. The photoelectric sensor 16 is a through-beam photoelectric switch. The detection beam of the photoelectric sensor 16 is horizontally across the front edge of the vertical projection area directly below the rubber-coated friction wheel 6. The detection height is flush with the top of the limit baffle 11. The photoelectric sensor 16 is used to detect whether the head of the wood board enters the working range of the rubber-coated friction wheel 6 and sends a feed start signal to the external controller. An extension block is fixed on the upper side of the distance sensor 17 near the sander body 12. The extension block extends horizontally above the support plate 8.

[0061] A distance sensor 17 is fixed at the bottom of the extension block. The distance sensor 17 is a high-precision ultrasonic distance sensor, which is installed vertically downward. The probe of the distance sensor 17 is directly facing the surface of the top layer of wood on the support plate 8. The distance sensor 17 is used to detect the absolute height position of the top layer of wood in real time and feed it back to the external controller with an analog signal to control the lifting position of the lifting mechanism 2 in a closed loop, as well as to detect the polishing progress of the top layer of wood. Guide plates 18 are fixed on both sides of the inner top surface of the frame 1. The guide plates 18 are wedge-shaped and are used to automatically guide the two sides of the stacked wood when the support plate 8 rises, preventing the wood from shifting laterally during the lifting process. The wedge-shaped surface of the guide plate 18 forms a sliding contact with the side of the wood. The guide plate 18 is made of self-lubricating polyoxymethylene material.

[0062] When the photoelectric sensor 16 detects that the head of the wooden board enters the working area of ​​the rubber-coated friction wheel 6, the external controller starts the third drive motor 21, which drives the rubber-coated friction wheel 6 to rotate through the planetary reducer 22. At the same time, the proportional valve 15 adjusts the air pressure of the input cylinder 14 in real time according to the set air pressure value, so that the cylinder 14 outputs a constant thrust. The cylinder 14 drives the feeding mechanism 4 to drive the rubber-coated friction wheel 6 to press the wooden board and apply a constant vertical positive pressure. Under the action of this positive pressure, the rubber-coated friction wheel 6 drives the wooden board to move forward through friction, so that the wooden board smoothly crosses the limit baffle 11 and enters the feeding conveyor belt of the sander body 12. During this process, the limit baffle 11 physically intercepts the lower layer of wooden boards, so that the lower layer of wooden boards, except for the top layer, cannot cross the limit baffle 11. When a wooden board completely leaves the support plate 8, the distance sensor 17 detects a sudden change in height. The external controller controls the second drive motor 20 to drive the lifting mechanism 2 to lift the support plate 8 upward by a distance of one board thickness, so that the upper surface of the next layer of wooden boards reaches the reference working plane again.

[0063] The lifting mechanism 2 includes four worm gear lifts 201 and bevel gear steering units 202 disposed between adjacent worm gear lifts 201. Through holes 25 are provided at the four corners of the support plate 8. The lower end of each worm gear lift 201 passes through the corresponding through hole 25. The adjacent ends of the worms of the four worm gear lifts 201 are fixed to the horizontal output ends of the corresponding bevel gear steering units 202. A hexagonal drive shaft 203 is provided between each pair of adjacent bevel gear steering units 202. The four hexagonal drive shafts 203 are horizontally arranged along the four sides of the frame 1. Hexagonal sliding sleeves 204 are movably fitted at both ends of each hexagonal drive shaft 203. The hexagonal drive shafts 203 are inserted into the horizontal ports of the bevel gear steering units 202 via the hexagonal sliding sleeves 204.

[0064] The hexagonal sliding sleeve 204 and the hexagonal drive shaft 203 are axially slidingly fitted to compensate for axial dimensional errors generated during the welding and assembly of the frame 1. The lengths of the two hexagonal drive shafts 203 arranged along the length of the frame 1 are greater than the lengths of the other two hexagonal drive shafts 203 arranged along the width of the frame 1. The outer side of the middle of the two longer hexagonal drive shafts 203 is rotatably fitted with a support seat 205. The bottom end of the support seat 205 is fixedly connected to the top end of the middle plate 7. The worm input end of any one of the worm gear jacks 201 is fixedly connected to the output end of the second drive motor 20, and the other end of the worm is still connected to the transmission closed loop formed by the hexagonal drive shaft 203 and the bevel gear steering gear 202.

[0065] In use, the second drive motor 20 is started, driving the worm input end of one of the worm gear jacks 201 to rotate. The other end of the worm is still connected to the transmission closed loop formed by the hexagonal drive shaft 203 and the bevel gear steering gear 202. The rotation of the worm drives the adjacent bevel gear steering gear 202 to rotate, thereby causing the bevel gear steering gear 202 to transmit power to the adjacent hexagonal drive shaft 203. The hexagonal drive shaft 203 transmits the rotational power to the next bevel gear steering gear 202, so that the power is transmitted sequentially along the entire closed-loop transmission chain, forcing the worms of the four worm gear jacks 201 to rotate synchronously.

[0066] The centering mechanism 3 includes a bidirectional ball screw 301 and sliding seats 302 threaded at both ends of the bidirectional ball screw 301. A bidirectional threaded hole 305 is provided at the lower center of the sliding seat 302, and the bidirectional ball screw 301 is threaded through the corresponding bidirectional threaded hole 305. The shape of the sliding seat 302 matches the cross-sectional shape of the clearance grooves on both sides of the support plate 8. The upper end of the sliding seat 302 extends upward through the clearance groove, and a sliding gap is maintained between the sliding seat 302 and the groove wall, allowing the sliding seat 302 to slide within the clearance groove. A slide rail 303 is fixedly installed at the top of the middle layer plate 7 below the sliding seat 302. The cross-sectional shape of the slide rail 303 matches the shape of the groove at the bottom of the sliding seat 302, and the sliding seat 302 is slidably mounted on the slide rail 303. Both ends of the bidirectional ball screw 301 are rotatably fitted with mounting seats 304. The bottom end of the mounting seat 304 is fixed to the top end of the middle layer plate 7. A circular hole is opened in the middle of the mounting seat 304, and both ends of the bidirectional ball screw 301 rotatably pass through the corresponding circular hole. One end of the bidirectional ball screw 301 extending out of one of the mounting seats 304 is fixedly connected to the output end of the first drive motor 19.

[0067] In use, by starting the first drive motor 19, the bidirectional ball screw 301 is driven to rotate, causing the two sliding seats 302 to move towards each other at the same speed or away from each other at the same speed along the slide rail 303. Since the upper ends of the two sliding seats 302 extend upward through the clearance grooves on both sides of the support plate 8 and are fixedly connected to the lower ends of the opposite sides of the two centering push plates 9, the two centering push plates 9 slide synchronously with the sliding seats 302 in the first rectangular groove 23, so that the two sliding seats 302 maintain a linear motion trajectory under the drive of the bidirectional ball screw 301, and thus the two centering push plates 9 always move in parallel. The mounting seat 304 provides rotational support to both ends of the bidirectional ball screw 301, so that the bidirectional ball screw 301 rotates smoothly, thereby completing the centering and positioning of the top layer of the wooden board.

[0068] The feeding mechanism 4 includes a transmission plate 401 and a connecting rod 402 rotatably mounted at one end of the transmission plate 401. A connecting rod 403 is rotatably mounted at the end of the connecting rod 402 away from the transmission plate 401, and the end of the connecting rod 403 away from the connecting rod 402 is fixed to the piston rod end of the cylinder 14. A first rotating hole 407 is opened in the middle of one end of the transmission plate 401, and a second rotating hole 408 is opened at the lower end of the connecting rod 403. The rotating shafts at the middle of both ends of the connecting rod 402 rotatably pass through the first rotating hole 407 and the second rotating hole 408, respectively. A rotating rod 404 is fixedly mounted in the middle of both sides of the first rotating hole 407. A fixing block 406 is rotatably sleeved at the end of the rotating rod 404 away from the transmission plate 401, and the bottom end of the fixing block 406 is fixed to the top end of the frame 1.

[0069] In use, the piston rod of cylinder 14 extends and retracts, driving the connecting rod 402 to move via the connecting rod 403. Since one end of the connecting rod 402 is rotatably connected to the transmission plate 401 through the first rotating hole 407, and the other end of the connecting rod 402 is rotatably connected to the connecting rod 403 through the second rotating hole 408, the transmission plate 401 swings around the axis of the rotating rod 404 under the pushing and pulling action of the connecting rod 402. This causes the mounting bracket 405 to swing synchronously with the transmission plate 401, thereby driving the rubber-coated friction wheel 6 to float up and down with the mounting bracket 405. The rubber-coated friction wheel 6 adaptively presses or loosens the upper surface of the top layer of wood board according to the change in the thickness of the wood board.

[0070] The transmission plate 401 swings around the axis of the rotating rod 404. Mounting brackets 405 are fixed on both sides of the end of the transmission plate 401 away from the connecting rod 402, and the mounting brackets 405 are generally L-shaped. One mounting bracket 405 has a third rotating hole 409 at its end away from the transmission plate 401, and the other mounting bracket 405 has a fourth rotating hole 410 at its end away from the transmission plate 401. The rotating shafts at both ends of the rubber-coated friction wheel 6 rotate through the third rotating hole 409 and the fourth rotating hole 410, respectively. One end of the rubber-coated friction wheel 6, extending from the rotating shaft of the third rotating hole 409, is fixed to the output end of the planetary reducer 22. The housing of the planetary reducer 22 is fixed to the side wall of the corresponding mounting bracket 405. The input shaft of the planetary reducer 22 is fixed to the output shaft of the third drive motor 21. The housing of the third drive motor 21 is fixed to the housing of the planetary reducer 22.

[0071] After the rubber-coated friction wheel 6 presses the top layer of wood board, the third drive motor 21 starts. The output shaft of the third drive motor 21 drives the input shaft of the planetary reducer 22 to rotate. After the planetary reducer 22 reduces speed and increases torque, the output end of the planetary reducer 22 drives the rubber-coated friction wheel 6 to rotate through the shaft of the third rotating hole 409. This causes the rubber-coated friction wheel 6 to rotate around its own axis. The friction between the rubber-coated friction wheel 6 and the upper surface of the top layer of wood board drives the wood board to move forward, completing the feeding and pushing of the wood board.

[0072] The anti-adhesion mechanism 5 includes a pry bar 501 and a first rotating shaft 502 fixedly inserted through the middle of the pry bar 501. The pry bar 501 is rotatably disposed in the transverse long groove at the end of the limiting baffle 11. A rotating groove 507 is provided in the middle of the pry bar 501. The middle of the first rotating shaft 502 is fixedly inserted through the rotating groove 507. The two ends of the first rotating shaft 502 are rotatably connected to the inner walls of the second rectangular grooves 24 on both sides of the transverse long groove of the limiting baffle 11. A connecting shaft 503 is fixedly provided at both ends of the first rotating shaft 502. A first transmission rod 504 is rotatably sleeved on the outer side of the connecting shaft 503. A first circular hole 508 is provided at the end of the first transmission rod 504 near the connecting shaft 503. The connecting shaft 503 rotatably passes through the first circular hole 508. A second rotating shaft 510 is fixedly provided at the end of the first transmission rod 504 away from the connecting shaft 503.

[0073] In operation, the transmission plate 401 of the feed mechanism 4 swings around the rotating rod 404. Since the two L-shaped rods 506 are fixedly connected to the two sides of the transmission plate 401 near the connecting rod 402, the L-shaped rods 506 move synchronously with the transmission plate 401, driving the second transmission rod 505 to move. The second transmission rod 505 is rotatably connected to the first transmission rod 504 via the second rotating shaft 510, causing the first transmission rod 504 to move in conjunction with the second transmission rod 505.

[0074] A second transmission rod 505 is rotatably sleeved on the outer side of the second rotating shaft 510. A second circular hole 509 is provided at the end of the second transmission rod 505 near the first transmission rod 504. The second rotating shaft 510 rotates through the second circular hole 509. An L-shaped rod 506 is fixed at the end of the second transmission rod 505 away from the first transmission rod 504. The ends of the two L-shaped rods 506 away from the second transmission rod 505 are respectively fixed to the two sides of the transmission plate 401 near the connecting rod 402. When the transmission plate 401 swings around the rotating rod 404, the L-shaped rods 506 move synchronously with the transmission plate 401, driving the connecting shaft 503 to rotate via the second transmission rod 505 and the first transmission rod 504, thus rotating the first rotating shaft 502 and causing the front end of the pry bar 501 to extend or retract from the long groove of the limiting baffle 11.

[0075] The first transmission rod 504 rotates around the connecting shaft 503. Since the connecting shaft 503 is fixed to the end of the first rotating shaft 502, the first rotating shaft 502 rotates synchronously with the connecting shaft 503. Through the fixed connection between the first rotating shaft 502 and the rocker plate 501, the rocker plate 501 rotates around the axis of the first rotating shaft 502, thereby causing the front end of the rocker plate 501 to extend or retract from the transverse long groove of the limiting baffle 11.

[0076] A reset torsion spring (not shown in the figure) is connected between the rocker arm 501 and the inner wall of the transverse long groove of the limiting baffle 11 to provide a retraction reset force after the rocker arm 501 extends; the second transmission rod 505 and the L-shaped rod 506 are connected by a sliding sleeve structure with a buffer spring (not shown in the figure) to absorb impact loads when the front end of the rocker arm 501 encounters resistance to avoid deformation of the transmission rod.

[0077] When the transmission plate 401 swings under the drive of the cylinder 14, causing the rubber-coated friction wheel 6 to press against the wooden board, the front end of the pry bar 501 retracts into the transverse long groove. When the topmost wooden board is completely removed from the working area of ​​the rubber-coated friction wheel 6, the distance sensor 17 detects a height change signal and feeds it back to the external controller. The external controller then controls the piston rod of the cylinder 14 to retract through the three-position five-way solenoid reversing valve, causing the transmission plate 401 to swing in the opposite direction, causing the rubber-coated friction wheel 6 to lift up. The lifting mechanism 2 then raises the support plate 8 by one board thickness. At this time, the front end of the pry bar 501 tilts upward from the transverse long groove and extends out, then inserts into the gap between the second and third layers of wooden boards. The wedge-shaped front end of the pry bar 501 separates the two layers of wooden boards that are stuck together, thereby preventing the two layers of wooden boards from entering the sander body 12 at the same time.

[0078] The photoelectric sensor 16 and the distance sensor 17 are electrically connected to an external controller via signal lines. The external controller is electrically connected to the first drive motor 19, the second drive motor 20, and the third drive motor 21 via a drive circuit. The external controller is also electrically connected to the control terminal of the proportional valve 15. When the distance sensor 17 detects that the height of the upper surface of the top layer of the wooden board is lower than a preset threshold, the controller sends a forward rotation signal to the second drive motor 20, driving the lifting mechanism 2 to lift the pallet 8 upward until the height value fed back by the distance sensor 17 returns to the preset reference working plane height. When the photoelectric sensor 16 detects that the head of the wooden board enters the working area of ​​the rubber-coated friction wheel 6, the controller sends a start signal to the third drive motor 21, driving the rubber-coated friction wheel 6 to rotate and push the wooden board forward. After the wooden board is completely pushed away, the distance sensor 17 detects a sudden change in height, and the controller sends a forward rotation signal to the second drive motor 20 to raise the next layer of wooden boards by one board thickness until the height value fed back by the distance sensor 17 returns to the reference working plane height again.

[0079] The implementation principle of the feeding device of a wood sander in this application embodiment is as follows: During use, the operator places the stacked wood boards on the pallet 8. The external controller drives the lifting mechanism 2 through the second drive motor 20 to lift the wood boards layer by layer upwards. The distance sensor 17 provides real-time feedback on the height of the top wood board and controls it in a closed loop to always be flush with the top of the limit baffle 11. Then, the first drive motor 19 drives the centering mechanism 3 to drive the two centering push plates 9 to move towards each other at the same speed, forcing the longitudinal center line of the wood board to align with the feeding center axis of the sander body 12. When the photoelectric sensor 16 detects that the head of the wood board has entered the working rubber-coated friction wheel 6... During the interval, the controller starts the third drive motor 21 to drive the rubber-coated friction wheel 6 to rotate. At the same time, the proportional valve 15 adjusts the air pressure of the cylinder 14 in real time to output a constant thrust. Through the feeding mechanism 4, the rubber-coated friction wheel 6 presses the wooden board with a constant positive pressure and pushes it over the limit baffle 11 and into the sander body 12 by relying on friction. The limit baffle 11 physically intercepts the lower layer of wooden boards to achieve unidirectional release layer by layer. The anti-adhesion mechanism 5 inserts the warping piece 501 into the board seam at the moment of material change to prevent double-layer feeding. After a single wooden board is fed, the distance sensor 17 triggers the lifting mechanism 2 to raise it by one board thickness. The cycle continues until the entire stack of wooden boards is fed.

[0080] The above are merely optional embodiments of this disclosure and are not intended to limit this disclosure. Various modifications and variations can be made to this disclosure by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A feeding device for a wood sander, characterized in that: The system includes a frame (1) and a lifting mechanism (2) installed at the lower end of the frame (1). A middle layer plate (7) is fixed inside the lower end of the frame (1). The lifting mechanism (2) is installed at the top of the middle layer plate (7). A support plate (8) for supporting stacked wooden boards is installed above the lifting mechanism (2). A centering mechanism (3) is also installed at the top of the middle layer plate (7). A centering push plate (9) is symmetrically slidably installed in the middle of the upper end of the frame (1). Multiple guide balls (10) are rotatably installed on opposite sides of the two centering push plates (9). A feeding mechanism (4) is installed on one side of the top of the frame (1). A rubber-coated friction wheel (6) is installed at the end of the feeding mechanism (4). The top of the frame (1) is close to the feeding mechanism. A gantry bracket (13) is fixed at the feeding mechanism (4). A proportional valve (15) is fixed at the top of the gantry bracket (13). A cylinder (14) for driving the feeding mechanism (4) is fixed on the inner top surface of the gantry bracket (13). A sander body (12) is provided at one end of the frame (1). A limiting baffle (11) is fixed at the middle of the side of the top of the frame (1) near the sander body (12). A photoelectric sensor (16) is embedded in the inner wall of the upper end of the frame (1) near the feeding mechanism (4). A distance measuring sensor (17) is fixed at the bottom of the extension block of the gantry bracket (13) near the sander body (12). The probe of the distance measuring sensor (17) is facing the surface of the top layer of the wooden board on the tray (8).

2. The feeding device of a wood sander according to claim 1, characterized in that: The lifting mechanism (2) includes four worm gear lifts (201) and bevel gear steering gears (202) arranged between adjacent worm gear lifts (201). The four worm gear lifts (201) are respectively installed at the top four corners of the middle plate (7). A hexagonal drive shaft (203) is arranged between two adjacent bevel gear steering gears (202). Both ends of the hexagonal drive shaft (203) are movably fitted with hexagonal sliding sleeves (204). The hexagonal drive shaft (203) is connected to the bevel gear steering gear (202) through the hexagonal sliding sleeves (204). One end of the worm of one of the worm gear lifts (201) is connected to a second drive motor (20), and the other end of the worm of the worm gear lift (201) is connected to a transmission closed loop composed of the hexagonal drive shaft (203) and the bevel gear steering gear (202).

3. The feeding device for a wood sander according to claim 1, characterized in that: The centering mechanism (3) includes a bidirectional ball screw (301) and sliding seats (302) threaded on both ends of the bidirectional ball screw (301). Both sides of the support plate (8) are provided with clearance grooves. The upper ends of the two sliding seats (302) pass through the clearance grooves on the corresponding sides and are fixedly connected to the lower end of the opposite side of the centering push plate (9). One end of the bidirectional ball screw (301) is connected to a first drive motor (19). The top end of the middle plate (7) is fixedly provided with a slide rail (303). The sliding seats (302) are slidably disposed on the slide rail (303). Both ends of the bidirectional ball screw (301) are rotatably fitted with mounting seats (304). The bottom end of the mounting seats (304) is fixed to the top end of the middle plate (7).

4. The feeding device for a wood sander according to claim 1, characterized in that: The feeding mechanism (4) includes a transmission plate (401) and a connecting rod (402) rotatably disposed at one end of the transmission plate (401). A connecting rod (403) is rotatably disposed at the end of the connecting rod (402) away from the transmission plate (401). The end of the connecting rod (403) away from the connecting rod (402) is fixedly connected to the piston rod end of the cylinder (14). Rotating rods (404) are fixedly disposed in the middle of both sides of the transmission plate (401). A fixing block (406) fixed to the frame (1) is rotatably sleeved at the end of the rotating rod (404) away from the transmission plate (401). Mounting brackets (405) are fixedly disposed on both sides of the end of the transmission plate (401) away from the connecting rod (402). The rubber-coated friction wheel (6) is rotatably disposed between the two mounting brackets (405).

5. The feeding device of a wood sander according to claim 4, characterized in that: The frame (1) is provided with an anti-adhesion mechanism (5) on the side near the limiting baffle (11). The anti-adhesion mechanism (5) includes a pry bar (501) and a first rotating shaft (502) fixedly inserted through the middle of the pry bar (501). The limiting baffle (11) has a transverse long groove at one end near the rubber-coated friction wheel (6). The pry bar (501) is rotatably disposed in the transverse long groove at the end of the limiting baffle (11). Both ends of the pry bar (501) are fixed with connecting shafts (503). A first transmission rod (504) is rotatably sleeved on the outer side of (503). A second rotating shaft (510) is rotatably provided at the end of the first transmission rod (504) away from the connecting shaft (503). A second transmission rod (505) is rotatably sleeved on the outer side of the second rotating shaft (510). An L-shaped rod (506) is fixed at the end of the second transmission rod (505) away from the first transmission rod (504). The end of the L-shaped rod (506) away from the second transmission rod (505) is fixed to the transmission plate (401).

6. The feeding device of a wood sander according to claim 1, characterized in that: The upper middle part of the frame (1) is symmetrically provided with a first rectangular groove (23). The two centering push plates (9) are respectively slidably disposed in the corresponding first rectangular groove (23). Multiple spherical grooves (26) are provided on the opposite side surface of the centering push plate (9). The guide ball (10) is rotatably disposed in the spherical groove (26). The groove diameter of the spherical groove (26) is smaller than the spherical diameter of the guide ball (10). The guide ball (10) protrudes from the inner working surface of the centering push plate (9).

7. The feeding device of a wood sander according to claim 1, characterized in that: One end of the frame (1) is fixed with a sander body (12). The upper surface of the feed conveyor belt of the sander body (12) is flush with the top horizontal edge of the limiting baffle (11). Guide plates (18) are fixed on both sides of the inner top surface of the frame (1).

8. The feeding device for a wood sander according to claim 4, characterized in that: A planetary reducer (22) is provided at one end of the rubber-coated friction wheel (6). The housing of the planetary reducer (22) is fixed to the side wall of the mounting bracket (405) on the corresponding side. A third drive motor (21) is provided at the end of the planetary reducer (22) away from the rubber-coated friction wheel (6). The housing of the third drive motor (21) is fixed to the housing of the planetary reducer (22). The output end of the third drive motor (21) is fixed to the input end of the planetary reducer (22). The output end of the planetary reducer (22) is fixed to the end of the rubber-coated friction wheel (6).

9. The feeding device of a wood sander according to claim 5, characterized in that: The top two sides of the frame (1) and the corresponding positions at both ends of the transverse long groove of the limiting baffle (11) are provided with second rectangular grooves (24), and the two ends of the first rotating shaft (502) are respectively rotatably connected to the inner wall of the second rectangular groove (24).

10. The feeding device of a wood sander according to claim 1, characterized in that: The detection beam of the photoelectric sensor (16) is horizontally spanned across the front edge of the vertical projection area directly below the rubber-coated friction wheel (6), and the height of the detection beam is flush with the top of the limiting baffle (11).

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