A curve groove wheel type rice seedling tray longitudinal precision conveying device and a conveying method thereof

Abstract

The application discloses a curve slot wheel type rice seedling tray longitudinal precision conveying device and a conveying method thereof. In the application, a roller is hinged to a hitting rod, two cams are fixed on a rotating shaft, one end of a rocker is fixed to the rotating shaft, a middle part of the rocker is fixed to a tension spring, two ends of a connecting rod are hinged to the other end of the rocker and one end of a swing rod, the other end of the swing rod is supported on a hollow shaft which is integrally formed on a driving gear through a one-way bearing, a plurality of driven gears are hinged to a gear frame, the driven gears are engaged with the driving gear, two circular pins which are symmetrically arranged are fixed on the driven gears, the ball and the spring are arranged in a cylindrical barrel which is integrally formed on a braking hollow disc, and a part of the ball is exposed outside the cylindrical barrel; the ball is pressed by the spring; the part of the ball which is exposed outside the cylindrical barrel and an annular groove of the driving gear form a rolling friction pair, and the ball is initially embedded in a groove which is arranged in the annular groove. The application realizes the longitudinal conveying work of the seedling tray, and the precision is high, and then the precision of the transplanting work can be ensured.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of agricultural machinery, and particularly relates to a curve groove wheel type rice seedling tray longitudinal precision conveying device and a conveying method thereof. BACKGROUND

[0002] Rice seedling tray longitudinal intermittent interval conveying is a prerequisite for a rice pot seedling transplanting machine to realize precision transplanting. The existing rice seedling tray longitudinal conveying mechanism is mainly a ratchet type. However, the existing ratchet type rice seedling tray longitudinal conveying mechanism has the problems of large rigid impact and unsatisfactory self-locking effect when working, which affects the precision of the seedling tray longitudinal conveying and further affects the precision of the transplanting work. SUMMARY

[0003] The present application belongs to the technical field of agricultural machinery, and particularly relates to a curve groove wheel type rice seedling tray longitudinal precision conveying device and a conveying method thereof.

[0004] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0005] The present application is a curve groove wheel type rice seedling tray longitudinal precision conveying device, which comprises a rotating shaft, a striking rod, a roller, a cam, a one-way bearing, a rocker, a tension spring, a connecting rod, a swing rod, a driving gear, a gear carrier, a curve groove wheel mechanism and a brake mechanism.

[0006] The roller is hinged to the striking rod, and two cams are fixed on the horizontally arranged rotating shaft at an interval. One end of the rocker is fixed to the rotating shaft, the two ends of the connecting rod are hinged to the other end of the rocker and one end of the swing rod, and one end of the tension spring is fixed to the middle part of the rocker. The other end of the swing rod is supported on the hollow shaft which is integrally formed on the driving gear and coaxially arranged through the one-way bearing. An annular groove is formed on the driving gear, and a plurality of grooves are uniformly distributed on the bottom surface of the annular groove in the circumferential direction. The curve groove wheel mechanism comprises a curve groove wheel, a driven gear and a round pin. A plurality of driven gears which are uniformly distributed in the circumferential direction of the driving gear are hinged to the gear carrier and meshed with the driving gear, and two round pins which are symmetrically arranged with respect to the center of the driven gear are fixed on each driven gear. The curve groove wheel is coaxially arranged with the driving gear, and a plurality of wheel grooves are uniformly distributed on the curve groove wheel in the circumferential direction. The brake mechanism comprises a brake hollow disc, a ball, a spring and a brake fixed housing. The brake hollow disc is fixed on the brake fixed housing, the ball and the spring are arranged in the cylindrical barrel which is integrally formed on the brake hollow disc, and part of the ball is exposed outside the cylindrical barrel. The ball is pressed by the spring. The part of the ball exposed outside the cylindrical barrel and the annular groove of the driving gear form a rolling friction pair. In the initial state, the part of the ball exposed outside the cylindrical barrel is embedded in one of the grooves, one round pin on each driven gear is embedded in one wheel groove of the curve groove wheel, and the round pins in each wheel groove are uniformly distributed in the circumferential direction.

[0007] Preferably, the swing lever is fixed with the outer ring of the one-way bearing, and the inner ring of the one-way bearing is fixed with the hollow shaft.

[0008] Preferably, the inner thread is formed on the end of the cylindrical barrel away from the ball, and the ball and the bolt are in contact with the two ends of the spring respectively.

[0009] Preferably, the theoretical profile line of the curve groove wheel is composed of an arc part and a straight line part, and the design process of the theoretical profile line of the curve groove wheel is as follows: assuming that the rotation center of one of the driven gears is point A, the rotation center of the curve groove wheel is point B, the initial positions of the centers of the two round pins on the driven gear are C1 and D1 respectively, the locus circle of the centers of the round pins intersects with the line segment AB at P1 when the round pins rotate with the driven gear, assuming that the two round pins rotate from C1 and D1 to C2 and D2 respectively when the driven gear drives the two round pins to rotate by an angle θ, the curve groove wheel stops, the two round pins rotate from C2 and D2 to D1 and C1 respectively when the round pins continue to rotate by an angle Φ with the driven gear, and the curve groove wheel rotates; during the movement of the curve groove wheel, the centers of the round pins always move along the theoretical profile line, so that the arc D1D2 with A as the rotation center is the curve part of the theoretical profile line of the curve groove wheel when the curve groove wheel stops; the arc part and the straight line part of the theoretical profile line of the curve groove wheel intersect at D2, the tangent line of the arc D1D2 is drawn at D2, and the position of P2 is reached when the center of the round pin moves along the tangent line from D2 to the end point P2 of the tangent line relative to the curve groove wheel, so that the position of P2 reaches the position of P1, the intersection point of the circle with B as the center and BP1 as the radius and the tangent line is P2, the straight line D2P2 is the straight line part of the theoretical profile line of the curve groove wheel, and the theoretical profile line of the curve groove wheel is obtained.

[0010] More preferably, assuming that the rotation angle of the driven gear during the process that the round pin enters the wheel groove to exits the wheel groove is 2α0, the corresponding rotation angle of the curve groove wheel is Since the arc part of the theoretical profile line is tangent to the locus circle of the center of the round pin at the wheel groove exit point, ∠AC1B=90°, and 2α0, and the number of wheel grooves Z of the curve groove wheel has the following relationship:

[0011]

[0012]

[0013] When the center of the round pin moves from the starting point to the ending point of the straight line part of the theoretical profile line, the driven gear turns through an angle γ, at this time the cylindrical surface of the round pin moves to the bottom of the wheel groove, i.e. the center of the round pin moves from the point D2 to the point P1, and the curve groove wheel turns through an angle ∠P1BP2, if the driven gear turns again through an angle γ, the center of the round pin moves from the ending point to the starting point of the straight line part of the theoretical profile line, i.e. the center of the round pin exits from the straight line part and enters the curve part, and let:

[0014]

[0015] Let the time for the driven gear to turn one round be T, the indexing motion time of the curve groove wheel be t f , and the rest time be t d , then the motion coefficient τ and the static coefficient g of the curve groove wheel mechanism are respectively

[0016]

[0017]

[0018] The motion-rest ratio k of the curve groove wheel mechanism is the ratio of the indexing time t f of the curve groove wheel to the rest time t d , so

[0019]

[0020] More preferably, the relationship between the number of wheel grooves of the curve groove wheel and the rotation radius of the seedling tray is

[0021]

[0022] In the formula, l is the distance of the longitudinal movement of the seedling tray each time, and r is the rotation radius of the seedling tray.

[0023] More preferably, the analysis process of the relationship between the rotation angle α of the driven gear and the rotation angle of the curve groove wheel in a single motion period of the curve groove wheel is as follows:

[0024] When the round pin exits from the curve groove wheel, α=α0, and α∈[-γ,π / 2-π / Z] during the rotation of the curve groove wheel, the stages of the motion of the curve groove wheel are divided into three stages according to the entering and exiting of the round pin from the straight line part as the segmentation basis:

[0025] (1) the center of the round pin moves from the point D2 to the point P1, at this time α∈[-γ,0];

[0026] (2) the center of the round pin moves from the point P1 to the straight line part where the round pin exits from the curve groove wheel, at this time α∈(0,γ);

[0027] (3) the center of the round pin moves from the entering of the curve part to the exiting of the curve groove wheel, at this time α∈[γ,π / 2-π / Z].

[0028] Let the initial position of the theoretical contour line be D1D2P2, the curve groove wheel is in the initial position of the 3-stage movement when the center of the round pin is at the D2 point, the rotation center of the driven gear is the O1 point, the rotation center of the curve groove wheel is the O2 point, the coordinate system is established with the O2 point as the coordinate origin, the straight line O2O1 as the X axis, and the straight line perpendicular to the straight line O2O1 and parallel to the end surface of the driven gear as the Y axis, the distance from the center of the curve groove wheel to the center of the driven gear is L, the distance from the center of the driven gear to the center of the round pin is R, the position point of the center of the round pin in the curve groove wheel is P, the length of the line segment O2P is ρ, the angle between the straight line O2P and the X axis is β1, the circle with the O2 as the center and the ρ as the radius is drawn, the theoretical contour line is intersected at the point P0(x0, y0), and the angle between the straight line O2P0 and the X axis is β2, then

[0029]

[0030]

[0031]

[0032] In addition, according to the relationship between R and L and , there are:

[0033]

[0034] When the P0 point is located on the straight line part of the theoretical contour line, the coordinates of the P0 point satisfy

[0035]

[0036] When the P0 point is located on the circular arc part of the theoretical contour line, the coordinates of the P0 point satisfy

[0037]

[0038] The 3-stage movement process is analyzed, the rotation angle of the curve groove wheel in the first-stage movement process is The rotation angle of the curve groove wheel in the second-stage and third-stage movement processes is

[0039]

[0040] The conveying method of the curve groove wheel type rice seedling tray longitudinal precise conveying device is as follows:

[0041] The end of the rod far from the roller is fixed with the double screw shaft in the rice pot seedling transplanting machine, the rotating shaft is parallel to the double screw shaft, and the rotating shaft and the seedling box frame in the rice pot seedling transplanting machine form a rotating pair, and the end of the tension spring far from the rocker is fixed with the seedling box frame; the curved groove wheel is fixed on the dial shaft in the rice pot seedling transplanting machine, the hollow shaft of the driving gear is arranged on the dial shaft, and the dial shaft and the driving gear form a rotating pair, and the brake fixing shell and the gear frame are both fixed on the seedling box frame; wherein the dial shaft in the rice pot seedling transplanting machine and the seedling box frame form a rotating pair;

[0042] When the rice pot seedling transplanting machine performs the transplanting work, the driving part drives the double screw shaft to rotate, the double screw shaft drives the seedling box frame to transversely reciprocate and translate, and drives the rod and the roller to rotate; when a row of seedlings on the seedling tray at the seedling taking position is taken, the seedling box frame is translated to the corresponding limit position, and a corresponding cam is translated to be aligned with the roller, the roller is in contact with the cam, the roller positively rotates through the cam, the rocker and the connecting rod, the rocker positively rotates through the connecting rod, the tension spring is stretched, the outer ring of the one-way bearing positively rotates through the rocker, the inner ring and the outer ring of the one-way bearing are locked, the rocker positively rotates through the one-way bearing, the ball is separated from the corresponding groove, and the ball moves relatively along the annular groove, the spring is further compressed, the driving gear is engaged with each driven gear, and each round pin is reversely rotated through each driven gear, each round pin is engaged with the wheel groove of the curved groove wheel, the curved groove wheel is positively rotated, the dial shaft is rotated, and the seedling tray is longitudinally moved through the dial mechanism on the dial shaft; when the roller is separated from the cam, the ball moves to the next groove, the spring pushes the ball to be embedded in the next groove, the driving gear stops rotating, each driven gear rotates by half a circle, another round pin on each driven gear is embedded in the corresponding next wheel groove, the curved groove wheel stops rotating, the next row of seedlings on the seedling tray is longitudinally moved to the seedling taking position, the tension spring reversely rotates the rocker to the original position, the rocker reversely rotates the cam to the original position through the rotating shaft, and reversely rotates the rocker to the original position through the connecting rod, and when the outer ring of the one-way bearing reversely rotates, the outer ring and the inner ring of the one-way bearing are not locked, the rocker does not drive the driving gear to rotate when the rocker reversely rotates, and the longitudinal conveying work of the seedling tray is completed, and then the double screw shaft drives the seedling box frame to translate to the opposite direction.

[0043] The present application has the following beneficial effects:

[0044] The present application can realize the accurate longitudinal conveying work of the seedling tray; specifically, the present application drives the roller to hit the cam through the hitting rod, the cam drives the swing lever to rotate forward through the rotating shaft, the swing lever drives the driving gear to rotate forward through the one-way bearing, the driving gear drives each driven gear to rotate reversely, the round pin of each driven gear drives the curve groove wheel to rotate forward, the curve groove wheel drives the dial shaft to rotate, the winding disc mechanism on the dial shaft drives the seedling tray to move longitudinally, thereby realizing the longitudinal conveying work of the seedling tray; compared with the ratchet mechanism, the impact mode of the curve groove wheel mechanism is mainly flexible impact, compared with the straight-line groove wheel mechanism, the flexible impact is smaller, and the two round pins are arranged on the driven gear in the curve groove wheel mechanism, so that the positioning and self-locking of the curve groove wheel can be realized, the positioning accuracy is higher, and the accuracy of the longitudinal conveying work of the seedling tray is improved; further, the brake mechanism is arranged in the present application, the ball is embedded in a groove on the driving gear through the spring, so that the driving gear will not continue to rotate due to inertia in the case of not rotating, and the vibration of the seedling box in the non-longitudinal conveying work does not affect the positions of the gears, further ensuring the accuracy of the longitudinal conveying work of the seedling tray. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 It is a structure schematic view of the present application installed on a rice pot seedling transplanting machine;

[0046] Figure 2 It is a structure schematic view of the present application;

[0047] Figure 3 It is a sectional view of the driving gear and the brake mechanism after removing the brake fixed shell in the present application;

[0048] Figure 4 It is a geometric schematic view of the curve groove wheel mechanism in the present application;

[0049] Figure 5 It is a schematic view of the longitudinal conveying of the seedling tray;

[0050] Figure 6 It is a relationship analysis diagram of the rotation angle alpha of the driven gear and the rotation angle beta of the curve groove wheel in the present application;

[0051] Figure 7 It is an angular velocity and angular acceleration curve schematic view of the curve groove wheel in the present application;

[0052] Figure 8 It is an angular velocity and angular acceleration curve schematic view of the straight-line groove wheel under the same size. DETAILED DESCRIPTION

[0053] The present application will be further described below in combination with the drawings.

[0054] As Figure 1 , Figure 2 and​Figure 3 As shown, the present invention provides a longitudinal precision conveying device for a curved grooved wheel type rice seedling tray, comprising a rotating shaft, a striking rod 1, a roller 2, a cam 3, a rocker arm 4, a tension spring 5, a connecting rod 6, a swing arm 7, a drive gear 8, a one-way bearing 12, a gear frame, a curved grooved wheel mechanism, and a braking mechanism. Roller 2 is hinged to lever 1. Two cams 3 are fixed at intervals on a horizontally arranged rotating shaft. One end of rocker arm 4 is fixed to the rotating shaft. Both ends of connecting rod 6 are hinged to the other end of rocker arm 4 and one end of swing arm 7. One end of tension spring 5 is fixed to the middle of rocker arm 4. The other end of swing arm 7 is fixed to the outer ring of one-way bearing 12. The inner ring of one-way bearing 12 is fixed to a hollow shaft integrally formed and coaxially arranged on the drive gear 8. The drive gear 8 has an annular groove, and the bottom surface of the annular groove has multiple grooves evenly distributed circumferentially. The curved grooved wheel mechanism includes a curved grooved wheel 9, a driven gear 10, and a round pin 11. The multiple driven gears 10 evenly distributed circumferentially along the drive gear 8 are all hinged to the gear carrier. All driven gears 10 mesh with the driving gear 8, and each driven gear 10 has two pins 11 fixed on it, symmetrically arranged about the center of the driven gear 10. The curved grooved wheel 9 is coaxially arranged with the driving gear 8, and has multiple grooves evenly distributed circumferentially. The braking mechanism includes a brake hollow disc 13, balls 14, springs 15, and a brake fixing housing 16. The brake hollow disc 13 is fixed to the brake fixing housing 16. The balls 14 and springs 15 are both placed inside a cylindrical tube integrally formed on the brake hollow disc 13, and a portion of the balls 14 protrudes from the cylindrical tube. The balls 14 are pressed by the springs 15. The portion of the balls 14 protruding from the cylindrical tube forms a rolling friction pair with the annular groove of the driving gear 8. In the initial state, the portion of the balls 14 protruding from the cylindrical tube is embedded in one of the grooves, the driving gear 8 is locked, and one pin 11 on each driven gear 10 is embedded in one groove of the curved grooved wheel 9, located at the same position in each groove (the pins in each groove are evenly distributed circumferentially).

[0055] In a preferred embodiment, the end of the cylindrical tube away from the ball 14 has an internal thread and is connected to the bolt 17 by the thread. The two ends of the spring 15 are in contact with the ball 14 and the bolt 17 respectively. The preload of the spring 15 can be adjusted by controlling the depth of the bolt 17 screwed into the cylindrical tube.

[0056] The present invention discloses a conveying method for a longitudinal precision conveying device for a curved grooved wheel-type rice seedling tray, the specific details of which are as follows:

[0057] like Figure 1As shown, the existing ratchet type mechanism for achieving the longitudinal conveying function of the seedling tray in the rice pot seedling transplanting machine is replaced by the present application, the end of the beating rod 1 away from the roller 2 is fixed with the double helical shaft 20 in the rice pot seedling transplanting machine, the rotating shaft is parallel to the double helical shaft 20 and forms a rotating pair with the seedling box frame in the rice pot seedling transplanting machine, the end of the tension spring 5 away from the rocker 4 is fixed with the seedling box frame, the curved groove wheel 9 is fixed on the dial shaft 21 in the rice pot seedling transplanting machine, the hollow shaft of the driving gear 8 is arranged on the dial shaft and forms a rotating pair with the dial shaft, the brake fixed housing 16 and the gear frame are both fixed on the seedling box frame. Among them, the dial shaft in the rice pot seedling transplanting machine forms a rotating pair with the seedling box frame.

[0058] When the rice pot seedling transplanting machine performs the transplanting work, the driving member drives the double helical shaft 20 to rotate, the double helical shaft 20 drives the seedling box frame to move transversely and reciprocally, and drives the beating rod 1 and the roller 2 to rotate; when a row of seedlings on the seedling tray 19 at the seedling taking position is taken, the seedling box frame moves to the corresponding limit position, and the corresponding cam 3 moves to the position aligned with the roller 2, the roller 2 contacts the cam 3, and the rotating shaft is driven to rotate forward by the cam 3, the rotating shaft drives the swing rod 7 to rotate forward through the rocker 4 and the connecting rod 6, the tension spring 5 is stretched, when the outer ring of the one-way bearing 12 is driven to rotate forward by the swing rod 7, the inner ring and the outer ring of the one-way bearing 12 are locked, then the swing rod 7 drives the driving gear 8 to rotate forward through the one-way bearing 12, the ball 14 is separated from the corresponding groove, and moves relatively along the annular groove, the spring 15 is further compressed, and the driving gear 8 is engaged with each driven gear 10, thereby driving each round pin 11 to rotate reversely through each driven gear 10, each round pin 11 is engaged with the wheel groove of the curved groove wheel 9, thereby driving the curved groove wheel 9 to rotate forward, so as to drive the dial shaft to rotate, and the winding disc mechanism 18 on the dial shaft drives the seedling tray 19 to move longitudinally; when the roller 2 is separated from the cam 3 with the continuous rotation of the double helical shaft 20, the ball 14 moves to the next groove, the spring 15 drives the ball 14 to be embedded in the next groove, the driving gear 8 stops rotating, each driven gear 10 rotates half a circle, and another round pin 11 on each driven gear 10 is embedded in the corresponding next wheel groove, the curved groove wheel 9 stops rotating, the next row of seedlings on the seedling tray 19 moves longitudinally to the seedling taking position, at the same time, the tension spring 5 drives the rocker 4 to rotate reversely to the original position, the rocker 4 drives the cam 3 to rotate reversely to the original position through the rotating shaft, and drives the swing rod 7 to rotate reversely to the original position through the connecting rod 6, and when the outer ring of the one-way bearing 12 is driven to rotate reversely by the swing rod 7, the outer ring of the one-way bearing 12 is not locked with the inner ring, then the swing rod 7 does not drive the driving gear 8 to rotate reversely when it rotates reversely, thereby completing the longitudinal conveying work of the seedling tray once, and then the double helical shaft 20 drives the seedling box frame to move to the opposite direction. Among them, the winding disc mechanism 18 includes a positioning frame 22 and a disc feeding steel wire 23, the positioning frame 22 is fixed on the dial shaft 21, and a plurality of disc feeding steel wires 23 are fixed on the positioning disc 22 in the circumferential direction, and one disc feeding steel wire 23 drives the seedling tray 19 to move longitudinally for one row when each driven gear 10 rotates half a circle.

[0059] Wherein, the theoretical profile line of the curve slot wheel 9 is composed of a circular arc part and a straight line part, and the design process of the theoretical profile line of the curve slot wheel 9 is as follows:

[0060] As shown in Figure 4 , it is assumed that the rotation center of one of the driven gears 10 is point A, the rotation center of the curve slot wheel 9 is point B, the initial positions of the centers of the two round pins 11 on the driven gear 10 are C1 and D1 respectively, the trajectory circle of the center of the round pin 11 when the round pin 11 is rotated by the driven gear 10 intersects with the line segment AB at P1, the curve slot wheel mechanism is an intermittent motion mechanism, it is assumed that when the two round pins 11 are rotated by an angle θ from the initial positions C1 and D1 respectively, the two round pins 11 are rotated to C2 and D2 respectively, the curve slot wheel 9 stops, and when the round pins 11 are continuously rotated by an angle Φ by the driven gear 10, the two round pins 11 are rotated to D1 and C1 respectively from C2 and D2 respectively, and the curve slot wheel 9 rotates; in the motion process of the curve slot wheel, in order to avoid the occurrence of motion distortion, the center of the round pin should always move along the theoretical profile line, so that the circular arc D1D2 with the rotation center A is the curve part of the theoretical profile line of the curve slot wheel 9 when the curve slot wheel 9 stops; at the D2 point, the circular arc part and the straight line part of the theoretical profile line of the curve slot wheel 9 intersect, in order to ensure that the speed curve is continuous and smooth at the intersection point of the circular arc part and the straight line part of the theoretical profile line during the motion process of the curve slot wheel 9, the circular arc part and the straight line part are tangent to each other, the tangent line of the circular arc D1D2 is drawn at the D2 point, and the center of the round pin moves along the tangent line from the D2 point to the end point P2 of the tangent line, and the P2 point on the curve slot wheel 9 reaches the P1 point, then a circle with the B point as the center and BP1 as the radius is drawn, and the intersection point of the circle and the tangent line is the P2 point, and the straight line D2P2 is the straight line part of the theoretical profile line of the curve slot wheel 9, thereby obtaining the theoretical profile line of the curve slot wheel 9, and since the two round pins 11 are symmetrically arranged on the driven gear 10, the curve slot wheel 9 has two motion periods and rotates through two wheel grooves for each rotation of the driven gear 10.

[0061] In addition, it is assumed that the rotation angle of the driven gear 10 from the time when the round pin enters the wheel groove (the symmetrical point of the C1 point with respect to the line segment AB is the entry point) to the time when the round pin exits the wheel groove (the C1 point is the exit point) is 2α0, and the corresponding rotation angle of the curve slot wheel 9 is Since the circular arc part of the theoretical profile line at the wheel groove exit point is tangent to the trajectory circle of the center of the round pin, ∠AC1B=90°, and 2α0, and the number of wheel grooves Z of the curve slot wheel satisfy the following relationship:

[0062]

[0063]

[0064] Suppose that when the center of the circular pin moves from the starting point to the ending point of the straight section of the theoretical contour line, the driven gear 10 rotates through an angle γ. At this time, the cylindrical surface of the circular pin moves to the bottom of the groove, that is, the center of the circular pin moves from point D2 to point P1. Simultaneously, the curved groove wheel rotates through ∠P1BP2. If the driven gear rotates through an angle γ again, the center of the circular pin moves from the ending point to the starting point of the straight section of the theoretical contour line, that is, the center of the circular pin exits from the straight section and begins to enter the curved section. Let:

[0065]

[0066] Let T be the time it takes for the driven gear 10 to rotate one revolution, and t be the indexing time of the curved grooved wheel 9. f (The circular center moves from point D2 to point C1), with a rest time of t. d Then the motion coefficient τ and the stationary coefficient g of the Geneva mechanism are respectively

[0067]

[0068]

[0069] The stop-start ratio k of the curved Geneva mechanism is the indexing time t of the curved Geneva. f With rest time t d The ratio of them, then

[0070]

[0071] As shown in the above equation, the motion law of the curved Geneva mechanism is determined by the number of grooves in the curved Geneva wheel. As the number of grooves Z of the curved Geneva wheel increases, the motion-to-stop ratio k of the curved Geneva wheel mechanism decreases, and the motion time t of the curved Geneva wheel increases. f Reducing the number of grooves improves the working efficiency of the curved grooved wheel mechanism. Furthermore, while the center distance between the curved grooved wheel and the driven gear only affects the overall size of the curved grooved wheel, the number of grooves on the wheel influences its theoretical profile shape and determines the radius of rotation when the seedling tray passes around the bottom of the seedling box. If the radius of rotation is too large, the seedling picking point is too high, affecting the uprightness of the seedlings; if the radius of rotation is too small, the seedling tray undergoes excessive deformation during winding. Greater deformation leads to greater resistance during tray transport and a higher likelihood of tray damage. Therefore, the number of grooves on the curved grooved wheel is a key indicator in designing the winding mechanism. Figure 5 As shown, let the longitudinal movement distance of the seedling tray 19 each time be l, and the radius of rotation of the seedling tray 19 be r. According to the working principle, the seedling tray 19 moves longitudinally a distance l for each rotation of the curved groove wheel through one groove. Therefore, the relationship between the number of grooves Z of the curved groove wheel and the radius of rotation r of the seedling tray is:

[0072]

[0073] Furthermore, based on the motion process of the curved grooved wheel, the driven gear rotation angle α and the curved grooved wheel rotation angle are calculated during a single motion cycle of the curved grooved wheel. Analyzing the relationship between them, when the pin leaves the curved grooved wheel, α = α0. During the rotation of the curved grooved wheel, α ∈ [-γ, π / 2 - π / Z]. Since the theoretical contour line of the curved grooved wheel is asymmetrical, the motion law is also not symmetrical during the motion. Based on the entry and exit of the pin from the straight section, the motion stage of the curved grooved wheel is divided into 3 segments:

[0074] (1) The center of the circular pin moves from point D2 to point P1 (that is, when the center of the circular pin moves from point D2 to point P2 along the straight section of the curved groove wheel 9 relative to the curved groove wheel 9), at which time α∈[-γ,0];

[0075] (2) The center of the circular pin rotates from point P1 to the straight part (i.e., the curved part) away from the curved groove wheel 9, at which point α∈(0,γ);

[0076] (3) The center of the circular pin extends from the part entering the curve to the part leaving the curve groove wheel, at which point α∈[γ,π / 2-π / Z].

[0077] During these three motions, α and The relationships between them are different. Analyzing the three-segment motion process, the initial position of the theoretical contour line is represented as D1D2P2. When the center of the circular pin is at point D2, the curved grooved wheel is at the starting position of the three-segment motion, such as... Figure 6 As shown, let the rotation center of the driven gear be point O1, and the rotation center of the curved Geneva wheel be point O2. Establish a coordinate system with point O2 as the origin, line O2O1 as the X-axis, and the line perpendicular to line O2O1 and parallel to the end face of the driven gear as the Y-axis. Let the distance from the center of the curved Geneva wheel to the center of the driven gear be L, the distance from the center of the driven gear to the center of the pin be R, the position of the pin center in the curved Geneva wheel be P, the length of line segment O2P be ρ, and the angle between line O2P and the X-axis be β1. Draw a circle with O2 as the center and ρ as the radius, intersecting the initial position of the theoretical contour line at point P0(x0,y0). The angle between line O2P0 and the X-axis is β2. Then...

[0078]

[0079] In addition, such as Figure 4 As shown, R and L and The relationships are:

[0080]

[0081] And when point P0 is located on the straight section of the theoretical contour line, the coordinates of point P0 satisfy (the equation is formulated by the relationship between the differences between the x and y coordinates of point P0 and the x and y coordinates of point D2 in the triangle, where...). )

[0082]

[0083] When P0 point is located at the circular arc part of the theoretical profile line, the coordinates of P0 point satisfy

[0084]

[0085] The analysis of the 3-stage motion process shows that the rotation angle of the curve groove wheel in the first stage is The rotation angles of the curve groove wheel in the second and third stages are both Wherein, at the beginning of the 3-stage motion, the center of the round pin is located at D2 point on the straight line part of the theoretical profile line, when the round pin rotates by an angle of -γ, the cylindrical surface of the round pin is located at the groove bottom of the curve groove wheel, and the center of the round pin is located on the straight line O2O1, i.e. P point is located on the straight line O2O1, and the corresponding P0 point is located at P2 point on the straight line part of the theoretical profile line as shown in Figure 4 , at this time, α = 0, β1 and ρ are obtained by substituting formula (7) and formula (9), and then x0 and y0 of P0 point are obtained by formula (11), and β2 is obtained by formula (8), and finally The analysis and calculation show that the rotation angles of the curve groove wheel at different positions in the motion process are and

[0086] As known from the above, the rotation angle of the curve groove wheel and the rotation angle α of the driven gear exist a functional relationship, let The first and second order derivatives of f(α) with respect to time t are obtained, and the angular velocity and angular acceleration formulas of the curve groove wheel are obtained, which are respectively

[0087]

[0088]

[0089] In the formula, ω1 is the angular velocity of the driven gear 10, and ω2 is the angular velocity of the curve groove wheel 9.

[0090] As shown in Figure 7 , the curve graph of ω2 and ε2 is drawn by Matlab software, and from Figure 7It can be seen that in the first motion, the angle velocity of the curve groove wheel gradually increases after the round pin enters the curve groove wheel, but the maximum value of the angle velocity of the curve groove wheel does not occur at the position of α = 0°. When the round pin leaves the straight line part of the profile line of the curve groove wheel, i.e., the second motion is completed, the angle velocity of the curve groove wheel is the maximum value at this moment, the angular acceleration is 0, and the direction of the angular acceleration is ready to reverse. In the third motion process, the curve groove wheel starts to decelerate, and the angle velocity slowly decreases until the round pin completely exits the curve groove wheel. And the angular acceleration is not 0 when the round pin enters and exits the curve groove wheel, which shows that there is still a flexible impact in the special-shaped groove wheel. In order to prove that the flexible impact of the mechanism is smaller than that of the linear groove wheel with the same L and R sizes, the motion of the linear groove wheel with the same L and R sizes is analyzed.

[0091] In the motion process of the linear groove wheel mechanism, the rotation angle α2 of the dial plate and the rotation angle of the linear groove wheel always satisfy the following formula:

[0092]

[0093] Note that the rotation angle is the rotation angle of the current position of the curve groove wheel relative to the straight line BP2 position, and the rotation angle is the rotation angle of the current position of the linear groove wheel relative to the position of the straight line groove wheel and the center line of the dial plate. Although the reference straight line has an angle difference, the angle difference is a constant value and does not affect the rotation angle or the rotation angle The comparison of the angular velocity and the angular acceleration after derivation.

[0094] By taking the first and second order derivatives of the above formula with respect to time, the relationship between the angular velocity ω 21 of the dial plate, the angular velocity ω 22 of the linear groove wheel and the angular acceleration ε 22 of the linear groove wheel can be obtained, which is

[0095]

[0096]

[0097] The curve graphs of ω 22 and ε 22 are drawn by Matlab software, as shown in Figure 8 . In the single motion process of the linear groove wheel mechanism with the same L and R sizes, the rotation angle α2 of the dial plate is ∈ [-3π / 7, 3π / 7], the angular velocity variation curve is symmetrical about α2 = 0°, and the angular velocity reaches the maximum value at α2 = 0°. The comparison of Figure 7 and Figure 8It is found that the curve groove wheel angular acceleration mutation is smaller than the linear groove wheel angular acceleration mutation at the start of movement, proving that the curve groove wheel has smaller flexible impact relative to the L and R size same linear groove wheel, that is, the impact force of the curve groove wheel when it is about to move is smaller than the impact force of the linear groove wheel when it is about to move, so the curve groove wheel mechanism in the present application has smaller noise than the existing linear groove wheel mechanism.

[0098] And the impact force of the linear groove wheel mechanism when it is about to move is obviously smaller than the impact force of the ratchet mechanism when it is about to move, so using the present application to replace the existing ratchet type mechanism for realizing the function of longitudinal transportation of the seedling tray will not have the problem of large rigid impact when the existing ratchet type mechanism for realizing the function of longitudinal transportation of the seedling tray works, but has smaller flexible impact than the linear groove wheel mechanism, and can solve the problem of unsatisfactory self-locking effect of the ratchet mechanism (the ratchet mechanism is connected flexibly by a spring to realize movement), greatly improving the precision of the longitudinal transportation of the seedling tray, and further improving the precision of the transplanting work.

Claims

1. A curve slot wheel type rice seedling tray longitudinal precision conveying device, comprising a punch rod, a roller, a cam and a one-way bearing, characterized in that: The application also relates to a cam mechanism, which comprises a rotating shaft, a rocker, a tension spring, a connecting rod, a swing lever, a driving gear, a gear frame, a curve slot wheel mechanism and a brake mechanism; the roller is hinged to the hitting lever; two cams are arranged at intervals on the horizontally arranged rotating shaft; one end of the rocker is fixed to the rotating shaft; the two ends of the connecting rod are hinged to the other end of the rocker and one end of the swing lever; one end of the tension spring is fixed to the middle part of the rocker; the other end of the swing lever is supported on the hollow shaft which is integrally formed on the driving gear and coaxially arranged; the annular groove is arranged on the driving gear; the bottom surface of the annular groove is provided with a plurality of grooves which are uniformly distributed along the circumference; the curve slot wheel mechanism comprises a curve slot wheel, a driven gear and a round pin; a plurality of driven gears which are uniformly distributed along the circumference of the driving gear are hinged to the gear frame and engaged with the driving gear; two round pins which are symmetrically arranged with respect to the center of the driven gear are fixed to each driven gear; the curve slot wheel is coaxially arranged with the driving gear; the curve slot wheel is provided with a plurality of wheel grooves which are uniformly distributed along the circumference; the brake mechanism comprises a brake hollow disc, a ball, a spring and a brake fixed shell; the brake hollow disc is fixed to the brake fixed shell; the ball and the spring are arranged in the cylindrical barrel which is integrally formed on the brake hollow disc; and part of the ball is exposed outside the cylindrical barrel; the ball is pressed by the spring; the part of the ball which is exposed outside the cylindrical barrel and the annular groove of the driving gear form a rolling friction pair. In the initial state, the part of the ball which is exposed outside the cylindrical barrel is embedded in one of the grooves; and one round pin on each driven gear is embedded in one wheel groove of the curve slot wheel.

2. The longitudinal precision conveying device for the curve groove wheel type rice seedling tray according to claim 1, characterized in that: The swing lever is fixed to the outer ring of the one-way bearing; and the inner ring of the one-way bearing is fixed to the hollow shaft.

3. The longitudinal precision conveying device for the curve groove wheeled rice seedling tray according to claim 1, characterized in that: The end of the cylindrical barrel which is far away from the ball is provided with an internal thread and is connected with the bolt through the thread; and the two ends of the spring are respectively in contact with the ball and the bolt.

4. The longitudinal precision conveying device for the curve groove wheeled rice seedling tray according to claim 1, characterized in that: The theoretical profile line of the curve slot wheel is composed of a circular arc part and a straight line part; and the design process of the theoretical profile line of the curve slot wheel is as follows: Let the rotation center of one of the driven gears be point A, the rotation center of the curve groove wheel be point B, the initial positions of the centers of the two round pins on the driven gear be points C1 and D1 respectively, the locus of the centers of the round pins intersect line segment AB at point P1 when the round pins are rotated by the driven gear, let the two round pins rotate by angle θ from the initial positions C1 and D1 to C2 and D2 respectively when the curve groove wheel is stopped, the round pins continue to rotate by angle Φ from C2 and D2 to D1 and C1 respectively when the curve groove wheel is rotated, the centers of the round pins always move along the theoretical contour line during the movement of the curve groove wheel, then the arc D1D2 of the curve groove wheel with the rotation center A is the curve part of the theoretical contour line of the curve groove wheel; the arc part and the straight line part of the theoretical contour line of the curve groove wheel intersect at point D2, the tangent of the arc D1D2 at point D2 is drawn, and the position of point P2 is reached when the center of the round pin moves along the tangent from D2 to the end point P2 of the tangent, then the circle with the center B and the radius BP1 is drawn, the intersection of the circle and the tangent is point P2, the straight line D2P2 is the straight line part of the theoretical contour line of the curve groove wheel, and the theoretical contour line of the curve groove wheel is obtained.

5. The longitudinal precision conveying device for the curve groove wheeled rice seedling tray according to claim 4, characterized in that: The rotation angle of the driven gear from the entry of the wheel groove to the exit of the wheel groove is 2α0, and the corresponding rotation angle of the curved groove wheel is Since the circular pin center is tangent to the circular arc part of the theoretical profile line at the exit point of the wheel groove, and the trajectory of the circular pin center is tangent to ∠AC1B=90°, then 2α0、 And the number of grooves Z of the curved groove wheel has the following relationship: Let the driven gear rotate by angle γ when the center of the round pin moves from the starting point to the end point of the straight line part of the theoretical contour line, at this time, the cylindrical surface of the round pin moves to the bottom of the wheel groove, i.e. the center of the round pin moves from D2 to P1, and the curve groove wheel rotates by angle P1BP2, if the driven gear rotates by angle γ again, the center of the round pin moves from the end point to the starting point of the straight line part of the theoretical contour line, i.e. the center of the round pin exits from the straight line part and enters the curve part, and let: Let the time for one revolution of the driven gear be T, and the time for the indexing motion of the cam wheel be t f , and the dwell time be t d , then the motion coefficient τ and the static coefficient g of the cam wheel mechanism are respectively The ratio k of the curve slot wheel mechanism is the ratio of the dwell time t f to the dwell time t d of the curve slot wheel.

6. The longitudinal precision conveying device for the curve groove wheeled rice seedling tray according to claim 5, characterized in that: The relationship between the number of the wheel grooves of the curve groove wheel and the rotation radius of the seedling tray is wherein, l is the distance of the longitudinal movement of the seedling tray each time, and r is the rotation radius of the seedling tray.

7. The longitudinal precision conveying device for the curve groove wheeled rice seedling tray according to claim 4, characterized in that: The driven gear rotation angle α and the curved groove wheel rotation angle during a single motion cycle of the curved groove wheel The process of analyzing the relationship between them is as follows: When the round pin exits from the curve groove wheel, α=α0, during the rotation of the curve groove wheel, α∈[-γ,π / 2-π / Z], the movement stages of the curve groove wheel are divided into three stages according to the entering and exiting of the round pin from the straight line part: (1) the center of the round pin moves from D2 to P1, at this time, α∈[-γ,0]; (2) the center of the round pin moves from P1 to the straight line part of the curve groove wheel, at this time, α∈(0,γ); (3) the center of the round pin moves from the entering of the curve part to the exiting of the curve groove wheel, at this time, α∈[γ,π / 2-π / Z]; Let the initial position of the theoretical contour line be represented as D1D2P2, the curve groove wheel is in the initial position of the three-section movement when the center of the round pin is at the D2 point, let the rotation center of the driven gear be the O1 point, the rotation center of the curve groove wheel be the O2 point, a coordinate system is established with the O2 point as the coordinate origin, the straight line O2O1 as the X axis, and the straight line perpendicular to the straight line O2O1 and parallel to the end surface of the driven gear as the Y axis, let the distance from the center of the curve groove wheel to the center of the driven gear be L, the distance from the center of the driven gear to the center of the round pin be R, the position point of the center of the round pin in the curve groove wheel be P, the length of the line segment O2P be ρ, the angle between the straight line O2P and the X axis be β1, a circle is drawn with the O2 point as the center and the ρ as the radius, the circle intersects the initial position of the theoretical contour line at the point P0(x0, y0), and the angle between the straight line O2P0 and the X axis be β2, then Further, from the relation of R and L and there are: When the P0 point is located on the straight line portion of the theoretical contour line, the coordinates of the P0 point satisfy When the P0 point is located on the circular arc portion of the theoretical contour line, the coordinates of the P0 point satisfy The 3-stage movement process is analyzed. The rotation angle of the curved groove wheel in the 1st stage movement process is The rotation angle of the curved groove wheel in the 2nd and 3rd stage movement processes is 8. The method of claim 1 to 7, wherein the method is characterized in that: Specifically as follows: The end of the punch rod away from the roller is fixed with the double helical shaft in the rice pot seedling transplanting machine, the rotating shaft is parallel to the double helical shaft and forms a rotating pair with the seedling box frame in the rice pot seedling transplanting machine, the end of the tension spring away from the rocker is fixed with the seedling box frame; the curve groove wheel is fixed on the dial shaft in the rice pot seedling transplanting machine, the hollow shaft of the driving gear is sleeved on the dial shaft and forms a rotating pair with the dial shaft, the brake fixed housing and the gear frame are fixed on the seedling box frame; wherein, the dial shaft in the rice pot seedling transplanting machine forms a rotating pair with the seedling box frame; When the rice seedling transplanting machine is working, the driving member drives the double screw shaft to rotate, the double screw shaft drives the seedling box frame to reciprocate horizontally, and drives the punch rod and the roller to rotate; when the row of seedlings on the seedling tray at the seedling taking position is taken, the seedling box frame translates to the corresponding limit position, and the corresponding cam is aligned with the roller, the roller contacts the cam, and the cam drives the rotating shaft to rotate forward, the rotating shaft drives the swing rod to rotate forward through the rocker and the connecting rod, the tension spring is stretched, and the swing rod drives the outer ring of the one-way bearing to rotate forward, the inner ring and the outer ring of the one-way bearing are locked, then the swing rod drives the driving gear to rotate forward through the one-way bearing, the ball is separated from the corresponding groove, and moves relatively along the annular groove, the spring is further compressed, and the driving gear is engaged with each driven gear, thereby driving each round pin to reverse through each driven gear, each round pin is engaged with the wheel groove of the curve groove wheel, thereby driving the curve groove wheel to rotate forward, so as to drive the dial shaft to rotate, and the seedling tray is moved longitudinally by the seedling tray mechanism on the dial shaft; with the continuous rotation of the double screw shaft, when the roller is separated from the cam, the ball moves to the next groove, the spring pushes the ball into the next groove, the driving gear stops rotating, each driven gear rotates half a circle, and another round pin on each driven gear is embedded in the corresponding next wheel groove, the curve groove wheel stops rotating, the next row of seedlings on the seedling tray moves to the seedling taking position, at the same time, the tension spring drives the rocker to reverse to the original position, the rocker drives the cam to reverse to the original position through the rotating shaft, and drives the swing rod to reverse to the original position through the connecting rod, and when the swing rod drives the outer ring of the one-way bearing to reverse, the outer ring of the one-way bearing is not locked with the inner ring, then the swing rod does not drive the driving gear to rotate when it reverses, thereby completing the longitudinal conveying work of the seedling tray once, and then the double screw shaft drives the seedling box frame to translate in the opposite direction.

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