A nonlinear stiffness flexible threshing element for corn critical crushing force unloading

Abstract

The present invention discloses a nonlinear stiffness flexible threshing element that can unload corn at its critical crushing force. This technical solution designs a nonlinear stiffness flexible threshing element, which includes: a diaphragm spring, a threshing finger, an intermediate rod, a base, a top cover, an outer cylinder, and a pin shaft; the critical pressure of the diaphragm spring is designed to be the minimum force for crushing corn kernels. After the contact force between the threshing element and the corn kernels reaches the critical pressure of the spring diaphragm, the elastic force of the diaphragm spring drops sharply, the stroke increases, and the long rod of the threshing finger quickly tilts backward, increasing the gap between the threshing finger and the concave plate; the long rod and the short rod of the threshing finger are a lever mechanism with their right angles as fulcrums, which reduces the contact force between the corn and the threshing finger and increases the stroke of the threshing finger. The nonlinear stiffness flexible threshing element of the present invention has the characteristic of adaptive stiffness change, can achieve unloading when the corn reaches its critical crushing force, and avoids the problem of corn kernels being crushed or damaged due to the rigid contact of traditional threshing elements.

Description

Technical Field

[0001] The invention belongs to the technical field of agricultural machinery, and in particular relates to a nonlinear rigidity flexible threshing element for unloading corn critical crushing force. Background Art

[0002] During corn harvesting, the threshing element, the primary working component of the threshing system, relies primarily on direct contact between the threshing element and the corn cob, generally considered rigid threshing. Problems such as kernel breakage and bruising caused by threshing are a major cause of corn yield reduction and mold.

[0003] National standards stipulate that corn kernel moisture content should be no higher than 25% during direct harvesting. However, in practice, corn moisture content is often higher than the national standard due to the competitive nature of the harvest season. This is particularly true in the Huanghuaihai region, a major grain-producing region with two crops per year. Current rigid threshing technology, which requires direct contact between the threshing element and the corn kernel, inevitably increases the rate of kernel bruises and breakage. Therefore, designing a flexible threshing element is a new approach to reducing these rates in mechanized corn harvesting.

[0004] The spike-tooth threshing element has a greater impact strength on the kernels and a higher kernel breakage rate. The threshing efficiency depends entirely on the frequency and force of the threshing element's impact on the corn. The greater the frequency and force, the higher the efficiency of corn threshing, but the higher the breakage rate. Both the plate-tooth and corrugated-rod threshing elements remove the kernels by kneading, which has a lower impact strength on the kernels. Although this reduces the kernel breakage rate to a certain extent, it results in unclean threshing and low threshing efficiency, and the structure is relatively complex. Comb threshing relies on the impact and pulling force of the threshing element on the corn cobs to achieve threshing, resulting in low efficiency and poor threshing quality. Vibration threshing uses the threshing components to apply high-frequency vibration to the cobs to thresh, resulting in low operating efficiency.

[0005] In addition to the aforementioned threshing elements, combined threshing elements are also widely used. These elements are mounted on the disengagement drum, with spike-tooth threshing elements at the front and plate-tooth or ribbed threshing elements at the middle and rear. The spike-tooth threshing elements strike the corn ears at multiple points, while the ribbed threshing elements then rub the ears at these points, increasing threshing efficiency and cleanliness. However, due to the high moisture content of corn harvested in the Huanghuaihai region, this type of threshing element can still result in a high rate of corn breakage.

[0006] Existing spike-tooth, plate-tooth, corrugated rod, and spike-tooth-corrugated rod combination threshing elements are all fixedly mounted on the threshing drum. During the threshing process, the contact between the threshing elements and the corn kernels is rigid, and the contact force between the kernels and the threshing elements cannot be adjusted. This is rigid threshing, resulting in a high rate of corn kernel breakage. Threshing elements equipped with coil springs, although the contact force between the kernels and the threshing elements can be adjusted during the threshing process, will still cause kernel damage and breakage when the spring force exceeds the critical force for kernel breakage. Therefore, in response to the new trend of high-speed and high-feed corn harvesting operations in the Huanghuaihai region, designing new flexible threshing elements is one of the effective ways to reduce the kernel breakage rate. Summary of the Invention

[0007] The first technical problem to be solved by the present invention is: under the premise of ensuring the unchanged threshing effect and efficiency, how to change the traditional rigid threshing method such as nail teeth and plate teeth into a flexible threshing method with nonlinear stiffness characteristics to reduce the breakage rate and gnawing rate of corn kernels.

[0008] The second technical problem to be solved by the present invention is that during the threshing process of the flexible threshing element of the coil spring, although the contact force between the grains and the threshing element can be adjusted, when the spring force is greater than the critical force of the grain breakage, the grains will still be damaged and broken.

[0009] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0010] The present invention is based on the ideal nonlinear characteristics of the stiffness change of the diaphragm spring, and innovatively designs a flexible threshing element with variable stiffness. When the pressure on the diaphragm spring used in the threshing element increases to a limit point, the elastic force of the diaphragm spring will drop sharply, and at the same time, the stroke of the diaphragm spring will increase. Therefore, compared with the ordinary coil spring, the threshing element with adaptive stiffness change of the diaphragm spring is more suitable for flexible threshing.

[0011] The load and deformation calculation model of the nonlinear stiffness flexible threshing element with corn critical crushing force unloading can predict and determine the load deformation curve of the threshing element equipped with a diaphragm spring, which satisfies:

[0012]

[0013] Where F is the load at the large end L, R is the outer radius of the diaphragm spring; h is the height of the inner truncated cone of the diaphragm spring part (inner cone height); L is the outer support radius; E is the elastic modulus of the material; k1 is the lever arm ratio, k1 = (Rr) / (L-1); λ1 is the deformation at the large end L; r is the inner radius of the diaphragm spring part (outer radius of the window hole); t is the spring plate thickness of the diaphragm spring (plate thickness); l is the inner support radius; η is the Poisson's ratio.

[0014] The threshing element is fixed to the drum by bolts and consists of an outer cylinder (6), a base (4), a top cover (5), a diaphragm spring (1), a threshing finger (2), a pin (8), and an intermediate rod (3).

[0015] The top cover (5) is in contact with the drum and is mounted by direct welding to the outer surface of the drum.

[0016] The outer cylinder (6) and the top cover (5) are connected via threads, and the intermediate rod (3), the diaphragm spring (1), and the base (4) are sequentially installed in the outer cylinder from top to bottom.

[0017] The small end of the diaphragm spring (1) is placed downward to contact the base (4), and the large end is in contact with the top cover (5). The middle rod (3) and the base (4), the middle rod (3) and the threshing finger (2), and the threshing finger (2) and the top cover (5) are all connected via a pin shaft.

[0018] Preferably, the threshing elements are welded to the drum, with the threshing fingers facing at right angles opposite to the direction of rotation of the drum.

[0019] Preferably, the diaphragm spring is circular and has a free travel of 3 to 4 mm. When the spring is compressed by 2.8 to 3.8 mm, the ear passes through the threshing finger (2). The diaphragm spring is characterized in that when the pressure reaches the limit pressure point, the elastic force drops sharply, the diaphragm spring travel increases, and the gap between the threshing finger (2) and the concave plate increases, thereby reducing the breakage of the corn kernels.

[0020] Preferably, the diaphragm spring is a spring with nonlinear stiffness. When the pressure reaches the critical crushing force of corn, the spring is compressed and the stroke is greatly increased compared to the compression stroke before the critical point.

[0021] Preferably, the top cover (5) has a hole in the middle and a threaded bottom end. The diameter of the top cover is 20 to 100 mm. The top cover (5) is welded to the inner surface of the drum and connected to the outer cylinder (6) through a threaded connection.

[0022] Preferably, the upper end of the outer cylinder (6) is processed with an internal thread, the overall height of the outer cylinder (6) is 9 to 11 mm, the bottom thickness is 3 to 4 mm, and the diameter is 20 to 100 mm.

[0023] Preferably, the base (4) is placed in the outer cylinder and connected to the middle rod (3) through a pin shaft. The diaphragm spring (1) is installed on the base with the small end facing downward and the large end in contact with the top cover (5). The middle rod (3) extends from the hole with a length of 17 to 20 mm.

[0024] Preferably, a through hole is provided at the upper end of the intermediate rod (3), which is connected to the threshing finger (2) via a pin, and is connected to the short rod of the threshing finger (2) via the pin, and the threshing finger (2) is connected to the top cover (5) at the bending part via the pin.

[0025] Preferably, the threshing finger (2) has a right angle, a long rod having a spike tooth shape and a length of 38 to 52 mm, a short rod having a length of 7.6 to 10.4 mm, and a ratio of the length of the short rod to the long rod of the threshing finger of 1:5.

[0026] Preferably, the threshing finger is connected to the top cover (5) at a right angle through a pin, limiting the threshing finger's five degrees of freedom, and the long rod and the short rod are a lever mechanism with the right angle as a fulcrum, reducing the contact force between the corn and the threshing finger.

[0027] During threshing, the kernels come into contact with the threshing fingers. As the contact force increases, the fingers drive the intermediate rod and base upward, compressing the diaphragm spring. Due to the contact force, the long teeth of the threshing fingers tilt backward, increasing the gap between the fingers and the concave plate, allowing the corn ears to pass through without being damaged by the kernels.

[0028] The critical pressure of the diaphragm spring is set as the minimum force for crushing corn kernels. When the contact force between the threshing finger and the kernel reaches the critical point of the spring pressure, the long teeth of the threshing finger tilt backward to prevent the threshing finger from damaging the corn kernels.

[0029] The present invention operates as follows: During threshing, corn ears contact the threshing fingers 2. As the contact force increases, the fingers 2 drive the intermediate rod 3 and base 4 upward, compressing the diaphragm spring 1. Due to the contact force, the long teeth of the threshing fingers 2 tilt backward, increasing the gap between the fingers 2 and the intaglio plate, allowing the corn ears to pass through and preventing damage to the ears. When the pressure reaches the critical crushing force of the corn, the diaphragm spring 1 is compressed, and the stroke increases compared to the compression stroke before the critical point. The minimum force required to crush the corn kernels is set to the critical pressure of the diaphragm spring 1. When the contact force between the threshing fingers 2 and the kernels reaches the critical point of the spring pressure, the long teeth of the threshing fingers tilt backward rapidly, preventing the threshing fingers from damaging the kernels.

[0030] The beneficial effects of the present invention are concentrated in the following aspects: 1. After the contact force between the threshing fingers and the kernels reaches the critical pressure of the spring diaphragm, the minimum stress for crushing the corn kernels is set to the critical pressure of the diaphragm spring, and the long teeth of the threshing fingers quickly tilt backwards, increasing the gap between the threshing fingers and the concave plate, so that the corn can pass over the threshing elements, avoiding the problem of corn kernels being crushed or gnawed due to the rigid contact of traditional threshing elements.

[0031] 2. A nonlinear stiffness flexible threshing element for unloading the critical crushing force of corn. The threshing finger has a right angle and a long rod with a spike-tooth shape. The length ratio of the short rod to the long rod of the threshing finger is designed to be 1:5. The threshing finger is connected to the top cover at the right angle through a pin shaft, which limits the threshing finger to 5 degrees of freedom. The long rod and the short rod form a lever mechanism with the right angle as the fulcrum, reducing the contact force between the corn and the threshing finger. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the axonometric view of the nonlinear stiffness flexible threshing element after removing the top cover and outer cylinder;

[0033] Figure 2 is a cross-sectional view of a nonlinear stiffness flexible threshing element;

[0034] Figure 3 It is the overall axonometric view of the nonlinear stiffness flexible threshing element.

[0035] Figure 4 It is the curve diagram of the change of diaphragm spring displacement and spring force;

[0036] Figure 5 Schematic diagram of the lever formed by the long and short rods for threshing;

[0037] In the picture:

[0038] 1. Diaphragm spring; 2. Threshing finger; 3. Intermediate rod; 4. Base; 5. Top cover; 6. Outer cylinder; 7. Pin assembly. DETAILED DESCRIPTION

[0039] The following is a detailed description of specific embodiments of the present invention. To avoid excessive unnecessary detail, well-known structures or functions will not be described in detail in the following examples. Approximate language used in the following examples can be used for quantitative expression to indicate that a certain amount of variation is allowed without changing the basic function. Unless otherwise defined, technical and scientific terms used in the following examples have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0040] The present invention will be described in further detail below with reference to the embodiments and accompanying drawings. Figure 1 The rear axle side view of the nonlinear stiffness flexible threshing element after removing the top cover and outer cylinder consists of 1-diaphragm spring, 2-threshing finger, 3-intermediate rod, 4-base, and 7-pin shaft group.

[0041] The diaphragm spring 1 is a nonlinear stiffness flexible threshing element. The diaphragm spring stiffness reaches the critical crushing force of corn and unloads. The diaphragm spring is circular and has a free stroke of 3 to 4 mm. When the spring is compressed by 2.8 to 3.8 mm, the ear passes through the threshing finger (2). The characteristic of the diaphragm spring is that when the pressure reaches the limit pressure point, the elastic force drops sharply, the diaphragm spring stroke increases, and the gap between the threshing finger (2) and the concave plate increases, thereby reducing the crushing of corn kernels.

[0042] The angle of the threshing finger 2 is a right angle, the long rod has a spike tooth shape, the length is 38-52 mm, the short rod has a length of 7.6-10.4 mm, and the ratio of the length of the short rod to the long rod of the threshing finger is 1:5. The threshing finger is connected to the top cover (5) at the right angle through a pin shaft, limiting the threshing finger's five degrees of freedom. The long rod and the short rod are a lever mechanism with the right angle as the fulcrum, reducing the contact force between the corn and the threshing finger.

[0043] A through hole is provided at the upper end of the intermediate rod (3), which is connected to the threshing finger (2) via a pin, and is connected to the short rod of the threshing finger (2) via the pin.

[0044] The base (4) is placed in the outer cylinder and connected to the middle rod (3) through a pin shaft. The diaphragm spring (1) is installed on the base, with the small end facing downward and the large end in contact with the top cover (5). The middle rod (3) extends from the hole with a length of 17 to 20 mm.

[0045] The working process of a nonlinear stiffness flexible threshing element with corn critical crushing force unloading: During threshing, the corn cob contacts the threshing finger 2. As the contact force increases, the threshing finger 2 drives the intermediate rod 3 and base 4 upward, compressing the diaphragm spring 1. Under the contact force, the long teeth of the threshing finger 2 tilt backward, increasing the gap between the threshing finger 2 and the concave plate, allowing the corn cob to pass through and preventing damage to the corn cob. When the pressure reaches the critical crushing force of the corn, the diaphragm spring 1 is compressed, and the stroke increases compared to the compression stroke before the critical point. The minimum force for crushing the corn kernels is set to the critical pressure of the diaphragm spring 1. When the contact force between the threshing finger 2 and the kernel reaches the critical point of the spring pressure, the long teeth of the threshing finger tilt backward rapidly, preventing the threshing finger from damaging the corn kernels.

[0046] The embodiments described are only preferred implementations of the present invention, but the present invention is not limited to the above implementations. Any obvious improvements, replacements or modifications that can be made by any technician familiar with this technical field fall within the scope of protection of the present invention.

Claims

1. A nonlinear stiffness flexible threshing element for corn critical crushing force unloading, characterized by: The nonlinear stiffness flexible threshing element comprises an outer cylinder (6), a top cover (5), a base (4), a diaphragm spring (1), a threshing finger (2), a pin shaft group (7), and an intermediate rod (3). The top cover (5) has a hole in the middle and a thread is processed on the outside of the lower end. The diameter of the top cover is 20-100 mm. The top cover (5) is welded to the inner surface of the drum and connected to the outer cylinder (6) through a thread. The upper end of the outer cylinder is processed with an internal thread. The overall height of the outer cylinder (6) is 9-11 mm and the bottom surface thickness is 3-4 mm. The diameter is 20 to 100 mm. The base (4) is placed in the outer cylinder and connected to the middle rod (3) through a pin. The diaphragm spring (1) is installed on the base, with the small end facing downward and the large end in contact with the top cover (5). The middle rod (3) extends from the hole and has a length of 17 to 20 mm. A through hole is provided at the upper end of the middle rod (3) and is connected to the threshing finger (2) through a pin. The pin is used to connect to the short rod of the threshing finger (2). The threshing finger (2) is connected to the top cover (5) at its bending part through the pin. The diaphragm spring is circular and has a free travel of 3 to 4 mm. When the diaphragm spring stiffness reaches the critical crushing force of corn, unloading occurs. When the spring is compressed by 2.8 to 3.8 mm, the ear passes through the threshing finger (2). The diaphragm spring is characterized in that when the pressure reaches the limit pressure point, the elastic force drops sharply, the diaphragm spring travel increases, and the gap between the threshing finger (2) and the concave plate increases, thereby reducing the crushing of corn kernels. The threshing finger (2) has a right angle, a long rod in a spike-tooth shape, a length of 38 to 52 mm, a short rod in a length of 7.6 to 10.4 mm, and a length ratio of the short rod to the long rod of the threshing finger is 1:

5. The threshing finger is connected to the top cover (5) at a right angle through a pin shaft, limiting the threshing finger's five degrees of freedom. The long rod and the short rod form a lever mechanism with the right angle as a fulcrum, reducing the contact force between the corn and the threshing finger. All the nonlinear stiffness flexible corn threshing elements are welded on the threshing drum, and their installation directions are perpendicular to the axis of the drum. The right-angle direction of the threshing fingers is opposite to the rotation direction of the threshing drum.

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