Rotary grading and vibration screening device for snakegourd seeds

Abstract

The invention solves the problem of snakegourd seed stagnation or accumulation caused by too single vibration mode, and relates to the field of snakegourd seed screening, in particular to a snakegourd seed rotary grading vibration screening device which comprises a base and a bourdon tube, a rotary assembly is installed on the base, a screening assembly is connected to the bottom of the bourdon tube, and a bottom frame is installed at the bottom of the screening assembly. Rail groove frames are installed on the two sides of the screening assembly and the two sides of the bottom frame correspondingly, the rotating assembly is slidably connected with the multiple rail groove frames, the rotating assembly operates to drive the screening assembly to rotate and shake internal snakegourd seeds in the front-back axial direction in a swinging mode, and the screening assembly comprises a plurality of four-edge frames arranged up and down. The widths of the four-edge frames and the bottom frame are gradually increased from top to bottom, side edge sieve plates are embedded in the front faces and the back faces of the four-edge frames, and bottom surface sieve plates are installed at the bottoms of the four-edge frames. By driving the screening assembly and the bottom frame to rotate in a large-amplitude swinging mode in the front-back axial direction, the snakegourd seed screening effect is improved, and meanwhile screening hole blocking is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of Trichosanthes kirilowii Maxim. seed screening, specifically to a rotary grading vibration screening device for Trichosanthes kirilowii Maxim. seeds. Background Art

[0002] During the production process of Trichosanthes kirilowii Maxim. seeds, through vibration screening, Trichosanthes kirilowii Maxim. seeds of different specifications can be separated, making it easy to process in subsequent processing and ensuring the stable quality of the product.

[0003] The basic structure of a conventional vibration screening device for Trichosanthes kirilowii Maxim. seeds consists of a sieve frame, a base, an elastic structure connected between the sieve frame and the base, and a vibration motor. By operating the vibration motor, a fixed linear vibration mode is provided for the sieve frame. Among them, Trichosanthes kirilowii Maxim. seeds usually only fluctuate up and down within a small surrounding range, resulting in poor fluidity of Trichosanthes kirilowii Maxim. seeds. The single vibration method easily causes material accumulation during the screening process of Trichosanthes kirilowii Maxim. seeds, thereby affecting the screening efficiency and effect, and causing sieve hole blockage. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a rotary grading vibration screening device for Trichosanthes kirilowii Maxim. seeds to solve the problem of stagnation or accumulation of Trichosanthes kirilowii Maxim. seeds caused by the overly single vibration mode in the above-mentioned background art.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A rotary grading vibration screening device for Trichosanthes kirilowii Maxim. seeds, including a base and a spring tube. A rotary component is installed on the base. The bottom of the spring tube is connected with a screening component. The bottom of the screening component is installed with a bottom frame. Track groove frames are installed on both sides of the screening component and the bottom frame. The rotary component is slidably connected with a plurality of track groove frames. The operation of the rotary component drives the screening component to swing and rotate axially back and forth to shake the Trichosanthes kirilowii Maxim. seeds inside. The screening component includes a plurality of four-sided frames arranged up and down. The widths of the plurality of four-sided frames and the bottom frame gradually increase from top to bottom. Side sieve plates are embedded on the front and back of the four-sided frames. The bottom of the four-sided frames is installed with a bottom sieve plate. The apertures of the plurality of side sieve plates and the bottom sieve plate gradually decrease from top to bottom. A cover frame is installed outside the side sieve plates, and the top of the four-sided frames is in contact with the bottoms of the two upper cover frames. The bottom sieve plate is formed by arranging a plurality of flat parts and convex parts at intervals.

[0006] Preferably, the heights and widths of the plurality of convex parts gradually decrease from the middle to both sides, and the spacing width between adjacent two convex parts is greater than the top surface width of the convex part.

[0007] Preferably, the side slope of the convex part is less than 45°, and the flat parts at the front and back ends of the bottom sieve plate are in contact with the four-sided frames.

[0008] Preferably, discharge outlets are formed in the front surfaces of several of the side sieve plates and the bottom frame located on the front side, and outlet pipes are connected to the outer sides of the discharge outlets. Plugging plates are inserted into several of the outlet pipes.

[0009] Preferably, an extension plate is provided on the front side of the bottom frame. The end of the extension plate is fixedly connected to the tops of several plugging plates. A storage battery-powered electric push rod is installed on the front surface of the bottom frame, which drives the extension plate to lift and lower, driving several plugging plates to adjust positions along several outlet pipes.

[0010] Preferably, a guiding block is installed between the frontmost corners of the bottom sieve plate and the four side frames, and the guiding block is in the shape of a triangular prism. One of its pointed ends is located at the edge of the discharge outlet.

[0011] Preferably, the rotating assembly includes a cross beam frame rotatably inserted into the extended end of the top surface of the base. A driving structure drivingly connected to the cross beam frame is installed on the top surface of the base. Connecting frames slidably connected to several track groove frames are installed on both sides of the cross beam frame.

[0012] Preferably, a roller ring is rotatably sleeved on the cross beam frame, and the top of the roller ring is in contact with the bottom of the bottom frame.

[0013] Preferably, elastic structures are installed on the front and rear inner walls of the track groove frame. The elastic structures are composed of compression springs and shock-absorbing blocks, and the shock-absorbing blocks are connected to one ends of the compression springs.

[0014] By means of the above technical solution, the present invention provides a trichosanthes seed rotating grading vibration screening device, which at least has the following beneficial effects: 1. The present invention controls the screening spaces at each level and the bottom frame in the screening assembly through the rotating assembly to perform large-amplitude swinging dynamic rotation back and forth, so that the trichosanthes seeds in the screening space constantly collide and roll with the sieve plates, effectively improving the screening effect, and at the same time reducing the problems of uneven screening and clogging of sieve holes caused by the stagnation of trichosanthes seeds.

[0015] 2. The present invention adds side sieve plates to the front and rear walls of the screening spaces at each level in the screening assembly, so that the trichosanthes seeds of appropriate size have more paths to pass through the screening space at their respective levels. At the same time, as the screening assembly as a whole swings and rotates back and forth, it is easy to turn the lighter trichosanthes seeds to the upper layer. As the screening assembly dynamically tilts, the lighter trichosanthes seeds in the upper layer will preferentially contact the side sieve plates and pass through the sieve holes therein, and fall into the screening space of the next level along the channels formed by the side sieve plates and the cover frame, thereby further improving the screening efficiency and effect.

[0016] 3. The ground screen plate of the present invention is formed by a plurality of plane parts and a trapezoidal convex part arranged at intervals, which can effectively increase the area for screening the Trichosanthes seeds in a single-level space. At the same time, it is easier to break the static accumulation of the Trichosanthes seeds, and further optimize its screening effect and efficiency.

[0017] 4. The height of the several raised structures of the combined bottom sieve plate of the present invention gradually increases from the two sides to the middle part, so that when the screening component as a whole is tilted significantly, the Trichosanthes seeds on the upper side of the bottom sieve plate will slide down smoothly after the tilt. During the sliding process, they will collide with the side of the raised part for many times, which can promote the separation between the Trichosanthes seeds, reduce sticking, optimize the screening efficiency, and enhance the screening accuracy.

[0018] 5. The present invention drives the extension plate to drive a number of blocking plates to adjust the position relationship with the discharge outlets on each level of screening space in the screening component and the bottom frame space through the advancement and contraction of the battery-powered electric push rod, thereby optimizing the control structure and reducing costs.

[0019] 6. The present invention adds an elastic structure in the track groove frame, so that the front and rear swings of the screening assembly and the bottom frame can produce a vibration effect, which helps to improve the movement speed and screening efficiency of the Trichosanthes seeds. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 It is a schematic diagram of the installation structure of the screening component and the bottom frame of the present invention; Figure 3 This is a schematic diagram of the split structure of the screening component of the present invention; Figure 4 It is a structural schematic diagram of the bottom screen plate of the present invention; Figure 5 It is a schematic diagram of the swing amplitude of the bottom screen plate of the present invention; Figure 6 It is a structural schematic diagram of the rotating assembly of the present invention; Figure 7 It is a schematic diagram of the installation structure of the track groove frame and the elastic structure of the present invention; Figure 8 This is a schematic diagram of the bottom frame and screening assembly of the present invention rotating forward.

[0021] In the figure: 1, base; 2, bourdon tube; 3, rotating assembly; 301, crossbeam frame; 302, driving structure; 303, connecting frame; 304, roller ring; 4, screening assembly; 401, four-sided frame; 402, side sieve plate; 403, bottom sieve plate; 4031, flat part; 4032, convex part; 404, cover frame; 405, outlet pipe; 4051, plugging plate; 4052, extension plate; 4053, storage battery electric push rod; 406, guiding block; 5, bottom frame; 6, track groove frame; 601, elastic structure. Detailed implementation manner

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0023] Embodiment 1 Please refer to 1- Figure 8, in this embodiment, a trichosanthes seed rotary classification vibration screening device is proposed, which can effectively solve the problem of trichosanthes seeds stagnating or accumulating due to too single vibration mode. The trichosanthes seed screening device includes a base 1 and a spring tube 2. A rotary assembly 3 is installed on the base 1. The rotary assembly 3 specifically includes a crossbeam frame 301 rotatably inserted into the extended end of the top surface of the base 1, a driving structure 302 arranged on the top surface of the base 1, and connecting frames 303 installed on both sides of the crossbeam frame 301. The driving structure 302 is composed of a motor, spur gears installed on the output end of the motor and the crossbeam frame 301, and the two spur gears are connected through tooth grooves. The purpose is to control the crossbeam frame 301 to drive the connecting frames 303 to rotate according to a set program under the transmission of the two spur gears by operating the motor. The bottom of the spring tube 2 is connected with a screening assembly 4, and a bottom frame 5 is installed at the bottom of the screening assembly 4. Track groove frames 6 are installed on both sides of the screening assembly 4 and the bottom frame 5. The connecting frames 303 in the rotary assembly 3 are slidably connected with a plurality of track groove frames 6. The operation of the rotary assembly 3 drives the screening assembly 4 to swing and rotate axially back and forth to shake the trichosanthes seeds inside. The screening assembly 4 includes a plurality of four-sided frames 401 arranged up and down. The widths of the plurality of four-sided frames 401 and the bottom frame 5 gradually increase from top to bottom. Side sieve plates 402 are embedded in the front and back of the four-sided frames 401, and a bottom sieve plate 403 is installed at the bottom of the four-sided frames 401. The apertures of the plurality of side sieve plates 402 and the bottom sieve plate 403 gradually decrease from top to bottom. A cover frame 404 is installed outside the side sieve plate 402, and the top of the four-sided frame 401 is in contact with the bottom of the two cover frames 404 above.

[0024] Operate the rotary assembly 3 to drive the overall component formed by the screening assembly 4 and the bottom frame 5 to rotate forward by a set angle, then rotate back to the original position, and then rotate backward by a set angle. This set angle is between 45° and 55°. Then continuously repeat the above actions to form a dynamic rotation of swinging back and forth, so as to drive the screening assembly 4 to shake greatly in space, making the trichosanthes seeds within the space range of each layer of the four-sided frames 401 continuously collide, roll and turn with the side sieve plates 402 and the bottom sieve plate 403, enhancing their jumping ability, being more conducive to loosening the bonded particles in the trichosanthes seeds, and at the same time increasing the effective contact with the side sieve plates 402 and the bottom sieve plate 403. The dynamic operation makes the trichosanthes seeds more evenly distributed on the sieve plate, thereby improving the screening effect, reducing the problem of uneven screening caused by the stagnation of trichosanthes seeds, and effectively preventing the trichosanthes seeds from blocking the sieve holes in the screening assembly 4.

[0025] Continuing from the above, during the process of the screening component 4 swinging and rotating back and forth, under the action of gravity, the trichosanthes seeds move in different directions. Generally, the heavier trichosanthes seeds will settle on the bottom sieve plate 403, while the lighter trichosanthes seeds are more likely to stay on the upper layer. Based on this, in this embodiment, side sieve plates 402 are added to the front and rear wall bodies of the four-sided frame 401, and a channel for the trichosanthes seeds to fall into the space of the next-level four-sided frame 401 is formed between the side sieve plate 402 and the matching cover frame 404. During actual application, when the screening component 4 swings and rotates back and forth, within the enclosed space of each four-sided frame 401, the lighter trichosanthes seeds on the upper layer will tend to shift towards the areas where the two side sieve plates 402 are located under the action of inertia. The trichosanthes seeds of appropriate size will pass through the side sieve plate 402 under the action of inertia and the pushing force during the swinging of other trichosanthes seeds, and fall into the next-level screening space in the screening component 4 through the channel formed between the side sieve plate 402 and the cover frame 404. Based on this embodiment, there are multiple levels of upper and lower screening spaces in the screening component 4, and finally, trichosanthes seeds of different sizes and weights can be effectively separated according to multiple size specifications of the trichosanthes seeds. In addition, by adding the side sieve plates 402, the trichosanthes seeds of appropriate size have more paths to pass through the screening space of the corresponding level.

[0026] And by controlling the screening component 4 to swing and rotate back and forth axially by the rotating component 3, the fluidity of the trichosanthes seeds in each level of the screening space can be enhanced, avoiding the trichosanthes seeds staying on the bottom sieve plate 403 for a long time and on the side sieve plate 402 when the screening component 4 is inclined. At the same time, the repeated back-and-forth swinging and rotating is equivalent to providing additional power to the trichosanthes seeds, making it easier for them to pass through the pores on the side sieve plate 402 and the bottom sieve plate 403, thus effectively avoiding the blockage of the pores of the two.

[0027] Embodiment Two Continuing from Embodiment One above, the bottom sieve plate 403 is formed by arranging a number of planar parts 4031 and convex parts 4032 at intervals. As Figure 3 and Figure 4 shown, the convex part 4032 presents a trapezoidal shape. During the overall back-and-forth swinging and rotating process of the screening component 4, local eddies are formed, which are likely to break the static accumulation of the trichosanthes seed particles, promote the floating of the lighter trichosanthes seeds and broken shells, and the trapezoidal convex part 4032 effectively increases the area of the region for sieving on the basis of the bottom sieve plate 403 in a planar state.

[0028] Embodiment Three As Figures 3 - 5As shown, several raised portions 4032 that make up the bottom sieve plate 403 have their height and width gradually decreasing from the middle to both sides, and the side slope of the raised portion 4032 is less than 45°. The spacing width between two adjacent raised portions 4032 is greater than the top surface width of the raised portion 4032. The grooves formed between two adjacent raised portions 4032 can promote the jumping and rolling of trichosanthes seeds on the bottom sieve plate 403. And when the screening assembly 4 swings, the trichosanthes seeds are subjected to vibration forces in different directions, prompting the trichosanthes seeds to generate more displacements and rolling on the sieve surface, which helps to change the movement direction of the trichosanthes seeds, enhance their fluidity, and make it easier for them to pass through the sieve mesh, avoiding the retention or accumulation of trichosanthes seeds. The flat portions 4031 where the front and rear ends of the bottom sieve plate 403 are in contact with the four-side frame 401 are provided to reserve sufficient space for the bottom sieve plate 403 near the front and rear side sieve plates 402. During the process of performing the actions in Embodiment 1, when the screening assembly 4 is controlled to rotate forward or backward by an angle between 45° and 55°, the bottom sieve plate 403 in each level of the screening space is inclined, and the raised portion 4032 is also inclined. And due to the angle difference between the overall rotation angle and the side slope of the raised portion 4032, the side of the inclined raised portion 4032 is in a slightly downward inclined state instead of a flat state. Thus, the trichosanthes seeds at the raised portion 4032 with a lower height near the side sieve plate 402 can slide down to the side of the adjacent higher raised portion 4032, increasing the number of collisions between the trichosanthes seeds and the bottom sieve plate 403 during a single swing, thereby further improving the screening effect and efficiency.

[0029] Embodiment 4 As Figure 2 and Figure 3As shown, under normal circumstances, in the device structure for multi-level screening of Trichosanthes kirilowii seeds, a control structure needs to be equipped at the outlet on one side of each level of screening space, resulting in the complexity of the overall device structure and increased energy consumption. Based on this problem, in this embodiment, discharge ports are provided on the front sides of several side sieve plates 402 and the front of the bottom frame 5. A discharge pipe 405 is connected to the outside of the discharge port. A plugging plate 4051 is inserted into each of the several discharge pipes 405. When the bottom of the plugging plate 4051 is in contact with the bottom wall of the discharge pipe 405, it indicates that the inside of the discharge pipe 405 is in a closed state. At this time, it can be avoided that the Trichosanthes kirilowii seeds in the screening assembly 4 are discharged along the discharge pipe 405 during the subsequent forward and backward swing-type rotation of the screening assembly 4. An extension plate 4052 is provided on the front side of the bottom frame 5, and the end of the extension plate 4052 is fixedly connected to the tops of several plugging plates 4051. A battery-powered electric push rod 4053 is installed on the front of the bottom frame 5, which drives the extension plate 4052 to move up and down, driving several plugging plates 4051 to adjust their positions along several discharge pipes 405. Through the combined application of the above structure, after the screening of Trichosanthes kirilowii seeds is completed, the battery-powered electric push rod 4053 is activated, and it itself advances upward by a set amount, which is consistent with the height of the discharge port. At the same time, it drives the extension plate 4052 to move upward accordingly, thereby driving several plugging plates 4051 connected to the extension plate 4052 to move upward together, causing each plugging plate 4051 to form a dislocation with the discharge port, and adjusting the discharge pipe 405 to a dredged state. Then, in cooperation with the activation of the rotation assembly 3 again, the screening assembly 4 and the bottom frame 5 are adjusted to a state of being inclined downward from the back to the front, so that the Trichosanthes kirilowii seeds reserved in each screening space of the screening assembly 4 and the space of the bottom frame 5 can be discharged outward along the inclined discharge pipe 405.

[0030] Continuing from the above, a guiding block 406 is installed between the frontmost corner of the bottom sieve plate 403 and the four-sided frame 401, and the guiding block 406 is in the shape of a triangular prism. One of its pointed ends is located at the edge of the discharge port. Since the length of the discharge port is set to be less than the length of the four-sided frame 401, therefore, at the corner of the four-sided frame 401, Trichosanthes kirilowii seeds are likely to remain. By adding the guiding block 406, this part of the remaining Trichosanthes kirilowii seeds can be guided to slide down along the discharge port into the discharge pipe 405 and be discharged.

[0031] Embodiment Five As Figure 1 、 Figure 2 、 Figures 6 - 8As shown, a roller ring 304 is rotatably sleeved on the crossbeam frame 301, and the top of the roller ring 304 is in contact with the bottom of the bottom frame 5, enhancing the support for the bottom frame 5 and the structures above. Elastic structures 601 are installed on the front and rear inner walls of the track groove frame 6. The elastic structures 601 are composed of a contraction spring and a shock-absorbing block, and the shock-absorbing block is connected to one end of the contraction spring. When using the rotating assembly 3 to control the front and rear swing-type rotation of the structure composed of the screening assembly 4 and the bottom frame 5, the part of the connecting frame 303 inserted into the track groove frame 6 first contacts the shock-absorbing block. Due to inertia, an extrusion force will be generated on the contraction spring. Under the action of the elasticity and resetting characteristics of the contraction spring itself, a vibration effect is generated in the front and rear swing of the screening assembly 4 and the bottom frame 5, which helps to improve the movement speed and screening efficiency of the trichosanthis seeds.

[0032] As described above, only the preferred specific embodiments of the present invention are given, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. Trichosanthis Semen Rotary Classification Vibration Screening Device, characterized in that: The invention comprises a base (1) and a spring tube (2), wherein a rotating assembly (3) is mounted on the base (1), a screening assembly (4) is connected to the bottom of the spring tube (2), a bottom frame (5) is mounted on the bottom of the screening assembly (4), track slot frames (6) are mounted on both sides of the screening assembly (4) and the bottom frame (5), the rotating assembly (3) and a plurality of track slot frames (6) are slidably connected, and the operation of the rotating assembly (3) drives the screening assembly (4) to rotate and shake the internal Trichosanthes seeds along the front and rear axial direction in a swinging manner; The screening assembly (4) comprises a plurality of four-sided frames (401) arranged in an upper and lower manner, the widths of the four-sided frames (401) and the bottom frame (5) gradually increase from top to bottom, the front and back sides of the four-sided frames (401) are both embedded with side sieve plates (402), the bottom of the four-sided frames (401) is provided with a bottom sieve plate (403), the apertures of the side sieve plates (402) and the bottom sieve plates (403) are both decreased from top to bottom, a cover frame (404) is provided on the outer side of the side sieve plate (402), and the top of the four-sided frames (401) is in contact with the bottom of the two cover frames (404) above; The bottom sieve plate (403) is formed by a plurality of plane portions (4031) and raised portions (4032) arranged at intervals.

2. The trichosanthes seed rotary classification vibration screening device according to claim 1, characterized in that: The height and width of the plurality of raised portions (4032) gradually decrease from the middle to the two sides, and the spacing width between two adjacent raised portions (4032) is greater than the width of the top surface of the raised portion (4032).

3. The Trichosanthes kirilowii Maxim seeds rotary classification vibration screening device according to claim 2, characterized in that: The side slope of the raised portion (4032) is less than 45°, and the front and rear ends of the bottom sieve plate (403) are in contact with the four side frames (401) via the flat surface portion (4031).

4. The trichosanthes seed rotary classification vibration screening device according to claim 1, wherein: A plurality of the side sieve plates (402) and the front side of the bottom frame (5) are provided with discharge outlets, and an outlet pipe (405) is connected to the outside of the discharge outlet, and a blocking plate (4051) is inserted into the plurality of outlet pipes (405).

5. The Trichosanthes kirilowii Maxim. seed rotary classification vibration screening device according to claim 1, wherein: An extension plate (4052) is provided on the front side of the bottom frame (5), and the end of the extension plate (4052) is fixedly connected to the top of the plurality of blocking plates (4051). A storage-type electric push rod (4053) is installed on the front side of the bottom frame (5), which drives the extension plate (4052) to rise and fall, thereby driving the plurality of blocking plates (4051) to adjust their positions along the plurality of outlet pipes (405).

6. The trichosanthes seed rotary classification vibration screening device according to claim 1, wherein: A guide block (406) is installed between the bottom screen plate (403) and the frontmost corner of the four frames (401), and the guide block (406) is triangular in shape, with a sharp corner at one end located at the edge of the discharge port.

7. The Trichosanthes kirilowii Maxim. seed rotary classification vibration screening device according to claim 1, wherein: The rotating assembly (3) comprises a crossbeam frame (301) rotatably plugged onto an extended end of the top surface of the base (1); a driving structure (302) drivingly connected to the crossbeam frame (301) is installed on the top surface of the base (1); and connecting frames (303) slidably connected to a plurality of track slot frames (6) are installed on both sides of the crossbeam frame (301).

8. The Trichosanthes kirilowii Maxim. seed rotary classification vibration screening device according to claim 7, wherein: A roller ring (304) is rotatably sleeved on the crossbeam frame (301), and the top of the roller ring (304) is in contact with the bottom of the bottom frame (5).

9. The Trichosanthes kirilowii Maxim. seed rotary classification vibration screening device according to claim 1, characterized in that: Elastic structures (601) are installed on the front and rear inner walls of the track groove frame (6). The elastic structures (601) are composed of contraction springs and shock-absorbing blocks, and the shock-absorbing blocks are connected to one end of the contraction springs.

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