Angle steel guiding and pressing unit

Abstract

The utility model provides an angle steel guide material pressing unit, it aims at solving the problem of unstable clamping and low positioning accuracy of angle steel workpiece with deviation in geometric shape. The device comprises a guide material supporting mechanism and a material pressing mechanism, the guide material supporting mechanism comprises a material supporting element for contacting the lower side of the angle steel flange and a material supporting universal hinge mechanism connecting the material supporting element and a material supporting driving element; the material pressing mechanism comprises a material pressing element for contacting the upper side of the angle steel flange and a material pressing universal hinge mechanism connecting the material pressing element and a material pressing driving element, the material supporting universal hinge mechanism and the material pressing universal hinge mechanism both allow the respective contact elements to swing in multiple degrees of freedom, thereby being able to adaptively fit the angle steel flange profile with deviations in shape such as distortion and bending. Through the adaptive fitting in the upward and downward directions, stable and reliable clamping of irregular angle steel workpieces is realized, thereby ensuring the stability of the subsequent angle steel machining accuracy.

Description

Technical Field

[0001] This utility model relates to the technical field of angle steel processing equipment, specifically to an angle steel guiding and pressing unit. Background Technology

[0002] In automated production lines for angle steel, in order to ensure the accuracy of subsequent processing steps such as drilling, the angle steel workpiece must first be accurately and reliably positioned and clamped. Angle steel positioning and clamping devices are the key components for achieving this function.

[0003] Existing angle steel positioning and clamping devices typically employ rigid V-blocks, fixed jaws, or pressure blocks. While these designs are simple in structure, in actual production processes, due to the influence of rolling, transportation, and storage, angle steel workpieces generally exhibit certain degrees of geometric shape deviations, such as twisting, bending, non-standard included angles between the two flanges, or uneven surfaces. When using traditional rigid clamps to hold these irregular angle steel workpieces, a series of problems arise: 1. Poor positioning accuracy: The rigid fixture can only form point contact or line contact with the surface of the irregular angle steel workpiece, and cannot establish a stable and repeatable positioning reference. This will result in slight differences in the posture of the workpiece each time it is clamped, which will directly affect the accuracy of the drilling position and lead to unstable product quality. 2. Workpiece deformation and damage: In order to compensate for poor contact, operators often increase the cutting force. However, excessive clamping force concentrated on a few contact points will generate huge stress concentration, which can easily cause plastic deformation or twisting of the angle steel workpiece. 3. Low process reliability: In high-load machining processes such as drilling, unstable clamping conditions may cause the angle steel workpiece to slide or vibrate under the action of cutting force. This will not only cause the machining dimensions to be out of tolerance, but in severe cases, it may also cause damage or even breakage of the drill bit and other tools, resulting in scrap and production interruption.

[0004] Therefore, there is an urgent need for a new type of angle steel positioning and clamping device that can automatically compensate for geometric deviations of angle steel workpieces and provide stable and uniform clamping force, thereby ensuring the stability of the processing accuracy of angle steel workpieces. Utility Model Content

[0005] In view of the above-mentioned shortcomings of existing devices, this utility model provides an angle steel guiding and pressing unit, which is designed to automatically adapt to and compensate for the geometric shape deviation of angle steel workpieces caused by rolling, transportation and other reasons, so as to ensure the stability of the positioning, clamping and processing accuracy of angle steel workpieces.

[0006] To achieve the above objectives, this utility model provides the following technical solution: An angle steel guiding and pressing unit, characterized in that it comprises: The guide material support mechanism is located below the conveying path of the angle steel and is used to contact and support the lower side of the angle steel flange. The pressing mechanism is located above the conveying path of the angle steel and is used to apply a vertically downward pressing force to the upper side of the flange of the angle steel. The guiding material support mechanism includes: Material support components; The material support drive element has its movable end connected to the material support element, and is used to drive the material support element to move up and down to contact the lower side of the angle steel flange; A universal hinge mechanism for supporting materials is connected between the movable end of the supporting material element and the supporting material drive element, and the universal hinge mechanism for supporting materials allows the supporting material element to swing with multiple degrees of freedom so that it conforms to the lower side profile of the angle steel flange. The pressing mechanism includes: Pressing elements; The pressure drive element has its movable end connected to the pressure element, and is used to drive the pressure element to move up and down to contact the upper side of the angle steel flange; A universal joint mechanism for pressing material is connected between the movable end of the pressing material drive element and the pressing material element. The universal joint mechanism for pressing material allows the pressing material element to swing in multiple degrees of freedom so that the pressing material element can adaptively conform to the upper side profile of the angle steel flange.

[0007] Furthermore, the material support element includes a roller seat and two sets of rollers located on both sides of the lower side of the angle steel flange. The two sets of rollers are rotatably connected to the roller seat, and their rotation axes are distributed along the width direction of the angle steel flange, respectively for rolling contact with the lower side of the two flanges of the angle steel.

[0008] Furthermore, the material support universal hinge mechanism includes a material support lug, a material support spherical bearing, and a material support pin. The outer ring of the material support spherical bearing is fixedly connected to the roller seat, and the inner ring is connected to the material support lug through the material support pin. In addition, the lower end of the material support lug is fixedly connected to the movable end of the material support drive element.

[0009] Furthermore, the material support driving element is a material support cylinder, the lower end of the material support ear is provided with a threaded hole, the upper end of the piston rod of the material support cylinder is provided with an external thread that is threadedly connected to the threaded hole of the material support ear, and the outer side of the material support ear is also provided with a fixing hole communicating with its threaded hole, and a first tightening screw is provided in the fixing hole.

[0010] Furthermore, the pressing element consists of a middle pressing clamp plate and a front pressing clamp plate and a rear pressing clamp plate that are detachably and fixedly connected to the front and rear sides of the middle pressing clamp plate. The front pressing clamp plate and the rear pressing clamp plate are respectively provided with a lower pressing surface on both sides for fitting with the upper side of the two flanges of the angle steel.

[0011] Furthermore, the pressing element also includes a pressing slide plate, the upper end of which is connected to the pressing universal hinge mechanism, and the lower end is rotatably connected to the upper part between the front pressing clamp plate and the rear pressing clamp plate through a rotating pin, and the pressing slide plate and the middle pressing clamp plate are spaced apart in the vertical direction.

[0012] Furthermore, the pressure element is provided with a drilled relief groove on the side of the upper surface of the two flanges of the angle steel to be processed, which provides clearance space for the processing tool.

[0013] Furthermore, the universal joint mechanism for pressing materials includes a pressing lug, a pressing spherical bearing, and a pressing pin. The upper end of the pressing lug is fixedly connected to the movable end of the pressing drive element, and the lower end is connected to the inner ring of the pressing spherical bearing through the pressing pin. The pressing element is fixedly connected to the outer ring of the pressing spherical bearing.

[0014] Furthermore, the pressing drive element is a pressing cylinder, the upper end of the pressing lug is provided with a threaded hole, the movable end of the piston rod of the pressing cylinder is provided with an external thread that is threadedly connected to the threaded hole of the pressing lug, and the outer side of the pressing lug is also provided with a fixing hole that communicates with the threaded hole, and a second tightening screw is provided in the fixing hole.

[0015] Furthermore, it also includes a pressure base, the pressure mechanism is fixedly connected to the pressure base, the pressure base is provided with a limit switch, and the movable end of the pressure drive element is provided with a signaling component distributed corresponding to the position of the limit switch.

[0016] The technical solution provided by this utility model has the following advantages compared with the prior art: 1. Both the guiding and pressing mechanisms adopt universal joints to connect with the corresponding supporting and pressing elements, so that the supporting and pressing elements are no longer rigidly fixed, but can swing freely like a universal joint. When an angle steel workpiece with torsion or bending deviation enters the guiding and pressing unit, these elements can automatically adjust their posture to find the best position to fully fit the irregular surface of the angle steel, thus forming a stable and uniform multi-line or multi-face contact. The "shape-fitting" clamping method fundamentally eliminates the risk of workpiece swaying and sliding caused by poor contact, ensuring that the angle steel is accurately locked in the predetermined position before processing, laying a solid foundation for subsequent drilling, cutting and other processes. 2. Because the pressure element can adaptively conform to the surface of the angle steel workpiece, the clamping force can be evenly distributed over a larger contact area, avoiding the stress concentration phenomenon caused by rigid clamps. Therefore, under the premise of ensuring sufficient clamping force, it can effectively prevent the angle steel workpiece from being crushed or permanently deformed. 3. By setting a drilling relief groove on the pressure element, when drilling the angle steel workpiece, after the drill bit penetrates the flange of the angle steel, its tip can enter the drilling relief groove, thereby avoiding direct collision between the drill bit and the pressure element. This not only extends the service life of the drill bit, but also protects the pressure element itself from damage. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2 This is the front view of the present utility model; Figure 3 This is the left view of the present invention; Figure 4 This is a top view of the present invention; Figure 5 A schematic diagram of the three-dimensional structure of the guiding material support mechanism; Figure 6 A three-dimensional sectional view of the guiding material support mechanism; Figure 7 This is a schematic diagram of the three-dimensional structure of the pressing mechanism; Figure 8 This is the front view of the pressing mechanism; Figure 9 for Figure 8 Sectional view of AA; Figure 10 for Figure 8 BB section view.

[0019] in: 1-Pressure seat, 101-Pressure guide plate, 102-Pass through port; 2-Guide material support mechanism, 201-Roller, 202-Roller seat, 203-Material support ear seat, 204-Material support cylinder, 205-Material support pin, 206-Material support joint bearing, 207-First tightening screw; 3-Pressure mechanism, 301-Cylinder seat, 302-Pressure cylinder, 303-Pressure ear seat, 304-Pressure slide plate, 305-Front pressure clamp plate, 306-Middle pressure clamp plate, 307-Rear pressure clamp plate, 308-Pressure pin, 309-Pressure joint bearing, 310-Second tightening screw, 311-Rotating pin, 312-Fastening bolt, 313-Drilled relief groove; 4-angle steel; 5-travel switch; 6-signal transmitting assembly. Specific Embodiments

[0020] To make the objectives, technical solutions and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are some embodiments of the present utility model, rather than all of them. Based on the embodiments of the present utility model, all other embodiments obtained by a person skilled in the art without creative work fall within the scope of protection of the present utility model.

[0021] It should be noted that in this embodiment, the direction shown by the arrow in Figure 1 is the processing direction of angle steel 4, that is, the front-rear direction, and the two mutually perpendicular flanges of angle steel 4 are face A and face B respectively.

[0022] As Figures 1-10 shows, the present utility model provides an angle steel guiding and pressing unit, comprising a pressing seat 1, a guiding material supporting mechanism 2 and a pressing mechanism 3. The pressing seat 1 is generally of a frame structure, which is detachably connected with a drilling equipment bed or other fixed components by bolts, and a material passing opening 102 penetrating front and back is arranged on the pressing seat 1 for the angle steel 4 to be processed to pass through the pressing seat 1 front and back driven by a conveying manipulator; two sets of the guiding material supporting mechanisms 2 are provided and respectively fixedly connected to the lower sides of the front and rear end faces of the pressing seat 1, and the guiding material supporting mechanism 2 is located below the material passing opening 102, which is used for supporting and guiding the lower side surfaces of the two flanges of the angle steel 4; the pressing mechanism 3 is fixedly connected to the upper part of the pressing seat 1, and is used for vertically pressing the upper side surfaces of the two flanges of the angle steel 4 to be processed.

[0023] Specifically, in this embodiment, the material passing opening 102 on the pressing seat 1 has a 90° included angle and is symmetrically distributed left and right, that is, the two inner side surfaces at the lower end and the center line in the vertical direction shown in Figure 2 are all distributed at a 45° included angle.

[0024] The guiding material supporting mechanism 2 is as shown in Figures 1-2 and Figures 5-6 , comprising three parts: a material supporting element, a material supporting driving element and a material supporting universal hinge mechanism. Specifically, it is composed of a roller 201, a roller seat 202, a material supporting ear seat 203, a material supporting oil cylinder 204, a material supporting pin shaft 205 and a material supporting joint bearing 206; wherein, mounting holes corresponding to the positions of the pressing seat 1 are provided on both sides of the lower part of the roller seat 202, and the two are detachably and fixedly connected by bolts; two sets of the rollers 201 are provided, and the two sets of rollers 201 are along Figure 2The vertical center lines shown are symmetrically distributed on both sides and rotatably connected to the roller seats 202. The rotation axes of the two sets of rollers 201 are distributed along the width directions parallel to the A and B surfaces of the flanges of the angle steel 4, respectively. Figure 2 In the indicated direction, the rotation axes of both sets of rollers 201 form a 45° angle with the horizontal plane. Furthermore, it should be noted that the generatrix of the supporting inclined surfaces of the two sets of rollers 201 is coplanar with the positioning support surfaces of the flanges A and B of the angle steel 4 within the material passage 102 on the pressure seat 1. Additionally, a through-hole is provided at the lower center of the roller seat 202, into which a material support bearing 206 is installed. The outer ring of the material support bearing 206 is fixedly connected to the mounting hole of the roller seat 202. A groove is provided on the upper part of the material support ear seat 203 that mates with the lower center of the roller seat 202. A through hole corresponding to the position of the mounting hole on the roller seat 202 is provided through the groove from front to back. The material support pin 205 passes sequentially through the through hole on the material support ear seat 203 and the inner ring of the material support bearing 206 from front to back. The material support pin 205 is also connected to the material support bearing 206. The inner ring of the bearing 206 is fixedly connected, meaning that the roller seat 202 can swing within a certain range through the material support joint bearing 206 to adapt to the shape of the outer surface (support surface) of the flange A and B of the angle steel 4, thereby eliminating the influence of the shape deviation of the outer surface of the flange of the angle steel 4. In addition, the piston rod axis of the material support cylinder 204 is distributed vertically and the upper movable end is provided with an external thread. The lower end of the material support ear seat 203 is also provided with a vertically distributed threaded hole. The piston rod of the material support cylinder 204 is threadedly connected to the material support ear seat 203. Furthermore, the outer surface of the material support ear seat 203 is also provided with a fixing hole communicating with the threaded hole. The fixing hole is provided with a first tightening screw 207. When the vertical position between the piston rod of the material support cylinder 204 and the material support ear seat 203 is determined, the two can be fixed by the first tightening screw 207.

[0025] Material pressing mechanism 3 Figures 1-2 , Figures 7-10As shown, it includes three parts: a pressing element, a pressing drive element, and a pressing universal hinge mechanism. Specifically, it consists of a cylinder seat 301, a pressing cylinder 302, a pressing ear seat 303, a pressing slide plate 304, and a pressing clamp plate. The cylinder seat 301 is fixedly connected to the upper end of the pressing base 1. The cylinder body of the pressing cylinder 302 is fixed to the cylinder seat 301. The piston rod of the pressing cylinder 302 is distributed vertically, and its lower end is universally hinged to the pressing slide plate 304 through the pressing ear seat 303. Its connection structure is similar to that of the guide and material support mechanism. Specifically, a pressing spherical bearing 309 is fixedly connected in the groove at the lower end of the pressing ear seat 303, and a through hole is provided on the outer side. The outer ring of the pressing spherical bearing 309 is fixedly connected to the pressing slide plate 304. The upper end of the pressing slide plate 304 is provided with mounting holes that are distributed in a front-to-back manner and correspond to the positions of the through holes. The pressing pin 308 passes through the pressing base from front to back. The through hole on the ear seat 303 and the inner ring of the pressure plate bearing 309 are fixedly connected, and the pressure pin 308 is fixedly connected to the inner ring of the pressure plate bearing 309. The pressure plate ear seat 303 can swing within a certain range through the pressure plate bearing 309, so that the pressure plate adapts to the shape of the inner side (pressing surface) of the flange A and B of the angle steel 4, thereby avoiding the problem of machining accuracy being affected by the shape deviation of the inner side of the flange of the angle steel 4 during the drilling process. Moreover, the lower end of the piston rod of the pressure cylinder 302 is also provided with an external thread, and the upper end face of the pressure plate ear seat 303 is provided with vertically distributed threaded holes. The two are threadedly connected, and the outer side of the pressure plate ear seat 303 is provided with a fixing hole communicating with the threaded hole. A second tightening screw 310 is provided in the fixing hole, which is convenient to adjust the position of the piston rod of the pressure cylinder 302 and the pressure plate ear seat 303 in the vertical direction and then fix them by the second tightening screw 310.

[0026] In addition, such as Figures 7-10As shown, the clamping jaws consist of a front clamping jaw 305, a middle clamping jaw 306, and a rear clamping jaw 307. The front clamping jaw 305 and the rear clamping jaw 307 are located on the front and rear sides of the middle clamping jaw 306, respectively, and threaded holes are provided between the three. The three are detachably fixed together by fastening bolts 312 and nuts. The left and right sides of the front clamping jaw 305 and the rear clamping jaw 307 are downward pressing surfaces that respectively fit against the inner surfaces of the A and B surfaces of the flange of the angle steel 4. The left and right sides of the front clamping jaw 305 and the rear clamping jaw 307 are also provided with drilled relief grooves. 313, to avoid contact between the drill bit and the clamping jaws during drilling; in addition, a groove is formed between the upper parts of the front clamping jaws 305 and the rear clamping jaws 307, and the lower end of the clamping slide 304 is located in the groove. The upper parts of the front clamping jaws 305 and the rear clamping jaws 307, and the lower part of the clamping slide 304, are all provided with mounting holes that are distributed through the front and rear and correspondingly positioned. A rotating pin 311 is installed in each mounting hole. It should be noted that when the rotating pin 311 is installed, there is a certain distance between the lower end of the clamping slide 304 and the upper end of the middle clamping jaws 306, such as... Figure 9 As shown, this allows the pressure plate 304 to swing around the rotating pin 311 within a certain range, enabling the pressure clamp plate to automatically adjust its posture to fully fit the inner side (pressing surface) of the flange of the angle steel 4, further avoiding the problem of affecting the drilling accuracy due to the shape deviation of the inner side of the flange of the angle steel 4.

[0027] In addition, such as Figures 1-4 As shown, pressure guide plates 101 are fixedly connected to the left and right inner sides of the pressure base 1. The pressure slide plate 304 is slidably connected to the pressure base 1 on both the left and right sides through a set of pressure guide plates 101. A limit switch 5 is also provided on the left side of the pressure base 1. A signaling component 6 is fixedly connected to the left side of the pressure slide plate 304. When the pressure cylinder 302 drives the pressure slide plate 304 to slide up and down, the positioning, pressing and releasing signals of the angle steel 4 can be realized through the signaling component 6 and the limit switch 5.

[0028] This device can be combined with angle steel drilling equipment, angle steel cutting equipment, or other angle steel processing equipment, as well as conveying channels and conveying robots to form an automated angle steel production line, so as to realize precise positioning and clamping operations before angle steel processing, thereby ensuring the stability of the accuracy of subsequent angle steel processing.

[0029] The working principle and processing flow of this device for drilling holes in angle steel workpieces are as follows: Angle steel raw material conveying - guide and support mechanism 2 lifts the angle steel - returns to the drilling position of the angle steel and positions itself - pressing mechanism 3 presses the angle steel - drilling unit drills - pressing mechanism 3 releases the angle steel - guide and support mechanism 2 lifts the angle steel - returns to the next drilling position of the angle steel and positions itself - pressing mechanism 3 presses the angle steel - drilling unit drills - pressing mechanism 3 releases the angle steel - ... - finished angle steel. The entire drilling process from raw angle steel to finished angle steel is completed, and the entire drilling process is repeated.

[0030] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of this utility model.

Claims

1. An angle steel guiding and pressing unit, characterized in that, include: The guide material support mechanism is located below the conveying path of the angle steel and is used to contact and support the lower side of the flange of the angle steel; The pressing mechanism is located above the conveying path of the angle steel and is used to apply a vertically downward pressing force to the upper side of the flange of the angle steel. The guiding material support mechanism includes: Material support components; The material support drive element has its movable end connected to the material support element, which is used to drive the material support element to move up and down to contact the lower side of the angle steel flange; A universal hinge mechanism for supporting materials is connected between the movable end of the supporting material element and the supporting material drive element, and the universal hinge mechanism for supporting materials allows the supporting material element to swing with multiple degrees of freedom so that it conforms to the lower side profile of the angle steel flange. The pressing mechanism includes: Pressing element; The pressure drive element has its movable end connected to the pressure element, which is used to drive the pressure element to move up and down to contact the upper side of the angle steel flange; The universal joint mechanism for pressing material is connected between the movable end of the pressing material drive element and the pressing material element. The universal joint mechanism for pressing material allows the pressing material element to swing in multiple degrees of freedom so that the pressing material element can adaptively conform to the side profile of the angle steel flange.

2. The angle steel guiding and pressing unit according to claim 1, characterized in that, The material support element includes a roller seat and two sets of rollers located on both sides of the lower side of the flange of the angle steel. The two sets of rollers are rotatably connected to the roller seat, and their rotation axes are distributed along the width direction of the flange of the angle steel, respectively, and are used to roll and contact the lower side of the two flanges of the angle steel.

3. The angle steel guiding and pressing unit according to claim 2, characterized in that, The material support universal hinge mechanism includes a material support lug, a material support spherical bearing, and a material support pin. The outer ring of the material support spherical bearing is fixedly connected to the roller seat, and the inner ring is connected to the material support lug through the material support pin. Furthermore, the lower end of the material support lug is fixedly connected to the movable end of the material support drive element.

4. The angle steel guiding and pressing unit according to claim 3, characterized in that, The material support driving element is a material support cylinder. The lower end of the material support lug is provided with a threaded hole. The upper end of the piston rod of the material support cylinder is provided with an external thread that is threaded to the threaded hole of the material support lug. Furthermore, the outer side of the material support lug is also provided with a fixing hole that communicates with its threaded hole. A first tightening screw is provided in the fixing hole.

5. The angle steel guiding and pressing unit according to claim 1, characterized in that, The pressing element consists of a middle pressing clamp plate and a front pressing clamp plate and a rear pressing clamp plate that are detachably and fixedly connected to the front and rear sides of the middle pressing clamp plate. The front pressing clamp plate and the rear pressing clamp plate each have a lower pressing surface on both sides for fitting against the upper side of the two flanges of the angle steel.

6. The angle steel guiding and pressing unit according to claim 5, characterized in that, The pressing element also includes a pressing slide plate. The upper end of the pressing slide plate is connected to the pressing universal hinge mechanism, and the lower end is rotatably connected to the upper part between the front pressing clamp plate and the rear pressing clamp plate through a rotating pin. The pressing slide plate and the middle pressing clamp plate are distributed at intervals in the vertical direction.

7. The angle steel guiding and pressing unit according to claim 1, characterized in that, The pressure element is provided with a drilled relief groove on the side of the upper surface of the two flanges of the angle steel to be processed, which provides clearance space for the processing tool.

8. The angle steel guiding and pressing unit according to claim 1, characterized in that, The universal joint mechanism for pressing materials includes a pressing lug, a pressing spherical bearing, and a pressing pin. The upper end of the pressing lug is fixedly connected to the movable end of the pressing drive element, and the lower end is connected to the inner ring of the pressing spherical bearing through the pressing pin. The pressing element is fixedly connected to the outer ring of the pressing spherical bearing.

9. The angle steel guiding and pressing unit according to claim 8, characterized in that, The pressing drive element is a pressing cylinder. The upper end of the pressing lug is provided with a threaded hole. The movable end of the piston rod of the pressing cylinder is provided with an external thread that is threaded to the threaded hole of the pressing lug. Furthermore, the outer side of the pressing lug is also provided with a fixing hole that communicates with its threaded hole. A second tightening screw is provided in the fixing hole.

10. The angle steel guiding and pressing unit according to any one of claims 1-9, characterized in that, It also includes a pressure base, the pressure mechanism is fixedly connected to the pressure base, the pressure base is provided with a limit switch, and the movable end of the pressure drive element is provided with a signaling component distributed corresponding to the position of the limit switch.

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