Zero calibration structure of four-axis robot

Abstract

The invention provides a zero calibration structure of a four-axis robot, and belongs to the technical field of robots. The technical problem that an existing four-axis robot is difficult to consider zero calibration precision, efficiency and reliability of a screw rod shaft of the robot at the same time is solved. The four-axis robot comprises a small arm and a lead screw shaft, the lead screw shaft is connected to one end of the small arm, the zero-point calibration structure comprises a strip-shaped calibration rod and a strip-shaped zero-position barrier strip, the lower portion of the zero-position barrier strip is in a rectangular plate shape, and a rectangular notch is formed in the corner of the zero-position barrier strip. The inner wall of the notch is provided with a first datum plane in a vertical plane shape and a second datum plane in a horizontal plane shape, one end of the calibration rod is fixedly connected to the lower end of the lead screw shaft, the upper end of the zero-position blocking strip is fixedly connected to the small arm, and a gap is reserved between the zero-position blocking strip and the lead screw shaft. And the calibration rod is axially parallel to the first reference surface and the second reference surface at the same time. Efficiency, precision and reliability of zero calibration of the lead screw shaft can be considered.

Description

Technical Field

[0001] The invention belongs to the technical field of robots and relates to a zero point calibration structure of a four-axis robot. Background Art

[0002] After prolonged operation, industrial robots may experience zero-point loss in their respective motion axes, leading to errors in the end effector's trajectory and inability to accurately complete its intended task. This necessitates manual calibration of the mechanical zero position of the motion axes to restore the robot's original transmission accuracy. A common method for zero-point calibration of industrial robots is visual observation. Mechanical zero marks are engraved on the housings where the robot's motion axes generate relative motion. The housings can be rotated to observe and verify alignment of the mechanical zero marks.

[0003] The patent with application number CN202122035027.2 discloses a dual-joint robot module and a robot, which includes a first joint and a second joint, and the dual-joint robot module also includes an elbow; wherein the elbow is a hollow tubular elbow, and the first joint and the second joint are respectively detachably fixedly connected to the two ends of the elbow; and the elbow is provided with a zero-position calibration groove that corresponds one-to-one with the first joint and the second joint.

[0004] The above-mentioned robot can determine the zero position by observing whether the zero position calibration groove on the joint of the casing is aligned to facilitate assembly and calibration. However, for a four-axis robot, it has a screw shaft that can move up and down and rotate axially, and it also needs to be calibrated when zero-point drift occurs. However, there is no relevant calibration structure, and the calibration accuracy and efficiency are poor when it is directly judged by the operator's naked eye. For this reason, general technicians in this field usually consider: 1. Setting a zero position calibration groove on the periphery of the screw shaft to determine whether it is aligned with the calibration groove opened at the corresponding position on the casing to confirm the circumferential zero position calibration status; 2. Setting angle sensors and position sensors to monitor the vertical position and angular position of the screw shaft, and identify it when returning to zero position. Summary of the Invention

[0005] In view of the above problems existing in the prior art, the present invention provides a zero point calibration structure for a four-axis robot. The technical problem to be solved by the present invention is: how to balance the zero point calibration accuracy, efficiency and reliability of the robot's lead screw shaft.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] The cam is connected to the control wheel shaft and the control wheel shaft is connected to the control wheel shaft by a screw thread, and the control wheel shaft is connected to the control wheel shaft by a screw thread, and the control wheel shaft is connected to the control wheel shaft by a screw thread, and the control wheel shaft is connected to the control wheel shaft by a screw thread.

[0008] The screw shaft is an existing component that can achieve vertical movement and circumferential rotation under the action of the existing transmission assembly in the robot's forearm, so as to facilitate the grasping of materials. By setting a horizontal calibration rod and a vertical zero-position stop bar, a rectangular notch is set at the lower corner of the zero-position stop bar, and a vertical plane-shaped reference plane 1 and a horizontal plane-shaped reference plane 2 are formed in the notch, and one end of the calibration rod is fixed to the screw shaft, and the other end can be against the reference plane 1 and the reference plane 2. In this way, when performing zero-position calibration, first control the calibration rod to rotate slowly so that the calibration rod can be moved into the notch. When observed from the outside, when the calibration rod contacts and abuts against the reference plane 1, it stops rotating, which can be regarded as the completion of the circumferential zero-position calibration. Then control the calibration rod to move up slowly, and observe that when the calibration rod contacts and abuts against the reference plane 2, it stops moving, which means that the vertical zero-position calibration is completed. During the entire calibration process, the outer end of the horizontally extended calibration rod is away from the screw shaft. , a very small rotation of the screw shaft will also cause a certain distance of displacement at the outer end of the calibration rod, which can amplify the visibility of the circumferential angle change of the screw shaft to improve the adjustment accuracy. The calibration condition is judged by the contact between the outer end of the calibration rod and the zero-position stop bar. Observing the movement distance and position status of the calibration rod is conducive to more accurate judgment of the circumferential angular position of the screw shaft, thereby helping to reduce the circumferential zero-position error of the screw shaft and improve the calibration accuracy; in addition, it is also conducive to the operator to more conveniently and clearly observe the actual contact between the calibration rod and the reference surface one and the reference surface two from the outside, avoiding the situation where the operator's line of sight is blocked and the contact condition of the calibration parts cannot be accurately judged, resulting in pressure damage to the calibration parts, thereby taking into account the efficiency, accuracy and reliability of the screw shaft zero-position calibration.

[0009] In the zero-point calibration structure of the above-mentioned four-axis robot, the zero-point calibration structure also includes a C-shaped clasp, the two ends of which are fixed by through-bolts. The clasp is fixed to the outer periphery of the screw shaft, and one end of the calibration rod is U-shaped, and the two forked arms of the end are respectively fixed to the two sides of the clasp fracture. This makes it convenient for the clasp to be conveniently sleeved on the lower end of the screw shaft with a larger inner diameter in the initial state, and then tighten the bolts to fix the clasp hoop to the screw shaft, and further fix the two forks at the end of the calibration rod to the two sides of the clasp fracture. While achieving the fixation of the calibration rod to the screw shaft, it is also beneficial to provide further clamping constraints to the two ends of the clasp through the two arms of the calibration rod, thereby preventing the clasp from loosening and displacing, resulting in failure to calibrate, and ensuring the accuracy of the zero-position calibration.

[0010] In the zero-point calibration structure of the four-axis robot, the other end of the calibration rod is arranged radially outward from the lead screw shaft. This ensures that the other end of the calibration rod is aligned with the radial angle of the lead screw shaft, facilitating confirmation of the precise angular position of the lead screw shaft during subsequent debugging.

[0011] In the zero-point calibration structure of the aforementioned four-axis robot, the upper end of the zero-position bar is horizontally bent into an L-shape toward the side where the forearm is located and connected to the outer edge of the housing. The horizontal end of one side of the zero-position bar is fixed to the outer edge of the forearm and extends along the length of the forearm. The vertical side of the zero-position bar is positioned downward, and the notch is formed at the lower portion of the vertical side of the zero-position bar. This L-shaped zero-position bar increases the distance between the vertical portion of the zero-position bar and the lead screw shaft, moving the contact point between the calibration rod and the zero-position bar further outward for easier identification by the operator. Furthermore, the outward orientation of the zero-position bar prevents interference with components such as the robot's main arm during operation.

[0012] In the aforementioned zero-point calibration structure for a four-axis robot, the inner edge of the retaining ring has a vertically extending clearance opening, located radially opposite the ring's fracture. This ensures the retaining ring has sufficient radial width to provide ample space for assembling the calibration rod, while also ensuring that the retaining ring can easily deform under load, allowing it to be tightened to the outer circumference of the lead screw shaft.

[0013] In the zero-point calibration structure for the four-axis robot, the cross-section of the other end of the calibration rod is rectangular. This facilitates the vertical side surface of the other end of the calibration rod to completely align with the first and second reference surfaces, making it easier for the operator to identify the zero-point calibration status based on whether they align, making identification more intuitive and convenient.

[0014] In the aforementioned zero-point calibration structure for a four-axis robot, the vertical dimension of datum plane 1 is greater than the vertical dimension of the other end of the calibration rod, and the vertical dimension of datum plane 2, along datum plane 1, is greater than the width of the other end of the calibration rod. This ensures that, when the calibration rod rotates into the notch, datum planes 1 and 2 provide support and constraints for the entire side of the calibration rod over a wide range, preventing the calibration rod from moving out of the notch during rotation or upward movement, ensuring a smooth calibration process.

[0015] In the zero-point calibration structure of the four-axis robot, the edges of the notch are rounded to prevent the calibration rod from contacting the notch edge and causing scratches that could damage the mating surface, thus ensuring accurate subsequent calibration.

[0016] Compared with the prior art, the advantages of the present invention are as follows:

[0017] When the zero-point calibration structure of this four-axis robot is performing zero-position calibration, the operator can conveniently observe from the outside when the calibration rod is in contact with the reference plane 1 and the reference plane 2, and can judge whether the vertical zero-position calibration of the screw shaft has been completed. The calibration rod amplifies the axial displacement of the screw shaft. The entire process is easy to observe and identify accurately, and it is not easy to misjudge and cause damage to the calibration components, thereby realizing the axial and vertical zero-position calibration of the screw shaft efficiently, accurately and reliably. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the three-dimensional structure of this embodiment.

[0019] Figure 2 yes Figure 1 Enlarged view of part A in .

[0020] Figure 3 It is a three-dimensional schematic diagram of the local structure from another perspective of this embodiment.

[0021] Figure 4 It is a three-dimensional exploded schematic diagram of the local structure of this embodiment.

[0022] Figure 5 It is a schematic diagram of the partial structure of the embodiment before calibration.

[0023] Figure 6 FIG. 4 is a schematic diagram of a partial structure of the embodiment after calibration is completed.

[0024] In the figure, 1. Forearm; 2. Screw shaft; 3. Calibration rod; 4. Zero position stop bar; 41. Notch; 411. Reference plane 1; 412. Reference plane 2; 5. Snap ring; 51. Clearance; 6. Bolt; 7. Lamp bead. DETAILED DESCRIPTION

[0025] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.

[0026] like Figure 1 、 Figure 2 As shown, the four-axis robot includes an elongated arm 1 and a vertically arranged screw shaft 2. The screw shaft 2 is connected to one end of the arm 1 and can move vertically and rotate circumferentially. The screw shaft 2 is an existing component and can achieve vertical movement and circumferential rotation under the action of the existing transmission assembly in the arm 1, so as to facilitate the grasping of materials. The zero-point calibration structure includes a horizontally arranged strip-shaped calibration rod 3 and an L-shaped zero-position stopper 4. One end of the zero-position stopper 4 is horizontally arranged and fixed to the outer edge of the arm 1 and arranged along the length of the arm 1. The other end of the zero-position stopper 4 is vertically arranged and horizontally spaced from the screw shaft 2. The lower portion of the zero-position stopper 4 is rectangular and has a rectangular notch 41 at the corner. The edges of the notch 41 are rounded, and the inner wall of the notch 41 has a vertical plane datum plane 1 411 and a horizontal plane datum plane 2 412. The zero-point calibration structure also includes a C-shaped retaining ring 5, the two ends of which are fixed by through-bolts 6. The retaining ring 5 is sleeved and fixed on the outer periphery of the screw shaft 2. One end of the calibration rod 3 is fixed to the retaining ring 5. The other end of the calibration rod 3 has a rectangular cross-section and is arranged radially outward along the screw shaft 2. The vertical dimension of the reference plane 1 411 is greater than the vertical dimension of the other end of the calibration rod 3. The vertical dimension of the reference plane 2 412 along the reference plane 1 411 is greater than the width dimension of the other end of the calibration rod 3. When the other end of the calibration rod 3 is located in the notch 41 and abuts against the reference plane 1 411, the calibration rod 3 is axially parallel to both the reference plane 1 411 and the reference plane 2 412. During operation, the screw shaft 2 moves downward to escape the constraint range of the zero-position stop bar 4 and achieve normal rotation.

[0027] like Figure 3 、 Figure 4 As shown, one end of the calibration rod 3 is U-shaped, and the two bifurcated arms of this end are fixedly screwed to either side of the fracture of the retaining ring 5. The inner edge of the retaining ring 5 has a vertically extending retaining bar 451, which is located radially opposite the fracture of the retaining ring 5. An LED lamp bead 7 capable of emitting light in a circumferential direction is fixed to the lower inner side of the zero-position retaining bar 4. Lamp bead 7 is located at the junction of reference plane 1 411 and reference plane 2 412. The light can be red or green for easy identification, so that the light can simultaneously illuminate the two vertical surfaces of the outer periphery of the calibration rod 3, forming a light spot on the surface for easy observation from the other side.

[0028] like Figure 5As shown, in this state, the screw shaft 2 is in a state before zero calibration, and the calibration rod 3 is located outside the notch 41. The calibration rod 3 can be controlled to rotate slowly so that it can move into the notch 41. When the calibration rod 3 contacts and abuts against the first reference surface 411 as observed from the outside, it stops rotating, indicating that the circumferential zero calibration of the screw shaft 2 is completed. The calibration rod 3 can then be controlled to move slowly upward. When the calibration rod 3 contacts and abuts against the second reference surface 412, it stops moving, indicating that the vertical zero calibration is completed.

[0029] like Figure 6 As shown, the two vertical surfaces of the outer periphery of the calibration rod 3 are in contact with the reference plane 1 411 and the reference plane 2 412. At this time, the user can confirm that the calibration is completed if no light gap is seen between the outer periphery of the calibration rod 3 and the reference plane 1 411 and the reference plane 2 412 from the outside.

[0030] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Persons skilled in the art may make various modifications, additions, or substitutions to the described specific embodiments without departing from the spirit of the present invention or exceeding the scope of the appended claims.

Claims

1. A zero point calibration structure for a four-axis robot, the robot comprising a long strip-shaped arm (1) and a vertically arranged columnar screw shaft (2), wherein the screw shaft (2) is connected to one end of the arm (1) and can move vertically and rotate circumferentially, characterized in that: The zero point calibration structure comprises a horizontally arranged strip-shaped calibration rod (3) and a vertically arranged strip-shaped zero position stop bar (4); the lower portion of the zero position stop bar (4) is in the shape of a rectangular plate and has a rectangular notch (41) at the corner; the inner wall of the notch (41) has a vertical plane-shaped reference plane 1 (411) and a horizontal plane-shaped reference plane 2 (411); one end of the calibration rod (3) is fixedly connected to the outer periphery of the lower end of the screw shaft (2); the upper end of the zero position stop bar (4) is fixedly connected to the small arm (1) and has a gap between it and the screw shaft (2); when the other end of the calibration rod (3) is located in the notch (41) and abuts against the reference plane 1 (411), the calibration rod (3) is axially parallel to both the reference plane 1 (411) and the reference plane 2 (411).

2. The zero point calibration structure of the four-axis robot according to claim 1, characterized in that: The zero point calibration structure further comprises a C-shaped snap ring (5), both ends of which are fixed by penetrating bolts (6). The snap ring (5) is sleeved and fixed on the outer periphery of the screw shaft (2). One end of the calibration rod (3) is U-shaped, and the two forked arms of the end are respectively fixed to the two sides of the fracture of the snap ring (5).

3. The zero point calibration structure of the four-axis robot according to claim 1, characterized in that: The other end of the calibration rod (3) is arranged outward along the radial direction of the screw shaft (2).

4. The zero-point calibration structure of the four-axis robot according to claim 3, characterized in that: The upper end of the zero-position stop bar (4) is horizontally bent into an L-shape toward the side where the small arm (1) is located and is fixed to the outer edge of the housing (1).

5. The zero point calibration structure of the four-axis robot according to claim 2, characterized in that: The inner edge of the clamping ring (5) has a vertically penetrating clearance opening (51), and the clearance opening (51) is located at a position opposite to the fracture of the clamping ring (5) along the radial direction of the clamping ring (5).

6. The zero-point calibration structure of the four-axis robot according to claim 1, characterized in that: The cross section of the other end of the calibration rod (3) is rectangular.

7. The zero-point calibration structure of the four-axis robot according to claim 6, characterized in that: The vertical dimension of the reference plane 1 (411) is greater than the vertical dimension of the other end of the calibration rod (3), and the vertical dimension of the reference plane 2 (411) along the reference plane 1 (411) is greater than the horizontal width dimension of the other end of the calibration rod (3).

8. The zero-point calibration structure of a four-axis robot according to claim 1, characterized in that: The edges of the notch (41) are processed with rounded transition.

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