(19)
(11)EP 3 490 762 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
17.06.2020 Bulletin 2020/25

(21)Application number: 17737451.9

(22)Date of filing:  29.06.2017
(51)International Patent Classification (IPC): 
B25J 19/06(2006.01)
B23K 9/10(2006.01)
B23K 9/32(2006.01)
B23K 37/00(2006.01)
B23K 9/173(2006.01)
(86)International application number:
PCT/US2017/039890
(87)International publication number:
WO 2018/022245 (01.02.2018 Gazette  2018/05)

(54)

TOOL HOLDERS FOR ROBOTIC SYSTEMS HAVING COLLISION DETECTION

WERKZEUGHALTER FÜR ROBOTISCHE SYSTEME MIT KOLLISIONSDETEKTION

PORTE-OUTILS POUR SYSTÈMES ROBOTIQUES À DÉTECTION DE COLLISION


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 26.07.2016 US 201615219591

(43)Date of publication of application:
05.06.2019 Bulletin 2019/23

(73)Proprietor: Illinois Tool Works, Inc.
Glenview, Illinois 60025 (US)

(72)Inventor:
  • BASIT, Nauman
    Glenview, Illinois 60025 (US)

(74)Representative: Trinks, Ole 
Meissner Bolte Patentanwälte Rechtsanwälte Partnerschaft mbB Postfach 10 26 05
86016 Augsburg
86016 Augsburg (DE)


(56)References cited: : 
US-A- 4 998 606
US-A- 5 361 881
US-A1- 2004 175 227
US-A- 5 002 173
US-A- 6 069 415
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    RELATED APPLICATIONS



    [0001] This international application claims priority to U.S. Patent Application Serial No. 15/219,591, filed July 26, 2016, entitled "Tool Holders for Robotic Systems Having Collision Detection."

    BACKGROUND



    [0002] The invention relates to a robotic tool holder and to a robotic welding system comprising such a robotic tool holder and having collision detection.

    [0003] Document US 5002173 A discloses a robotic tool holder according to the preamble of appended claim 1.

    SUMMARY



    [0004] Tool holders for robotic systems having collision detection are disclosed, substantially as illustrated by and described in connection with at least one of the figures, as set forth more completely in the claims.

    BRIEF DESCRIPTION OF THE DRAWINGS



    [0005] 

    FIG. 1 is a block diagram illustrating an example robotic system having collision detection and including a tool holder in accordance with aspects of this disclosure.

    FIG. 2 is an exploded view of an example implementation of the tool holder of FIG. 1.

    FIG. 3 is an assembled view of the example tool holder of FIG. 2.

    FIG. 4 illustrates a cross-section of an actuator and a housing of the example tool holder of FIGS. 2 and 3.

    FIG. 5 illustrates a cross section of an example set of dowels in line contact.

    FIG. 6 illustrates a cross section of the example tool holder of FIG. 4.

    FIG. 7 is a more detailed view of the interfaces between the actuator, the housing, and the pressure plate of FIG. 6.

    FIG. 8 is a cross-section view of the example tool holder of FIGS. 2 and 3 illustrating responses of the actuator and the pressure plate to a shock applied to the tool holder such as by a collision involving the tool.

    FIG. 9 is a cross section view of the example actuator illustrating example force vectors that may affect the actuator when returning to a reference position.


    DETAILED DESCRIPTION



    [0006] Automated welding can be performed using robots that hold welding torches are that are programmed to perform one or more welding operations. Robots have the benefit of providing highly repeatable, high quality welds. In some applications, robots are programmed to use very precise movements to perform a weld that has a very short arc length (e.g., a few millimeters). Repeatable precision movements may be achieved by depending on the movable components in the robot and/or the welding torch having a consistent reference position to which the program can return the robot. The robot may then use the reference position in the program, such as by implementing an inertial coordinate system having the reference position as a designated point in the coordinate system.

    [0007] Shock sensors (also referred to as collision detectors) regulate the positional accuracy of a tool with respect to an inertial coordinate system. In the welding context, a welding torch is mounted to an actuator of a shock sensor and a housing is rigidly mounted to the robot. In the event of a shock or impact, the actuator moves from its rest positon or Tool Center Point (TCP) which triggers a normally closed switch to open and signal the robot controller to stop. The welding gun is required to return to the TCP in an accurate and precise manner. A TCP error is magnified at the contact tip and results in degradation of weld quality (e.g., due to inconsistent welding arc lengths), requiring re-programming.

    [0008] As described in more detail below, disclosed tool holders include features that reduce friction forces that reduce the positional accuracy and/or reliability of conventional tool holders.

    [0009] As used herein, "line contact" is defined as contact substantially along a single line, accounting for deformation along the line of contact. As used herein, "line contact" also includes point contact, or contact at a single point (e.g., between two round surfaces), accounting for deformation at the point of contact.

    [0010] According to the invention, the robotic tool holder includes a housing, an actuator, a pressure plate, springs, a mounting plate, and a sensor switch. The housing has a proximal end and a distal end. The actuator is disposed within the housing and configured to hold a tool, the housing and the actuator being in contact via a plurality of dowels to limit movement of the actuator toward the distal end of the housing. In disclosed examples, ones of the plurality of dowels that are in contact are in line contact. The pressure plate is in line contact with the actuator within the housing around a circumference of the pressure plate. The springs are in contact with the pressure plate to bias the actuator toward the distal end of the housing via the pressure plate. The mounting plate couples the robotic tool holder to a robot, and the springs are in contact with the mounting plate opposite the pressure plate. The sensor switch detects a shock force on the actuator and to output a signal in response to detecting the shock force. The ones of the plurality of dowels that are in contact are in a triangular geometry. The dowels which are in contact in a triangular geometry include two or more sets of dowels spaced around an inner circumference of the housing and the outer circumference of the actuator. Each set of dowels includes two dowels attached to the housing and one dowel attached to the actuator or includes two dowels attached to the actuator and one dowel attached to the housing.

    [0011] In some examples, the actuator is configured to hold a welding torch such that shock force applied to the welding torch is transferred to the actuator. In some example robot tool holders, the actuator and the pressure plate are configured to transfer at least a portion of the shock force to the plurality of springs. In some examples, the sensor switch is in communication with a robot control system configured to control the robotic tool holder to move to a predetermined position in response to the sensor switch signal.

    [0012] In some example robotic tool holders, the triangular geometry of contacting ones of the dowels is configured to endure acceleration of the robotic tool holder up to at least a selected acceleration without causing the sensor switch to falsely detect the shock force, where the triangular geometry includes diameters of the dowels and a space between at least two of the dowels in the triangular geometry.

    [0013] In some examples, the housing, the actuator, the pressure plate, the mounting plate, and the sensor switch have coaxial interior spaces to permit a cable to traverse through the robotic tool holder to a weld torch coupled to the actuator. In some examples, the springs exert a spring force on the pressure plate that is greater than a total of a first friction force between the pressure plate and the actuator along the line contact and a second friction force between ones of the dowels attached to the actuator and corresponding ones of the dowels attached to the housing.

    [0014] In some examples, the dowels include Stainless Steel Alloy 416 or titanium.

    [0015] In some examples, the springs are die springs, and the mounting plate and the pressure plate include cavities to retain the plurality of springs. In some such examples, the mounting plate and the pressure plate are configured to retain the plurality of springs parallel to a centerline of the housing. In some examples, the cavities in the pressure plate are tapered to reduce deflection of the plurality of springs when the pressure plate is tilted within the housing.

    [0016] In some examples, an end of the actuator that is in contact with the pressure plate has a curved surface around a circumference of the actuator such that the actuator and the pressure plate form a ball-and-socket-type joint. In some such examples, the line contact changes with respect to the pressure plate when force is transferred by the actuator, and the actuator and the pressure plate are configured to tilt with respect to the housing based on a direction of the shock force. In some examples, an outer edge of the pressure plate is rounded to permit the pressure plate to rotate within the housing.

    [0017] According to another aspect of the invention, a robotic welding system capable of detecting impacts to a welding torch manipulated by a robot, comprises a robot arm, a welding torch, a robotic tool holder as described above and a robot controller. The robot arm is configured to move a welding end of the robot arm. The robot controller receives the signal as an input and, in response to receiving the signal, controls the robot arm to assume a preset position.

    [0018] FIG. 1 is a block diagram illustrating an example robotic system 100 having collision detection and including a tool holder 102. The example robotic system 100 and the tool holder 102 of FIG. 1 are configured to perform automated (e.g., programmatic) welding using a welding torch 104 held by the tool holder 102. The example robotic system 100 includes a robot controller 106 that controls the movement and/or orientation of a robot arm 108, where the welding torch 104 is attached to the robot arm 108 via the tool holder 102. To perform welding, the example robotic system 100 includes or is provided with a welding power supply 110 to provide welding-type power to the welding torch 104 and/or a wire feeder 112 to provide welding wire to the welding torch 104.

    [0019] The robot controller 106 controls the robot arm 108 to perform programmed movements using one or more joints of the robot arm 108. The robot controller 106 may reference the movements from a reference orientation of the robot arm 108, which also includes a reference orientation of the tool holder 102 and the welding torch 104. When the robot arm 108, the tool holder 102, and the welding torch 104 are in the reference position (e.g., within an acceptable margin of error, which may be very small), the robot controller 106 can be confident that commanded movement of the robot arm 108 translates into desired positions of the welding torch 104.

    [0020] Collisions between the welding torch 104 and another object can cause the welding torch 104 to be out of the position from the position commanded by the robot controller 106. Thus, in response to detecting a collision, the robot controller 106 returns the robot arm 108, the tool holder 102, and the welding torch 104 to the reference position to reestablish positional accuracy. As described in more detail below, the example tool holder 102 includes a collision detection system that detects collisions or shock forces at the welding torch 104, absorbs at least a portion of the shock force on the welding torch 104, and/or communicates the collision event to the robot controller 106 to take corrective action.

    [0021] FIG. 2 is an exploded view of an example implementation of the tool holder 102 of FIG. 1. The example tool holder 102 includes a housing 202, an actuator 204, a pressure plate 206, springs 208, a mounting plate 210, and a sensor switch 212. FIG. 3 is an assembled view of the example tool holder 102 of FIG. 2.

    [0022] The example actuator 204 is disposed within the housing 202. The actuator 204 is configured to hold a tool, such as the welding torch 104. The housing 202 and the actuator 204 are in contact via sets of dowels (e.g., actuator dowel 214, housing dowels 216) that limit movement of the actuator 204 with respect to the housing 202. For example, one or more dowel(s) of the actuator 204 may abut one or more opposing dowel(s) of the housing 202. To reduce friction between the dowels that may prevent the tool holder 102 from returning to the tool center point, respective ones of the dowels 214, 216 that are in contact are in a line contact and/or point contact and, in some examples, each set of dowels 214, 216 are in a triangular geometry. Example dowel arrangements are described in more detail below with reference to FIGS. 4 and 5.

    [0023] The example pressure plate 206 of FIG. 2 is in a line contact with the actuator 204 within the housing 202 around a circumference of the pressure plate 206. In particular, the end of the actuator 204 that is in contact with the pressure plate 206 has a curved surface around a circumference of the actuator 204, such that the actuator 204 and the pressure plate 206 form a ball-and-socket-type joint. That is, the actuator 204 may rotate within the pressure plate 206. As the actuator 204 and the pressure plate 206 rotate, the pressure plate 206 remains in a line contact with the actuator 204 and the contact line may shift along the end of the actuator 204 and the pressure plate 206. However, the springs 208 and the housing 202 restrict the rotation of the pressure plate 206 with respect to the housing 202.

    [0024] The springs 208 are in contact with the pressure plate 206 to bias the actuator 204 into contact with (e.g., toward the tool end of) the housing 202 via the pressure plate 206. The springs 208 are industrial heavy-duty die springs. In combination with the springs 208, the pressure plate 206 extends the life of the tool holder 102 relative to conventional tool holders. The mounting plate 210 couples the robotic tool holder 102 to the robot arm 108. The springs 208 are in contact with the mounting plate 210 opposite the pressure plate 206. The springs 208 are arranged around a circumference of the pressure plate 206 and the mounting plate 210. The example mounting plate 210 includes cavities 218 to retain the springs 208 in position.

    [0025] In the example of FIG. 2, the springs 208 are die springs and the cavities 218 are deep enough to prevent substantial deflection of the springs 208. The example pressure plate 206 likewise includes cavities 220 that retain the springs 208. The cavities 220 in the pressure plate 206 are shallower than the cavities 218, and are tapered toward the outer circumference of the pressure plate 206 to reduce or prevent deflection of the springs 208 when the pressure plate 206 is tilted away from the tool center point (e.g., in response to a shock force).

    [0026] The actuator 204 holds welding torch 104 such that shock force applied to the welding torch 104 is transferred to the actuator 204. The actuator 204 further transfers the shock force to the pressure plate 206 and to one or more of the springs 208. The actuator 204 and the pressure plate 206 may be tilted out of alignment with the tool center point in response to the shock force (e.g., based on a direction of a collision), and transfer the shock force to corresponding ones of the springs 208.

    [0027] The example sensor switch 212 detects shock force on the actuator 204 and outputs a signal in response to detecting the shock force. For example, the sensor switch 212 may implement a normally closed circuit which also includes the dowels 214, 216. When any of the dowels break contact (e.g., in response to a shock that moves the actuator 204), the circuit is opened and the sensor switch 212 generates and transmits a collision signal (e.g., to the robot controller 106 of FIG. 1). The collision signal causes the robot controller 106 to cease movement of the robot arm 108 to reduce the likelihood of damage to the welding torch 104.

    [0028] FIG. 4 illustrates a cross-section of the actuator 204 and the housing 202 of the example tool holder 102 of FIGS. 2 and 3. Sets of dowels, indicated using reference numerals 402, 404, and 406, are shown in FIG. 4. The example tool holder 102 includes three sets of dowels 402, 404, 406 spaced around an inner circumference of the housing 202 and the outer circumference of the actuator 204. However, the tool holder 102 may use fewer sets or more sets of dowels than the three sets shown in FIG. 4. Additionally or alternatively, the actuator 204 may be located on an exterior of the housing 202 such that the sets of dowels 402, 404, 406 are spaced around an outer circumference of the housing 202 and an inner circumference of the actuator 204. The sets of dowels 402-406 function as an alignment mechanism to easily align the housing 202 and the actuator 204. The example sets of dowels 402-406 may be evenly or unevenly spaced around the housing 202 and the actuator 204.

    [0029] The set of dowels 402 includes two dowels 408, 410 attached to the housing 202 and a dowel 412 attached to the actuator 204. The set of dowels 404 includes two dowels 414, 416 attached to the housing 202 and a dowel 418 attached to the actuator 204. The set of dowels 406 includes two dowels 420, 422 attached to the housing 202 and a dowel 424 attached to the actuator 204. The example dowels 408, 410, 414, 416, 420, 422 each have a first diameter d, and the example dowels 412, 418, 424 each have a second diameter D. FIG. 5 illustrates a cross section of the set of dowels 402 in line contact. As illustrated in FIG. 5, when the dowels 408-412 are in contact, the dowels 408-412 have a triangular geometry. The diameters D and/or d, the angular geometry (e.g., the angle α shown in FIG. 5), and/or the spacing between the dowels 408, 410 may be adjusted based on, for example, a number of sets of dowels on the device.

    [0030] Conventional alignment systems use the face of an actuator-type device to create a cylindrical cavity which aligns with a dowel on the housing. Due to imperfections in the surface profile of the cavity, differences in material(s), surface finish(es), and/or hardness differences between the actuator cavity and the housing dowels, the sliding friction force between these surfaces is much higher. The dowel sets 402, 404, 406 of disclosed examples are arranged such that two dowels (e.g., 408, 410) on the housing 202 align with one dowel (e.g., 412) on the actuator 204. The dowel arrangement of the disclosed examples reduces the friction force F1 significantly compared to conventional dowel systems, and improves the accuracy and repeatability of the tool positioning.

    [0031] The example of FIGS. 2-8 alignment mechanism works with three sets of dowels. Each set includes one dowel on the actuator 204 and two dowels on the housing 202. In some examples, the two dowels 408, 410 per set are attached to or part of the actuator 204, and the single dowel 412 is attached to or part of the housing 202. Each actuator dowel 412, 418, 424 forms line contacts with the corresponding pair of dowels 408, 410, 414, 416, 420, 422 on the housing 202, with one line contact between the actuator dowel 412, 418, 424 and each of the corresponding housing dowels (e.g., dowel 412 has one line contact with dowel 408 and one line contact with dowel 410). The line contacts substantially reduce the friction as compared to the surface contact in conventional designs. Furthermore, the dowels 408-424 on the actuator 204 and the housing 202 are made from the same material, the same surface finish, and/or the same hardness specifications to reduce (e.g., minimize) wear and to maintain accuracy and repeatability of the alignment mechanism. An example material is steel alloy 416, which has a high machinability and enables a high surface finish. Steel alloy 416 can be tempered or hardened to achieve a desired surface hardness. The corrosion resistance property of steel alloy 416 ensures that the dowel surfaces will retain the hardness and finish properties, and enables the shock sensor to be used with water cooled robotic welding guns and in high humidity industrial applications. Other example materials that may be used to implement the dowels 408-424 include titanium, martensitic stainless steels and titanium, and precipitation-hardened stainless steels and titanium.

    [0032] The diameters D, d of the dowels 408-424 and the distance between the dowels 408-424 on the housing affect the stability and accuracy of the system. For example, the alignment mechanism is required to operate above a threshold limit for acceleration and vibration so that the sensor switch 212 does not provide false feedback during high acceleration moves. The diameters "D" and "d" are selected based on the annular space available for the alignment mechanism between the housing 202 and the actuator 204 and the strength required to withstand a collision or impact. Dimensional variables d, D and 1 in the triangle shaped geometry illustrated in FIG. 5 formed with each set of three dowels are selected to achieve stability of the tool holder 102 and accuracy and repeatability of the positioning of the tool holder 102 and of the welding torch 104.

    [0033] As illustrated in FIGS. 2, 3, and 4, the housing 202, the actuator 204, the pressure plate 206, the mounting plate 210, and the sensor switch 212 have coaxial interior spaces to permit a cable to traverse through the tool holder 102 to the weld torch 104 coupled to the actuator 204.

    [0034] FIG. 6 illustrates a cross section of the example tool holder 102 of FIG. 4. As shown in FIG. 6, the actuator 204 and the pressure plate 206 are aligned along a tool center point 602. When aligned at the tool center point, the welding torch 104 can be accurately positioned at the reference position by the robot controller 106.

    [0035] FIG. 7 is a more detailed view of the interfaces between the actuator 204, the housing 202, and the pressure plate 206 of FIG. 6. As shown in FIG. 7, the actuator 204 includes a flange 702 that seats against the housing 202. The actuator 204 also has a rounded edge 704 that interfaces with a rounded surface 706 of the pressure plate 206 as a ball-and-socket-type joint.

    [0036] FIG. 7 also illustrates a cross-section of the contact line 708 between the rounded edge 704 of the actuator 204 and the rounded surface 706 of the pressure plate 206. As the rounded edge 704 of the actuator 204 shifts in and/or around the rounded surface 706, the contact line 708 may also change position with respect to the rounded edge 704 and/or the rounded surface 706. The rounded surface 706 of the pressure plate 206 extends to the edges of the pressure plate 206 (e.g., at the interface between the pressure plate 206 and the housing 202) to enable the pressure plate 206 to rotate within the housing 202 without jamming or sticking.

    [0037] FIG. 8 is a cross-section view of the example tool holder 102 of FIGS. 2 and 3 illustrating responses of the actuator 204 and the pressure plate 206 to a shock applied to the tool holder 102 such as by a collision involving a welding torch attached to the actuator 204. A force vector Fc is illustrated in FIG. 8 to show a direction of the force causing the displacement of the actuator 204. As the center line 802 of the actuator 204 diverges from the tool center point 602, the following occurs: 1) one or more of the dowels of the actuator 204 (e.g., the dowels 412, 418, 424) are disengaged from their opposing dowels attached to the housing 202; 2) a portion of the actuator 204 is forced further into the housing 202, pushing on the pressure plate 206 in an asymmetrical manner; 3) the pressure plate 206 is pushed toward the mounting plate 210, while the springs 208 resist the movement of the pressure plate 206 and attempt to maintain the pressure plate 206 in line with the tool center point 602; 4) because the actuator 204 is being forced out of alignment with the tool center point 602 and the springs 208 are urging the pressure plate into alignment with the tool center point 602, the actuator 204 rotates within the rounded curved surface 706 of the pressure plate 206 (e.g., as a ball-and-socket-type joint); and 5) the line contact 706 between the rounded edge 704 of the actuator 204 and the rounded surface 706 of the pressure plate 206 changes from the initial line contact location shown in FIG. 7 as the actuator 204 rotates with respect to the pressure plate 206.

    [0038] When the actuator 204 is moved such that fewer than all of the dowel sets are in contact, the sensor switch 212 transmits the signal (e.g., to the robot controller 106). In response, the robot controller 106 stops any movement of the robot arm 108 and tool holder 102, and returns the robot arm 108 and the tool holder 102 (and the welding torch 104) to the reference position. The return of the robot arm 108 and the tool holder 102 to the reference position eliminates the forces on the actuator 204, enabling the actuator 204 and the pressure plate 206 to be urged into alignment with the tool center point 602.

    [0039] FIG. 9 is a cross section view of the example actuator 204 illustrating example force vectors Fs, Fm, F1, F2 that may affect the actuator 204 when returning to a reference position. Fs is the spring force applied by the springs 208 to the pressure plate 206 and the actuator 204. The spring force (Fs) has to overcome three primary forces: 1) resulting force due to the mass of the welding gun (Fm), 2) friction force (F1) at the interface between the dowels, and 3) friction force (F2) at the point of application of the spring force Fs on the actuator 204 (e.g., friction in the ball-and-socket-type joint between the actuator 204 and the pressure plate 206).

    [0040] As the actuator 204 returns to alignment with the tool center point position 602, the spring force Fs approaches a lower spring force limit. However, to reliably and accurately return the tool holder 102 to the tool center point 602, in the example of FIGS. 2-8 the lower limit of the spring force Fs is greater than the sum of the forces Fm, F1, and F2 (e.g., Fs > Fm + F1 + F2). In contrast with conventional tool holders, the examples of FIGS. 2-8 reduce the friction forces F1 and F2 as described in more detail below to improve the reliability and accuracy of positioning the tool holder 102.

    [0041] Conventional tool holders use opposing surfaces of an actuator-like device and a pressure plate-like device to apply spring forces to the actuator-like device. The surface contact results in a higher frictional force, which hinders the return of conventional tool holder to the tool center point and reduces the reliability and/or accuracy of the positioning of the tool holder and/or the welding torch at the reference position. Some conventional tool holders use customized wave springs, which occupy less space than die springs and do not use a pressure plate to transfer the spring force to the actuator due to an ability to flex laterally. However, wave springs are not designed for high number of cycles and the spring force reduces significantly over time.

    [0042] Disclosed examples have a line contact between the pressure plate 206 and the actuator 204 instead of a surface contact. Relative to a surface contact, the line contact reduces the magnitude of the resulting frictional force F2. Disclosed examples also use die springs, which have a longer operational life and a more consistent spring force over time, ensuring long-term accuracy and reliability of the tool positioning.

    [0043] The example tool holder 102 includes an interior cavity to permit one or more cables (e.g., a power cable, air-cooling and/or water-cooling cables, wire brake hoses, airblast hoses, inert gas supply hoses, electrode liners, etc.) to be fed through the center of the tool holder 102 from the welding power supply 110 and/or the robot arm 108 to the welding torch 104. The expanded interior cavity of the actuator 204 creates a bell-shaped cavity that reduces damage to cable(s) caused by rotation of the actuator 204 during impact.

    [0044] While the present robotic tool holder has been described with reference to certain implementations, it will be understood by those skilled in the art that various changes may be made without departing from the scope of the appended claims.


    Claims

    1. A robotic tool holder (102), comprising:

    - a housing (202) having a proximal end and a distal end;

    - an actuator (204) disposed within the housing (202) and configured to hold a tool, the housing (202) and the actuator (204) being in contact via a plurality of dowels (214, 216) to limit movement of the actuator (204) toward the distal end of the housing (202), in which ones of the plurality of dowels (214, 216) that are in contact are in line contact;

    - a pressure plate (206) in line contact with the actuator (204) within the housing (202) around a circumference of the pressure plate (206);

    - a plurality of springs (208) in contact with the pressure plate (206) to bias the actuator (204) toward the distal end of the housing (202) via the pressure plate (206);

    - a mounting plate (210) to couple the robotic tool holder (102) to a robot, the plurality of springs (208) in contact with the mounting plate (210) opposite the pressure plate (206); and

    - a sensor switch (212) to detect a shock force on the actuator (204) and to output a signal in response to detecting the shock force,

    characterized in that
    the ones of the plurality of dowels (214, 216) that are in contact are in a triangular geometry,
    wherein the dowels (214, 216) comprise two or more sets of dowels (214, 216) spaced around an inner circumference of the housing (202) and an outer circumference of the actuator (204), each set of dowels (214, 216) comprising two dowels attached to one of the housing (202) or the actuator (204), and one dowel attached to the other of the housing (202) or the actuator (204).
     
    2. The robotic tool holder (102) as defined in claim 1,
    wherein the actuator (204) is configured to hold a welding torch (104) such that the shock force applied to the welding torch (104) is transferred to the actuator (204).
     
    3. The robotic tool holder (102) as defined in claim 1 or 2,
    wherein the actuator (204) and the pressure plate (206) are configured to transfer at least a portion of the shock force to the plurality of springs (208).
     
    4. The robotic tool holder (102) as defined in one of the preceding claims, where the sensor switch (212) is in communication with a robot control system configured to control the robotic tool holder (102) to move to a predetermined position in response to the sensor switch (212) signal.
     
    5. The robotic tool holder (102) as defined in one of the preceding claims, wherein the triangular geometry of contacting ones of the dowels (214, 216) is configured to endure acceleration of the robotic tool holder (102) up to at least a selected acceleration without causing the sensor switch (212) to falsely detect the shock force, the triangular geometry including diameters of the dowels (214, 216) and a space between at least two of the dowels in the triangular geometry.
     
    6. The robotic tool holder (102) as defined in one of the preceding claims, wherein the housing (202), the actuator (204), the pressure plate (206), the mounting plate (210), and the sensor switch (212) have coaxial interior spaces to permit a cable to traverse through the robotic tool holder (102) to a weld torch (104) coupled to the actuator (204).
     
    7. The robotic tool holder (102) as defined one of the preceding claims, wherein the springs (208) exert a spring force on the pressure plate (206) that is greater than a total of a first friction force between the pressure plate (206) and the actuator (204) along the line contact and a second friction force between ones of the dowels (214) attached to the actuator (204) and corresponding ones of the dowels (216) attached to the housing (202).
     
    8. The robotic tool holder (102) as defined in one of the preceding claims, wherein the dowels (214, 216) comprise Stainless Steel Alloy 416 or titanium.
     
    9. The robotic tool holder (102) as defined in one of the preceding claims, wherein the plurality of springs (208) are die springs (208), the mounting plate (210) and the pressure plate (206) comprising cavities to retain the plurality of springs (208).
     
    10. The robotic tool holder (102) as defined in claim 9,
    wherein the mounting plate (210) and the pressure plate (206) are configured to retain the plurality of springs (208) parallel to a centerline of the housing (202).
     
    11. The robotic tool holder (102) as defined in claim 9,
    wherein the cavities in the pressure plate (206) are tapered to reduce deflection of the plurality of springs (208) when the pressure plate (206) is tilted within the housing (202).
     
    12. The robotic tool holder (102) as defined in one of the preceding claims, wherein an end of the actuator (204) that is in contact with the pressure plate (206) has a curved surface around a circumference of the actuator (204) such that the actuator (204) and the pressure plate (206) form a ball-and-socket-type joint.
     
    13. The robotic tool holder (102) as defined in claim 12,
    wherein the line contact changes with respect to the pressure plate (206) when force is transferred by the actuator (204), and the actuator (204) and the pressure plate (206) are configured to tilt with respect to the housing (202) based on a direction of the shock force.
     
    14. The robotic tool holder (102) as defined in one of the preceding claims, wherein an outer edge of the pressure plate (206) is rounded to permit the pressure plate (206) to rotate within the housing (202).
     
    15. A robotic welding system (100) capable of detecting impacts to a welding torch (104) manipulated by a robot, the robotic welding system (100) comprising:

    - a robot arm (108) configured to move a welding end of the robot arm (108);

    - the welding torch (104);

    - a robotic tool holder (102) as defined in one of the preceding claims, and

    - a robot controller (106) to receive the signal as an input and, in response to receiving the signal, to control the robot arm to assume a preset position.


     


    Ansprüche

    1. Robotischer Werkzeughalter (102), umfassend:

    - ein Gehäuse (202) mit einem proximalen Ende und einem distalen Ende,

    - einen Aktuator (204), der in dem Gehäuse (202) angeordnet und dafür ausgelegt ist, ein Werkzeug zu halten, wobei das Gehäuse (202) und der Aktuator (204) über eine Vielzahl von Passstiften (214, 216) in Kontakt stehen, um Bewegung des Aktuators (204) zum distalen Ende des Gehäuses (202) hin zu begrenzen, wobei solche aus der Vielzahl von Passstiften (214, 216), die in Kontakt stehen, in Linienkontakt stehen,

    - eine Druckplatte (206), die mit dem Aktuator (204) in dem Gehäuse (202) entlang eines Umfangs der Druckplatte (206) in Linienkontakt steht,

    - eine Vielzahl von Federn (208), die mit der Druckplatte (206) in Kontakt steht, um über die Druckplatte (206) den Aktuator (204) zum distalen Ende des Gehäuses (202) hin vorzuspannen,

    - eine Montageplatte (210), um den robotischen Werkzeughalter (102) an einen Roboter zu koppeln, wobei die Vielzahl von Federn (208) der Druckplatte (206) gegenüberliegend mit der Montageplatte (210) in Kontakt steht, und

    - einen Sensorschalter (212), um eine Stoßkraft auf den Aktuator (204) zu erfassen und in Reaktion auf Erfassen der Stoßkraft ein Signal auszugeben,

    dadurch gekennzeichnet, dass
    sich diejenigen der Vielzahl von Passstiften (214, 216), die in Kontakt stehen, in einer Dreiecksgeometrie befinden,
    wobei die Passstifte (214, 216) zwei oder mehr Sätze aus Passstiften (214, 216) umfassen, die entlang eines Innenumfangs des Gehäuses (202) und eines Außenumfangs des Aktuators (204) beabstandet angeordnet sind, wobei jeder Satz aus Passstiften (214, 216) zwei Passstifte, die an entweder dem Gehäuse (202) oder dem Aktuator (204) angebracht sind, und einen Passstift umfasst, der an dem jeweils anderen von Gehäuse (202) oder Aktuator (204) angebracht ist.
     
    2. Robotischer Werkzeughalter (102) nach Anspruch 1,
    wobei der Aktuator (204) dafür ausgelegt ist, einen Schweißbrenner (104) derart zu halten, dass die auf den Schweißbrenner (104) aufgebrachte Stoßkraft auf den Aktuator (204) übertragen wird.
     
    3. Robotischer Werkzeughalter (102) nach Anspruch 1 oder 2,
    wobei der Aktuator (204) und die Druckplatte (206) dafür ausgelegt sind, zumindest einen Teil der Stoßkraft auf die Vielzahl von Federn (208) zu übertragen.
     
    4. Robotischer Werkzeughalter (102) nach einem der vorhergehenden Ansprüche,
    wobei der Sensorschalter (212) mit einem robotischen Steuersystem in Datenaustausch steht, das dafür ausgelegt ist, in Reaktion auf das Signal des Sensorschalters (212) den robotischen Werkzeughalter (102) so zu steuern, dass sich dieser in eine vorab bestimmte Position bewegt.
     
    5. Robotischer Werkzeughalter (102) nach einem der vorhergehenden Ansprüche, wobei die Dreiecksgeometrie in Kontakt stehender Passstifte (214, 216) dafür ausgelegt ist, Beschleunigung des robotischen Werkzeughalters (102) bis zu mindestens einer ausgewählten Beschleunigung auszuhalten, ohne eine Falscherfassung der Stoßkraft durch den Sensorschalter (212) zu verursachen, wobei die Dreiecksgeometrie Durchmesser der Passstifte (214, 216) und einen Abstand zwischen mindestens zweien der Passstifte in der Dreiecksgeometrie beinhaltet.
     
    6. Robotischer Werkzeughalter (102) nach einem der vorhergehenden Ansprüche, wobei das Gehäuse (202), der Aktuator (204), die Druckplatte (206), die Montageplatte (210) und der Sensorschalter (212) koaxiale Innenräume aufweisen, um zu ermöglichen, dass ein Kabel den robotischen Werkzeughalter (102) bis zu einem an den Aktuator (204) gekoppelten Schweißbrenner (104) durchläuft.
     
    7. Robotischer Werkzeughalter (102) nach einem der vorhergehenden Ansprüche,
    wobei die Federn (208) auf die Druckplatte (206) eine Federkraft ausüben, die größer ist als eine Summe aus einer ersten Reibungskraft zwischen der Druckplatte (206) und dem Aktuator (204) entlang des Linienkontakts und einer zweiten Reibungskraft zwischen an dem Aktuator (204) angebrachten Passstiften (214) und entsprechenden der an dem Gehäuse (202) angebrachten Passstifte (216).
     
    8. Robotischer Werkzeughalter (102) nach einem der vorhergehenden Ansprüche, wobei die Passstifte (214, 216) Edelstahllegierung 416 oder Titan umfassen.
     
    9. Robotischer Werkzeughalter (102) nach einem der vorhergehenden Ansprüche, wobei es sich bei der Vielzahl von Federn (208) um Matrizenfedern (208) handelt, wobei die Montageplatte (210) und die Druckplatte (206) Hohlräume umfassen, um die Vielzahl von Federn (208) zu sichern.
     
    10. Robotischer Werkzeughalter (102) nach Anspruch 9, wobei die Montageplatte (210) und die Druckplatte (206) dafür ausgelegt sind, die Vielzahl von Federn (208) parallel zu einer Mittellinie des Gehäuses (202) zu sichern.
     
    11. Robotischer Werkzeughalter (102) nach Anspruch 9, wobei die Hohlräume in der Druckplatte (206) verjüngt sind, um eine Ablenkung der Vielzahl von Federn (208) zu verringern, wenn die Druckplatte (206) in dem Gehäuse (202) gekippt wird.
     
    12. Robotischer Werkzeughalter (102) nach einem der vorhergehenden Ansprüche,
    wobei ein mit der Druckplatte (206) in Kontakt stehendes Ende des Aktuators (204) entlang eines Umfangs des Aktuators (204) eine gekrümmte Fläche derart aufweist, dass der Aktuator (204) und die Druckplatte (206) ein Kugelgelenk bilden.
     
    13. Robotischer Werkzeughalter (102) nach Anspruch 12, wobei sich der Linienkontakt in Bezug auf die Druckplatte (206) ändert, wenn durch den Aktuator (204) Kraft übertragen wird, und der Aktuator (204) und die Druckplatte (206) dafür ausgelegt sind, auf Grundlage einer Richtung der Stoßkraft in Bezug auf das Gehäuse (202) zu kippen.
     
    14. Robotischer Werkzeughalter (102) nach einem der vorhergehenden Ansprüche, wobei ein Außenrand der Druckplatte (206) gerundet ist, um zu ermöglichen, dass sich die Druckplatte (206) in dem Gehäuse (202) dreht.
     
    15. Robotisches Schweißsystem (100), das in der Lage ist, Schläge auf einen durch einen Roboter manipulierten Schweißbrenner (104) zu erfassen, wobei das robotische Schweißsystem (100) Folgendes umfasst:

    - einen Roboterarm (108), der dafür ausgelegt ist, ein Schweißende des Roboterarms (108) zu bewegen,

    - den Schweißbrenner (104),

    - einen robotischen Werkzeughalter (102) nach einem der vorhergehenden Ansprüche und

    - eine Robotersteuerung (106), um das Signal als Eingabe zu empfangen und in Reaktion auf Empfangen des Signals den Roboterarm so zu steuern, dass dieser eine vorab eingestellte Position einnimmt.


     


    Revendications

    1. Porte-outils robotique (102), comprenant :

    - un boîtier (202) ayant une extrémité proximale et une extrémité distale ;

    - un actionneur (204) disposé à l'intérieur de ce boîtier (202) et configuré de façon à tenir un outil, le boîtier (202) et l'actionneur (204) étant en contact via une pluralité de goujons (214, 216) afin de limiter le mouvement de l'actionneur (204) vers l'extrémité distale du boîtier (202), les goujons parmi la pluralité de goujons (214, 216) qui sont en contact étant en contact linéaire ;

    - une plaque de pression (206) en contact linéaire avec l'actionneur (204) à l'intérieur du boîtier (202) autour d'une circonférence de la plaque de pression (206) ;

    - une pluralité de ressorts (208) en contact avec la plaque de pression (206) pour solliciter l'actionneur (204) vers l'extrémité distale du boîtier (202) par l'intermédiaire de la plaque de pression (206) ;

    - une plaque de montage (210) pour coupler le porte-outils robotique (102) à un robot, la pluralité de ressorts (208) étant en contact avec cette plaque de montage (210) en face de la plaque de pression (206) ; et

    - un contacteur de détection (212) pour détecter une force de choc sur l'actionneur (204) et pour fournir un signal en réponse à la détection de cette force de choc,

    caractérisé en ce que
    ceux des goujons de la pluralité de goujons (214, 216) qui sont en contact sont dans une géométrie triangulaire,
    les goujons (214, 216) comprenant deux ensembles de goujons (214, 216) ou plus espacés autour d'une circonférence intérieure du boîtier (202) et d'une circonférence extérieure de l'actionneur (204), chaque ensemble de goujons (214, 216) comprenant deux goujons attachés soit au boîtier (202), soit à l'actionneur (204), et un goujon attaché à l'autre que le boîtier (202) ou que l'actionneur (204) .
     
    2. Porte-outils robotique (102) selon la revendication 1,
    dans lequel l'actionneur (204) est configuré de façon à tenir une torche de soudage (104) de manière à ce que la force de choc appliquée sur cette torche de soudage (104) soit transférée à l'actionneur (204).
     
    3. Porte-outils robotique (102) selon la revendication 1 ou 2,
    dans lequel l'actionneur (204) et la plaque de pression (206) sont configurées de façon à transférer au moins une partie de la force de choc à la pluralité de ressorts (208).
     
    4. Porte-outils robotique (102) selon l'une quelconque des revendications précédentes, dans lequel le contacteur de détection (212) est en communication avec un système de commande de robot configuré de façon à commander le porte-outils robotique (102) pour qu'il bouge jusqu'à une position prédéterminée en réponse au signal du contacteur de détection (212).
     
    5. Porte-outils robotique (102) selon l'une quelconque des revendications précédentes, dans lequel la géométrie triangulaire des goujons en contact (214, 216) est configurée de façon à supporter l'accélération du porte-outils robotique (102) jusqu'à au moins une accélération sélectionnée sans que le contacteur de détection (212) ne détecte de façon erronée la force de choc, la géométrie triangulaire comprenant les diamètres des goujons (214, 216) et un espace entre au moins deux des goujons dans la géométrie triangulaire.
     
    6. Porte-outils robotique selon (102) l'une quelconque des revendications précédentes,
    dans lequel le boîtier (202), l'actionneur (204), la plaque de pression (206), la plaque de montage (210) et le contacteur de détection (212) ont des espaces intérieurs coaxiaux pour permettre à un câble de passer à travers le porte-outils robotique (102) jusqu'à une torche de soudage (104) couplée à l'actionneur (204).
     
    7. Porte-outils robotique (102) selon l'une quelconque des revendications précédentes, dans lequel les ressorts (208) exercent une force de ressort sur la plaque de pression (206) qui est plus grande qu'un total d'une première force de frottement entre la plaque de pression (206) et l'actionneur (204) le long du contact linéaire et d'une deuxième force de frottement entre les goujons (214) attachés à l'actionneur (204) et les goujons correspondants (216) attachés au boîtier (202) .
     
    8. Porte-outils robotique (102) selon l'une quelconque des revendications précédentes, dans lequel les goujons (214, 216) consistent en un alliage d'acier inoxydable 416 ou en du titane.
     
    9. Porte-outils robotique (102) selon l'une quelconque des revendications précédentes, dans lequel la pluralité de ressorts (208) sont des ressorts matricés (208), la plaque de montage (210) et la plaque de pression (206) comportant des cavités pour retenir la pluralité de ressorts (208) .
     
    10. Porte-outils robotique (102) selon la revendication 9,
    dans lequel la plaque de montage (210) et la plaque de pression (206) sont configurées de façon à maintenir la pluralité de ressorts (208) parallèles à un axe du boîtier (202).
     
    11. Porte-outils robotique (102) selon la revendication 9,
    dans lequel les cavités dans la plaque de pression (206) sont tronconiques afin de réduire la flexion de la pluralité de ressorts (208) lorsque la plaque de pression (206) est inclinée à l'intérieur du boîtier (202).
     
    12. Porte-outils robotique (102) selon l'une quelconque des revendications précédentes, dans lequel une extrémité de l'actionneur (204) qui est en contact avec la plaque de pression (206) a une surface incurvée autour d'une circonférence de l'actionneur (204) de manière à ce que l'actionneur (204) et la plaque de pression (206) forment une articulation de type à rotule.
     
    13. Porte-outils robotique (102) selon la revendication 12,
    dans lequel le contact linéaire change par rapport à la plaque de pression (206) lorsqu'une force est transférée par l'actionneur (204), et l'actionneur (204) et la plaque de pression (206) sont configurées de façon à s'incliner par rapport au boîtier (202) en fonction d'une direction de la force de choc.
     
    14. Porte-outils robotique (102) selon l'une quelconque des revendications précédentes,
    dans lequel un bord extérieur de la plaque de pression (206) est arrondi de façon à permettre à la plaque de pression (206) de tourner à l'intérieur du boîtier (202).
     
    15. Système de soudage robotique (100) capable de détecter des impacts sur une torche de soudage (104) manipulée par un robot, ce système de soudage robotique (100) comprenant :

    - un bras robotisé (108) configuré de façon à bouger une extrémité de soudage du bras robotisé (108),

    - la torche de soudage (104) ;

    - un porte-outils robotique (102) selon l'une quelconque des revendications précédentes, et

    - une unité de commande de robot (106) pour recevoir le signal comme une entrée et, en réponse à la réception de ce signal, pour commander le bras robotisé pour qu'il prenne une position prédéfinie.


     




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    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description