Drive unit for an expander tool

Abstract

The invention relates to a drive unit (1) for an expander tool, comprising a mechanical connection (4) for kinematically attaching the expander tool to a longitudinal displacement body (9) which runs out in a tapering manner, an annular rotary driver (11) which surrounds the displacement body, and a combined indexing and oscillating drive (3) comprising an input shaft (13), a first kinematic path for converting a continuous rotation of the input shaft (13) into a periodic linear movement, and a second kinematic path for converting a continuous rotation of the input shaft (13) into an incremental rotational movement. The input shaft (13) is connected to an electric rotary drive unit (2), the first kinematic path is connected to the displacement body (9) in order to transmit the periodic linear movement, and the second kinematic path is connected to the rotary driver (11) in order to transmit the incremental rotational movement. The first and second kinematic path coincide solely with respect to a continuous rotational movement transmission. The second kinematic path is designed to convey an incremental rotation to the rotary driver (11) from a periodic pivoting movement of an intermediate element (20) by means of a number of axial ramps (25, 26), which rotate uniformly together with the input shaft, a number of pivotally mounted contact surfaces (27, 28), and a freewheel (29).

Description

[0001] Drive unit for an expander tool

[0002] Technical area

[0003] The present disclosure relates to a drive unit for an expander tool, which is configured for stepwise rotation and periodic linear drive of the expander tool. In particular, the present disclosure relates to such a drive unit for an expander tool with a combined stepping and pendulum gear.

[0004] Expander tools for expanding metal pipes and plastic hoses are known from the official publications DE 10 2010 004 426 A1, WO 2012 037935 A1, DE 20 2019 107 067 U1 and US 2019 / 0351605 A1. Drive units for such and similar expander tools with the same or comparable intended purpose are known from the other official publications DE 20 2011 050 988 U1, EP 3 275 626 B1, EP 2 374 554 B1, EP 1 938 950 B1 and WO 2023 / 179809 A1. For the purpose of possibly completing or supplementing the present descriptions, express reference is made to the cited official publications (printed documents). It is noted that the cited printed documents may assign a meaning to identical terms that differs from the present one. In particular, reference is made to the disclosures in the printed documents regarding the design of the expander tools to be driven by the drive unit.

[0005] The power tools and machines further disclosed in the documents comprise drive units for expander tools with a pendulum gear, by means of which the continuous rotation of an electric motor, an electric gear motor or an equivalent electric rotary drive is converted into a cyclical expansion movement of the jaw arrangement of the connected expander tool. Furthermore, the drive units disclosed in the documents

[0006] 1

[0007] CONFIRMATION COPY Drive units for expander tools are supplemented with indexing gears to gradually rotate the jaw assembly of the connected expander tool during the opening cycle. This additional rotation counteracts the effect of the multi-part jaw assembly imprinting on the inner surface of the workpiece.

[0008] Some of the known drive units for an expander tool comprise numerous mechanical components and require considerable assembly effort. Other known drive units for an expander tool require complex mechanical components. Accordingly, under certain circumstances, there may be a need for a mechanical design of a drive unit for an expander tool with a few easily manufactured mechanical components.

[0009] Concepts

[0010] The technical concept of claim 1 fundamentally addresses this need. Related fundamental embodiments and alternatives are specified in the dependent claims.

[0011] Short description of the characters

[0012] The attached drawings show the design of an exemplary embodiment of a novel drive unit for an expander tool as well as the underlying basic mechanical concepts:

[0013] Fig. 1 shows an exemplary drive unit for an expander tool in a perspective view obliquely from the front;

[0014] Fig. 2 shows a perspective exploded view of the mechanical details in the exemplary drive unit according to Fig. 1 in a view obliquely from the front; Fig. 3 shows a perspective partial sectional view of the exemplary drive unit according to Figs. 1 and 2 in a first operating position; and

[0015] Fig. 4 shows a perspective partial sectional view of the exemplary drive unit according to Fig. 1 and 2 in a second operating position.

[0016] Examples of implementation

[0017] In particular, according to Fig. 1, an exemplary drive unit 1 for an expander tool can be divided into three functional units, namely an electric rotary drive 2 for outputting a continuous rotational movement, a combined stepping and pendulum gear 3 for converting the continuous rotational movement into several cyclical movements and a mechanical tool connection 4 for the kinematic connection of an expander tool to the several cyclical movements. The three functional units mentioned can be combined in a single housing, as shown by way of example, or by a single housing 5, as shown in Fig. 1. In the illustration, the upper cover of the housing above the combined stepping and pendulum gear 3 is omitted.

[0018] The electric rotary drive 2 can be implemented, in particular, as a geared motor and configured to perform a continuous rotary movement or rotation on an output shaft 6 during operation. The geared motor can comprise a DC motor, and in particular a brushless DC motor. Furthermore, the electric rotary drive 2 can comprise a multi-stage gear, and in particular a multi-stage planetary gear.

[0019] In typical applications, the electric rotary actuator 2 will be connected to an electrical power source via an electrical switching or control element. The electrical switching or control element will include an operator interface with which an operator can control the power supply to the rotary actuator as required. Typically, the electrical power source will be a rechargeable battery. In applications with higher power requirements, a mains-powered voltage converter can be used as an alternative. This is not shown in the exemplary views.

[0020] According to Fig. 1, the mechanical connection 4 can comprise a fastening flange 7 which is designed for the detachable connection of a selection of expander tools. The fastening flange 7 can in particular be equipped with a bayonet, wrench or screw connection in order to allow easy replacement of the expander tool. Furthermore, designs are available which adapt both tools with a screw connection and tools with a bayonet connection. For details in this regard, reference is made to the documents mentioned at the outset. In the exemplary embodiment, the fastening flange 7 is designed as an external thread on a protruding end of a flange housing 8.

[0021] Furthermore, the mechanical connection 4 can have a tapered, elongated displacement body, which is exemplified as a sectionally conical expanding mandrel 9. The expanding mandrel 9 is designed to act in a linear movement along the axis of symmetry of the conical section 10 against the jaw arrangement of an expander tool attached to the fastening flange 7 in order to drive them apart in the radial direction with respect to the axis of symmetry of the expanding mandrel 9.

[0022] In variations, the expanding mandrel 9 shown could have several conical sections with different cone angles or another tapered shape instead of a uniformly conical section 10. Likewise, it is not necessary for the displacement body to have a rotationally symmetrical shape, as is the case with the conical section 10 of the expanding mandrel 9. It can be advantageous if the displacement body has a symmetry that is coordinated with the gradual rotation of the jaw arrangement of the expander tool during operation, as will be explained in more detail below.

[0023] Furthermore, the mechanical connection 4 comprises an exemplary ring-shaped rotary driver 11, which is arranged coaxially to the axis of symmetry of the conical section 10 on the expanding mandrel 9. The side of the rotary driver 11 facing the tip of the expanding mandrel 9 and thus towards a connected expander tool is equipped with a tooth structure 12 or a comparable arrangement of projections for a particularly axial engagement with the jaws of the connected expander tool.

[0024] The tooth structure 12 or projections of the rotary driver 11 are designed to mesh with correspondingly shaped recesses or counter-contours on the jaws of the connected expander tool or otherwise to form an engagement around the axis of symmetry of the conical section on the expanding mandrel 9, via which engagement a rotation of the rotary driver 11 can be transmitted to the jaws of the connected expander tool.

[0025] To drive the expanding mandrel 7 and the rotary driver 11, the exemplary drive unit 1 comprises the combined stepping and pendulum gear 3. The combined stepping and pendulum gear 3 can be configured to generate a linear pendulum motion, to which the displacement body and in particular the expanding mandrel 9 is connected in a suitable manner, as well as to generate a stepping rotary motion, to which the rotary driver 11 is connected in a suitable manner. In particular, the combined stepping and pendulum gear 3 can comprise a branched drive train that diverts the continuous rotation supplied from the electric rotary drive 2 via different kinematic paths to two different output elements, as explained below.

[0026] In particular, according to Fig. 2, the exemplary embodiment of the combined stepper and pendulum gear 3 comprises an input shaft 13 connected to the rotary drive 2 and, in particular, to the output shaft 5 of the exemplary geared motor. Two kinematic paths extend from the input shaft 13, along which the aforementioned different movements are generated.

[0027] For the purposes of further explanation, the first kinematic path will be referred to as the one for converting continuous rotation into cyclic linear motion. A general cyclic linear motion is sometimes referred to as a pendulum motion in common parlance. The second kinematic path will be referred to as the one for converting continuous rotation into stepwise rotation.

[0028] 2 and 3, the first named kinematic path runs from the input shaft 13 via a drive disk 14 which has an outer drive cam track 15 profiled radially and parallel to the axis and is sometimes also referred to in specialist circles as a radial cam disk. The drive disk 14 is connected in a torsionally rigid manner to the input shaft 13 by means of a wedge connection, for example, and is suspended via the input shaft 13 in a suitable bearing so as to be rotatable about the axis A. The bearing of the drive disk 14 can, as shown, comprise two ball bearings 16, 17, between which the drive disk 14 is enclosed, as shown by way of example. In an alternative design, the drive disk could be mounted on one side. In a further alternative, the drive disk could be connected to the input shaft in a torque-transmitting manner via a coaxial gear.In particular, a reduction gear in the form of a planetary or eccentric gear could be provided as the coaxial gear. A reduction gear integrated into the drive pulley could completely or partially eliminate the need for a gear within the electric rotary drive, as shown in the example.

[0029] In the arrangement shown, the first named kinematic path further contains a roller 18 which is suspended for free rotation and is held in a linear guide which runs radially to the axis A. In the situation shown, the linear guide is formed by a cylindrical rear section 19 of the expanding mandrel 9 and a bearing bore surrounding this in a pivot sleeve 20. A further bearing point for the linear guide is provided by the elongated holes 21 at the top and bottom in the flange housing 8. The roller 18 can also be held, as in the situation shown as an example, by a bolt 22 in terminal fastening eyes 23 on the expanding mandrel 9.

[0030] The axis of rotation of the roller 18, defined by the bolt 22, can run parallel to the axis A of rotation of the drive disk 14, as is the case in the exemplary situation. As a result, the roller 18 can have the exemplary cylindrical outer shape, and the drive cam track 15 can, as shown in the example, be translationally symmetrical to the axis A, i.e., prismatic. In this situation, the contact of the roller 18 with the drive cam track 15 always lies on a contact line parallel to the axis A.

[0031] In the first kinematic path mentioned, a return spring 24 can also be provided, which acts on the expanding mandrel 9 with a preload opposite to its direction of movement when driving the jaw assembly apart. The return spring 24 can keep the roller 18 in constant contact with the drive cam track 15.

[0032] The second named kinematic path runs in the illustrated situation from the input shaft 13 to a first, upper and a second, lower crescent-shaped axial ramp 25 and 26, respectively. In the exemplary situation, the first axial ramp 25 is, according to the orientation of the illustration, on the upper side of the drive disk 14 and the second axial ramp

[0033] 26 is arranged on the underside of the drive disk 14. The first and second axial ramps 25 and 26, respectively, are designed to come into contact with the pivot sleeve 20 at different angular positions of the drive disk 14 in order to periodically pivot the pivot sleeve 20 by a predetermined angular amount about the axis of the expanding mandrel 10.

[0034] In particular, in Figs. 3 and 4 it can be seen how, in the exemplary embodiment, the upper axial ramp 25 is designed to form a first terminal rounding

[0035] 27 to press the contact surface formed on the pivot sleeve 20 upwards in a first angular range during the rotation of the drive disk 14 and thereby to pivot the pivot sleeve 20 clockwise by a predetermined angular amount in the direction of view towards the tip of the expanding mandrel 10.

[0036] Without further illustration, it is understandable that a lower contact surface corresponding to the lower axial ramp 26 is configured in a similar manner to be pressed downwards in a second angular range during the rotation of the drive disk 14, thereby pivoting the pivot sleeve 20 counterclockwise by a predetermined angular amount in the direction of view toward the tip of the expanding mandrel 10. The lower contact surface is formed in a similar manner by a second, lower terminal rounding 28 on the pivot sleeve 20.

[0037] In the exemplary embodiment, the first angular range is traversed while or after the expanding mandrel 10 has returned to the starting position and the roller 18 has moved from a position remote from the axis A to a position closer to the axis A. In the exemplary embodiment, the second angular range is traversed while the roller 18 moves away from the axis A and the expanding mandrel 10 passes approximately the mid-position between the beginning and end of the movement.

[0038] The first and second terminal rounded portions 27 and 28 on the pivot sleeve 20 are arranged relative to one another and relative to the axial ramps 25 and 26 respectively associated with them such that, upon continued rotation of the drive disk 14, the periodic pivoting movement of the pivot sleeve results from the alternating contact of its terminal rounded portions 27, 28 with the respectively associated axial ramps 25, 26. For example, after the first axial ramp 25 has passed the first rounded portion 27, the pivot sleeve must be in an angular position in which the first rounded portion is at the greatest axial height of the axial ramp 25.

[0039] In this situation, the second terminal rounding 28 is located directly on the underside of the drive disk 1, except for a small, technically necessary play. In this position of the pivot sleeve 20, as the drive disk 14 continues to rotate, its second terminal rounding 28 is touched by the second axial ramp 26 and pressed downwards. The pivot sleeve 20 is thereby moved into an angular position in which its first terminal rounding 27 rests on the upper side of the drive disk 14, except for a technically necessary play.

[0040] Accordingly, the pivot sleeve 20 is periodically pivoted in opposite directions by a design-specified angle due to the alternating contact with the axial ramps 25, 26. Thus, the pivot sleeve 20 performs a periodic pivoting movement during a uniform rotation of the drive disk 14.

[0041] The swivel sleeve 20 is connected to the rotary driver 11 via a freewheel at its end facing away from the axis A. The freewheel 29 ensures that the swivel movement of the swivel sleeve 20 is transmitted to the rotary driver 11 in only one direction. As a result, the inherently periodic movement of the swivel sleeve 20 is converted into a step-by-step rotary movement of the rotary driver 11. The freewheel 29 can be implemented as a clamping roller freewheel, the rollers of which interact directly with a cylindrical section 30 of the rotary driver 11.

[0042] To achieve axial resilience of the rotary driver 11, the clamping roller freewheel 29 can be installed in an axially displaceable coupling sleeve N31, as shown by way of example. The rotation of the pivot sleeve 20 is connected to the coupling sleeve 31, for example, via an axially compensating rotary coupling. The axially compensating rotary coupling can be implemented, as indicated in the drawings, by a first claw structure 32 on the pivot sleeve 20 and a corresponding second claw structure 33 on the coupling sleeve 30.

[0043] In some situations, the spring preload of the rotary driver 11 can be applied without additional design effort by the return spring 24, by supporting it against the rear collar of the roller clutch 29. This applies to situations in which the preload and / or spring rate of the return spring 24 can be adjusted within limits to the preload requirement of the driver 11 without detriment to the return function.

[0044] Since in this situation the spring lies between two parts rotating relative to one another, it may be necessary to counteract excessive torque flow via the return spring 24 by means of an axial bearing. In the exemplary embodiment, this axial bearing comprises a sliding ring 34 which is installed between the rear collar of the roller clamp freewheel 29 and a collar disk 35. It is obvious that torques from the rotary driver 11 can act back on the pivot sleeve 20 in at least one direction via the freewheel 29. Such reacting torques can lead to the angular positions of the pivot sleeve 20 not being determined exclusively by its contact with the axial cams 25, 26. This can be seen in particular with regard to Figs. 4 and 5 for the exemplary embodiment.

[0045] If the drive disk 14 rotates by approximately 40° from the operating position in FIG. 4, the upper rounded portion 27 loses contact with the upper side of the upper axial cam 25. The angular position of the pivot sleeve 20 is therefore no longer fixed to that achieved in FIG. 4. If a sufficiently large torque is introduced by the rotary driver 11, turning anti-clockwise as viewed towards the tip of the expanding mandrel 10, this torque is transferred via the locking freewheel 29 to the pivot sleeve 20 and pivots it until the upper rounded portion 27 stops on the upper side of the drive disk 14.

[0046] This possibility of externally influenced pivoting of the pivot sleeve 20 will not cause any fundamental disadvantages in most applications. In an alternative embodiment, this possibility can be prevented by extending the upper or lower side of the axial cams 25 and / or 26 over a more or less extensive circular arc in a wider angular range of the drive disk, or can be prevented completely. A consistently defined positive guidance of the pivot sleeve 20, except for the necessary design clearance, obviously requires complementary run-off slopes at its outlet.

[0047] The specific design of the freewheels with the clamping roller sleeve 29 chosen in the exemplary drive unit can obviously be replaced by other functionally equivalent freewheel designs. Indexing or continuous freewheels can be used depending on the desired result. Indexing freewheels have discrete locking positions distributed around the circle and thus allow only a finite number of relative angular positions between the coupled parts. Continuous freewheels, such as the clamping roller freewheel described as an example, can lock in any relative angular position.

[0048] Reference symbol

[0049] Drive unit . 1

[0050] Rotary drive . 2

[0051] Stepper and pendulum gears . 3 Mechanical connection . 4

[0052] Housing . 5

[0053] Rotary drive, output shaft . 6

[0054] Mounting flange . 7

[0055] Flange housing . 8 Expanding mandrel . 9

[0056] Expanding mandrel, conical section . . . 10

[0057] Rotary driver . 11

[0058] Rotary driver, tooth structure . 12

[0059] Input shaft . 13 Drive pulley . 14

[0060] Drive cam track . 15

[0061] Ball bearings . 16

[0062] Ball bearings . 17

[0063] Roll . 18 Expanding mandrel, rear section 19

[0064] Swivel sleeve . 20

[0065] Flange housing, slotted holes. 21

[0066] Bolt . 22

[0067] Expanding mandrel, fastening eyes 23 Return spring . 24

[0068] Axial ramp, upper . 25

[0069] Axial ramp, lower . 26

[0070] Swivel sleeve, upper rounding. 27

[0071] Swivel sleeve, lower rounding . . . . 28 Freewheel . 29

[0072] Rotary driver, cylindrical section . . 30

[0073] Coupling sleeve . 31

[0074] Coupling sleeve, claw structure . . . . 32

[0075] Swivel sleeve, claw structure . 33 Slide ring . 34

[0076] Collar disc . 35

Claims

Claims 1. A drive unit (1) for an expander tool, comprising a mechanical connection (4) for the kinematic connection of the expander tool, wherein the mechanical connection (4) comprises a tapered elongated displacement body (9) and an annular rotary driver (11) enclosing the latter, as well as a combined stepping and pendulum gear (3) with an input shaft (13), a first kinematic path for converting a continuous rotation of the input shaft (13) into a periodic linear movement, and a second kinematic path for converting a continuous rotation of the input shaft (13) into a stepwise rotary movement, wherein the input shaft (13) is connected to an electric rotary drive unit (2), wherein the first kinematic path for transmitting the periodic linear movement is connected to the displacement body (9),wherein the second kinematic path is connected to the rotary driver (11) for transmitting the stepwise rotary movement, wherein the first and second kinematic paths coincide exclusively with regard to a continuous rotary movement transmission, and wherein the second kinematic path is configured to derive a stepwise rotation onto the rotary driver (11) from a periodic pivoting movement of an intermediate member (20) by means of a number of axial ramps (25, 26) rotating uniformly with the input shaft, a number of pivotably mounted contact surfaces (27, 28) and a freewheel (29).

2. Drive unit (1) for an expander tool according to claim 1, wherein the axial ramps (25, 26) and the contact surfaces (27, 28) are assigned to one another in pairs and arranged such that during the rotation of the drive disk (14) the freewheel (29) is rotated by a predetermined angular amount by the interaction of the respective axial ramp (25, 26) with the respectively assigned contact surface (27, 28).

3. Drive unit (1) for an expander tool according to claim 2, wherein the contact surfaces (27, 28) are pivotable about an axis inclined to the axis of rotation (A) of the drive disk (14).

4. Drive unit (1) for an expander tool according to claim 2 or 3, wherein the contact surfaces (27, 28) are pivotable about the axis of rotation of the rotary driver (11).

5. Drive unit (1) for an expander tool according to claim 4, wherein the contact surfaces (27, 28) are formed on a pivotably mounted intermediate member (20).

6. Drive unit (1) for an expander tool according to claim 5, wherein the displacement body (9) is designed as an expanding mandrel with a front conical section (10) and the pivotably mounted intermediate member is a pivot sleeve (20) arranged coaxially to the central axis (B) of the conical section (10) of the expanding mandrel (9).

7. Drive unit (1) for an expander tool according to claim 6, wherein the central axis (B) of the conical section (10) of the expanding mandrel (9) runs perpendicular to the axis of rotation (A) of the drive disc (14).

8. Drive unit (1) for an expander tool according to one of the preceding claims, wherein the tapered elongated displacement body (9) has a conical section (10) and in particular comprises a conical tip and is connected to the drive cam track (15) via a roller (18).

9. Drive unit (1) for an expander tool according to one of the preceding claims, wherein the drive disk (14) is a radial cam disk with a drive cam track (15) that is translationally symmetrical to the axis of rotation (A).

10. Drive unit (1) for an expander tool according to one of the preceding claims, wherein the freewheel is a clamping roller freewheel (29).

11. Drive unit (1) for an expander tool according to claim 8, wherein the return spring (24) is further configured to preload the displacement body (9) into a retracted position toward the mechanical connection (4).

12. Assembly comprising a drive unit (1) according to one of the preceding claims and an expander tool, wherein the expander tool is connected to the mechanical connection (9) of the drive unit (1) and comprises a jaw arrangement with a plurality of individually movably held jaws, wherein the jaws are equipped with a first and a second contact surface, wherein the first contact surface is designed to cooperate with a counter surface on the displacement body (9), and wherein the second contact surface is designed to cooperate with the rotary driver (11).

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