WO2008106951A1

WO2008106951A1 - Spread band mechanism having forced guidance via slide shoes

Info

Publication number: WO2008106951A1
Application number: PCT/DE2008/000384
Authority: WO
Inventors: Andreas Dätig; Nikolai Kashaev
Original assignee: Schaeffler Kg
Priority date: 2007-03-08
Filing date: 2008-03-04
Publication date: 2008-09-12
Also published as: DE102007011341A1

Abstract

The invention relates to a spread band mechanism having improved guidance of the spread spectrum (1). Spread band mechanisms are utilized as machine elements for drive technologies. The spread band mechanism according to the invention comprises a take-up reel (2) for rolling the spread band up and off. Furthermore, the spread band mechanism comprises at least one slide shoe (4) for the forced guidance of the spread band, the shoe being disposed on the periphery of the spread band rolled up on the take-up reel. Defined rolling up and off processes are enabled via the slide shoe. The stress on the spread band is low, resulting in low wear, which is ultimately reflected in significantly reduced maintenance costs.

Description

Name of the invention

Spreader belt mechanism with a forced guidance through sliding shoes

description

Field of the invention

The invention relates to a Spreizbandmechanik with improved guidance of the spreader. Spreader belt mechanisms are used as a machine element in drive technology.

A Spreizbandmechanik allows a transmission of tensile and compressive forces and bending moments to a limited extent by profiled metal bands. In this case, the stiffness property of a curved transversely to the winding direction metal strip is exploited, so that thus both tensile and compressive forces can be transmitted in the longitudinal direction of the belt, in contrast to the known Zugmittelgetrieben with metal bands. To transfer these forces to the drive rollers, the property of width variation of a curved band is used, which assumes its entire width in the wound state, while it is narrower in the developed and then curved in cross-section state. This change in width is used to clamp the band between the side windows (ribs) of the drive roller, whereby a positive and possibly positive connection is made.

In its basic structure, a Spreizbandmodul consists of a role and a band and has a rotationally mounted, driven roller over two degrees of freedom in one plane. Forces can be transmitted via this basic structure only in the longitudinal direction of the strip, moments exclusively perpendicular to the longitudinal direction of the strip and to the axial direction of the roll. By combining several Spreizbandmodule that unite as a joint-member combination drive and guide member to parallel kinematics very compact robot can be built. These are characterized by a very good ratio of working space to space and a comparatively simple mechanical structure.

A disadvantage of spreading band mechanisms is the high stress which the metal band is subjected to during the transition from the wound to the unwound stretched state. This is given in particular by the necessary clamping of the expansion band between the two side windows of the drive roller.

Spreizbandmechaniken are known in which the side windows of the drive roller in the circumferential direction have a profiling and are selectively biased. As a result, the loads of the spreader are to be reduced and the power transmission can be made more efficient and accurate. However, even with this solution, the loads of the spreader are very high. The wear behavior of such a solution is not yet known. Another disadvantage of this solution is that a very accurate production of the side surfaces of the spreader is required to allow for improved power transmission. An increased positioning accuracy can only be achieved by complex control technology. The object of the present invention is thus to provide an improved spreading band mechanism in which the stress of the expanding band is significantly reduced, in particular during the transition from the wound to the unwound stretched state, and at the same time a more efficient and precise force transmission is made possible. The improved spread-band mechanism should be distinguished by a high reliability, a long service life and a reduced production and maintenance costs.

This object is achieved by a spreading band mechanism according to the appended claim 1. The expansion band mechanism according to the invention initially comprises a spreading band, which can be reversibly converted from a stretched state into a winding state. In the extended state, the spreader has a profile in cross section. As a result, the spreader is suitable for receiving bending moments. However, if a part of the spreading belt has been transferred to the winding state, this part of the spreading belt has essentially lost its profile. This part of the spreading band is therefore flat in cross section. This transfer can take place continuously, so that the spreader can be transferred continuously in relation to its longitudinal direction in the winding state. This transfer is reversible, so that the spreader at any time back to the extended state can be transferred, in which it again has the cross-sectional profile. The spreading band mechanism according to the invention furthermore has a winding roll known per se for rolling up and unwinding the spreading band. That portion of the spreader, which is located between the take-up roller and the stretched portion of the spreader, undergoes a bending moment, by which the spreader is transferred at this position from the extended state to the winding state. As a result, it loses its profile and is flat in cross section. The flat expansion band is now elastic enough to be rolled up on the take-up roll. This transfer takes place in the reverse direction, when the spreader is unrolled from the take-up roll. On the take-up reel large spreader lengths can be kept in a small space. Finally, the expanding band mechanism according to the invention has at least one sliding shoe for restraint guidance of the spreading belt, which is arranged at least in sections circumferentially around the spreading belt wound on the take-up reel.

The use of sliding shoes enables defined up and down procedures. During the unwinding process, the spreader belt is prevented from slipping due to the sliding shoe guide, thus allowing movement in the direction of thrust Strain on the spreader and thus less wear, which is reflected not least in significantly reduced maintenance costs.

In an advantageous embodiment of the invention Spreizband- this has a plurality of sliding shoes. The sliding shoes surround the expansion belt rolled up on the take-up roll circumferentially in several sections, but overall in an angular range of more than 180 °, but at least one threading opening remains kept free. Due to the sliding shoes, the guidance of the spreader belt is set in the entire area of the take-up roll. The spreader ribbon is passed through the threading hole and can be wound on the take-up roll and unwound from the take-up roll. The shoes are arranged substantially circular, since they enclose the take-up roll circumferentially. The use of multiple sliding shoes instead of a single shoe can prove to be cheaper for manufacturing reasons. According to a preferred embodiment, grooves are provided in the sliding surfaces of the sliding shoes facing the wound-up spreading band, which grooves extend transversely or longitudinally to the circumferential direction. With this design, the sliding friction occurring between the sliding shoe and the spreading belt can be reduced. The reduced friction leads to less wear and thus to increased reliability and longevity of Spreizbandführung. A reduction of the friction is particularly important at high speeds of the spreading, since it usually comes to increased forces between the spreader and its leadership. Increased frictional forces could lead to overheating of the spreader belt and resulting wear.

In connection with the minimization of friction, it has also proven to be expedient if the sliding blocks have a low-friction coating on their surface facing the wound-up spreader belt. In this way, the sliding friction between shoe and spreader can be further reduced. It should not be limited to the aforementioned possibilities for reducing the sliding friction. An application of other methods to minimize friction is quite conceivable and should not be ruled out. For example, it may be advantageous if, in use, a plurality of sliding shoes can be selectively brought into contact with the surface of the expansion band. Depending on the speed of unwinding and unwinding and possibly on the current diameter of the take-up reel filled with spreading belt, several or possibly only one of the sliding shoes may be brought into contact with the spreading belt in order to adapt the resulting friction values to the operating situation.

The sliding shoes are preferably urged by force on the spreader roll wound on the winding roller. Consequently, the sliding shoes can adjust in terms of their distance from the take-up of the amount of rolled up on the take-up reel spreader. The sliding shoes can be urged by springs or actuators on the rolled-up on the take-up reel spreader, for example. There is a larger amount of spreader on the take-up reel, so the radius of a spreader roll formed by the wound spreader is significantly larger than the radius of the take-up roll. If, on the other hand, there is only little spread on the reel, the radius of the spreader roll is barely greater than the radius of the take-up reel. The arrangement of the sliding shoes is adapted to the ever-changing radius of the spreader roll formed by the wound spreader ribbon. In this embodiment of the inventive spreading band mechanism, it is ensured that the expansion band is guided in a defined manner in the area between the sliding shoes and the already wound spreader belt. Otherwise it could come in this area to an uncontrolled transfer from the stretched state to the winding state, whereby the spreader would be unnecessarily stressed.

The take-up roll is preferably drivable. The driving torque of the take-up roll is transferred during unwinding of the spreader due to the leadership of the shoes loss and precise as a thrust on the stretched portion of the spreader. The take-up reel can also be braked or operated free-running.

The profile of the spreader is preferably formed by a simple curvature of the spreader. This profile shape of a spreader has proven to be the most suitable form for most applications. However, the spreading band mechanism according to the invention is in principle also suitable for other profiles of the spreader belt. For example, wavy or triangular profiles are usable. The expansion band may also have a profile in longitudinal section, for example in the form of holes or prongs. The expansion band is preferably made of an elastic metal or an elastic plastic. Due to the elasticity of the spreader, this can be reversibly transferred from the stretched state to the winding state. Due to internal forces, the expansion band strives to take the profile and thus assume the stretched state. If a bending moment acts on the expansion band, the expansion band can initially withstand the bending moment due to the transverse profile. However, if the bending moment is greater than a transfer bending moment, then the expansion strip abruptly buckles at the point of action of the bending moment and loses its profile there. However, the profileless sections of the spreader belt can be deformed with lower bending moments so that the spreader belt can be wound up. If the bending moment acting on the spreading band becomes smaller than a return bending moment, the expanding band resumes its profile and jumps into the stretched state.

In a preferred embodiment of the spreading band mechanism, the spreading band is wider in the winding state than in the stretched state. Due to the loss of the profile in the winding state, the spreader is flat and therefore wider. This property can be exploited, for example, for additional guidance in the take-up roll.

Further advantages, details and developments of the present invention will become apparent from the following description of a preferred embodiment, with reference to the drawings. Show it:

Fig. 1 is a perspective view of a preferred embodiment of a spread tape mechanism according to the invention;

Fig. 2 is a schematic diagram of a preferred embodiment of the invention Spreizbandmechanik; Fig. 3 is a schematic diagram for illustrating the forces acting during winding forces;

Fig. 4 is a schematic diagram for illustrating the forces acting during the Ab-- ekeleln forces.

; Fig. 1 shows a perspective view of a preferred embodiment of a spreadable band mechanism according to the invention. The spreading band mechanism comprises a spreading band 01, which can serve as an actuator for positioning, for example. About the spreading 01 tensile and compressive forces, but also bending moments are transferable to a limited extent. At its proximal end, the spreading belt 01 is wound on a take-up roll 02. At the distal end, for example, a tool may be attached, which is to be positioned by the spreader.

The spreading band 01 is shown in two states. The portion of the spreading belt 01 which is wound on the take-up reel 02 is in a winding state. The other portion of the spreader belt 01 shown is in an extended condition. The expansion band 01 is stretched in a straight line substantially rectilinear and has a curved profile in cross section.

In the winding state, the spreading belt 01 is flat in cross-section and thus slightly wider than in the extended state. If necessary, it only has a bulge. The spreading belt 01 located in the winding state changes its shape in the longitudinal direction when bending moments occur, so that it can be wound onto the winding roller 02. The transition from the extended state to the winding state or vice versa takes place continuously during the winding or unwinding in the longitudinal direction of the spreading belt 01. 2, two sliding shoes 04 are arranged on the circumference of a spreading belt roll 03 formed by the rolled-up spreading belt 01. However, it could also be used more than two shoes or only a shoe. The spreader roller 03 is enclosed by the sliding shoes 04 almost over its entire circumference. However, the spreader roller 03 is not enclosed in a region of a threading opening 06 by the sliding shoes 04. The threading opening 06 serves to carry out the spreading belt 01, so that this can be wound or unwound onto the take-up reel 02. Each of the two sliding shoes 04 is rotatably mounted in a pivot point 08, so that the sliding shoes 04 can be pivoted in the direction of the take-up roll 02. Furthermore acts on each of the two sliding blocks 04 each have a spring 09, which urges the sliding shoes 04 in the direction of the take-up roll 02. This ensures that even then a large portion of the Gleitschu- 04 is in contact with the surface of the spreader roller 03 when the Spreizbandrolle 03 is largely unwound and consequently has a reduced radius. The spring 09 is preferably designed as a compression spring.

When the spreading belt 01 is moved in the direction of the winding roller 02, it is pushed into the circular path formed by the sliding shoes 04, so that a bending moment acts on the transition region between the stretched section and the section in the winding state. By the bending moment the spreading belt 01 is continuously transferred to the winding state, whereby the bending moment is simultaneously reduced. This transfer is continuous and continuous. Due to the circular guide, the expansion belt 01 winds on the take-up roll 02, regardless of whether the take-up roll 02 is driven and thereby exerts a tensile force on the spreading belt 01, or whether the take-up roll 02 is free-running.

Fig. 3 shows a schematic diagram for illustrating the forces acting during winding forces. This schematic representation is based on the expansion band mechanism shown in FIGS. 1 and 2, wherein for reasons of clarity It was not necessary to present individual features. On the winding roller 02, a torque Mi acts, so that the spreading belt 01 is moved in a direction 11 (winding). The torque Mi acts counter to a tensile force Fz on the expansion belt 01. Starting from the expansion belt roller 03, radially outwardly, individual forces FR _{X are produced} , which result from the tendency of the expansion belt to take the curved state in cross section. On the other hand, from the sliding shoes 04, individual forces Fp _{x must act} on the surface of the spreader roller 03 in order to prevent the spreader belt from assuming the curved state. The individual forces Fp _x result in their sum in a force Fp, which corresponds to a normal force FN. The friction of the sliding shoe 04 with respect to the spreading belt 01 has a coefficient of friction μ. The spreader roller 03 has a radius r. Consequently:

M ₁ = F _z ^■ r + (μ ^■ F _N ), wherein the first addend corresponds to the drive torque and the second addend corresponds to the friction torque of the sliding shoes 04.

Fig. 4 shows a schematic diagram for illustrating the forces acting during unwinding forces. This principle illustration is again based on the expanding band mechanism shown in FIGS. 1 and 2, wherein the illustration of individual features has been omitted for reasons of clarity. On the winding roller 02 now acts a torque Mi with respect to the illustration in Fig. 3 opposite sense of direction, so that the spreading belt 01 is moved in a direction 12 (unwinding). The torque M ₁ counteracts a thrust force Fs on the expansion belt 01. From the Spreizbandrolle 03 act individual forces F _Ry on the shoes 04. From the shoes 04 act on individual forces F _0x on the surface of the Spreizbandrolle 03. The friction of the shoes 04 against the spreader 01 has a friction coefficient μ. The spreader roller 03 has a radius. Consequently:

M ₁ = F _s - r + [(μ - F _N ) + (μ - F _Ry )]. LIST OF REFERENCE NUMBERS

01 spreading band

02 Take-up reel 03 Spreader roll

04 sliding shoe

05 -

06 threading opening

07 - 08 Fulcrum

09 spring

10 -

11 direction of the Zi

12 direction of the Zi

Claims

Schaeffler KG Industriestr. 1 - 3, 91074 HerzogenaurachPatentansprüche

1. Spreading band mechanism for transmitting tensile and compressive forces and bending moments, comprising:

- An expansion belt (01), which has a profile in cross-section in an extended state, wherein the spreading belt (01) is continuously reversibly convertible into a winding state in which the expansion belt (01) is formed flat transverse to the longitudinal direction; and

- A take-up roller (02) for winding and unwinding of the expansion belt (01); characterized in that circumferentially around the on the take-up roll (02) wound spreader (02) at least one shoe (04) for guiding the spreader (01) is arranged, which is urged force loaded on the surface of the wound spreader (01).

2. Spreizbandmechanik according to claim 1, characterized in that it has a plurality of sliding shoes (04), which on the take-up roll (02) rolled up spreading belt (01) in sections circumferentially in one

Include angular range of more than 180 °, wherein at least one Einfädelöffnung is kept free of the shoes.

3. Spreizbandmechanik according to claim 1 or 2, characterized in that in the wound-up spreader belt facing sliding surfaces of the sliding shoes (04) grooves are introduced, which preferably extend transversely and / or longitudinally to the circumferential direction.

4. Spreizbandmechanik according to one of claims 1 to 3, characterized in that the sliding shoes (04) on its the wound spreader facing sliding surface having a coating with a small coefficient of friction.

5. Spreading band mechanism according to one of claims 1 to 4, character- ized in that the sliding shoes (04) are urged by one spring (09) against the wound on the take-up roll (02) Spreader (01).

6. Spreizbandmechanik according to one of claims 1 to 4, characterized in that the sliding shoes (04) are urged by in each case an actuator against the wound on the take-up reel (02) Spreader (01).

7. Spreizbandmechanik according to one of claims 1 to 6, characterized in that the take-up roller (02) is driven by a motor to a rotation.

8. Spreizbandmechanik according to one of claims 1 to 7, characterized in that the expansion band (01) consists of an elastic metal or an elastic plastic.

9. Spreizbandmechanik according to one of claims 1 to 8, characterized in that the expansion belt (01) changes upon application of a bending moment from the extended state to the winding state, wherein the acting bending moment is greater than a transfer bending moment.

10. Spreizbandmechanik according to one of claims 1 to 9, characterized in that the spreading belt (01) is wider in the winding state than in the stretched state.