Workpiece carrier system

Abstract

The present application relates to a workpiece carrier system (1) comprising a stationary main body (2), a circulating traction means (18), at least one workpiece carrier (10), at least one guide rail (23) for guiding rollers (20) of the workpiece carrier (10), said guide rail being disposed on the main body (2), wherein: the workpiece carrier (10) comprises a coupling device (3) for force-lockingly coupling the workpiece carrier (10) to the traction means (18) as needed; the workpiece carrier (10) comprises a plurality of rollers (20) which are guided in the guide rail (23) so that the workpiece carrier (10) is rollably supported on the main body (2) by means of the rollers (20). The aim of the invention is to create a workpiece carrier system which can be operated more safely. To achieve this aim, the coupling device (3) is designed such that, for force-locking coupling to the traction means (18), the coupling device engages exclusively with a top side (4) of the traction means (18) facing away from the main body (2), and the guide rail (23) provides a stop (41) for the rollers (20) which faces away from the main body (2), so that lifting of the workpiece carrier (10) from the main body (2) due to coupling engagement of the coupling device (3) with the top side (4) of the traction means (18) is limited.

Description

Workpiece carrier system Description

[0001] The invention relates to a workpiece carrier system having the features of the preamble of claim 1.

[0002] Workpiece carrier systems are used to transport workpieces to various workstations, for example, along a production line. One upper side of each workpiece carrier can always remain on top. These workpiece carriers run either side by side (the workpiece carriers run in a common horizontal plane), one above the other (the workpiece carriers run in parallel, spaced-apart horizontal planes), or, in special cases, in a combined system (the workpiece carriers, for example, first run in a common plane and are lifted to other planes by a lifting system). A drive is required for each plane and each lifting system. State of the art

[0003] DE 1718135 U describes a workpiece carrier system in which the workpiece carriers are designed as trolleys that run on rails and are connected to an endless traction device. When the trolleys reach the end of the production line, they are returned to the beginning of the production line. The return is achieved by means of a bridge over the production line. The bridge is arranged at an incline from the end of the production line to the beginning of the line and is supported by two stands arranged at the beginning and end of the production line. The stands contain elevators as lifting systems whose task is to lift the trolleys at the end of the production line up to the return bridge and, after they have passed through it, lower them back onto the production line. The workpiece carriers therefore run on different levels, for which a lifting system must be used.The lifting systems each require a drive, which makes this design of the workpiece carrier system expensive and complex.

[0004] Another workpiece carrier system described in DE 29620 A comprises a machine frame in which an endless, driven traction mechanism, in particular a chain, is guided, which carries the workpiece carriers supported on it by frictional force. The chain is deflected at two deflection stations, one of which is driven.

[0005] A general problem with workpiece carrier systems is the potential for a buildup of workpiece carriers. In this situation, the workpiece carriers should be decoupled from the traction mechanism. DE 9421 998 III describes a workpiece carrier system in which the workpiece carriers can be disengaged from the traction mechanism. For this purpose, fixed holding and relief elements are provided, which can be used to disengage the passing workpiece carriers, which are moved by friction with the traction mechanism. The holding and relief elements lift the workpiece carriers vertically, thus removing the frictional connection between the workpiece carrier and the traction mechanism.

[0006] CH 669 167 A5 describes a workpiece carrier system that runs on a single plane, in which a traction device carries a workpiece carrier via a friction shoe. To ensure that the entire weight of the workpiece and the workpiece carrier does not rest on the traction device, an adjustable portion of the weight is transferred to a support track by rollers. A chain that acts as a traction device runs in a U-shaped guide. The friction shoe on the workpiece carrier is spring-loaded and pressed onto the traction device with a predetermined force, while the remaining weight not supported by the traction device is transferred to the support track by the rollers of the workpiece carrier. Means are also provided for reducing or eliminating friction, which act automatically when one workpiece carrier collides with another, for example in the event of a jam.

[0007] The above-mentioned documents do not describe a workpiece carrier system with forward and return sections on two different levels, which, with only one drive, enables safe deflection of the workpiece carriers together with the traction device at the deflection points as well as a defined force connection between the traction device and the workpiece carrier during normal operation, while at the same time ensuring safe operation in accumulation mode.

[0008] The subject matter of patent EP1 999 043 B1 offers advantages in this regard. However, it has the disadvantage that the frictional coupling of a respective workpiece carrier to the traction device can only be achieved by means of a clamping mechanism, which requires engagement with both the underside and the top side of the traction device. This requires gripping the edges of the traction device, so that the coupling of the workpiece carrier and the traction device requires interaction at or in the lateral edge areas of the traction device.

[0009] Patent DE 102017210 160 A1 shows a similar solution. There, a coupling element of a coupling device of the workpiece carrier has a self-locking This means that the frictional connection between the coupling element and the traction mechanism increases automatically. The disadvantage here is that if the associated release mechanism is damaged, the coupling element is not safe for the operator, as the frictional connection between the coupling element and the traction mechanism would not be automatically released. If, for example, a worker or an object, e.g., a stop device, does not stop the workpiece carrier and the workpiece carrier does not release from the traction mechanism, this can result in injury to the worker and / or damage to the mechanism. Task

[0010] Accordingly, the object of the present application is to produce a workpiece carrier system that can be operated more safely. Solution

[0011] The object is achieved according to the invention by means of a workpiece carrier system having the features of claim 1. Advantageous embodiments emerge from the associated subclaims and the description.

[0012] The workpiece carrier system comprises a stationary base body on which a revolving traction means is drivably mounted. For this purpose, the base body can, for example, have at least two deflection stations at which the endless traction means can continuously rotate, wherein the traction means are guided in horizontal planes oriented parallel to one another. Thus, the traction means is guided in a first direction of movement in an upper run of the workpiece carrier system, deflected at an end deflection station, and returned in the opposite direction of movement in a lower run. The opposite deflection station, in turn, guides the traction means into the upper run. The transport of workpieces typically takes place in the upper run, with the workpieces resting on a supporting surface of at least one workpiece carrier. Alternatively, it is also conceivable for workpieces to be transported in the lower run ("suspended operation").The workpieces are then hung on the respective workpiece carrier. It is conceivable that the traction means is driven at at least one deflection station by means of a drive, which can be formed by an electric motor, for example. The distance between the deflection stations can be several meters, for example. The traction means can, for example and preferably, be designed in the manner of an endless flat belt, the width of which is significantly greater than its thickness. The traction means can, for example and preferably, be formed from polyurethane with inserted reinforcing strands. Other designs are also conceivable. The traction means has a top side and a bottom side, wherein in the sense of the present. Registration the top side is the side facing away from the base body and the bottom side is the side facing the base body.

[0013] The workpiece carrier system comprises at least one workpiece carrier that can interact with the traction mechanism and is thus movable along a transport path. The workpiece carrier is intended and configured to carry at least one workpiece, whereby it is conceivable for a workpiece to be transported by means of the interaction of several workpiece carriers. The at least one workpiece carrier has a plurality of rollers by means of which it can be guided in at least one guide rail arranged on the base body, wherein the rollers can roll on a rolling plane of the guide rail. In this way, the workpiece carrier can "travel" along the guide rail.

[0014] Preferably, a stand-alone workpiece carrier has at least two rollers on each of its two sides, wherein the base body has two guide rails, each assigned to a side of the workpiece carrier. In this way, the workpiece carrier can be guided on the base body, similar to a car, by means of four rollers arranged on a total of two axles, namely a front and a rear axle. A workpiece carrier in the form of a non-stand-alone trailer is also conceivable, which, for example, has only one axle and therefore only two rollers (one roller per side). Such a workpiece carrier can be connected to another workpiece carrier as intended. This can be advantageous for transporting workpieces whose dimensions exceed the dimensions of a single workpiece carrier.

[0015] In order to drive the at least one workpiece carrier by means of the traction mechanism, the workpiece carrier is positioned above the traction mechanism. This means that the traction mechanism can, in a sense, pass beneath the workpiece carrier. The workpiece carrier comprises a coupling device by means of which it can be coupled to the traction mechanism in a force-locking manner as required. The coupling to the traction mechanism is achieved, for example, by means of a frictional connection, whereby the drive force exerted on the traction mechanism, which causes the traction mechanism to rotate on the base body, is transferred to the workpiece carrier, so that the workpiece carrier is "dragged" along by the traction mechanism.In order to couple the workpiece carrier to the traction means, the coupling device can be transferred between a coupling state and a decoupling state, wherein the coupling device, when in the coupling state, forms a non-positive engagement with the traction means as intended, so that a driving force exerted on the traction means can be transferred from the traction means to the workpiece carrier and the. The workpiece carrier can be driven in this way along a movement axis of the traction device, and wherein the coupling device is decoupled from the traction device when in the uncoupled state, so that the traction device can move relative to the workpiece carrier without accelerating the workpiece carrier as intended. In other words, when the coupling device is in its uncoupled state, the traction device moves beneath the workpiece carrier without interacting with the workpiece carrier. The workpiece carrier is therefore stationary.

[0016] The coupling state can occur in different forms, with the force connection between the coupling device and the traction mechanism varying in magnitude depending on the form, so that the force transmission from the traction mechanism to the workpiece carrier can also occur with varying degrees of intensity. The stronger the force connection between the coupling device and the traction mechanism, the greater the force transmission from the traction mechanism to the workpiece carrier before the traction mechanism slips relative to the workpiece carrier or the coupling device.

[0017] The workpiece carrier system is characterized in that the coupling device is configured to engage, for the frictional coupling with the traction device, exclusively with an upper side of the traction device facing away from the base body. The frictional connection is thus achieved by engagement, for example, of a coupling element with the upper side of the traction device. Accordingly, clamping of the traction device on both sides by means of a combined action of two coupling elements that jointly grip the traction device at its upper side and its lower side is not provided.

[0018] Furthermore, the workpiece carrier system is characterized in that the guide rail, in which at least some of the rollers of the at least one workpiece carrier are guided, provides a stop for the rollers facing away from the base body. This stop limits, in particular in the upper run of the workpiece carrier system, a lifting of the workpiece carrier from the base body during a coupling engagement of the coupling device with the upper side of the traction means. This follows the consideration that with only one-sided interaction of the coupling device with the traction means, namely as a result of the described non-positive engagement of the coupling device with the upper side of the traction means, a lifting force directed away from the traction means takes place in reaction to a "pressing", for example of a coupling element of the coupling device, onto the upper side of the traction means. This can lead to the workpiece carrier being lifted contrary to its The workpiece carrier is lifted by gravity. To limit such lifting, the described guide for the rollers of the workpiece carrier is provided in the guide rail, which provides an upper stop for the rollers. To form the stop, the at least one guide rail can be designed, for example, in the form of a C-profile. The stop is preferably formed on both the upper and lower strands of the respective guide rail.

[0019] A basic idea of ​​the invention is to achieve the frictional connection between the workpiece carrier and the traction means via a one-sided clamping. For this purpose, the workpiece carrier has the described coupling device, which preferably has at least one coupling element that is intended and configured to act on the upper side of the traction means, i.e. in particular to press on the upper side of the traction means while forming a force or frictional connection. By means of this coupling element, the workpiece carrier can be coupled to the traction means in the manner described. The traction means, in turn, is supported on the base body, which can be coated with a sliding coating on a guide surface on which the traction means is guided to reduce wear. Additionally or alternatively, the underside of the traction means can be coated with a sliding coating. The base body is firmly connected to the guide rail orThe latter is arranged on the base body. For example, the guide rail can be screwed onto the base body, welded, or glued to it.

[0020] As soon as a normal force acting between the coupling element and the traction device in the upper run of the workpiece carrier system, with which the coupling element is effectively pressed onto the upper side of the traction device, is greater than the weight of the workpiece carrier (including any workpiece supported on it), the workpiece carrier is lifted in a direction away from the base body (vertically upwards). For this reason, the guide rail has the described stop for the rollers, which only allows the workpiece carrier (including the rollers) to be lifted slightly. This is because, beyond a certain lifting distance by which the workpiece carrier is lifted, the rollers hit the stop and may rotate in a direction opposite to the previous direction of rotation on a lower rolling plane of the guide rail, thereby rolling relative to the guide rail. This rolling takes place relative to the stop.After all, the traction device is not clamped between an upper and a lower coupling element, but is only subjected to a compressive force from above.

[0021] A particular advantage of the invention is that the at least one workpiece carrier can be coupled to the traction device merely by means of a one-sided interaction between the coupling device and the traction device. Accordingly, two-sided clamping, as described in the prior art, is not required. This allows the coupling device to be arranged away from the lateral edge regions of the traction device, which must be encompassed in the case of two-sided clamping. Instead, it is possible, for example, for the coupling device to interact with a central region of the traction device (viewed in the width direction of the traction device), for example by means of at least one coupling element. The edge regions of the traction device can be left free accordingly and / or used for other purposes, for example for interaction with a guide device.A corresponding design is described separately below.

[0022] The elimination of the need to grip the edge of the traction device has the particular advantage that the workpiece carrier can be released from the traction device much more easily, since no counterpressure elements or similar engage with the underside of the traction device, meaning that the workpiece carrier does not have to be unthreaded when removing it from the workpiece carrier system. Furthermore, a workpiece carrier can be transferred very easily—even automatically—from one workpiece carrier system to the next. In this way, individual workpiece carriers can travel virtually any distance when several workpiece carrier systems are connected in series.

[0023] A further advantage is the general simplification of the design of at least one workpiece carrier. This can be made smaller and is more cost-effective, as the traction device is only gripped on its top side and not, as is usual, from both sides—i.e., the top and bottom.

[0024] A further advantage is that the traction means can be designed to be particularly narrow, since - if necessary - its entire width is available for engagement with the coupling device. The traction means preferably has a width of at most 20 mm, preferably at most 18 mm, more preferably at most 16 mm. However, other dimensions are also conceivable. For example, the traction means can have a width in the range between 30 mm and 50 mm. Typically, only a partial area of ​​the traction means, viewed in the width direction of the traction means, needs to be provided for interaction with the coupling device. In particular, a coupling element of the coupling device can engage with the traction means only in a central area of ​​the latter and thus bring about the coupling.

[0025] A narrow traction device width has the advantage that multiple workpiece carrier systems can be operated side by side, i.e., in a common plane. It is also possible to arrange workpiece carrier systems one above the other in parallel planes. This improves the flexibility of using the workpiece carrier system for various applications.

[0026] In an advantageous embodiment of the workpiece carrier system, the underside of the traction device and / or the upper side of a guide surface of the base body, on which the traction device is guided with its underside, is / are coated with a sliding coating. If the guide surface of the base body is provided with the sliding coating, only minimal wear occurs between the traction device and the sliding coating, even when the workpiece carrier is carried along by the traction device. The sliding coating can be formed, for example, from a PE layer, a PU layer, or another sliding material, such as Teflon or a polyamide fabric.The coupling device is preferably dimensioned such that the normal force acting between the coupling element and the traction means is of sufficient magnitude that the resulting maximum frictional force between the coupling element and the traction means reaches a magnitude that enables the workpiece carrier to be dragged along by the traction means.

[0027] If the coupling device of the at least one workpiece carrier comprises at least one coupling element, it is particularly advantageous if this is formed by an eccentric element. The coupling device preferably comprises exactly one coupling element, which in turn is preferably formed by an eccentric element. Such an eccentric element is characterized in that it has a non-constant radius relative to an axis of rotation about which it is rotatably mounted. In this way, the coupling element can be particularly easily brought into alternating pressing or frictional engagement with the upper side of the traction means and, conversely, such engagement can be released again. For this purpose, it is only necessary to rotate the coupling element about its axis of rotation.The rotation axis is arranged relative to the upper side of the traction device such that the distance between the rotation axis and the upper side is greater than a minimum radius of the coupling element and smaller than a maximum radius of the coupling element. The rotation axis is preferably oriented horizontally and transversely to the direction of movement of the traction device.

[0028] With this design, it is possible, for example, to transfer the coupling device from its decoupling state to its coupling state, which Coupling element to rotate around the axis of rotation and is thus relative to the The traction device is to be aligned so that a region of a radially outer friction surface of the coupling element is aligned with a comparatively large radius in the direction of the traction device. Since the radius in this region exceeds the distance between the top side of the traction device and the axis of rotation, the coupling element comes into frictional contact with the top side of the traction device with its radially outer friction surface, whereby the frictional connection and thus the coupling between the workpiece carrier and the traction device can be established as intended, as explained above. By further rotating the coupling element, the engagement with the traction device can be further increased if necessary. The coupling state of the coupling device can therefore exist in different forms, i.e. provide different "strengths" of coupling with the traction device.Conversely, the transition from the coupled state to the uncoupled state can be achieved by rotating the coupling element in the opposite direction around the rotation axis. Using a coupling element designed as an eccentric element, the desired frictional connection between the traction device and the workpiece carrier can be established and released smoothly. The intensity of the frictional connection can also be continuously adjusted.

[0029] Particularly preferably, the non-constant radius of the coupling element designed as an eccentric element is configured such that the coupling element rotates in the direction of a decreasing radius relative to the traction element as a result of the action of a tangential force component acting on the coupling element upon engagement with the traction means. This means that in this configuration, the coupling element would automatically lose engagement with the traction means as a result of the engagement with the traction means in the absence of external influence, since the tangential force component, which represents the counterforce to the frictional force acting between the coupling element and the traction means, "rotates" the coupling element away and thus disengages it.In order to nevertheless provide a proper frictional connection between the coupling element and the traction mechanism in such a configuration, it is necessary to apply a force component that counteracts the tangential force component. This can be provided, for example, by means of a spring element, which is explained below as being advantageous. This spring element, which can be preloaded, exerts, for example, a torque on the coupling element that tends to "rotate the coupling element against the traction mechanism," i.e., to rotate it about the axis of rotation in such a way that a portion of the friction surface of the coupling element bears against the traction mechanism, the radius of which exceeds the distance between the axis of rotation of the coupling element and the traction mechanism.

[0030] The described design of the coupling element has the advantage that the engagement between the coupling element and the traction mechanism is not self-reinforcing, but rather breaks up when resistance is encountered. This is a significant advantage for the operational safety of the workpiece carrier system, since in the event of an unintentional impact of a workpiece carrier, for example, in a collision with a foreign object or an operator, the traction mechanism can slip through the coupling device without significant, let alone increasing, forces being transferred between the traction mechanism and the coupling device. This could lead to injuries and damage.

[0031] Regardless of whether the coupling element is designed as an eccentric element, it can be advantageous if it is arranged above a rear axle of the workpiece carrier. This is advantageous for the force transfer via the rollers of the workpiece carrier arranged on the rear axle into the base body of the workpiece carrier system.

[0032] In a preferred embodiment, the traction means is provided on its upper side at least in an engagement area in which the at least one The coupling element of the coupling device can engage with the upper side, coated with an engagement layer. This can be formed, for example, and preferably, from polyurethane. Such an engagement layer can improve the frictional engagement of the coupling element with the traction means.

[0033] As already explained above, it can be particularly advantageous for the engagement area to be arranged in a central region of the traction device, viewed in the width direction of the traction device. It is also advantageous if the engagement area extends only over a portion of the entire width of the traction device in the width direction of the traction device. This configuration has the advantage that lateral edge areas of the traction device remain free and are available for other uses.

[0034] For example, the interaction of the traction means in its edge regions with a guide device is possible. For this purpose, it is advantageous if the traction means has a guide layer in at least one lateral edge region, preferably in both lateral edge regions. This is preferably formed from polyurethane or another sliding material, for example Teflon or a polyamide fabric. The guide layer is intended and configured to interact with a guide device that is arranged at least in a lower run of the workpiece carrier system. The guide device serves to guide the traction means vertically during its guidance along the lower run, so that a Gravity-induced downward sagging of the traction device is prevented. Coating the edge areas of the traction device with the guide layer reduces friction between the traction device and the guide mechanism, thus reducing wear on the traction device and the energy required to drive the traction device. Accordingly, it is advantageous if the guide layer is applied at least on the upper side of the traction device.

[0035] In a further advantageous embodiment of the workpiece carrier system, the coupling device comprises at least one spring element, which is preferably designed in the form of a tension spring. The spring element is provided and configured to exert a spring force on at least one coupling element of the coupling device. The latter can preferably be formed by an eccentric element, as explained above. The spring element has the task of effecting the non-positive coupling of the workpiece carrier with the traction means by exerting the spring force on the coupling element. In other words, the spring element can contribute to bracing the coupling element against the upper side of the traction means with a sufficiently large normal force, so that the resulting maximum frictional force that can act between the coupling element and the traction means is sufficient for the traction means to accelerate the workpiece carrier and subsequently "drag" it along.In the absence of other external forces, the coupling device is therefore in its coupling state due to the action of the spring element.

[0036] Preferably, the coupling device further comprises an adjustment device by means of which the preload of the spring element can be adjusted. This allows the force with which the respective coupling element is braced against the traction means to be adjusted. The force of the spring element can also be adjusted, if necessary, by using a different spring element, for example, one with a different spring wire thickness and / or a different length.

[0037] If the coupling element is formed by an eccentric element, it is further particularly advantageous if the spring element is applied to the coupling element in such a way that the spring force of the spring element causes the coupling element to rotate about its axis of rotation. This is configured such that, as explained above, the rotation of the coupling element leads to a reduction in the distance between the friction surface of the coupling element and the upper side of the traction element, until the coupling element engages the traction element in a force-locking manner as intended.

[0038] For safety reasons, the frictional force generated by the spring force between the coupling element and the traction device when operating the workpiece carrier system without a protective housing must not be so great that an operator could be trapped or injured by the workpiece carriers or the workpieces on them. In the presence of greater resistance, the traction device should "slip through" the respective workpiece carrier, or a slippage should occur as intended. In other words, the maximum frictional force that can be transmitted between the traction device and the coupling device should no longer be sufficient to drag the workpiece carrier against the resistance. This way, injuries can be avoided.

[0039] If the workpiece carrier system comprises a plurality of workpiece carriers, a so-called "jam operation" can occur. In this case, several workpiece carriers are jammed directly one behind the other along the traction device. In particular, this can happen that a workpiece carrier dragged along by the traction device, whose coupling device is in its coupled state, runs into a preceding workpiece carrier that is stationary. The coupling device of the preceding workpiece carrier can in particular be in a coupled state, whereby in the latter case the workpiece carrier remains stationary despite the engagement of the coupling device with the traction device. This can be achieved, for example, by means of a stop device against which the preceding workpiece carrier has run into.In this configuration, the degree of coupling for the preceding workpiece carrier can be comparatively low, meaning that the coupling device only establishes a low-level frictional connection with the traction device. This can be achieved, in particular, automatically through the interaction of a release element with a respective stop device, as explained separately below. The coupling device of the preceding workpiece carrier can also be in its uncoupling state.

[0040] If a rear workpiece carrier collides with a preceding workpiece carrier, it is advantageous if the coupling state of the coupling device of the approaching workpiece carrier is at least automatically loosened, i.e., the frictional connection between the coupling device and the traction device is reduced. It is also conceivable for the coupling device to be transferred from its coupled state to its uncoupled state, i.e., the frictional connection between the coupling device and the traction device is completely released.

[0041] For the automatic influencing of the coupling state of the coupling device, it can be particularly advantageous if at least one workpiece carrier has an impact device in a front region, viewed in the direction of movement of the traction device. If a respective workpiece carrier collides with a preceding workpiece carrier, this impact device impacts the preceding workpiece carrier and consequently influences the coupling device in such a way that the frictional connection between the coupling device and the traction device is reduced. Preferably, the coupling state is merely "mitigated," i.e., for example, a coupling element is pressed onto the upper side of the traction device with a reduced compressive force or normal force. This analogously reduces the maximum transmittable frictional force between the coupling element and the traction device.

[0042] In a particularly preferred manner, the impact device interacts with the coupling device and at least indirectly with a coupling element of the coupling device. This is particularly advantageous if the coupling element is formed by an eccentric element as explained above. In such a configuration, the coupling element causes the coupling element to rotate about its axis of rotation as a result of the impact device striking a preceding workpiece carrier. This occurs in such a way that the coupling element is rotated into a region with a smaller radius relative to the traction means, so that the radially outer friction surface of the coupling element is pressed less strongly against the upper side of the traction means or completely loses contact with the traction means.

[0043] In an advantageous embodiment of the workpiece carrier system, the impact device comprises an actuating head, wherein the actuating head impacts against a preceding workpiece carrier when the workpiece carrier collides with the preceding workpiece carrier. In other words, in an advantageous embodiment, the impact device can have an actuating head which, when the respective workpiece carrier collides with a preceding workpiece carrier, strikes against a stop surface of the preceding workpiece carrier. The actuating head is arranged at a distal end of the impact device, so that it first comes into contact with the preceding workpiece carrier when the respective workpiece carrier collides. According to the above explanation, the impact device can, for example, be connected at its proximal end directly to the coupling device for influencing a respective coupling element. Interaction, the latter being formed in particular by an eccentric element as explained above.

[0044] In a further embodiment of the workpiece carrier system, the same comprises at least one stop device arranged on the base body. This serves to stop at least one workpiece carrier that comes into contact with the stop device. This can be achieved without transferring the coupling device of the respective workpiece carrier to its uncoupling state, for example by counteracting the frictional force transmitted between the coupling device and the traction device with a counterforce that exceeds the frictional force. In other words, the stop device only needs to be so stable that the frictional force acting between the workpiece carrier and the traction device is insufficient to displace the stop device. The traction device then slips under the workpiece carrier and slides away from the coupling device.

[0045] In a particularly advantageous embodiment, the abutment of the at least one workpiece carrier against the stop device nevertheless results in the frictional connection between the coupling device and the traction mechanism being at least reduced. This prevents unnecessary wear on both the traction mechanism and the coupling device.

[0046] To influence the coupling device when the workpiece carrier strikes the stop device, the impact device described above can be used, for example. It is also conceivable for the at least one workpiece carrier to have a release element that can interact with the stop device in such a way that the frictional connection between the coupling device and the traction means is at least reduced as soon as the release element strikes the stop device. The use of such a release element has the advantage that the stop device does not have to interact with an impact device in a similar way to a preceding workpiece carrier, but can be specially adapted for interaction with the release element, for example, arranged only in an edge region of the base body.

[0047] If a stop device is present, it may further be advantageous if it can be transferred between an active position and a passive position, wherein the stop device, when present in the active position, is designed to stop a respective workpiece carrier, and wherein the at least one workpiece carrier, when present in its passive position, can be moved unhindered by means of the traction means For example, a respective stop device can be moved from its passive position to its active position into a travel range of the at least one workpiece carrier, so that, if necessary, an impact device or a release element can interact with the stop device. The movement can, for example, consist of a rotational movement (e.g., pivoting) or a linear movement (e.g., travel along a rail).

[0048] In a particularly preferred embodiment, in a workpiece carrier system comprising a plurality of workpiece carriers, the workpiece carriers interact with one another in a back-up operation in such a way that a back pressure does not increase as a function of the number of workpiece carriers moving towards one another. This is based on the consideration that a first workpiece carrier, which is positioned furthest forward in a row of workpiece carriers, comes to a standstill as a result of its interaction with a stop device. The interaction of the first workpiece carrier with the stop device results in the workpiece carrier pressing against the stop device due to the force-locking coupling with the traction device ("back pressure"). Although the traction device slips under the workpiece carrier, it still transmits forces to it due to its sliding friction with the coupling device of the first workpiece carrier.The first workpiece carrier is preferably designed such that, upon its impact against the stop device, the coupling of the coupling device to the traction means is partially released, i.e., the frictional connection between the coupling element and the traction means is reduced. This preferably occurs such that the dynamic pressure changes in proportion to the compressive force with which the coupling element presses against the upper side of the traction means. When the workpiece carrier comes to a stop at the stop device, the frictional connection of the coupling device to the traction means and the dynamic pressure are in equilibrium. The maximum transferable frictional force between the traction means and the coupling device is reduced such that the traction means can slip on the workpiece carrier, or slippage occurs.However, the frictional force is so small that neither the drive of the traction mechanism is subjected to excessive stress nor is the traction mechanism itself exposed to severe wear.

[0049] As soon as a second workpiece carrier moves onto the preceding, stationary workpiece carrier, the second workpiece carrier in turn presses against the preceding workpiece carrier with a force. This leads to the coupling device of the first workpiece carrier being completely transferred into its uncoupling state, i.e. the coupling element of the coupling device of the first workpiece carrier releases its engagement with the traction device, as it pushes from behind against the Stop device is pressed. The second workpiece carrier, however, is influenced analogously to the previous description as a result of striking the preceding workpiece carrier in such a way that the coupling state of the coupling device changes such that the frictional connection with the traction device is reduced. Consequently, the above-described slipping of the traction device or its slippage with respect to the workpiece carrier now occurs on the second workpiece carrier, but no longer on the preceding first workpiece carrier. The dynamic pressure applied to the stop device therefore continues to correspond only to the frictional force resulting from the slipping of the traction device on only one of the two workpiece carriers.

[0050] Each additional workpiece carrier that moves up causes the coupling device of the directly preceding workpiece carrier to be decoupled in the same way, so that regardless of the number of workpiece carriers piling up, only the frictional force of a coupling device of exactly one workpiece carrier, which is engaged with the traction device, acts on the front end of the row, i.e., on the stop device. Therefore, with this design, it is not necessary to provide multiple stop devices depending on the number of workpiece carriers piling up, which must divert the cumulative back-up forces of several individual workpiece carriers into the base body. Instead, regardless of the number of workpiece carriers piling up, only the back pressure of a single workpiece carrier needs to be diverted.

[0051] To achieve the described effect, it is particularly advantageous if the coupling device of a respective workpiece carrier interacts with both a spring element described above and with an impact device and / or a release element. By means of the spring element, the coupling element, which can in particular be formed by an eccentric element, is pressed against the upper side of the traction means in the manner described above. The impact device or the release element exerts a force on the coupling element counter to the spring force of the spring element upon impact with a stop device or upon collision with a preceding workpiece carrier, whereby the latter rotates about its axis of rotation and reduces the compressive force with which the friction surface of the coupling element presses against the upper side of the traction means.

[0052] The resulting system of the spring force, which causes the coupling with the traction device, and the dynamic pressure, which counteracts the spring force, automatically leads to an equilibrium in which the coupling element is still engaged with the traction device, so that a frictional force is transmitted between the traction device and the coupling device or the workpiece carrier. This frictional force causes The dynamic pressure of the respective workpiece carrier, with which the workpiece carrier presses against the stop device or the preceding workpiece carrier. The frictional force is then minimal, thus preserving the drive of the traction mechanism and protecting the traction mechanism from excessive wear.

[0053] When a subsequent workpiece carrier collides with a preceding workpiece carrier, this design additionally pushes the preceding workpiece carrier against the stop device or against a workpiece carrier in front of it, completely overcoming the spring force of the spring element of the preceding workpiece carrier. This results in the coupling element of the preceding workpiece carrier being rotated even further around the rotation axis against the spring force of the spring element and ultimately completely losing its engagement with the traction mechanism (decoupling state of the coupling device).According to this principle, each additional workpiece carrier moves the coupling device of the directly preceding workpiece carrier into its uncoupling state, so that in the entire row of workpiece carriers, only the coupling device of the last (furthest back in the row) workpiece carrier is still in its coupled state. As a result, in the manner described above, only the dynamic pressure of a single workpiece carrier acts on the stop device, regardless of the number of workpiece carriers accumulating at the stop device.

[0054] As explained above, the workpiece carrier system can have two deflection stations at which the traction mechanism is guided in a rotating manner. Typically, at least one of the deflection stations is driven, allowing the traction mechanism to be driven in a rotating manner.

[0055] If the workpiece carrier system is designed in this way, it can also be particularly advantageous if the at least one workpiece carrier has at least one pressure element, which, when the workpiece carrier is used as intended, is arranged in a plane of the workpiece carrier above the traction mechanism. The pressure element is preferably located, viewed in the longitudinal direction of the workpiece carrier, between two rollers of the workpiece carrier arranged one behind the other, in particular centrally between a rear roller and a front roller or between a rear axle and a front axle of the workpiece carrier.

[0056] Preferably, the pressure element is arranged relative to the traction means such that it is located slightly above the traction means when the workpiece carrier is located in the upper run and / or the lower run of the workpiece carrier system. For example, the The distance, measured vertically relative to the traction mechanism, between a pressure surface of the pressure element facing the traction mechanism and the upper side of the traction mechanism facing away from the base body should be at most 3 mm, preferably at most 2 mm, and more preferably at most 1 mm. Other distances are also conceivable, for example, 10 mm or 20 mm.

[0057] Such an arrangement of the pressure element means that when the workpiece carrier is deflected at a respective deflection station, it comes into frictional contact with the upper side of the traction device. This is due to the fact that the workpiece carrier is guided along the respective deflection station in an arc which is determined by the curvature of the deflection station (typically with a constant radius). In principle, this guidance means that the traction device is guided into a higher area of ​​the workpiece carrier between the front and rear axles of the workpiece carrier due to its curvature. Due to the small distance between the pressure element and the traction device, this distance is overcome and frictional contact occurs between the pressure element and the upper side of the traction device.In addition to the frictional connection between the workpiece carrier and the traction mechanism, this creates another component that results from the contact of the pressure element with the traction mechanism. This has the effect of making it more difficult for the traction mechanism to accidentally slip from the workpiece carrier.

[0058] Such slippage between the traction device and the workpiece carrier can occur particularly in the area of ​​a deflection station. This is especially true when transferring a workpiece carrier from the lower run to the upper run, since the weight of the workpiece carrier counteracts the frictional force acting between the traction device and the coupling device during the deflection of the workpiece carrier. Accordingly, it is advantageous to temporarily increase the frictional connection between the workpiece carrier and the traction device to prevent unintentional slippage between the traction device and the workpiece carrier.

[0059] Accordingly, the pressure element provides the advantage that the compressive force with which a coupling element presses on the traction device can be kept at a sufficient level so that it is sufficient for the horizontal movement of the workpiece carrier in the upper and lower strands. This compressive force would possibly lead to the described slippage for the lifting movement of the workpiece carrier in the area of ​​the deflection stations (especially from the lower strand to the upper strand). This is counteracted in the manner described by means of the pressure element. An improved effect is achieved if the traction device has an elastic surface that acts like a spring and can generate counterpressure for both a coupling element and a pressure element.

[0060] Preferably, the pressure element can be preloaded, allowing the pressure force with which it presses against the traction device to be adjusted. This allows for flexible response to different loading situations of a particular workpiece carrier.

[0061] Furthermore, a design of the workpiece carrier system can be advantageous in which the traction means is formed by a toothed belt, wherein an underside of the traction means facing the base body is provided with a toothed structure (“tooth side”). This design has the particular advantage that the traction means can be driven particularly easily, in particular at a deflection station. The toothed structure can, for example, mesh with a complementary tooth structure of a drive wheel. The design of the traction means in this form is only possible if the coupling device engages exclusively with the top side of the traction means. In the case of the double-sided hooping of the traction means, which is common in the prior art, it is necessary, however, that the underside of the traction means is also smooth so that it can be clamped and gripped by a respective coupling element. Examples of implementation

[0062] The invention is explained in more detail below using an exemplary embodiment illustrated in the figures. It shows: Fig. 1 : A schematic view of an inventive workpiece carrier system, Fig. 2: A schematic diagram of a coupling device of a workpiece carrier in Interaction with a traction device, Fig. 3: A schematic diagram of a workpiece carrier in interaction with a traction device, Fig. 4: A schematic cross-section through a traction device in interaction with a coupling element

[0063] An embodiment shown in Figures 1 to 4 comprises a workpiece carrier system 1 according to the invention, by means of which workpiece carriers 10 can be transported along a transport path. In the example shown, the workpiece carrier system 1 comprises a base body 2, which is mounted on a base 31 by means of stands 32. Furthermore, the workpiece carrier system 1 comprises two arranged deflection stations 25, around which a traction means 18 is tensioned. One of the deflection stations 25 is designed to be driven in rotation, wherein a drive wheel (not shown) of the deflection station 25 interacts with a drive (not shown), for example an electric motor, and can thus be driven in rotation about a deflection axis 30. In this way, the traction means 18 can be driven in rotation, wherein it moves in an upper run 39 of the workpiece carrier system 1 in a first direction of movement 33, is then deflected at a deflection station 25 and then moves in a parallel plane in a lower run 11 of the workpiece carrier system 1 in the opposite direction of movement 33. Between the deflection stations 25, the traction means 18 is guided on the base body 2, wherein it is guided in particular in the upper run 39 on a guide surface (not shown in the figures).In order to reduce the friction between an underside 5 of the traction means 18 facing the base body 2 and the base body 2, the guide surface of the base body 2 and / or an underside 5 of the traction means 18 facing the base body 2 can be coated with a sliding coating.

[0064] In the example shown, the traction means 18 is formed by a toothed belt and accordingly comprises a toothed structure 16 on its underside 5. This toothed structure is intended and configured to mesh with a complementary toothed structure of the drive wheel of the respective deflection station 25, which is responsible for driving the traction means 18. Accordingly, the other deflection station 25 can have a non-driven guide wheel, which is also provided with a complementary toothed structure for engagement with the toothed structure 16 of the traction means 18.

[0065] The workpiece carrier system 1 further comprises a plurality of workpiece carriers 10, which are particularly clearly shown in Figure 1 and Figure 3. The workpiece carriers 10 are provided and configured to transport workpieces 15 along the transport path of the workpiece carrier system 1. With reference to Figure 1, workpieces 15 are transported from a left end of the workpiece carrier system 1 in the direction of movement 33 in the upper run 39 to a right end of the workpiece carrier system 1. For this purpose, the workpiece carriers 10 can be coupled to the traction means 18, forming a frictional connection. For this purpose, the workpiece carriers 10 each comprise a coupling device 3, the operating principle of which is particularly clearly shown in Figure 2. In the example shown, the coupling device 3 comprises precisely one coupling element 19, which here is formed by an eccentric element.As such, the coupling element 19 is rotatably mounted about a horizontal axis of rotation 22 oriented transversely to a direction of movement of the traction means 18, wherein a radially outer friction surface 21 of the coupling element 19 in. a non-constant radius 38 relative to the axis of rotation 22. This has the consequence that by rotating the coupling element 19 about the axis of rotation 22, the friction surface 21 can be alternately brought into engagement with an upper side 4 of the traction means 18 facing away from the base body 2.

[0066] To create the described frictional connection, the coupling element 19 is rotated about the axis of rotation 22 such that the friction surface 21 comes into contact with the upper side 4 of the traction means 18. The corresponding direction of rotation is illustrated in Figures 2 and 3 by the arrow 35. As a result of the contact between the coupling element 19 and the traction means 18, a normal force 36 acting perpendicular to the upper side 4 of the traction means 18 arises between the two. This normal force causes a frictional connection between the traction means 18 and the coupling element 19, which is designed in the form of a frictional connection. The maximum frictional force 37 that can be transmitted between the traction means 18 and the coupling element 19 depends on the selected materials of the coupling element 19 and a respective engagement region 6 of the traction means 18 or the associated friction coefficients.

[0067] To release the frictional connection between the coupling element 19 and the traction means 18, the coupling element 19 can be rotated in the opposite direction about the rotation axis 22. The corresponding direction of rotation is illustrated in Figures 2 and 3 with an arrow 34. Rotation in this direction effectively detaches the friction surface 21 from the upper side 4 of the traction means 18, thereby releasing the frictional connection. As a result, the traction means 18 can pass under the respective workpiece carrier 10 without the workpiece carrier 10 becoming connected to the traction means 18.

[0068] The coupling element 19 is designed such that its non-constant radius decreases with respect to the traction means 18 when the coupling element 19 rotates in the direction of rotation indicated by arrow 34. A counterforce corresponding to the maximum frictional force 37, which acts tangentially with respect to the axis of rotation 22 on the coupling element 19 when the latter is engaged with the traction means 18, causes a torque on the coupling element 19 in precisely this direction of rotation. Accordingly, the coupling device 3 in the example shown is designed such that the frictional connection between the traction means 18 and the coupling element 19 automatically inhibits itself, for example, in the event of an unintentional stop of the workpiece carrier 10.

[0069] Irrespective of the interaction of the coupling device 3 with the traction means 18, each workpiece carrier 10 in the example shown is connected by means of a total of four rollers 20 mounted on the base body 2. The workpiece carrier 10 has two rollers on each side, wherein the workpiece carrier 10 has a total of two axes, namely a front axle and a rear axle. In order to guide the rollers 20 on the base body 2, the latter comprises, in the example shown, at least in the upper run 39 of the workpiece carrier system 1, here and preferably also in the lower run 11, two guide rails 23 arranged parallel to one another, which here are each designed in the form of a C-profile. Each of the guide rails 23 is provided for guiding the rollers 20 on one side of a respective workpiece carrier 10. In principle, the rollers 20 can be guided, at least in the upper run 39 of the workpiece carrier system 1, on a lower rolling plane 40 of the guide rails 23, i.e. the rolling plane facing the base body 2. In this case, a weight force of a respective workpiece carrier 10 (if applicable, includinga workpiece 15 mounted thereon) via the rollers 20 into the guide rails 23 and thus the base body 2.

[0070] If the coupling element 19 of the coupling device 3 now engages with the traction means 18, the above-explained normal force 36 acts. In reaction, this causes an oppositely oriented, lifting counterforce of the same magnitude on the coupling element 19 and thus the respective workpiece carrier 10. If the normal force 36 and thus the oppositely acting counterforce are greater than the weight of the workpiece carrier 10, the workpiece carrier 10 lifts upwards with its rollers 20 from the rolling planes 40 of the guide rails 23. In order to be able to guide the workpiece carriers 10 securely on the base body 2, the guide rails 23 have a stop 41 facing away from the base body 2, which stop is also designed here in the form of a rolling plane.Since the guide rails 23 in the example shown are formed by C-profiles, the lower rolling plane 40 is formed by a lower flange of the C-profile and the upper stop 41 is formed by an upper flange of the C-profile.

[0071] According to all of the above, it is possible with the workpiece carrier system 1 to force-fit a respective workpiece carrier 10 to the traction means 18 by the traction means 18 engaging only and exclusively on its upper side 4 with the coupling device 3 of the respective workpiece carrier 10. Clamping of the traction means 18 on both sides, as is known in the prior art, is not provided. Accordingly, in contrast to the prior art, it is not necessary for the coupling device 3 to interact with lateral edge regions 8 of the traction means 18. Instead, it is now possible to connect the coupling element 19 with an engagement region 6 of the traction means 18 in to bring into operative connection, which is arranged in a central region 29 of the traction means 18. This is particularly evident in Figure 4.

[0072] In the example shown, a width 17 of the traction means 18 is 16 mm, with a width of the engagement area 6 being 10 mm. In the engagement area 6, the traction means 18 is provided with an engagement layer 7, which is formed here from polyurethane. This engagement layer 7 can have a thickness of, for example, 2 mm oriented perpendicular to the upper side 4 of the traction means 18. It serves to directly engage with the coupling element 19, wherein a situation in which the coupling element 19 is in engagement with the traction means 18 is shown in Figure 4. The engagement layer 7 is merely optional.

[0073] Furthermore, in the example shown, the traction means 18 comprises a guide layer 9 in each of its lateral edge regions 8, which here is also made of polyurethane. This guide layer 9 serves to interact with a guide device 13, which in the example shown comprises two L-shaped guide elements. The guide device 13 can, in particular in the lower run 11 of the workpiece carrier system 1, contribute to guiding the height of the traction means 18, since it would sag downwards in the lower run 11 due to its weight. This sagging is prevented by the guide device 13. In the example shown, the lateral edge regions 8 each have a width of 3 mm, resulting in a total width 17 of the traction means 18 of 16 mm.

[0074] In order to organize the transport of workpieces 15 and the operation of the workpiece carrier system 1, it is regularly necessary to stop the workpiece carriers 10. For this purpose, the state of the coupling device 3 is regularly changed, in particular, to change a coupling state or to switch to the decoupling state. In the example shown, this is done mechanically, with the coupling device 3 having, on the one hand, a spring element 24 and, on the other hand, an impact device 12 and a release element 27. For an explanation of these components, reference is made in particular to Figures 2 and 3.

[0075] First, it can be seen that the spring element 24, which here is formed by a tension spring in the form of a spiral spring, causes a rotation of the coupling element 19 in the direction of rotation indicated by arrow 35 by means of a prestressed tensile force. This is due to the fact that the tensile force stored in the spring element 24 acts on an upper end of the coupling element 19, which has a lever arm relative to the rotation axis 22 and thereby generates a torque in the direction of rotation according to arrow 35. The spring element 24 therefore establishes the force-locking connection between the coupling device 3 and the traction means 18 as standard, so that the coupling device 3 is in its coupled state and the respective workpiece carrier 10 is carried or dragged along by the traction means 18.

[0076] A change in the coupling state of the coupling device 3 can be desired in particular in two different situations. Firstly, at various points along the transport path of the workpiece carrier system 1, it can be provided as standard that at least one workpiece carrier 10 stops or halts. For this purpose, the workpiece carrier system 1 in the example shown has a plurality of stop devices 26, which can be seen from Figure 1. The stop devices 26 can be alternately transferred between a passive position and an active position, for example by being pivoted into an active range for interaction with a respective workpiece carrier 10 or by being pivoted out of the active range (illustrated in Figure 3 by means of a double arrow). The workpiece carriers 10 each comprise a release element 27, which is provided and configured to engage orto strike against it, provided that the stop device 26 is in its active position.

[0077] The associated principle can be seen in Figure 3. There, the workpiece carrier 10, whose coupling device 3 is in its coupled state, is moved in the direction of movement 33 from right to left. Finally, the release element 27 abuts the stop device 26, which is in its active position. The release element 27 is operatively connected directly to the coupling device 3, whereby a force is exerted on the coupling element 19 against the spring force of the spring element 24, causing the coupling element 19 to rotate about the axis of rotation 22 in the direction of rotation illustrated by arrow 34. This leads to a reduction in the effective radius of the coupling element 19 with respect to the traction means 18, i.e., the contact between the friction surface 21 of the coupling element 19 and the upper side 4 of the traction means 18 is reduced. In other words, the normal force acting between coupling element 19 and traction means 18 is reduced.Despite the force acting on the coupling device 3 via the release element 27, the spring force of the spring element 24 continues to act. Due to the principle, this cannot be completely overcome, since this would result in a complete decoupling of the coupling device 3 from the traction means 18, so that the release element 27 would no longer exert any force on the coupling device 3. Instead of a complete transfer of the coupling device 3 into its decoupling state, a corresponding... Establish a state of equilibrium in which the coupling element 19 presses against the upper side 4 of the traction device 18 with just enough force that the force with which the release element 27 presses against or strikes the stop device 26 is balanced with the maximum frictional force transmitted between the traction device 18 and the coupling device 3. As a result, the traction device 18 slips beneath the workpiece carrier 10, whereby the described frictional force (sliding friction) acts but is overcome.

[0078] As soon as the stop device 26 is moved into its passive position, the spring element 24 retracts the coupling element 19 as explained above, so that the "full" engagement of the coupling element 19 with the traction means 18, as effected by the spring element 24, is restored. The workpiece carrier 10 is then again "dragged" by the traction means 18.

[0079] An interruption of the advance of a workpiece carrier 10 in the sense of transferring the coupling device 3 into its uncoupling state is also desired when a workpiece carrier 10 moves onto a preceding workpiece carrier 10. This can be the case in particular when the preceding workpiece carrier 10 is stopped at a stop device 26 as explained above and is therefore stationary. The principle of rotation of the coupling element 19 in the direction of rotation according to arrow 34 when the workpiece carrier 10 moves onto a preceding workpiece carrier 10 is identical to the above explanation when a respective stop device 26 interacts with the release element 27. For a stop on the preceding workpiece carrier 10, the workpiece carrier 10 comprises an impact device 12 equipped with an actuating head 14 at a front end as viewed in the direction of movement 33.When the workpiece carrier 10 collides with the preceding workpiece carrier 10, the actuating head 14 strikes a corresponding contact surface of the preceding workpiece carrier 10. The impact device 12 is operatively connected to the coupling device 3 in such a way that, as a result of the stop, a force is exerted on the coupling element 19, causing it to rotate about the axis of rotation 22 in the direction of rotation according to arrow 34. Analogous to the previous explanation, the frictional connection between the coupling element 19 and the traction means 18 is thereby reduced, so that the workpiece carrier 10 remains stationary, while the traction means 18 slips or slides beneath the workpiece carrier 10, transmitting a remaining frictional force.

[0080] A special feature in the example shown is that the stop of a respective workpiece carrier 10 on a preceding workpiece carrier 10 exerts a stop force on the latter, which, due to the stop of the release element 27 on the stop device 26, which is intensified as a result of the stop force, corresponds to the spring force of the spring element 24. As a result, the coupling element 19 is rotated in the direction of rotation according to arrow 34 about the rotation axis 22, whereby the coupling element 19 loses its engagement with the traction means 18. The coupling device 3 of the preceding workpiece carrier 10 is therefore henceforth in its uncoupled state. Thus, the frictional force of only one workpiece carrier 10 continues to be present at the stop device 26, namely the workpiece carrier 10 that is furthest back in the row of workpiece carriers 10 that bear against the stop device 26. Thus, the so-called “backup pressure” which is applied to the stop device 26 as a result of the accumulating workpiece carriers 10 and which is to be diverted into the base body 2, regardless of the number of workpiece carriers 10 which are accumulated in series at a stop device 26, is always only caused by a coupling of exactly one of the accumulated workpiece carriers 10 to the traction means 18.

[0081] In a particularly advantageous manner, the workpiece carriers 10 in the example shown each comprise a pressure element 28 which is arranged above the upper side 4 of the traction means 18, i.e. above a side of the traction means 18 facing away from the base body 2. A distance of the pressure element 28 from the traction means 18, measured perpendicular to the upper side 4, is approximately 2 mm in the example shown. Consequently, during a movement of the workpiece carrier 10 in the upper run 39 and / or the lower run 11, there is no contact between the pressure element 28 and the traction means 18. However, such contact does occur in the region of the deflection stations 25. There, a respective workpiece carrier 10 is guided on a curved path corresponding to a radius of the respective deflection station 25 around its deflection axis 30, wherein, due to the principle, the traction means 18 is guided higher relative to the workpiece carrier 10.This is due to the fact that the workpiece carrier 10 extends straight between its front axle and its rear axle, while the traction means 18 is guided in a radius between the front rollers 20 (front axle) and the rear rollers 20 (rear axle) at the respective deflection station 25. This results in the upper side 4 of the traction means 18 coming into contact with a surface of the pressure element 28 facing the traction means 18 in the region of the deflection stations 25. This creates an additional frictional connection between the respective workpiece carrier 10 and the traction means 18 in the region of the deflection stations 25. This can in particular counteract a decrease in the amount of force between the coupling device 3 and the traction means 18, which can occur as a result of the changing orientation of the weight force of the workpiece carrier 10 relative to the traction means 18 at the deflection stations 25. An unintentional slippage of the traction means 18 relative to the workpiece carrier 10 in the area of ​​the deflection stations 25 can therefore be avoided by means of the pressure element 28. This is particularly important in the case of a Change from the lower run 11 to the upper run 39 is important, since there the movement of the respective workpiece carrier 10 takes place upwards against the acting weight force. List of reference symbols 1 workpiece carrier system Basic body 3 Coupling device Top 5 Bottom 6 Intervention area 7 intervention layer 8 Marginal area 9 Leadership class 10 workpiece carriers 11 Lower strand 12 Impact device 13 Guide device 14 Actuating head 15 Workpiece 16 tooth structure 17 width 18 traction devices 19 Coupling element 20 rolls 21 Friction surface 22 axis of rotation 23 Guide rail 24 spring element 25 deflection station Stop device 27 Release element 28 Pressure element 29 Middle area 30 Deflection axis 31 Subsurface 32 Stand 33 Direction of movement 34 Arrow 35 Arrow 36 Normal force 37 Friction force 38 radius 39 Upper Drum 40 Rolling level 41 stop

Claims

Claims 1. Workpiece carrier system (1), comprising a stationary base body (2), a drivable traction means (18) rotating on the base body, at least one workpiece carrier (10), at least one guide rail (23) arranged on the base body (2) for guiding rollers (20) of the workpiece carrier (10), wherein the workpiece carrier (10) comprises a coupling device (3) for the frictional coupling of the workpiece carrier (10) to the traction means (18) as required, wherein the workpiece carrier (10) comprises a plurality of rollers (20) guided in the guide rail (23) so that the workpiece carrier (10) is mounted on the base body (2) in a rollable manner by means of the rollers (20), characterized in that the coupling device (3) is designed for the frictional coupling to the traction means (18) exclusively with an upper side (4) of the traction means (18) facing away from the base body (2). to intervene,wherein the guide rail (23) provides a stop (41) for the rollers (20) facing away from the base body (2), so that lifting of the workpiece carrier (10) from the base body (2) is limited during a coupling engagement of the coupling device (3) with the upper side (4) of the traction means (18).

2. Workpiece carrier system (1) according to claim 1, characterized in that the coupling device (3) has at least one coupling element (19), preferably exactly one coupling element (19), preferably in the form of an eccentric element.

3. Workpiece carrier system (1) according to claim 1 or 2, characterized in that the coupling device (3) comprises a coupling element (19) in the form of an eccentric element which is rotatable about an axis of rotation (22) and which has a preferably rounded friction surface (21) with a non-constant distance from the axis of rotation (22), wherein the friction surface (21) in the presence of the Coupling device (3) is in frictional contact with the upper side (4) of the traction means (18) in a coupling state.

4. Workpiece carrier system (1) according to one of claims 2 or 3, characterized in that an engagement region (6) of the traction means (18), in which the at least one coupling element (19) can engage with the traction means (18) to form the non-positive coupling, is arranged in a central region (29) of the traction means (18) viewed in the width direction of the traction means (18), wherein the engagement region (6) extends in the width direction of the traction means (18) only over part of a width (17) of the traction means (18).

5. Workpiece carrier system (1) according to claim 4, characterized in that the traction means (18) has a guide layer (9), preferably made of polyurethane, in at least one lateral edge region (8), preferably in both lateral edge regions (8), which is provided and designed to cooperate in a lower run (11) of the workpiece carrier system (1) with a guide device (13) arranged on the base body (2), so that sagging of the traction means (18) in the lower run (11) due to gravity is avoided.

6. Workpiece carrier system (1) according to one of the preceding claims, characterized in that the coupling device (3) has at least one spring element (24), preferably in the form of a tension spring, wherein the spring element (24) is provided and designed to exert a spring force on at least one coupling element (19), preferably in the form of an eccentric element, of the coupling device (3), wherein preferably the spring element (24) can effect the non-positive coupling of the workpiece carrier (10) with the traction means (18) by means of its spring force.

7. Workpiece carrier system (1) according to claim 6, characterized in that the coupling device (3) has an adjusting device for adjusting a preload of the spring element (24).

8. Workpiece carrier system (1) according to one of claims 2 or 3 in combination with one of claims 6 or 7, characterized in that the spring element (24) is applied to the coupling element (19) designed as an eccentric element in such a way that the spring force of the spring element (24) causes a rotation of the coupling element (19) in such a direction that a force-locking engagement of the coupling element (19) with the traction means (18) takes place.

9. Workpiece carrier system (1) according to one of the preceding claims, characterized in that the workpiece carrier (10) has an impact device (12) in a front area viewed in the direction of movement of the traction means (18), which, in the event of the workpiece carrier (10) colliding with a preceding workpiece carrier (10), is triggered as a result of a stop on the preceding workpiece carrier (10) and thereby reduces or completely dissolves the coupling of the coupling device (3) with the traction means (18).

10. Workpiece carrier system (1) according to one of the preceding claims, characterized by at least one stop device (26) arranged on the base body (2), wherein preferably the workpiece carrier (10) has a release element (27) which cooperates with the stop device (26) in such a way that the frictional connection between the coupling device (3) and the traction means (18) is reduced or released, wherein preferably the stop device (26) is transferable between an active position and a passive position, wherein the stop device (26) is configured to engage with the release element (27) of the at least one workpiece carrier (10) when in the active position, wherein the stop device (26) is arranged in such a way when in its passive position that engagement with the release element (27) is avoided.

11. Workpiece carrier system (1) according to one of the preceding claims, characterized in that the coupling device (3) has at least one spring element (24), wherein the spring element (24) is provided and configured to exert a spring force on a coupling element (19) of the coupling device (3) designed as an eccentric element, whereby the spring element (24) can effect the non-positive coupling of the workpiece carrier (10) with the traction means (18), wherein the workpiece carrier (10) further has, in a front region viewed in the direction of movement of the traction means (18), an impact device (12) which is triggered in the event of the workpiece carrier (10) colliding with a preceding workpiece carrier (10) as a result of a stop on the preceding workpiece carrier (10), wherein the impact device (12) is operatively connected to the coupling device (3), so that a stop force which is generated as a result of the collision with the impact device (12), is transmitted to the coupling device (3) and acts against the spring force of the spring element (24), whereby the non-positive coupling of the workpiece carrier (3) with the traction means (18) can be reduced or completely dissolved.

12. Workpiece carrier system (1) according to one of the preceding claims, characterized in that the base body (2) comprises at least two deflection stations (25) by means of which the traction means (18) is guided in a circumferential manner, wherein preferably at least one of the deflection stations (25) cooperates with a drive by means of which the traction means (18) can be driven directly or indirectly.

13. Workpiece carrier system (1) according to claim 12, characterized in that the workpiece carrier (10) has at least one pressure element (28) which is arranged on a plane of the workpiece carrier (10) above the traction means (18), preferably between rollers (20) of the workpiece carrier (10) as viewed in the longitudinal direction of the workpiece carrier (10), wherein the pressure element (28) is arranged relative to the traction means (18) in such a way that, during a deflection of the workpiece carrier (10), it comes into frictional contact with an upper side (4) of the traction means (18) at a deflection station (25), whereby an additional frictional connection is generated between the workpiece carrier (10) and the traction means (18).

14. Workpiece carrier system (1) according to claim 13, characterized in that the pressure element (28) can be pretensioned so that a pressing force with which the pressure element (28) presses against the pulling means (18) can be adjusted.

15. Workpiece carrier system (1) according to one of the preceding claims, characterized in that the traction means (18) is formed by a toothed belt, wherein an underside (5) of the traction means (18) facing the base body (2) is provided with a toothed structure (16).

Images