Ejector for A-Frame

Abstract

Ejector (18) for installation in an order picking machine (10), comprising: a driven separating mechanism (34) which is configured to push a bottommost article (20) of an article stack (22) buffered in a shaft (14) onto a conveyor (16) which can be arranged laterally thereto; characterized in that at least a part of a housing (24) of the ejector (18), on which the lowermost article (20) sits in the installed state of the ejector (18) and over which the lowermost article (20) is pushed during a singling process, has a surface finish (30) which has a lower coefficient of friction than a remainder of the housing (24).

Description

The present disclosure relates generally to an ejector for installation in a central belt picking machine, and more particularly to a friction minimized product support, a tensioning wheel, and a ventilation wheel.Automated picking machines are known which are also referred to as "A-frames" or "central-band automated picking machines" (see, for example, EP 2 576 401 B1). Further exemplary A-frames are shown in documents EP 0 560 206 A2. Automated picking machines are well-proven for use in automated logistics centers. They make it possible to quickly and automatically remove standardized piece goods from vertical shafts onto a central conveyor belt. In particular for so-called A-articles with a high transshipment frequency, these systems represent an established solution. Nevertheless, when technical details are considered precisely, in particular in the area of article separation, significant disadvantages and potential for optimization are evident.A conventional A-frame AF (cf. FIG. 6 ) is a (central belt) automated teller machine which is frequently used in storage logistics in order to pick piece goods (e.g. medicaments, cosmetics, small parts) quickly and efficiently. In a side view, the A-frame AF has the shape of the letter "A". To the left and / or right along slopes of this "A", i.e. the legs of the "A", there are many individual (feed) shafts SCH oriented substantially vertically next to one another-usually one per article or product type. The articles A move downward within the trays SCH by gravity. At the bottom, in the middle between the legs of the "A", a centrally arranged conveyor belt, a so-called central belt ZB, runs. There are also variants where the shafts SCH are arranged only on one side or one leg, wherein one nevertheless speaks of a central band ZB, even if this is loaded only on one side. When a (picking) order is processed, the vertical shafts SCH automatically eject the desired articles A laterally horizontally onto a section of the conveyor belt ZB assigned to the order by means of so-called ejectors AUSW at their lower ends. A controller (e.g. a material flow computer) ensures that all ejected articles A of a job are collected at the correct location on the moving central belt ZB (windowing). A (central) controller, which is often connected to a warehouse management system (WMS), monitors the inventory in the shafts SCH, controls the ejector or ejectors AUSW per order and coordinates the ejection in such a way that an entire order is picked synchronously on the conveyor belt ZB. The belt ZB transports the articles A ejected in a targeted manner to a collection point or into a order or shipping container. An advantage of such automated machines is an extremely fast article separation (e.g. >1000 picks / min) and they are ideal for articles with a high picking frequency (quick rotators or A articles according to an ABC analysis).There are various ejector mechanisms for separating the articles from the chutes.DE 41 01 615 A1 describes an air-based ejector. In this case, the lowermost article of a shaft is separated by an air blast, while an air cushion reduces the friction. However, this method requires additional pneumatic components, which increases system complexity, operating costs and maintenance costs. Moreover, the ejection of air can be inaccurate, especially in the case of light or sensitive products. The need for an additional holding-down device for securing articles increases the design complexity and can lead to movement mechanics which are prone to failure. This type of separation requires pneumatics in addition.EP 0 403 726 A1 describes a mechanical ejector mechanism which is referred to as a pusher. The singulating is effected via physical contact between the lowermost article and a rotatably driven cam. The ejector has a narrow housing and further consists essentially of: a revolving self-contained toothed belt with three drivers (ejector cams) arranged in a protruding manner; a driven gear which moves the toothed belt; a deflection roller which deflects the toothed belt; an electromagnet which switches a clutch; and a counter switch which registers that an article has been ejected. The cams each come into contact with the lowermost article of the stack and push it laterally out of the stack. Three articles can be separated per revolution of the toothed belt. These systems, although providing a simple basic function, often have problems during operation. The sliding friction between the article and the support surface can lead to increased force requirement, increased heating and uneven article behavior. Particularly at high picking speeds, static and sliding friction can lead to mis-designs, blockages or damage to the article packaging. In addition, the surface nature of the support leads to unnecessary wear and reduces the service life of the components.Furthermore, known systems often do not take account of the different physical properties of the articles to be separated, such as weight, shape, packaging material or surface sensitivity. There is no dynamic adaptation of the singulating mechanism to these parameters. The result is a limited system flexibility and an increased need for adjustment during article changes.Modern automated picking machines operate at very high clock rates, frequently in the range of several hundred to over thousand picks per minute. Conventional systems do not have any integrated measures for cooling the drive and mechanics, however. In sustained high power operation, this can lead to overheating, material deformation, power loss or failures.In systems with continuously revolving force transmission members such as chains or toothed belts, additional tensioning devices are often required in order to ensure the tensioning of the transmission member. These external clamping devices increase the installation space, the mechanical complexity and the maintenance outlay.It is therefore an object of the present disclosure to provide an ejector which enables low-friction, product-preserving and maintenance-friendly separation of articles in the automated picking machine, in particular without the need for complex additional systems.In particular, the ejector is intended to enable reliable, energy-efficient and product-preserving separation of articles and thereby significantly reduce the friction between the article and the product support. It would also be desirable to provide an ejector that manages without complicated pneumatic systems or external clamping devices, is low-maintenance and can be integrated easily into existing A-frame structures. It is preferably an additional object to provide a structurally simple possibility for regulating the voltage of a force-transmitting drive element and an integrated cooling for high-frequency operating conditions.This object is achieved by an ejector for installation in a central belt picking machine (A-frame), which comprises: a driven singulating mechanism which is configured to push a lowermost article of an article stack buffered in a shaft onto a conveyor (central belt) which can be arranged laterally thereto, wherein at least part of a housing of the ejector on which the lowermost article is seated in the installed state of the ejector and over which the lowermost article is pushed during a singulating operation has a surface finish which has a lower coefficient of friction than a remainder of the housing.The contact surface between the article and the housing (product support) has a selectively low friction surface with a lower coefficient of friction than the remainder of the housing. Sliding friction is reduced when the article is being pushed out. Less force is required for separation. The dicing process is more energy efficient and reliable because fewer errors can occur. Less wear occurs, so that the ejector requires less maintenance. The separation is more product-preserving. In high-speed operation, less disturbances occur. Singulation is less susceptible to blockages.Preferably, after production of the entire housing, in particular by plastic injection molding, the part of the housing is provided with a structurization, which in particular has a pattern that reduces an effective contact surface or improves a sliding behavior during the ejection.An effective contact area is reduced. This results in less adhesion and friction. The lubricity can be improved by a controlled surface pattern. The ejector can be optimized already during production without changing the base material.In particular, during or after manufacturing the entire package, the portion of the package is smoothed (e.g., by polishing, grinding, etc.) such that microscopic roughness is reduced, resulting in reduced mechanical meshing between the lowermost article and the portion of the package.Mechanical microtoothing between the article and the support (housing) is reduced. The friction is reduced. A sliding-on of the next article is improved. Less dirt is produced due to abrasion.Preferably, after the entire housing has been produced, the part of the housing is provided with a less frictional material coating (for example made of teflon (PTFE), MoS 2, graphite, ceramic or DLC (diamond-like carbon)).These materials result in an extremely low coefficient of friction. The ejector is low in wear, even when dry friction is involved. The ejector is suitable for delicate, coated or delicate articles.In particular, after production of the entire housing, in particular by plastic injection molding, the part of the housing has been nitrided, oxidized, phosphated, plasma activated and / or silanised, so that adhesion forces (molecular attraction) are reduced.Molecular adhesion (adhesion force) is reduced. A smooth sliding occurs. The articles adhere less strongly. No residue occurs on the support. The support does not stick together.The object is furthermore achieved by an ejector, the separating mechanism of which has an endlessly circulating, self-contained force transmission member which can be prestressed via a deflection wheel which has an inherent spring function.An automatic voltage compensation occurs. The force transmission member does not hang through. Slip is safely prevented. The ejector can be operated with less noise and maintenance-free. A longitudinal expansion, in particular thermal expansion, of the force transmission element can be compensated.Preferably, the idler gear comprises an inner ring, an outer ring and at least one strut configured to elastically connect the inner ring and the outer ring to each other along a radial direction.An elastic connection allows an integrated flexibility. No separate spring is necessary. This results in savings in installation space and costs. The deflection wheel has a vibration-damping effect and promotes smooth running of the force transmission member.The object is achieved by an ejector which is provided with a deflection wheel or drive wheel with a ventilation device in order to generate a cooling air stream within a housing of the ejector while the lowermost article of the stack is separated.The components of the ejector are actively cooled. The life of the components is extended. Thermal problems in high frequency operation are avoided. Self-cleaning is made possible by the air flow that is produced.Preferably, the venting means comprises a plurality of axially oriented vanes.The air is efficiently conveyed in the longitudinal direction. A uniform air flow is established. The ventilation device can be integrated compactly into existing wheels. No additional fan is required. The noise generation is low compared to external blowers.In particular, the ejector further comprises a housing in which the wheel is arranged.The ventilation device is protected. The air is guided in a directed manner. The housing protects the internal components from dust and particles.It is understood that the features mentioned above and those still to be explained below can be used not only in the respectively specified combination, but also in other combinations or alone, without departing from the scope of the present disclosure.Embodiments are illustrated in the drawings and are explained in more detail in the following description. The following are shown: FIG. 1 shows a block diagram of an ejector which can be installed in a central bank automated picking machine which can be used in a storage and picking system; FIG. 2 shows a perspective view of an ejector in the installed state, which is fitted with an article stack; FIG. 3 is a sectional side view of the ejector of FIG. 2 along a line III-III in FIG. 2 ; FIG. 4 shows a side view of a first deflection wheel of FIG. 3 ; FIG. 5 shows a perspective view of the second deflection wheel of FIG. 3 ; and FIG. 6 shows an A-frame according to the prior art.FIG. 1 shows a block diagram of a central band automated picking device 10, which can be used in an (intralogistic) storage and picking system 12 and which is also referred to below as an A-frame. The A-frame 10 is constructed as explained above. The A-frame 10 functions as explained above. The A-frame 10 includes one or more (article feeder) chutes 14, a (central belt) conveyor 16, and one or more ejectors 18. Each of the ejectors 18 is configured to separate a lowermost article 20 of an article stack 22 stored in each of the shafts 14 by pushing (cf. FIG. 2 ).The ejector 18 may include a housing 24, as shown in FIG. 2. The housing 24 may be made of plastic, for example by injection molding. A portion 26 of the housing 24 is configured to support the article stack 22 on its top side and to laterally push a lowermost article 20- 1 of the article stack 22. The stack 22 of FIG. 2 exemplarily comprises three articles 20- 1 to 20- 3. It will be appreciated that the stack 22 will decrease over the course of the operating time and may also include only a single article 20- 1.Preferably, the part 26 of the housing 24 is formed by a planar surface which extends along an ejection direction 28 and has a width (perpendicular to the ejection direction 28) adapted to the respective article (type) 20. The ejection direction 28 is usually oriented slightly downward, laterally horizontally. In an installed state of the ejector 18, the ejection direction 28 is furthermore aligned with the conveyor 16 (not illustrated here), which is arranged slightly lower than the ejector 18. The part 26 is shaped and dimensioned such that the articles 20 can be separated reliably and securely by lateral displacement.The housing 24 has an (outer) surface 30. A portion of the surface 30 is formed by the portion 26 of the housing 24. This portion of the surface 30 has a surface finish that has a lower coefficient of friction than a remainder of the housing 24. The differing surface condition can be produced after production of the actual housing 24. The coefficient of friction (also called friction value) is a dimensionless index which describes how strongly two bodies adhere or slide in contact with each other. The coefficient of friction is a measure of a resistance to movement that arises due to frictional forces. The greater the coefficient of friction, the more friction occurs between the bodies. Typical values range from 0.01 (teflon on teflon) to over 1.0 (rubber on rough asphalt). The coefficient of friction includes the coefficient of static friction and the coefficient of sliding friction. The following statements apply to both types of coefficient, even if the static friction is usually greater than the sliding friction.In order to facilitate the pushing-off of the lowermost article 20-1, the frictional action of the housing part 26 is to be reduced. The friction reduction can be achieved in a targeted manner in various ways (e.g. mechanically, chemically, material-related, etc.).The part 26 can be provided with a structurization 32, in particular during the production of the entire housing 24, as is illustrated in FIG. 2 by an enlargement of a region of the part 26 shown in isolation. The structurization 32 can be, for example, a laser texturing. The structurization 32 may have a pattern that reduces effective contact area between the lowermost article 20- 1 and the housing 24. The pattern can improve a sliding performance of the lowermost article 20-1 in its discharge. Laser texturing represents an exemplary surface technology method in which minute structures (micro- and / or nanostructures), i.e. characterization 32, are selectively produced on a material surface with the aid of a pulsed or continuous laser. The material can be locally removed, melted or formed, which is effected in particular without contact and is precise. The pattern may be implemented in the form of grooves, dots, a grid, depressions and / or elevations. The pattern brings about a selectively controllable roughness distribution. Surface roughness can have a decisive influence on friction, but not always in a direct, linear manner. The relationship is complex, since in addition to roughness, other factors such as material pairing, lubrication, contact forces and a relative speed can also play a role. A rough surface is distinguished by a stronger microtoothing between the contact surfaces, which results in a higher mechanical interlocking and thus tends to result in a greater friction. Smooth surfaces reduce the entanglement and thus the sliding friction. If the surface is too smooth, the friction may again increase due to adhesion (molecular attraction), so that an optimum of roughness is to be found. The roughness can be measured, for example, by means of a tactile section method (ISO 4287), optically, by interferometry or atomic force microscopy. Roughness is measured in micrometers and is a standard characteristic according to ISO 4287.The part 26 of the housing 24 can be subsequently processed, in particular after its production. The portion 26 may be smoothed, e.g., by polishing or grinding, such that microscopic roughness is reduced, resulting in reduced mechanical meshing between the lowermost article 20- 1 and the housing portion 26.The part 26 of the housing 24 can be coated with a less frictional material, in particular after its production. The material can be selected from, for example, teflon, MoS 2, graphite, ceramic or DLC (diamond-like carbon).The part 26 of the housing 24 can be nitrided, oxidized, phosphated, plasma activated and / or silanised, in particular after its production, so that adhesion forces (molecular attraction) are reduced.FIG. 3 is a side cross-sectional view of the ejector 18 taken along line III-III in FIG. 2, FIG. 3 illustrates the interior of the housing 24. the articles 20 of the stack 22 are not shown in FIG. 3 for ease of explanation. The ejector 18 comprises a driven separating mechanism 34 (cf. also FIG. 1 ). The separating mechanism 34 is configured to push the lowermost article 20- 1 of the article stack 22 buffered in the chute 14 onto the central belt (conveyor 16, not illustrated) arranged laterally thereto. The separating mechanism 34 is preferably a linear drive, such as a chain drive, belt drive, spindle drive, rack and pinion drive, linear motor or the like. A linear drive is a technical system that converts a rotational motion (e.g., of a motor) into a linear (linear) motion, or directly generates a linear motion (as in the linear motor). A chain drive is considered below by way of example.The separating mechanism 34 comprises a force transmission member (e.g. a roller chain, a toothed belt, etc.) 36, one or more (chain) drive wheels or wheels 38 (cf. also FIGS. 4 and 5 ), one or more push-off members (e.g. cams, slides, slides, drivers, etc.) 40, a drive, not shown in more detail, and a (drive) control 42, not shown in more detail. The force transmission member 36 is preferably closed on itself and rotates continuously. In FIG. 3, the force transmission member 36 is exemplarily designed as a roller chain. The two deflection wheels 38 of FIG. 3 are exemplarily designed as sprockets.FIG. 3 illustrates a position of the force transmission member 36 at the beginning of a singulating process. One of the, exemplarily two, push members 40 protruding (radially outward) from the upper strand of the force transmission member 36 is shown in a position in which the push member 40- 1 abuts laterally from (right) outward on the lowermost article 20- 1 (not illustrated). To single this article 20- 1, the force transmission bed 36 is moved selectively (i.e. controlled), e.g. counter-clockwise, by the controller to such an extent that the member 40- 1 pushes the lowermost article 20- 1 completely from the top side of the housing 24 (to the left in FIG. 3 ) in the ejection direction 28. After the end of the singulating process, the second link 40-2 is in the position of the first link 40-1 shown in Figure 3. This means that two articles 20 are separated by pushing them off per complete rotation of the force transmission element 36. A relative spacing of the links 40 is selected accordingly. It is understood that more or fewer links 40 can be provided, with their relative distances to be selected accordingly. For the push-off, a force is required which overcomes the static friction F of the lowermost article 20-1.The idler gear 38- 1 of FIG. 3 is shown in more detail in a side view of FIG. 4. The (chain) deflecting wheel 38- 1 is not solid, i.e. hollow on the inside, and is formed from an inner ring 44, an outer ring 46 and at least one strut 48. The deflection wheel 38- 1 is arranged in a stationary fixed manner, i.e. immovable, in the housing 24 and rotatably mounted. The deflection wheel 38- 1 is rotatably mounted about a locally fixed axis 50. The outer ring 46 can have an external toothing for positively interacting with a drive chain. The rings 44 and 46 are arranged concentrically with respect to one another. The rings 44 and 46 preferably each have a circular cross section (cf. dashed lines). The at least one strut 48 mechanically connects the rings 44 and 46 together. The struts 48 of FIG. 4 can be of arcuate configuration.The struts 48 may be configured to absorb and / or dissipate forces. The struts 48 are configured to transmit compressive and tensile forces. The struts 48 are configured in particular to absorb torsion forces or bending forces which arise when the rings 44 and 46 are rotated axially with respect to one another or are displaced in the sprocket plane. This twisting may be selectively caused by the controller 42 to generate a desired bias in the force transmitting member 36. The struts 48 of FIG. 3 are exemplarily formed in the shape of a circular arc, wherein the arc center points (not illustrated) are offset with respect to the common center point 50 of the rings 44 and 46. The struts 48 are connected, preferably equally spaced in the circumferential direction, to the ring 44 and / or the ring 46. The struts 48 may be formed in a similar material thickness to the rings 44 and 46. Further, circumferentially extending reinforcing ribs 52 may be provided that each extend from the distal (i.e., radially outer) end of the struts 48 along an inner edge of the outer ring 46 nearly to the distal end of the next, directly adjacent strut 48. It is understood that more or less than three struts 48 can be provided, in particular also only a single strut 48.The deflection wheel 38- 1 has a spring function integrated. In FIG. 4, the idler gear 38- 1 is shown in an unstressed condition. The resilient idler gear 38- 1 may be biased by displacing or twisting the inner ring 44 relative to the outer ring 46, e.g., by the motor (permanently) exerting some preset torque that is less than the stiction caused by the stack 22. The spring function of the wheel 38- 1 allows the force transmission member 36 to be prestressed. The resilient nature of the wheel 38-1 enables thermal expansions, chain elongations and the like to be compensated. The idler gear 38-1 is also compatible with timing belts and the like. It is possible to dispense with conventional (chain) tensioning devices for the force transmission member 36. The force transmission member 36 can be sufficiently prestressed by the deflection wheel 38 alone.The idler gear 38- 1 may be injection molded as a single part. The ejector 18 can be assembled more easily because of the deflection wheel 38- 1, in particular because fewer components are required, which can also result in a cost reduction.It is understood that the deflection wheel 38- 1 can also be used as a drive wheel for the force transmission member 36. In this case, the idler 38-1 may be connected via a clutch (not shown) or directly to the above-mentioned drive.FIG. 5 shows a perspective view of the second deflection wheel 38- 2 of FIG. 3, which can likewise be used as a drive wheel for the force transmission member 36. In other words, this means that the deflection wheels 38 do not necessarily have to deflect, but can also only drive.The deflection wheel 38- 2 can be disk-shaped. A main body of the idler gear 38-2 is in the form of a (continuous) disk. The deflection wheel 38- 2 has a ventilation device 56 on its front side 54. If the deflection wheel 38- 2 is used as a drive wheel, the deflection wheel 38- 2 can have a drive pinion 60 on its rear side 58, which drive pinion is operatively connected to the drive.The ventilation device 56 is configured to generate an air flow within the housing 24 for cooling the components within the housing 24. The idler gear 38-2 constitutes the rotor of the device 56, i.e. the centrally rotating element which moves the air. The ventilation device 56 can be formed from a plurality of blades 62, which are also referred to as vanes. The blades 62 are arranged at a distance from one another circumferentially and preferably project axially out of the disk-shaped body of the deflection wheel 38- 2. A cross-section of the vanes 62 (in a plane perpendicular to the axis of rotation 50) may be arcuate so that air is drawn in on one side and discharged in an opposite direction. The housing 24 may be provided with correspondingly positioned ventilation slots 64 (see FIG. 2 ). The ventilation device 56 can be designed as a tangential fan. Tangential fans are characterized by a tangential air guidance. They produce a uniform, wide air flow over the entire length of the vanes 62.It is understood that the ventilation device 56 could also be provided on the first deflection wheel 38- 1, in particular in addition to the spring function.In summary, it can be stated that the ejector 18 can be arranged in a lower region of the respective shaft 14 of the automated picking machine 10. In this case, it is positioned such that the article stack 22 is located directly above the housing part 24 of the ejector 18. The ejector 18 is structurally and functionally integrated into the picking system 12 and forms the interface between the shaft 14 and the central belt 16 arranged underneath.The ejector 18 is controlled by a central control unit (e.g. controller 42), which can be part of a superordinate inventory management system (WMS). The control unit is configured to selectively activate one or more ejectors 18 for each picking order to be executed in such a way that in each case exactly one article 20 is separated from the article stack 22 and is fed onto the central belt 16.The ejectors 18 operate synchronously with the feed of the central belt 16. As the conveyor belt 16 moves beneath the ejectors 18, the individual articles 20 are ejected by the singulating mechanism 34 at defined times. This can be done according to a so-called windowing method, in which each picking order is assigned a time window or section on the conveyor belt 16.The ejector 18 may be connected to the controller 42 via electrical connectors, bus interfaces, or wireless systems. Mechanically, the ejector 18 can be mounted in the housing of the automated picking machine 10 in a detachable manner via a holding device, in order to enable simple replacement or maintenance.In a typical sequence, an ejector 18 associated with a particular chute 14 having an article type 20 therein is activated by an electrical signal. The separating mechanism 34 within the ejector 18 then ejects the lowermost article 20 onto the central belt 16 in the horizontal direction, cf. ejection direction 28. The next article in stack 22 is then gravity fed into the eject position.The ejector 18 is compatible with further assemblies of the automated picking machine 10, in particular with refilling mechanisms, sensor systems for checking the filling level of the shafts 14 and automated maintenance units. Furthermore, the ejector 18 can be coupled to a detection unit which detects a faulty separation, for example double ejection, and triggers a correction.Each ejector 18 is designed as a self-contained functional unit. As a result, modular expansion of the picking machine 10 is possible by adding further shafts 14 with respectively associated ejector 18. The control unit 42 can be correspondingly extended or automatically adapted by plug-and-play mechanisms.LIST OF REFERENCE CHARACTERS:10 (Central belt) picking machine 12 storage and picking system 14 (article feeding) chute 16 conveyor 18 ejector 20 article 22 article stack 24 housing 26 part of 24 28 ejection direction B width of 24 30 surface of 24 32 characterization 34 separating mechanism 36 force transmission member 38 deflection wheel 40 pushing member 42 controller 44 inner ring 46 outer ring 48 strut 50 axis of rotation of 44+46 52 reinforcing rib 54 front side of 38 56 ventilation devices 58 rear side of 38 60 drive pinion 62 paddle 64 ventilation slotReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedEP 2 576 401 B1

[0002] EP 0 560 206 A2

[0002] DE 41 01 615 A1

[0005] EP 0 403 726 A1

[0006]

Claims

Ejector (18) for installation in an automated picking machine (10), comprising: a driven singulating mechanism (34) which is configured to push a lowermost article (20) of an article stack (22) buffered in a chute (14) onto a conveyor (16) which can be arranged laterally thereto; characterized in that at least part of a housing (24) of the ejector (18), on which housing the lowermost article (20) is seated in the installed state of the ejector (18) and over which the lowermost article (20) is pushed during a singulating operation, has a surface finish (30) which has a lower coefficient of friction than a remainder of the housing (24).Ejector (18) according to claim 1, wherein the part (26) of the housing (24) is provided with a structurization (32), which in particular has a pattern that reduces an effective contact area or improves a sliding behavior during the ejection.Ejector (18) according to claim 1 or 2, wherein the part (26) of the housing (24) is smoothed, during or after manufacturing the entire housing (24), in particular by plastic injection molding, so that a microscopic roughness is reduced, resulting in a reduced mechanical toothing between the lowermost article (20) and the part (26) of the housing (24).Ejector (18) according to one of Claims 1 to 3, wherein the part (26) of the housing (24), after production of the entire housing (24), is provided with a less friction material coating, in particular by plastic injection moulding.Ejector (18) according to one of Claims 1 to 4, wherein the part (26) of the housing (24), after production of the entire housing (24), has been nitrided, oxidized, phosphated, plasma-activated and / or silanised, in particular by plastics injection moulding, so that adhesion forces are reduced.Ejector (18) according to the preamble of claim 1, characterised in that the separating mechanism (34) has an endlessly circulating, self-contained force transmission member (36) which can be prestressed via a deflection wheel (38) which has an inherent spring function.Ejector (18) according to Claim 6, in which the deflection wheel (38) has an inner ring (44), an outer ring (46) and at least one strut (48) which is configured to elastically connect the inner ring (44) and the outer ring (46) to one another along a radial direction.Ejector (18) according to the preamble of claim 1, characterized in that a deflection wheel (38) or drive wheel is provided with a ventilation device (56) in order to generate a cooling air flow within a housing (24) of the ejector (18) while the lowermost article (20) of the stack (22) is separated.The ejector (18) of claim 8, wherein the venting means (56) includes a plurality of axially oriented vanes (62).The ejector (18) of claim 8 or 9, further comprising a housing (24) in which the wheel is disposed.

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