Nut and bolt for hygienic application

Abstract

The present invention relates to a bolt (1) comprising a bolt-head (2) having a shaft insertion (3), and a bolt-body (4) extending in substantially perpendicular direction from the bolt-head and forming a continued shaft insertion, the bolt-body comprising at least two threaded elements (4a, b) extending in perpendicular direction from the bolt-head, wherein the at least two threaded elements are placed around part of the continued shaft insertion of the bolt-body.

Description

[0001] NUT AND BOLT FOR HYGIENIC APPLICATION

[0002] Technical field of the invention

[0003] The present invention relates to a nut and bolt for a hygienic environment. In particular, the present invention relates to a nut and bolt for rotating elements in a hygienic environment.

[0004] Background of the invention

[0005] A drive unit, like a drum motor (or motorised pulley) is generally a geared electrical motor drive enclosed within a cylindrical shell providing a single component driving pulley in particular for conveyor belts.

[0006] The cylindrical shell comprising two exposed shafts extending from the ends of the cylindrical shell, and are used to install and fix the drum motor into a frame, e.g. a conveyor frame, and do not rotate.

[0007] The shaft may be a single "through" shaft where the motor and gearbox are assembled on, and fixed to, the shaft with keys or pins. However, this type of drum motor design may have a limited maximum radial load due to the bending stresses caused by the normal belt tension of a conveyor and is therefore used mainly for small light duty conveyors and loads.

[0008] For heavier loads, the most common design is to use two separate shafts, one fixed to the motor housing and one fixed to the gearbox housing where the mass of metal from the motor and gearbox significantly increases the strength of the drum motor allowing much higher payloads and longer conveyor applications.

[0009] It is often recognised that since the drum motor may be fully enclosed and has a smooth stainless steel and clean profile, maintenance may be limited and the drum motor are considered to be hygienically cleaned and sanitized regularly using high-pressure water, steam, or chemicals which makes it the drum motor a highly hygienic conveyor drive design. One of the challenges with the drum motors of today is the construction of the end-plates (at the end of the cylindrical shell), which comprises cavities where dirt, grime, microbial material and / or allergens may deposit or accumulation and where cleaning is difficult.

[0010] Furthermore, the fastening devices used for fixing the drum motor to the frame are not hygienic providing undesirable spaces and cavities for deposit or accumulation of dirt, grime, microbial material and / or allergens, and installation is often difficult leaving scratches and marks in the surface of the shaft from being tighten in the fastening device, increasing the risk of deposit and accumulation of dirt, grime, microbial material and / or allergens.

[0011] Thus, there are challenges with the fastening devices and the drive units (like the drum motor) of the prior art in that they are not sufficiently hygienic, they have a lot of play, clearance, slackness or wobble which may result in an unstable drive during conveying of goods. Furthermore, adjustment or tighten up of e.g. a conveyer belt to deal with the increased play, clearance, slackness or wobble may be difficult or even impossible.

[0012] Hence, an improved fastening device (and improved drive unit) would be advantageous, and in particular a more efficient stable and / or reliable fastening device (and drive unit) which may be hygienic, which may reduce or even avoid the presence or development of play, clearance, slackness or wobble, which is easy to apply, easy to exchange and which is easy to adjust and tighten if necessary would be advantageous.

[0013] Summary of the invention

[0014] Thus, an object of the present invention relates to a fastening device comprising a nut and bolt, preferably for drive unit, like a drum motor, in a hygienic environment.

[0015] In particular, it is an object of the present invention to provide an improved fastening device (and an improved drive unit) comprising a nut and a bolt that solves the above mentioned problems of the prior art with efficiency, stability, and / or reliability, hygienic requirements in certain environments and industries, which solves the presence or development of play, clearance, slackness or wobble, which is easy to apply, easy to exchange and which is easy to adjust and tighten if necessary.

[0016] Thus, one aspect of the invention relates to a bolt comprising a bolt-head and a bolt-body extending in substantially perpendicular direction from the bolt-head, the bolt-body comprising at least two threaded elements extending in substantially perpendicular direction from the bolt-head, the at least two threaded elements comprise a distal end, a proximal end connected to the bolt-head and a middle section comprising the thread of the threaded elements, wherein the middle section of the at least two threaded elements comprises in the range of 20-90% of the middle section of the threaded elements comprises a thread.

[0017] Yet an aspect of the invention relates to a bolt comprising a bolt-head having a shaft insertion, and a bolt-body extending in perpendicular direction from the bolt-head and forming a continued shaft insertion, the bolt-body comprising at least two threaded elements extending in substantially perpendicular direction from the bolt-head, wherein the at least two threaded elements are placed around part of the continued shaft insertion of the bolt-body.

[0018] A further aspect of the present invention relates to a nut comprising an internal part and an external part, wherein either the internal part or the external part comprises a thread and a shoulder.

[0019] Another aspect of the present invention relates to a nut comprising an internal part and an external part, the internal part comprises an internal thread and an internal shoulder.

[0020] Yet another aspect of the present invention relates to a fastening device comprising a bolt according to the present invention and a nut according to the present invention.

[0021] Still another aspect of the present invention relates to a drive unit comprising a rotating element, a shaft and a fastening device according to the present invention.

[0022] Yet an aspect of the present invention relates to a system comprising a fastening device according to the present invention, or a drive unit according to the present invention.

[0023] Another aspect of the present invention relates to the use of a fastening device according to the present invention, or a drive unit according to the present invention, for use in environments with high hygienic requirements, high cleaning requirements and / or environments where low (or no) deposit or accumulation of dirt, grime, microbial material and / or allergens is accepted.

[0024] Yet another aspect of the present invention relates to the use of a fastening device according to the present invention, or a drive unit according to the present invention for use in food production industry, feed production industry, and / or pharmaceutical industry. Description of the figures

[0025] Figures 1-3 shows a bolt (1) according to the present invention comprising a bolt-head (2) having a shaft insertion (3), and a bolt-body (4) extending in perpendicular direction from the bolt-head (2) and forming a continued shaft insertion (5), the bolt-body (4) comprising at least two threaded elements (4a / 4b) extending in perpendicular direction from the bolthead (2), wherein the at least two threaded elements (4a / 4b) are placed around part of the continued shaft insertion (5) of the bolt-body (4).

[0026] The bolt-body (4) and each of the threaded elements (4a / 4b) comprises a distal end (7) comprising a protrusion (6), a proximal end (8) connected to the bolt-head (2) and a middle section (9) comprising the thread of the threaded elements (4a / 4b). The middle section (9) may represent in the range of 10-95% of the outside surface of the bolt-body (4). The amount of the middle section (9) provided with a thread may vary depending on the particular application and construction. Preferably, 10-100%, such as in the range of 20-90%, e.g. in the range of 30-80, such as in the range of 40-70%, e.g. in the range of 50-60% of the middle section (9) of the at least two threaded elements (4a / 4b) may be provided with a threaded part and a first non-threaded part (25a) and a second nonthreaded part (25b). This threaded part and the non-threaded parts of the threaded elements demonstrates that the thread may preferably not be provided over the entire middle section or over the entire length of the threaded elements.

[0027] The bolt-body (4) may be provided with bolt-body openings (10) which are the open space between the at least two threaded elements (4a / 4b). The bolt-body openings (10) may be configured to match one or more engagement surfaces (11, but not shown in this figure) of a shaft, and the bolt-body openings (10) may, together with the engagement surfaces, engage with a frame when placed in a slit, immobilizing or fixing the shaft and the bolt from axial movement. When combined with the nut forming the fastening device of the present invention and tighten, any movements of the shaft and the fastening device may be avoided and the presence or development of play, clearance, slackness or wobble, may be avoided. At the same time the construction of the present fastening device allows easy adjustment in the slit and tighten if necessary.

[0028] To improve the hygienic usage of the bolt (1) of the present invention, a first groove (12) and a second groove (13) may be provided in the bolt for receiving a first bolt sealing (23 - not shown) and a second bolt sealing (24 - not shown). Figures 4-5 shows a nut (14) comprising an internal part (15) and an external part (16), the internal part (15) comprises an internal thread (18) and an internal shoulder (17). The internal shoulder (17) may be engaging with the protrusion (6 - not shown) of the bolt (1) or the bolt-body (4) when the bolt (1) and the nut (14) according to the present invention are assembled in the fastening device (not shown).

[0029] The nut (14) comprises a nut front-part (19) facing the bolt (1 - not shown) when assembled in the fastening device (not shown), and a nut back-part (20) facing away from the bolt (1 - not shown) when assembled in the fastening device (not shown).

[0030] The internal shoulder (17) according to the present invention has a diameter which is smaller than the diameter of the internal thread (18). The diameter of the internal shoulder (17) is in the range of 70-95% of the diameter of internal thread (18) of the nut (14).

[0031] The internal shoulder represents in the range of 5-70% of the internal part of the nut when measured from the nut front part (19) to the nut back part (20).

[0032] The internal shoulder (17) of the nut (14) comprises a flat plateau (21). This flat plateau (21) of the internal shoulder (17) of the nut (14) is provided to provide an even engagement, irrespective of how much the nut (14) may be tighten when assembled bolt (1- not shown) and engage with the protrusion (6 - not shown)

[0033] The nut (14) may be either an open nut or a closed nut. An open nut may be a nut having an open bottom providing an entry point (e.g. for providing access for an electrical wire providing electricity and / or wires for transmitting signals from various sensors) into or through the fastening device.

[0034] The sensors may include in a thermal sensor (to protect the motor from over-heating), a hall sensor (to determine the position of the motor), and / or a leak detection sensor.

[0035] The nut (14) comprises a third groove (22) in the outer periphery of the external part facing the bolt (1 - not shown), when the bolt (1 - not shown) and nut (14) are assembled and providing the fastening device (not shown). The third groove (22) is configured for receiving the nut-sealing (26 - not shown).

[0036] Figure 6 shows a part of a drive unit (27), e.g. a drum motor, comprising a cylindrical shell (28) comprising an end-plate (29), another end-plate (29) is placed in the other end of the cylindrical shell (28). The end-plate (29) comprises a plate thread (not shown) placed in outside periphery of the end-plate (29) and facing towards the centre of the end-plate (29) (or the centre of the cylindrical shell (28). The end-plate (29) may be screwed into a thread (not shown) of the cylindrical shell (28). The thread of the of the cylindrical shell (28) may be facing away from the centre of the cylindrical shell (28).

[0037] The end-plate (29) may be provided with a recess (30). The recesses (30) may be formed as a circular cavity and the circular cavity is configured in order to fulfil the hygienic requirements as mentioned herein, e.g. in respect of roughness, allowable angles and edges, material interfaces, and therefore allows for easier inspection, easier cleaning and where the risk of deposit or accumulation of dirt, grime, microbial material, or allergens, may be reduced or even avoided.

[0038] The recess (30) is provided for receiving an end-plate tool capable of providing a firm grip on the end-plate (29) to relieve or attach the end-plate (29) from the cylindrical shell (28).

[0039] The drive unit (27) comprises a bolt (1) and a nut (14) and is provided a first bolt-sealing (23), a second bolt-sealing (24) and a nut sealing (25) which are configured with contours which are adapted to the structure of the surfaces connected or elements connected and thereby substantially ensure a continuous or substantially continuous surface in the joints between surfaces or elements connected, resulting in that dirt, grime, microbial material (such as bacteria or fungus), or other fouling materials (e.g. allergens), may be hindered or prevented from hiding and / or accumulating.

[0040] The end-plate (29) comprises an end-plate sealing (31) which is placed in the space between the outer periphery of the end-plate (29) and the end of the cylindrical shell (28). The end-plate (29) comprises a glide sealing (32) between the end-plate (29) and the shaft(s). The glide sealing (32) comprises a lip seal providing a resilient contact with shaft (37).

[0041] The Fastening means (comprising the bolt (1) and the nut (14)) which are mounted in a slit (35) of a system comprising a frame (36) where the sides of the frame (36) surrounding the slit (35) are configured as grabbing means (34) for holding or fixing the shaft (37) and the bolt (1) and nut (14). The slit (35) is forming a trail capable of embracing the one or more bolt-body openings and the one or more engagement / holding surfaces (33) of the shaft (37).

[0042] The present invention will now be described in more detail in the following. Detailed description of the invention

[0043] Accordingly, the inventors of the present invention surprisingly found that a unique construction of a bolt and a nut resulted in a unique design and function of a fastening device that solves the above mentioned disadvantages of the prior art.

[0044] A preferred embodiment of the present invention relates to a bolt comprising a bolt-head and a bolt-body extending in substantially perpendicular direction from the bolt-head, the bolt-body comprising at least two threaded elements extending in substantially perpendicular direction from the bolt-head, the at least two threaded elements comprise a distal end, a proximal end connected to the bolt-head and a middle section comprising the thread of the threaded elements, wherein the middle section of the at least two threaded elements comprises in the range of 20-90% of the middle section of the threaded elements comprises a thread.

[0045] A preferred embodiment of the present invention relates to a bolt (1) comprising a bolthead (2) having a shaft insertion (3), and a bolt-body (4) extending in perpendicular direction from the bolt-head (2) and forming a continued shaft insertion (5), the bolt-body (4) comprising at least two threaded elements (4a / 4b) extending in substantially perpendicular direction from the bolt-head (2), wherein the at least two threaded elements (4a / 4b) are placed around part of the continued shaft insertion (5) of the bolt-body (4).

[0046] Preferably, the at least two threaded elements may comprise a distal end, a proximal end connected to the bolt-head and a middle section comprising the thread of the threaded elements. The middle section of the at least two threaded elements may preferably comprise in the range of 10-100%, such as in the range of 20-90%, e.g. in the range of 30-80, such as in the range of 40-70%, e.g. in the range of 50-60% of the middle section of the threaded elements comprises a thread.

[0047] A further preferred embodiment of the present invention relates to a bolt comprising a bolt-head having a shaft insertion, and a bolt-body extending in perpendicular direction from the bolt-head and forming a continued shaft insertion, the bolt-body comprising at least two threaded elements extending in substantially perpendicular direction from the bolt-head, wherein the at least two threaded elements are placed around part of the continued shaft insertion of the bolt-body, the at least two threaded elements comprise a distal end, a proximal end connected to the bolt-head and a middle section comprising the thread of the threaded elements, wherein the middle section of the at least two threaded elements comprises in the range of 20-90% of the middle section of the threaded elements comprises a thread. The term "substantially perpendicular direction" may relate to a deviation from perpendicular direction by at most 10%, such as at most 9% e.g. at most 8%, such as at most 7% e.g. at most 6%, such as at most 5% e.g. at most 4%, such as at most 3% e.g. at most 2%, such as at most 1% e.g. at most 0.5%, such as at most 0.1%.

[0048] A bolt according to the present invention relates to one part of a fastening device, where the other part of the fastening device may be a nut.

[0049] The inventor of the present invention surprisingly found that by providing a bolt-body having at least two threaded elements placed only around a part of the continued shaft insertion, the at least two threaded elements may provide a slight flexible, jigging or springy effect allowing the at least two threaded elements to squeeze around a shaft when inserted into the continued shaft insertion, when used in the fastening device according to the present invention.

[0050] The middle section of the at least two elements may comprise a first non-threaded part in the area between the proximal end connected to the bolt-head and the threaded part and / or the middle section of the at least two elements may comprise a second nonthreaded part in the area between the distal end and the threaded part.

[0051] Preferably, the first non-threaded part and / or the second non-threaded part may have a wall thickness which is smaller than the wall thickness at the threaded part.

[0052] The wall thickness determined at the threaded part may be determined at the root of the thread, between two crests of the thread.

[0053] In an embodiment of the present invention the wall thickness at the first non-threaded part is smaller than the thickness at the second non-threaded part.

[0054] In another embodiment of the present invention the wall thickness at the second nonthreaded part is smaller than the thickness at the first non-threaded part.

[0055] The first non-threaded part and / or the second non-threaded part may constitute 10-90% of the middle section of the threaded elements, such as in the range of 20-80%, e.g. in the range of 30-70%, such as in the range of 35-65%, e.g. in the range of 40-60%, such as in the range of 45-55%, e.g. about 50%. The wall thickness of the first non-threaded part may constitute 10-90% of the wall thickness of the threaded part, such as in the range of 20-80%, e.g. in the range of 30- 70%, such as in the range of 35-65%, e.g. in the range of 40-60%, such as in the range of 45-55%, e.g. about 50%.

[0056] The wall thickness of the second non-threaded part may constitute 10-90% of the wall thickness of the threaded part, such as in the range of 20-80%, e.g. in the range of 30- 70%, such as in the range of 35-65%, e.g. in the range of 40-60%, such as in the range of 45-55%, e.g. about 50%.

[0057] The wall thickness of the first non-threaded part and the second non-threaded part may constitute 10-90% of the wall thickness of the threaded part, such as in the range of 20- 80%, e.g. in the range of 30-70%, such as in the range of 35-65%, e.g. in the range of 40-60%, such as in the range of 45-55%, e.g. about 50%.

[0058] In an embodiment of the present invention the wall thickness of the second non-threaded part may constitute 10-90% of the wall thickness of the first non-threaded part, such as in the range of 20-80%, e.g. in the range of 30-70%, such as in the range of 35-65%, e.g. in the range of 40-60%, such as in the range of 45-55%, e.g. about 50%.

[0059] In an embodiment of the present invention the at least two threaded elements may constitute in the range of 10-90% of the perimeter of the bolt-body, such as in the range of 20-80%, e.g. in the range of 30-70%, such as in the range of 35-65%, e.g. in the range of 40-60%, such as in the range of 45-55%, e.g. about 50%.

[0060] In an embodiment of the present invention the bolt-body may comprise at least two threaded elements, and the at least two threaded elements may comprise at least two individual threaded elements.

[0061] The individual threaded elements may relate to threaded elements which are not connected. The individual threaded elements may relate to threaded elements which are connected via the bolt-head. Preferably, two or more individual threaded elements may be connected via the bolt-head, but not connected otherwise.

[0062] The bolt-body, or the at least two threaded elements, may form a continued shaft insertion extending from the shaft insertion of the bolt-heat to the end of the bolt-body, or to the end of the at least two threaded elements. Since only part of the bolt-body comprises threaded elements (at least two threaded elements), part of the bolt-body also comprises bolt-body openings.

[0063] The one or more bolt-body openings may constitute in the range of 10-90% of the perimeter of the bolt-body, such as in the range of 20-80%, e.g. in the range of 30-70%, such as in the range of 35-65%, e.g. in the range of 40-60%, such as in the range of 45- 55%, e.g. about 50%.

[0064] Preferably, the circular curve of each of the at least two threated elements may be the same. In this way, the bolt-body, and the at least two threaded elements, may be providing a strong fit to the shaft when inserted.

[0065] Preferably, the bolt-body may be circular shaped or partly circular shaped.

[0066] In an embodiment of the present invention the bolt-body may comprise at least two outside threaded elements or at least two inside threaded elements.

[0067] Preferably, the bolt-body or the at least two threaded elements may comprise an outside part and an inside part. The outside part may be facing away from the continued shaft insertion. The inside part may be facing towards the continued shaft insertion.

[0068] In an embodiment of the present invention the bolt-body (4) may comprise at least two outside threaded elements (4a / 4b).

[0069] Outside threaded may mean that the threaded element may be threaded on the side facing away from the continued shaft insertion.

[0070] The outside thread on the bolt-body and on the at least two outside threaded elements may be provided to engage with the tread of a nut as described herein.

[0071] The interaction between the outside threaded bolt and the nut according to the present invention may result in a radial movement of the threaded elements towards each other.

[0072] The threaded elements may comprise a distal end, a proximal end connected to the bolthead and a middle section comprising the thread of the outside threaded elements.

[0073] In an embodiment of the present invention, each of the threaded elements may comprise a distal end comprising the protrusion, a proximal end connected to the bolt-head and a middle section comprising the thread of the outside threaded elements. The middle section may represent in the range of 10-95% of the outside surface of the bolt-body, such as in the range of 30-90%, e.g. in the range of 50-85, such as in the range of 70-80%.

[0074] In an embodiment of the present invention the bolt-body may comprise at least two inside threaded elements.

[0075] Inside threaded may mean that the threaded element may be threaded on the side facing the centre of the bolt.

[0076] When the bolt is provided with inside threaded elements, the shaft insertion may preferably act as an opening for receiving a nut for engaging with the inside thread of the bolt. This interaction between inside threaded bolt and nut may result in a radial movement of the threaded elements away from each other.

[0077] As an example, the inside threaded bolt may be inserted into a pipe and when the nut is screwed into the inside threaded bolt the at least two threaded elements are moving away from each other and may be fastened to the inside of the pipe.

[0078] The threaded elements may comprise a distal end, a proximal end connected to the bolthead and a middle section comprising the thread of the inside threaded elements.

[0079] In an embodiment of the present invention, each of the threaded elements may comprise a distal end comprising the protrusion, a proximal end connected to the bolt-head and a middle section comprising the thread of the inside threaded elements.

[0080] The middle section may represent in the range of 10-95% of the outside surface of the bolt-body, such as in the range of 30-90%, e.g. in the range of 50-85, such as in the range of 70-80%.

[0081] The amount of the middle section which may be provided with a thread may vary depending on the particular application and construction.

[0082] In an embodiment of the present invention 10-100% the middle section of the at least two threaded elements may comprise a thread, such as in the range of 20-90%, e.g. in the range of 30-80, such as in the range of 40-70%, e.g. in the range of 50-60%.

[0083] The inside part of the bolt-body, or the at inside part of the at least two threaded elements may be smooth. Preferably, the shaft insertion may be formed to enclose the shaft to be inserted into the shaft insertion. Preferably, the continued shaft insertion may be formed to partly enclose the shaft to be inserted into the continued shaft insertion.

[0084] The disadvantage of marks, scratches and other crevices in the surface of the surface of the shaft may be that such positions may form attractive areas for the deposit or accumulation of dirt, grime, microbial material, or allergens, on, in or around the shaft, the fastener, the bolt and / or the nut.

[0085] Hence, there is a strong interest to provide a fastener comprising a nut and a bolt, and a bolt as such, having the advantage of reducing the number of marks, scratches and other crevices in the surface of the surface of the shaft and thereby avoid, limit and / or reduce deposition or accumulation of dirt, grime, microbial material, or allergens, on, in or around the shaft, the fastener, the bolt and / or the nut.

[0086] In an embodiment of the present invention the bolt-body is provided with a protrusion (6) in the distal end (7) of the bolt-body (4) relative to the bolt-head (2).

[0087] The protrusion may preferably be placed at the distal end of the bolt-body, at the end of the at least two threaded elements. In an embodiment of the present invention the boltbody is provided with a protrusion at the distal end of the bolt-body relative to the bolthead.

[0088] The term "in the distal end" may relate to a distance of the bolt-body and / or the threaded elements covering at most 20% of the total length of the bolt-body and / or the threaded elements and measured at the distal end and towards the bolt-head, such as at most 15%, e.g. at most 10%, such as at most 5%, e.g. at most 2%.

[0089] The term "at the distal end" may relate to the end of the bolt-body and / or the threaded elements relative to the bolt-head.

[0090] Preferably, the protrusion may be located on the same side, preferably on the outside, as the thread, on the bolt-body, or the threaded side of the at least two threaded elements.

[0091] The protrusion may extend for a shorter distance from the bolt-body than the extension of the threads of the threaded elements. Preferably, the protrusion comprises an angled surface which change the hight of the protrusion until the angled surface reach a protrusion top. The protrusion top may be in the form or a protrusion top spot, a protrusion top plateau.

[0092] The angled surface allows, together with the bolt according to the present invention, to press the distal ends of the at least two threaded elements (of the bolt-body) and forcing the at least two threaded elements move towards each other acting slight flexible or springy allowing the at least two threaded elements to squeeze around a shaft when inserted into the continued shaft insertion, when used in the fastening device according to the present invention.

[0093] In an embodiment of the present invention, the protrusion top may include a flat section being parallel to the longitudinal direction to the shaft, when the shaft is inserted into the continuous shaft insertion.

[0094] Preferably, the protrusion may follow the outer periphery of the bolt-body and / or the threaded elements, preferably near or at the distal end of the bolt-body and / or the threaded elements.

[0095] In an embodiment of the present invention the term "near the distal end" of the bolt-body and / or the threaded elements may be a distance determined as at most 20% of the total length of the bolt-body and / or the threaded elements from the from the distal (of the total length of the bolt-body and / or the threaded elements) and towards the bolt-head, such as at most 15%, e.g. at most 10%, such as at most 5%, e.g. at most 2%.

[0096] Preferably, the protrusion may follow the outer periphery of the bolt-body and / or the threaded elements at the distal end of the bolt-body and / or the threaded elements.

[0097] The protrusion may be provided as one or more spot protrusions on each of the at least two threaded elements, elongated dashed protrusions on each of the at least two threaded elements or as a solid elongated protrusion on each of the at least two threaded elements.

[0098] In an embodiment of the present invention the solid elongated protrusion on each of the at least two threaded elements may form a ring-like structure (e.g. like a collar), only interrupted by the open space between the at least two threaded elements (the bolt-body openings).

[0099] Preferably the distal end of the bolt-body (and / or the threaded elements) may be the opposite end of the bolt-body (and / or the threaded elements), relative to the bolt-head. In an embodiment of the present invention the bolt, and in particular the bolt-body comprises at least two threaded elements, such as at least 3 threaded elements, e.g. at least 4 threaded elements, such as at least 5 threaded elements, e.g. at least 6 threaded elements.

[0100] The number and / or size of the threaded elements may be determined based on the degree of flexibility or springiness relative to the strength that may be desirable to provide. Hence, in an embodiment of the present invention, the higher the number of threaded elements provided and / or the smaller the width of the threaded elements provided may result in a more flexible bolt-body.

[0101] In an embodiment according to the present invention the bolt, the bolt-head and / or the bolt-body (including the at least two threaded elements, may be made of metal or plastic, preferably metal. Preferably, the bolt, the bolt-head and / or the bolt-body (including the at least two threaded elements, may be made of stainless steel.

[0102] The bolt may be provided with a first bolt-sealing. The first bolt-sealing may be provided in the outer periphery of the bolt-head, preferably, in the outer periphery of the bolt-head facing the nut, when the bolt and nut are assembled in the fastening device of the present invention. In a further embodiment of the present invention, the first bolt-sealing may be provided in the outer periphery of the bolt-head facing the same direction as the boltbody.

[0103] Preferably, the first bolt-sealing may be providing a sealing between the bolt-head and a frame, when the bolt and nut are assembled in the fastening device and secured to the frame.

[0104] The bolt may be provided with a second bolt-sealing. The second bolt-sealing may be provided in the inner periphery around a shaft insertion of the bolt-head, preferably, in the inner periphery of the a shaft insertion of the bolt-head facing the opposite direction of the bolt-body.

[0105] Preferably, the second bolt-sealing may be providing a sealing between the bolt-head and the shaft, when the shaft is inserted into the bolt. The bolt-head may comprise a first groove in the outer periphery of the bolt-head, preferably, in the outer periphery of the bolt-head facing the nut, when the bolt and nut are assembled in the fastening device of the present invention.

[0106] The first grove may be configured for receiving the first bolt-sealing.

[0107] The bolt-head may comprise a second groove in the inner periphery around a shaft insertion of the bolt-head, preferably, in the inner periphery of the a shaft insertion of the bolt-head facing the opposite direction of the bolt-body.

[0108] The second grove may be configured for receiving the second bolt-sealing.

[0109] A preferred embodiment of the present invention relates to a nut comprising an internal part and an external part, wherein either the internal part or the external part comprises a thread and a shoulder.

[0110] A preferred embodiment of the present invention relates to a nut comprising an internal part and an external part, the internal part comprises an internal thread and an internal shoulder.

[0111] The shoulder, e.g. the internal shoulder, may be engaging with the protrusion of the bolt (from the bolt-body) when the bolt and the nut according to the present invention are assembled in the fastening device.

[0112] The nut according to the present invention may comprise a nut front-part facing the bolt when assembled in the fastening device, and a nut back-part facing away from the bolt when assembled in the fastening device.

[0113] The shoulder, e.g. the internal shoulder, according to the present invention may have a diameter which is smaller than the diameter of the diameter of the internal thread.

[0114] In an embodiment of the present invention, the diameter of the shoulder, e.g. the internal shoulder, may be in the range of 70-95% of the diameter of internal thread of the nut of the present invention, such as in the range of 75-93%, e.g. in the range of 91-80, such as in the range of 85-90%, e.g. about 88%.

[0115] In an embodiment of the present invention the shoulder, e.g. the internal shoulder, comprises a flat plateau. The flat plateau of the shoulder of the nut may be provided in order to provide an even engagement, irrespective of how much the nut may be tightened when assembled with the protrusion of the bolt (from the bolt-body) when the bolt and the nut according to the present invention may be assembled in the fastening device.

[0116] Hence, shoulder may have the same diameter over the entire flat plateau.

[0117] The radial surface of the shoulder, e.g. the internal shoulder, and / or the longitudinal surface of the shoulder, e.g. the internal shoulder, may comprise a flat plateau.

[0118] In an embodiment of the present invention the shoulder, e.g. the internal shoulder may comprise a chamfering edge.

[0119] The chamfering edge on the nut may improve the interaction and / or alignment between the protrusion provided on the bolt and the shoulder of the nut.

[0120] The nut according to the present invention may be either an open nut or a closed nut. An open nut may be a nut having an open bottom providing an entry point into or through the fastening device, and e.g. into the shaft when introduced into the nut and bolt.

[0121] The entry point may provide an access for an electrical wire providing electricity, signal(s) from one or more sensors, or the like, from one side of the fastening device to the other side.

[0122] In an embodiment of the present invention the nut may be provided with a nut-sealing. The nut sealing may be provided in the outer periphery of the external surface facing the bolt, when the bolt and nut are assembled and providing the fastening device of the present invention.

[0123] The nut according to the present invention may be provided with a third groove in the outer periphery of the external surface facing the bolt, when the bolt and nut are assembled and providing the fastening device of the present invention.

[0124] Preferably, the third groove is configured for receiving the nut-sealing.

[0125] In an embodiment to the present invention the internal thread may constitute in the range of 25-80% of the internal part of the nut, such as in the range of 30-75%, e.g. in the range of 45-70%, such as in the range of 55-65%, e.g. about 60%. The internal shoulder may represent in the range of 5-70% of the internal part of the nut, such as in the range of 15-60%, e.g. in the range of 25-50%, such as in the range of 35- 45%, e.g. about 40%.

[0126] In an embodiment according to the present invention the nut may be made of metal or plastic, preferably metal. Preferably, the nut may be made of stainless steel.

[0127] The nut may comprise two or more holding-surfaces for allowing suitable holding tools to hold securely when the nut needs to be tightened or loosened. Suitable holding tools to tighten or loosen the nut may be a wrench, a plier, spanner, or the like.

[0128] A preferred embodiment of the present invention relates to a fastening device comprising a bolt according to the present invention and a nut according to the present invention.

[0129] Preferably, the fastening device according to the present invention comprises a bolt as described in the present invention and a nut as described in the present invention, and wherein the internal thread of the nut is configured to interact with the at least two threaded elements of the bolt-body.

[0130] The fastening device according to the present invention comprises a bolt as described in the present invention and a nut as described in the present invention, and wherein the at least two threaded elements of the bolt-body is configured to interact with the internal thread of the nut.

[0131] Preferably, the fastening device according to the present invention comprises a bolt as described in the present invention and a nut as described in the present invention, and wherein the protrusion of the bolt-body is configured to interact with the shoulder, e.g. the internal shoulder, of the nut.

[0132] The fastening device according to the present invention comprises a bolt as described in the present invention and a nut as described in the present invention, and wherein the shoulder, e.g. the internal shoulder, of the nut is configured to interact with the protrusion of the bolt-body.

[0133] The interaction between the protrusion of the bolt-body and the shoulder, e.g. the internal shoulder, of the nut may result in a movement, preferably a slight movement, of the at least two threaded elements towards the centre of the bolt-body. The fastening device according to the present invention consists essentially of a bolt as described in the present invention and a nut as described in the present invention.

[0134] In the context of the present invention, the term "consists essentially of", relates to a limitation of the scope of a feature or a claim to the specified features or steps, and those features or steps, not mentioned and which do not materially affect the basic and novel characteristic(s) of the claimed invention.

[0135] A preferred embodiment of the present invention relates to a drive unit comprising a rotating element, a shaft and a fastening device according to the present invention.

[0136] The shaft may comprise engagement surfaces allowing the shaft to be fixed in a frame to avoid rotation of the shaft.

[0137] Preferably, the shaft comprises two or more engagement surfaces.

[0138] The drive unit may be an active drive unit or an inactive drive unit.

[0139] The active drive unit may comprise a rotating element that generates movement, preferably rotating movement, from an electrical motor placed in the drive unit, e.g. activated by electrical energy provided to the drive unit.

[0140] The inactive drive unit may comprise a rotating element that does not generate movement by itself, but moves as a consequence of a movement of a coupled moving unit, e.g. an active drive unit.

[0141] In an embodiment of the present invention the drive unit and / or the rotating element may be a drum motor.

[0142] The rotating element may be an active rotating element, preferably, the active rotating element may be an electrical motor.

[0143] As the active rotating element, e.g. the electrical motor, like a drum motor, may need electricity, an open nut according to the present invention may be provided in one end of the active rotating element and, preferably, a closed nut may be provided in the other end.

[0144] Preferably, an electrical wire sealing may be provided in the space between the open nut and the electrical wire, optionally using an intermediate open bolt (different from the bolt of the present invention). The electrical motor, in particular the drum motor may be an asynchronous electrical motor, or a synchronous electrical motor. The choice of motor type may depend on the specific requirements of an application.

[0145] Preferably, the electrical motor, in particular the drum motor, according to the present invention may be a synchronous electrical motor.

[0146] A drum motor may be a compact, totally enclosed single component drive unit with high efficiency and lower frictional losses compared to a conventional geared motor. The drum motor may be a geared motor drive enclosed within a steel shell providing a single component driving pulley, in particular for use in conveyor belts.

[0147] The drive unit according to the present invention may be configured for use in environments with high hygienic requirements. The drive unit according to the present invention may be configured for use in the food or feed industry, in the beverage industry, or in the pharmaceutical or medical industry.

[0148] The fastening device according to the present invention or the drive unit according to the present invention may be used for various purposes, however, application under high hygienic requirements, e.g. in the food or feed industry, in the beverage industry, or in the pharmaceutical or medical industry may be the primary purpose, since the accumulation of dirt, grime, microbial material (such as bacteria or fungus), or other fouling materials (e.g. allergens), may be hindered or prevented, as opposed to conventional drive units.

[0149] The drive unit according to the present invention may comprise a cylindrical shell having a first end-plate and a second end-plate (placed at each end of the cylindrical shell) and a shaft going through the first end-plate and a shaft going through the second end-plate.

[0150] The shaft going through the first end-plate and the shaft going through the second endplate may be the same shaft or the shaft going through the first end-plate may be a different shaft than the shaft going through the second end-plate.

[0151] In the drive unit the first shaft and the second shaft may be held by a bearing allowing rotation of the drive unit, in particular of the cylindrical shell, while the shaft(s) are kept immobile (when fixed, e.g. to a frame).

[0152] In the event the drive unit comprises an active rotating element, the shaft(s) may be connected to an electrical motor responsible for moving the active rotating element. In an embodiment of the present invention the drive unit comprises a cylindrical shell having a first end-plate and a second end-plate and a shaft going through the first endplate and a shaft going through the second end-plate, wherein the first and / or the second end plate(s) comprises at least one recess for receiving an end-plate tool.

[0153] The end-plate tool may be a device capable of providing a firm grip on the first end-plate and / or second end-plate to relieve the first end-plate and / or the second end-plate from the cylindrical shell, or to attach the first end-plate and / or the second end-plate from the cylindrical shell.

[0154] The cylindrical shell may preferably comprise an interference fit and / or a thread (either an inside thread or an outside thread). Preferably, the cylindrical shell may have open ends.

[0155] In an embodiment of the present invention the interference fit may include a hole at the ends of the cylindrical shell which may be little too small and at least one end-plate which may be a little too large in diameter, relative to the hole of the cylindrical shell. The at least one end-plate may be placed in the hole of the ends of the cylindrical shell, using force whereby the two parts are pressed together causing them to get stuck.

[0156] The first end-plate may be placed in one end of the cylindrical shell and the second endplate may be placed in the other end of the cylindrical shell.

[0157] The first end-plate and / or the second end-plate may comprise an inside thread facing the centre of the end-plate or an outside thread facing away from the centre of the end-plate. Preferably, the first end-plate and / or the second end-plate may comprise an inside thread facing the centre of the end-plate.

[0158] Both the first end-plate and / or the second end-plate may comprise an end-plate sealing which is placed in the space between the outer periphery of the first end-plate and / or the second end-plate, and the end of the cylindrical shell.

[0159] The first end-plate and / or the second end-plate may comprise a glide sealing between the first end-plate and / or the second end-plate and the shaft(s).

[0160] In an embodiment of the present invention the glide sealing may comprise a lip seal.

[0161] The lip seal according to the present invention may preferably provide a resilient contact with shaft(s). The lip seal may have a negative curvature construction or a neutral curvature construction relative to the glide sealing.

[0162] The recess provided in the first and / or the second end plate(s) may have a depth in the range of 2-30 mm, such as in the range of 3-25 mm, e.g. in the range of 4-20 mm, such as in the range of 5-18 mm, e.g. in the range of 7-17 mm, such as in the range of 10-15 mm.

[0163] Preferably, the recesses may be formed as a circular cavity. Preferably, the recesses are not provided for introducing fastening means, like a screw or a bolt, or the like. This allows for a further hygienic improved of the drive unit according to the present invention, since the recess becomes easier to inspect, easier to clean and the risk of deposit or accumulation of dirt, grime, microbial material, or allergens, may be reduced or even avoided.

[0164] A preferred embodiment of the present invention relates to a system comprising a fastening device according to the present invention, or a drive unit according to the present invention.

[0165] The system comprises a frame comprising at least one fastening device according to the present invention and / or a drive unit according to the present invention.

[0166] In an embodiment of the present invention the frame of the system may comprise multiple fastening devices according to the present invention and / or multiple drive units according to the present invention.

[0167] Preferably, the system comprises a combination of one or more active drive unit and one or more inactive drive unit. In an embodiment of the present invention the system comprises at least 5 inactive drive units per active drive unit, such as at least 7 inactive drive units per active drive unit, e.g. at least 10 inactive drive units per active drive unit, such as at least 12 inactive drive units per active drive unit, e.g. at least 15 inactive drive units per active drive unit, such as at least 17 inactive drive units per active drive unit, e.g. at least 20 inactive drive units per active drive unit, such as at least 25 inactive drive units per active drive unit, e.g. at least 35 inactive drive units per active drive unit, such as at least 50 inactive drive units per active drive unit, e.g. at least 75 inactive drive units per active drive unit, such as at least 90 inactive drive units per active drive unit, e.g. at least 100 inactive drive units per active drive unit. The system may be a conveyer belt, preferably a conveyer belt to be used in areas having high hygienic requirements, like the food or feed industry, the beverage industry, and / or the pharmaceutical industry.

[0168] One or more bolt-body openings may be configured to match one or more engagement surfaces of a shaft.

[0169] The one or more engagement surfaces of a shaft may engage with a grabbing means on a frame. The grabbing means may be configured as a slit forming a trail capable of embracing the one or more openings of the bolt-body and / or the one or more engagement surfaces of the shaft.

[0170] In an embodiment of the present invention the one or more engagement surfaces of the shaft may be located in continuation of the thread, preferably the outside thread, of the at least two threaded elements, when the shaft may be installed in the bolt according to the present invention. Continuation of the thread, preferably continuation of the outside thread, of the at least two threaded elements may be the longitudinal continuation of the path of the thread of the at least two threaded elements.

[0171] To further improve the hygienic effect of the fastening device, when fixed to a frame, a supportive plug may be provided. The supportive plug may be placed on the part of the bolt-body not covered by the frame. Preferably, the supportive plug may be placed on the threaded part of the bolt-body not covered by the frame.

[0172] In an embodiment of the present invention the drive unit may when placed in the slit of the frame comprise a part of the bolt-body that is not in contact with the frame and where the nut and bolt are not in contact with the frame.

[0173] A supportive plug may be used in these areas where the fastening device and the fare are not in contact.

[0174] Preferably, the supportive plug may be configured according to the thickness of the frame and / or the size of the slit.

[0175] In one embodiment of the present invention the fastening device may be placed at the end of the slit of the frame and a single supportive plug may be used at the end of the fastening device not in contact with the frame. Preferably, the supportive plug according to the present invention may be covering at least part of the thread of the bolt-body.

[0176] In another embodiment of the present invention the fastening device may be placed between the end of the slit of the frame and the start of the slit, and two supportive plugs may be used.

[0177] Preferably, when two supportive plugs are used a first supportive plug may be placed towards the end of the slit and preferably covering at least part of the thread of the boltbody and the part of the fastening device not in contact with the frame.

[0178] Preferably, when two supportive plugs are used a second supportive plug may be placed towards the start of the slit and preferably covering at least part of the thread of at boltbody and the part of the fastening device not in contact with the frame.

[0179] The supportive plug may act like a sealing and / or may provide at plug surface suitable for interacting with the nut-sealing and / or the first bolt sealing to provide a sealing, preferably a hygienic sealing, reducing or avoiding accumulation of dirt, grime, microbial material (such as bacteria or fungus), or other fouling materials (e.g. allergens).

[0180] The sealings provided by the present invention (in particular the first bolt-sealing, the second bolt-sealing and / or the nut sealing) may be configured with contours which are adapted to the structure of the surfaces connected or elements connected and thereby substantially ensure a continuous or substantially continuous surface in the joints between surfaces or elements connected, resulting in that dirt, grime, microbial material (such as bacteria or fungus), or other fouling materials (e.g. allergens), may be hindered or prevented from hiding and / or accumulating.

[0181] The seal or sealings according to the present invention may be prepared from a non- conductive material. The seal, sealings or conductive material may be silicone. Preferably, the seal or sealings may be prepared from soft silicone. Preferably, the seal has a blue color, preferably RAL 5010, which provides an improved visual inspection of the hygienic level and / or cleaning quality.

[0182] In an embodiment of the present invention the seal comprises a polymer material, preferably the seal comprises essentially a polymeric material.

[0183] The seal according to the present invention may preferably be provided in a one-piece material. In an embodiment of the present invention the polymeric material may comprise an organic compound. The organic compound may comprise an inert organic compound.

[0184] Preferably the polymer material comprises an olefin compound. The olefin compound may be formed like a fiber compound. Preferably the olefin compound may comprise polypropylene, polyethylene or a combination of polypropylene and polyethylene.

[0185] Preferably the seal comprises at least 10% organic compound; such as at least 20%; e.g. at least 30%; such as at least 40%; e.g. at least 50%; such as at least 75%; e.g. at least 80%; such as at least 90%; e.g. at least 95%.

[0186] The seal comprises less than 30% non-organic material; such as less than 20%; e.g. less than 10%; such as less than 5%; e.g. less than 3%; such as less than 1%.

[0187] Non-organic material may include metals, like steel, iron, silicate, or ceramics.

[0188] In an embodiment of the present invention the seal may comprise a Young modulus (or the modulus of elasticity in tension) in the range of 0.1-400 Mpa; such as in the range of 0.5-300 Mpa; e.g. in the range of 1-200 Mpa; such as in the range of 1.5-100 Mpa; e.g. in the range of 2-75 Mpa; such as in the range of 2-50 Mpa; e.g. in the range of 2.5-25 Mpa; such as in the range of 3-20 Mpa; e.g. in the range of 4-15 Mpa; such as in the range of 5- 10 Mpa; e.g. in the range of 7-9 Mpa, such as about 8 Mpa.

[0189] If the Young modulus (or the modulus of elasticity in tension) becomes too low, such as below 0.1 MPa, it may be difficult to maintain the shape of the seal. If the Young modulus (or the modulus of elasticity in tension) becomes too high, such as above 400 MPa the desired elasticity of the seal may be lost.

[0190] Young modulus (or the modulus of elasticity in tension) may relate to a measure of the ability of a material to withstand changes in length when under lengthwise tension or compression.

[0191] The coefficient of thermal expansion describes how the size of an object changes with a change in temperature. Specifically, it measures the fractional change in size per degree change in temperature at a constant pressure, such that lower coefficients describe lower propensity for change in size.

[0192] In an embodiment the seal comprises a moisture absorption less than 1% (w / w); such as less than 0.9% (w / w); e.g. less than 0.8% (w / w); such as less than 0.7% (w / w); e.g. less than 0.6% (w / w); such as less than 0.5% (w / w); e.g. less than 0.4% (w / w); such as less than 0.3% (w / w); e.g. less than 0.2% (w / w); such as less than 0.1% (w / w).

[0193] Moisture absorption as used in the present context relates to the capacity of the seal to absorb moisture from its environment. Absorbed moisture has been shown to act as a plasticizer, reducing the glass transition temperature and strength of plastic - which is a reversible effect.

[0194] In an embodiment of the present invention the seal comprises a moisture absorption in the range of 0.01-1% (w / w); such as in the range of 0.02-0.9% (w / w); e.g. in the range of 0.03-0.8% (w / w); such as in the range of 0.04-0.7% (w / w); e.g. in the range of 0.05- 0.6% (w / w); such as in the range of 0.06-0.5% (w / w); e.g. in the range of 0.07-0.4% (w / w); such as in the range of 0.08-0.3% (w / w); e.g. less than 0.09-0.2% (w / w); such about 0.1% (w / w)]

[0195] In a further embodiment of the present invention the seal comprises a max strain of at least 1%; such as at least 2%; e.g. at least 3%; such as at least 4%; e.g. at least 5%.

[0196] The max strain of the seal may relate to the maximum stress necessary in order to provide permanent or irreversible deformation of the seal.

[0197] In an embodiment of the present invention the seal may, when subjected to a constant stress resulting in a strain of 2%, at 20°C for at most 6 hours, provide at most 50% extension relative to the stain of 2%, such as at most 30%; such as at most 25%; e.g. at most 20%. Preferably, the seal may within 7 days in relax from the stress applied resume to at most 1% extension relative to the stain of 2%, such as at most 0.75%; such as at most 0.5%; e.g. at most 0.25%.

[0198] The seals (3) is prepared from a non-conductive soft silicone material. With a blue color, RAL 5010, which provides an improved visual inspection of the hygienic level and / or cleaning quality.

[0199] The sealings providing according to the present invention may assist in providing a bolt, a nut, a fastening device, a drive unit and a system being waterproof or substantially water proof and a hygienic bolt, a hygienic nut, a hygienic fastening device, a hygienic drive unit and a hygienic system by blocking entry and accumulation of water, dirt and microorganisms. The bolt, the nut, the fastening device, the drive unit and / or the system may be made in a metal material or a sturdy polypropylene material and the surface of the bolt, the nut, the fastening device, the drive unit and / or the system may be made smooth to allow drainage of water from the surface. The surface of the bolt, the nut, the fastening device, the drive unit and / or the system may have a roughness below Ra 4.0 pm, such as below 3.8 pm e.g. below 3.6 pm, such as below 3.4 pm e.g. below 3.0 pm, such as below 2.5 pm, e.g. below Ra 2.0 pm; such as Ra 1.8 pm; e.g. Ra 1.6 pm; such as Ra 1.4 pm; e.g. Ra 1.2 pm; such as Ra 1.0 pm; e.g. Ra 0.8 pm; such as Ra 0.6 pm; e.g. Ra 0.4 pm.

[0200] In an embodiment of the present invention all exposed surfaces of the bolt, the nut, the fastening device, the drive unit and / or the system may have a smooth finish such that dirt, grime, microbial material (such as bacteria or fungus), or other fouling materials, such as allergens, may be cleaned from the surface.

[0201] Preferably, the bolt, the nut, the fastening device, the drive unit and / or the system according to the present invention may be free of joints, pits, folds, cracks, crevices, and other imperfections in the final fabricated form, when installed on the machinery and / or when working within the specified load conditions.

[0202] Preferably, none of the exposed surfaces of the bolt, the nut, the fastening device, the drive unit and / or the system according to the present invention comprising knurled surfaces.

[0203] All the exposed surfaces of the bolt, the nut, the fastening device, the drive unit and / or the system according to the present invention may preferably be cleanable.

[0204] All the exposed surfaces of the bolt, the nut, the fastening device, the drive unit and / or the system according to the present invention may preferably be inspectable.

[0205] In the context of the present invention the terms "surface" and "exposed surface" may be used interchangeably and relates to any surface that may be accessible to dirt, grime, microbial material (such as bacteria or fungus), or other fouling materials, such as allergens.

[0206] In an embodiment of the present invention all the exposed surfaces of the bolt, the nut, the fastening device, the drive unit and / or the system according to the present invention may be self-draining. In a further embodiment of the present invention the bolt, the nut, the fastening device, the drive unit and / or the system comprises no surfaces which has one or more pockets which may retain liquids. In the context of the present invention, the term "self-draining" relates to a surface constructed, designed and / or fabricated in a manner allowing aqueous suspension, such as aqueous cleaning suspension, like water, to escape and / or leaving the surface.

[0207] In a preferred embodiment cleaning of the bolt, the nut, the fastening device, the drive unit and / or the system may be by manual cleaning. During manual cleaning, removal of dirt, grime, microbial material, or other fouling materials may be affected by an aqueous suspension, e.g. chemical and / or water rinses, optionally with the assistance of one or a combination of brushes, non-metallic scouring pads and scrapers. Rinses may be performed by high- or low-pressure hoses, and / or with cleaning aids manipulated by hand.

[0208] In order to limit accumulation and / or growth of dirt, grime, microbial material or other fouling materials on the exposed surfaces of the bolt, the nut, the fastening device, the drive unit and / or the system and to improve drainage of aqueous suspension, e.g. water, from the surface, the surface of the bolt, the nut, the fastening device, the drive unit and / or the system may be a smooth surface.

[0209] In an embodiment of the present invention the surface of the bolt, the nut, the fastening device, the drive unit and / or the system may be smooth. Preferably, the smooth surface of the bolt, the nut, the fastening device, the drive unit and / or the system may allow drainage, preferably self-drainage, of liquids from the surface.

[0210] Smoothness of the exposed surface of the bolt, the nut, the fastening device, the drive unit and / or the system according to the present invention may be determined by the "Roughness Average (Ra)". Roughness Average or Ra is an arithmetical mean of the absolute values of the surface profile departure within a sampling length. In the context of the present invention the roughness (Ra) of the surface of the bolt, the nut, the fastening device, the drive unit and / or the system may be determined according to the ISO 4287: 1997 standard.

[0211] Preferably the surface of the bolt, the nut, the fastening device, the drive unit and / or the system according to the present invention may comprise all the exposed surfaces of the bolt, the nut, the fastening device, the drive unit and / or the system.

[0212] The surface of the bolt, the nut, the fastening device, the drive unit and / or the system may have a roughness below Ra 2.0 pm; such as Ra 1.8 pm; e.g. Ra 1.6 pm; such as Ra 1.4 pm; e.g. Ra 1.2 pm; such as Ra 1.0 pm; e.g. Ra 0.8 pm; such as Ra 0.6 pm; e.g. Ra 0.4 pm. Preferably, the bolt, the nut, the fastening device, the drive unit and / or the system according to the present invention comprises no exposed surfaces; ledges and / or edges which are horizontal.

[0213] In an embodiment of the present invention the bolt, the nut, the fastening device, the drive unit and / or the system all exposed surfaces; ledges and / or edges are curvilinear or curved.

[0214] In order to ensure high drainage effect at least one of the exposed surfaces; ledges and / or edges, preferably all exposed surfaces; ledges and / or edges, may have an angle, may be founded or has a slope relative to horizontal.

[0215] In an embodiment the present invention at least one of the exposed surfaces; ledges and / or edges of the bolt, the nut, the fastening device, the drive unit and / or the system, preferably all exposed surfaces; ledges and / or edges, may have a radius of 1 mm or above improving water runoff from at least one of the exposed surfaces, preferably all the exposed surfaces; ledges and / or edges; such as a radius of 2 mm or above; e.g. a radius of as 3 mm or above, such as a radius of 3.2 mm or above; e.g. a radius of 3.5 mm or above; such as a radius of 4 mm or above, e.g. 5 mm or above.

[0216] Preferably no exposed surfaces; ledges and / or edges having an internal radius below 3.2 mm; such as below 3 mm; e.g. below 2.5 mm; such as below 1 mm; e.g. below 0.8 mm.

[0217] The internal radius may be an angle between two faces may be less than 180 degrees.

[0218] In an embodiment of the present invention all the exposed surfaces; ledges and / or edges may have an angle, may be founded or has a slope of at least 3 degrees relative to horizontal; e.g. 3.2 degrees or above relative to horizontal, such as 3.5 degrees or above relative to horizontal; e.g. 3.75 degrees or above relative to horizontal; such as 4 degrees or above relative to horizontal, e.g. 5 degrees or above relative to horizontal.

[0219] In an embodiment of the present invention the exposed surfaces, ledges and / or edges of the bolt, the nut, the fastening device, the drive unit and / or the system may be constructed, designed and / or fabricated in accordance with national standards and / or directives, like one or more of:

[0220] • EN 1672-2:2005 Food machinery I General design principles / Part 2: Hygiene requirements. • EN ISO 14 159 2004 Safety of machinery - Hygiene requirements for the design of machinery.

[0221] • Document 13 EHEDG guideline on the hygienic design of apparatus for open processes.

[0222] • EHEDG Class I: The hygienic design criteria evaluation report concludes that the designs meet the criteria for hygienic equipment class I for components situated in the non-food area and are accessible for easy cleaning without dismantling.

[0223] • 3-A sanitary standard for machine levelling feet and supports.

[0224] • USDA Guidelines for the sanitary design and fabrication of dairy processing equipment June 2001. and / or national regulations, such as one or more of:

[0225] • 852 / 2004 on the hygiene of foodstuffs.

[0226] • 853 / 2004 specific hygiene rules for food of animal origin.

[0227] • 854 / 2004 specific rules for the organization of official controls on products of animal origin intended for human consumption.

[0228] • 1935 / 2004 on materials and articles intended to come into contact with food.

[0229] It should be noted that embodiments and features described in the context of one of the aspects of the present invention also apply to the other aspects of the invention.

[0230] References

[0231] 1 : Bolt 19 : Nut front part

[0232] 2: Bolt-head 20 : Nut back part

[0233] 3: Shaft insertion 21 : Shoulder flat plateau

[0234] 4: Bolt-body 22 : Third groove

[0235] 4a / 4b: at least two threaded elements 23 : First bolt-sealing

[0236] 5: Continued shaft insertion 24: Second bolt-sealing

[0237] 6: Protrusion 25a: First un-threaded part

[0238] 7: Distal end 25b: Second un-threaded part

[0239] 8: Proximal end 26: Nut-sealing

[0240] 9: middle section 27: Drive unit

[0241] 10: Bolt-body openings 28: cylindrical shell

[0242] 11 : Engagement surfaces on the shaft 29: End-plate

[0243] 12: First groove 30 : Recess

[0244] 13 : Second Grove 31 : End-plate sealing

[0245] 14: Nut 32 : Glide sealing

[0246] 15: Internal part 33 : Holding surfaces

[0247] 16: External Part 34: Grapping means

[0248] 17: Internal shoulder 35: Slit

[0249] 18: Internal thread 36: Frame

[0250] 37: Shaft

Claims

Claims1. A bolt comprising a bolt-head and a bolt-body extending in substantially perpendicular direction from the bolt-head, the bolt-body comprising at least two threaded elements extending in substantially perpendicular direction from the bolt-head, the at least two threaded elements comprise a distal end, a proximal end connected to the bolt-head and a middle section comprising the thread of the threaded elements, wherein the middle section of the at least two threaded elements comprises in the range of 20-90% of the middle section of the threaded elements comprises a thread.

2. A bolt (1) comprising a bolt-head (2) having a shaft insertion (3), and a bolt-body (4) extending in perpendicular direction from the bolt-head (2) and forming a continued shaft insertion (5), the bolt-body (4) comprising at least two threaded elements (4a / 4b) extending in substantially perpendicular direction from the bolt-head (2), wherein the at least two threaded elements (4a / 4b) are placed around part of the continued shaft insertion (5) of the bolt-body (4), the at least two threaded elements comprise a distal end, a proximal end connected to the bolt-head and a middle section comprising the thread of the threaded elements, wherein the middle section of the at least two threaded elements comprises in the range of 20-90% of the middle section of the threaded elements comprises a thread.

3. The bolt (1) according to anyone of claims 1-2, wherein the middle section of the at least two elements comprise a first non-threaded part in the area between the proximal end connected to the bolt-head and the threaded part and / or the middle section of the at least two elements comprises a second non-threaded part in the area between the distal end and the threaded part.

4. The bolt (1) according to claim 3, wherein the first non-threaded part and / or the second non-threaded part has a wall thickness which is smaller than the wall thickness at the threaded part.

5. The bolt (1) according to anyone of the preceding claims, wherein the bolt-body (4) may comprise at least two outside threaded elements (4a / 4b) or at least two inside threaded elements (4c / 4d).

6. The bolt according to anyone of the preceding claims, wherein the bolt-body is provided with a protrusion (6) in the distal end (7) of the bolt-body (4) relative to the bolt-head (2).

7. A nut comprising an internal part and an external part, wherein either the internal part or the external part comprises a thread and a shoulder.

8. The nut according to claim 7 comprising an internal part and an external part, the internal part comprises an internal thread and an internal shoulder.

9. The nut according to anyone of claims 7-8, wherein the shoulder comprises a flat plateau.

10. The nut according to anyone of claims 7-9, wherein the shoulder comprises a chamfering edge.

11. A fastening device comprising a bolt according to anyone of claims 1-6 and / or a nut according to any one of claims 7-1012. A drive unit comprising a rotating element, a shaft and a fastening device according to claim 11.

13. The drive unit according to claim 12, wherein the drive unit is a drum motor.

14. The drive unit according to anyone of claims 12-13, wherein the drive unit comprises a cylindrical shell having a first end-plate and a second end-plate and a shaft going through the first end-plate and a shaft going through the second end-plate, wherein the first and / or the second end plate(s) comprises at least one recess for receiving an end-plate tool.

15. A system comprising a fastening device according to claim 11, or a drive unit according to anyone of claims 12-14.

16. Use of a fastening device according to claim 11, or a drive unit according to anyone of claims 12-15, for use in environments with high hygienic requirements, high cleaning requirements and / or environments where low (or no) deposit or accumulation of dirt, grime, microbial material and / or allergens is accepted.

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