WO2017050337A1

WO2017050337A1 - Protection against contamination of an opening, distance piece and method for protection against contamination of an opening

Info

Publication number: WO2017050337A1
Application number: PCT/DK2016/050290
Authority: WO
Inventors: Toms Hecht OLSEN; Jan NYGAARD
Original assignee: Ngi A/S
Priority date: 2015-09-21
Filing date: 2016-08-30
Publication date: 2017-03-30
Also published as: DK179015B1; DK201570599A1

Abstract

Prevention of contamination of an opening in an exterior surface on an elongated machine part (2). According to the invention, a flexible continuous circumferential band (3)is placed across the opening and towards the exterior surface, whereby the band either covers the opening, secures a plug in the opening or has been produced as a single piece with a plug that fits in, the opening in an interlocking manner.

Description

Protection against contamination of an opening, distance piece and method for protection against contamination of an opening

The invention relates to a safety system to prevent contamination of an opening in an exterior surface on an elongated machine part. The machine part surface must form a closed curve around a longitudinal axis so that a continuous band can be used to enclose the machine part at a level that is perpendicular to the longitudinal axis. Food, pharmaceutical and feed production plants have especially stringent requirements for high hygiene standards. WO2014075678 (A1 ) proposes the use of ball-shaped plug elements inserted in spherical recesses in the opening, but there is a risk that the plug elements may be flushed out of the recesses; this prior art, therefore, does not have the necessary approvals. The purpose of the invention is to provide protection that can be authorised in accordance with 3A and EHEDG standards while also being easy to use without significantly increasing costs.

This is achieved by placing a flexible continuous circumferential band across the opening and towards the exterior surface, whereby the band either covers the opening, secures a plug in the opening or has been produced as a single piece with an interlocking plug in the opening. The elongated machine part may be cylindrical, either with a circular or non- circular cross-section, transverse to the longitudinal axis, or as a square or oval tube. The continuous circumferential band should fit around the elongated machine part and provide a force that wraps around the entire opening. There must be compressive stress, not least in the material transition between the band material and the machine part material, so that foreign objects cannot enter here and are held between the band and the machine part. For further protection of the circumferential band, and in accordance with claim 2, the band is placed in a groove which extends around the machine part surface. Here, it is preferable for the groove to follow a generatrix of the machine part, extending transversely across the longitudinal axis, as this more effectively ensures that there is always compressive stress between the groove side walls and the contact surfaces of the circumferential band against the side walls.

In particular, it is preferred, as stated in claim 3, that the circumferential band has an axial extension, a radial thickness and a diameter size relative to the machine part and the opening, so that the material transition between the band material and the exterior surface of the machine part material always has compressive stress. This design ensures that both the circumferential band is well protected in the groove, so that it does not easily dislodge, and that it is also possible to establish a virtually smooth and seamless transition between the band and machine part, so that there are no crevices or recesses in which dirt can accumulate.

As specified in claim 4, it is preferable for the groove to be at least as wide in the axial direction as the diameter of the opening, across which the groove runs. At the same time, the groove must have a uniform depth. This ensures that the circumferential band has a contact surface at the bottom of the groove that runs all the way around the upper edge of the opening. Furthermore, the uniform depth of the groove ensures that the band can also be made with uniform wall thickness in the radial direction so that it can be put on in arbitrary rotation relative to the exterior surface of the machine part and that always still effectively cover all holes.

As specified in claim 5, it is further preferred that the groove be formed across the opening, with the centre of the opening centred relative to the groove extension in the axial direction. This ensures that the band has a contact surface around the entire opening at the bottom of the groove, and avoids any skew in which parts of the band slip down into the opening, for example.

The invention also provides a distance piece with two ends that includes a fastener element for a machine or other equipment at one end, and a foot adapted for contact pressure against a fixed part on the other end, and where the distance between the fastener element and the foot can be adjusted using a force-transmitting mechanism comprising an outer cylindrical part. Distance pieces of this nature are well-known and are often referred to as "machine feet", as the foot is usually adapted to abut against a level surface such as a floor. It is common to aim to ensure that the distance-regulating mechanism meets high hygiene requirements, e.g. by ensuring that there is no external access to threads or other crevices in which bacteria-filled material can accumulate. To protect openings, such as continuous threaded holes in an exterior cylindrical sleeve element of such a machine foot, the invention proposes the use of a circumferential band as specified above. Such protection extends the usage possibilities of this type of machine feet or distance pieces, which can now be authorised for use in the pharmaceutical industry, in food production and the production of animal feed.

As specified in claim 7, the distance piece has a threaded hole in the cylindrical outer machine element, and a pointed screw has been installed in the threaded hole so that the cylindrical machine part can be secured against unwanted movement both rotationally and axially.

As specified in claim 8, it is preferable that the circumferential band is made from relatively resilient rubber elastic with a predefined hardness of around 60 pts and a relatively low tensile strength of no less than 4 MPa. These parameters will guarantee a circumferential band that is very flexible, that can be easily installed or removed from the cylindrical machine element, and that it is also easy to make the band slide into the groove during installation by having a groove along the machine element surface.

In an alternative design of the distance piece, the band is made of a material that cannot be removed following initial installation. This ensures that a new band is always added in the event of changes, and that in the event of attempts to modify the distance piece after installation, there will be a visible marker showing that an intervention has taken place, at least until a new band is added to the distance piece.

The invention also relates to a safety system process to prevent contamination of an opening in an exterior surface on a cylindrical machine part. The process is unique as it has a flexible continuous band installed around the machine part that either secures a plug in the opening, that connects to a plug in the opening or that completely covers the opening, thereby establishing a force-locking contact between the machine part surface and the band. The force-locking contact between the machine part and the circumferential band ensures that cavities and crevices do not occur between the belt contact surface and the surface of the machine part. If, for example, flexible band materials such as Silicon Rubber 60 Shore A, Compound S6002F are used, it will be easy to size the circumferential band so that, during contact with the cylindrical exterior surface of the machine part, stretching will always occur with an elongation percentage of no more than the ultimate elongation of the material, which can be said to be >150% in accordance with test method D412 and, in turn, is extended by at least 3%, preferably at least 4-6% in addition to the tension-free neutral state.

The invention will now be explained in more detail with reference to the drawings, in which: Fig. 1 shows an enlarged cross-section of a piece of tape placed in a groove across an opening according to the invention.

Fig. 2 shows a frontal view of the entire machine foot from which the section in Fig. 1 has been taken.

Fig. 3 shows a section corresponding to Fig. 1 but from a machine foot with a slightly different design.

Fig. 4 is the frontal view of the entire machine foot from which the section in

Fig. 3 has been taken.

Fig. 5 is an example of prior art in the field.

Fig. 6A-Fig. 6D are images illustrating how the band is installed in the groove

Fig. 7 A and Fig. 7B are images illustrating how the band is removed.

It has been noted that in various embodiments of the invention, subjects that differ in appearance have the same reference number in so far that they perform substantially the same function in the context of the invention.

Fig. 5 shows an example of a safety system to prevent the contamination of an opening (12) in accordance with the prior art. Here, (2) refers to a cylindrical machine part. In the exterior surface of the machine part, there are openings (12) in the form of screw holes. For protection against contamination of the holes with e.g. bacteria-containing substances, spherical plugs (6) have been inserted therein. The plugs are designed so that they can easily be pushed into the spherical cavities established furthest out towards the cylindrical machine (2) part's surface and with an opening against the surface that is somewhat smaller than the largest diameter of the spherical cavity. The spherical plugs (6) can be removed with manual force. However, it has been found that such plugs are considered to be at risk of either being knocked out or flushed out of the spherical cavity during normal use, e.g. in food production, pharmaceutical production or other forms of production for which bacterial contamination must be managed. Such a plug, which has been inadvertently removed from its cavity involves several safety challenges: 1 ) the cavity and opening (12) are left unprotected against any bacteria-filled substances that could get lodged there; and 2) the spherical plug (6) is a safety issue, as it could become a foreign object in food, feed or medicine.

Fig.1 shows a safety system to prevent contamination of an opening (12) in accordance with the invention. In the exterior surface (1 ) on a cylindrical machine part (2), there is a flexible continuous circumferential band (3) placed over an opening (12).

In the illustrated example of the invention, the machine part is a circular cylinder, but non-circular cylinders or machine parts that are simply elongated and have a longitudinal axis are also the object of the invention as it simply requires that the machine part has an exterior surface that can be enclosed within a continuous band. If such a band can be installed on an elongated machine part's exterior surface, the band could cover and thereby protect openings in the surface of the machine part. The opening (12) faces the surface of the outer surface (1 ), and in the illustrated example, the band (3) also covers the opening (12). However, the band can also be placed across a plug of the type shown in Fig. 5, and secure the plug (6) in the opening. In another embodiment (not shown), the band (3) has been produced as a single piece with a plug that fits into the opening (12) in an interlocking manner so that the band (3) ensures that the plug remains in the opening (12). With these three invention uses, there will always be very clear signs of faults if the continuous band (3) is removed, in particular if the band has been designed with a clear colour contrast to the exterior surface of the machine part. Normally, the cylindrical machine part (2) is made from stainless steel of suitable quality for the level of chemical aggression in the environment. It is relatively easy to produce the continuous band (3) in a clear contrasting colour, such as blue, yellow or red. A quick glance can therefore determine whether all holes in a cylindrical machine part are adequately covered, including those situated on the rear of the machine part relative to the viewer, as the presence of the continuous band will indicate that the holes have been protected and no band will indicate inadequate protection.

As seen in Fig. 1 and Fig. 2, the machine part (2) has a circumferential groove (4) in its exterior cylindrical surface (1 ), and it has been designed exactly so that it will cover the opening (12). Here the band (3) is situated in the groove (4), and as illustrated in Fig. 1 , there will be a virtually unbroken transition between the exterior belt surface (5) and the exterior machine part surface (1 ). This ensures that the belt is not displaced along the exterior surface (1 ) and that the risk of the band being damaged in the event of random contact with moveable objects is low.

The exterior surface (1 ) can belong to any machine part that has openings to be protected, and the illustrated example in Fig. 1 and Fig. 2 has a cylindrical shape, but non-circular cylindrical machine parts and conical elements could also be used, e.g. square or oval tubes with radial openings or cone surfaces with radial openings could be protected in this way so that no foreign objects enter the openings.

In the example in Fig. 1 , the circular cylindrical machine part (2) is an exterior part of a machine foot or distance piece (10), where one part (9) of the distance piece (10) is installed in a machine (not shown), and the opposite end (8) comprises a foot (7) or holder that forms a support against the wall, ceiling, floor or a suspension for the machine when the machine foot is in use. This means that the continuous band cannot be removed from the distance piece (10) when it is in use, but can be pushed along the exterior cylindrical surface when the opening (12) needs to be accessible. This can be carried out, for example, by adjusting the screw (1 1 ) placed in an internal threading (1 3) in the opening ( 1 2).

It should be noted that the continuous circumferential band (3) has an axial elongation referred to as L, a radial thickness referred to as T and an interior diameter referred to as D, and these must be sized in proportion to one another so that the material transition ( 14) between the band material and the exterior machine part material always has compressive stress. Compressive stress is essential to prevent against foreign objects penetrating the two materials. If the band simply sits on the outside of the machine part (2) without a groove being provided, the most essential band dimension will be the interior diameter, and this requires the interior circumference of the band to not exceed the exterior circumference of the machine part (2). If the band is circular, cylindrical and in pristine condition, there will be a simple geometric correlation between the interior diameter of the band and the circumference along its inwardly facing surface.

The band (3) will typically be made from flexible rubber elastic material and will in practice always be cast as a circular cylindrical body, even if the machine part (2) has a non-circular generatrix perpendicular to its longitudinal axis or, for example, a conical exterior surface.

If the band (3) is be placed in a groove as shown in Fig. 1 , the L, T and D dimensions can be assumed to be the nominal dimensions of the band (3) when it is not around a cylindrical machine part (2) and the nominal volume Vband for the band can be calculated. Similarly, using the example in Fig. 2, a nominal volume V_gr0ove for the groove (4) can be calculated, and here the requirement will be that V_band is an appropriate percentage greater than groove. The percentage will typically fall within the range 1 % to 1 5% , preferably 5%. At the same time, it must be ensured that the L, T and D dimensions for the band (3) and the groove (4) respectively do not substantially deviate from one another, so that the band oversize relative to the groove is equally distributed between L and T, and always in such a way that the length of the interior circumference of the band is always smaller than the length of the periphery of the groove.

It is preferred that the groove is elongated in the axial direction along the exterior material surface (1 ) and has a uniform depth along its entire length, as the elongation of the groove (4) in the axial direction is no smaller than the diameter of the opening (12). Here it is assumed that the opening is circular, which would be the most common. The correlation between the circumferential groove (4) and the opening (12) ensures that there is a contact surface (15) all the way around the rim of the opening (12) that runs parallel to the surface (1 ) of the cylindrical machine part. This structure helps to ensure that the band (3) always lies flat against the rim of the opening to seal it. As can also be seen in Fig. 1 , the groove (4) is centred relative to the length of the opening along the centre axis of the machine part. This ensures that the section of the groove that exceeds the length of opening (12) in the axial direction is equally distributed on either side of the opening (12) and that there will be evenly distributed pressure between the band and the rim of the opening defining the contact surface (15).

The example of the illustration shown in Fig. 2 and Fig. 4 includes a distance piece (10), with two ends, (8) and (9), where one end (9) comprises an attachment against a machine (not shown) or other equipment. Such an attachment could be made from a threaded stub that can be screwed into a threaded hole in the machine, an interference fit or a welding tab so that the distance piece can be welded to the machine. Other well-known types of attachments between the distance piece and the machine can be used. The other end (8) provides a suitable foot (7) intended for contact pressure against a fixed part. Here the foot (7) can be arranged in different ways, as a gripper for installation around tubes or as a welding stub that is welded to a beam or other supporting part. Central to the distance piece function is that the distance between the attachment part (9) and the foot (7) is configurable by means of a force-transmitting mechanism and comprises a cylindrical exterior part (2) with a surface (1 ). Such a distance piece (10) is shown in Fig. 2 and Fig. 4 with a conventional foot (7) at one end, where the foot (7) comprises a rubber element (17) with a contact surface (18) adapted to be placed against e.g. the floor of a workshop or production facility. The rubber element (17) is then, for example, vulcanised in a metal fairing (19). Between the rubber element (17) and a force-transmitting leg (20), there may be a flexible joint such as a ball joint (21 ) which allows the force-transmitting leg (20) to be angled relative to the foot (7). Usually, a central part of the metal fairing (19) and the underside of the force-transmitting leg (20) is designed as two freely rotatable parts of a ball joint (21 ).

Between the force-transmitting leg (20) and the machine attachment (9), there is a mechanism for adjusting the length of the distance piece (10), which has not been shown in detail in the figure. It could be a cylinder piston pair or a spindle mechanism with exterior threading for the force- transmitting leg (20), for example, and a corresponding interior threading in a cylindrical tube. By rotating the tube relative to the leg, the two elements will perform a telescopic movement relative to one another and as the cylindrical tube is linked to the end (8) with a machine attachment, the distance between the foot (7) and the machine can be adjusted.

To protect against inadvertent rotation or displacement of the cylindrical machine part (2) relative to the force-transmitting leg (20), screws (1 1 ) have been inserted in designated openings (12) with threading (13) in the cylindrical machine part (12).

The cylindrical machine part can have other functions than those shown and described here, e.g. it could be a counter nut that must correspondingly be blocked using a grub screw (1 1 ). According to the invention, it is preferable that the circumferential band is made from silicone with a predefined Shore A hardness of between 55 and 70 pts, preferably a hardness of 60 pts and a tensile strength of no less than 4 MPa. This provides security both for the band to be installed relatively easily around the exterior cylindrical machine part (2) of a machine foot and for the band (3) to engage with sufficient force against the metal surface of this element and to create a seal.

In an alternative embodiment, the circumferential band has been created using a plastic type with such hardness and elastic expansion that its removal from the machine part would result in destruction of the band. This would allow the band to act as a tamper indicator, showing whether access to the sealed openings (12) has taken place at an earlier date.

In Fig. 3 and Fig. 4, a slightly different embodiment of a machine foot (10) is shown, in which the continuous band (3) sits on a conical extension (22) of the cylindrical machine part (21 ). This extension (22) is placed closest to the foot (7) but could be added to the opposite end of the machine part (2). As seen in Fig. 3, the groove has been formed at an angle with the axial end walls (23) perpendicular to the rectilinear cone surface generatrices (25) and a bottom (24) which is parallel to the rectilinear cone surface generatrix (25). A continuous band suitable for this groove must have a parallel-running cone-shaped interior and an exterior surface, and a uniform wall thickness in between them. In the example shown, the opening (12) is not centred relative to the upper rim or the bottom of the groove. However, it is, of course, possible to centre the opening (12) with the circumferential groove bottom (24), so that the upper rim of the opening (12) has the same distance in between the circumferential groove's four axial end walls (23) so that the parallel contact surface (15) always has a minimum dimension all the way around the opening (12). As indicated in the figure, the exterior conical surface of the band is slightly arched when the band is in the groove, thereby going a little outside the rectilinear generatrices (25) of the machine part. This is due to the band volume being slightly larger than the groove volume, in order to ensure compressive stress between the respective contact surfaces of the band and the groove, as described earlier.

The grooves in the above-mentioned examples have parallel sides that run perpendicular to the machine part surface, with a level bottom that is also parallel to the machine part surface in an intersecting plane passing through the longitudinal axis of the machine part. However, other types of grooves are also possible, e.g. with V-shaped walls and bevelled bottoms. Alternatively, the groove could be designed as a semi-circle in an intersecting plane through the axis of the machine part. In the transition of a groove side and the machine part surface, there could, for example, in each of the groove sides be a sharp inwardly directed flange, into which the rubber elastic band material is pushed for correct installation. Removal of the band will then become difficult and may necessitate the use of tools, on the other hand such a structure may provide improved hygienic protection.

Figures 6A-6D show a series of photographs illustrating the various stages of the band insertion:

- 6A, the band (3) is situated above the foot and has not been installed.

- 6B, lubricant, such as water and, if necessary, soap, has been applied to the band (3), and the band is moved into the groove by hand on the side of the machine foot that is facing away from the operator, and is now pushed and/or pulled out so that it can drop into the groove.

- 6C, the band is pushed the final way into the groove at the side of the machine foot that faces the operator.

- 6D, the band is massaged along its outer surface until it is evenly distributed around the surface of the cylindrical machine part so that there are no gaps between the band and the groove.

Figures 7 A and 7B show images of how the band (3) is removed:

- 7A, here the operator guides with a precision grip and some finger pressure around the band (3) with the fingers in the same direction, e.g. away from the operator, and the band surface on two opposite sides is exposed to shear force in the direction facing away from the operator. This results in the band in the area closest to the operator being stretched and extra band material accumulating in the area facing away from the operator.

- 7B, here you can see how the operator pushes their

fingertips or nails underneath the accumulated extra band material, which means that the band in this area is now sufficiently loose for this to be possible. When the fingers have slipped under the band, it can be stretched relatively easily and lifted out of the groove all the way around.

In the example shown, the band has an extension in the axial direction of the cylindrical machine part of 9.0 mm, while the groove has an extension in the axial direction of 7.5 mm. This ensures that the band, when situated in the groove, always fills the groove completely and applies compressive force against the sides of the groove.

Reference figures:

1 Exterior surface

2 Cylindrical machine part

3 Continuous circumferential band

4 Circumferential groove

5 Exterior surface of the band

6 Conical plugs

7 Foot

8 End with contact to fixed part

9 End with machine attachment

10 Machine foot or distance piece

1 1 Screw

12 Opening

13 Internal threading

14 Material transition

15 Parallel contact surface

16

17 Rubber element

18 Contact surface

9 Metal fairing

20 Force-transmitting legs

21 Ball joints

22 Conical elongation

23 End walls

24 Bottom of the groove

25 Rectilinear generatrices of the cone surface

Claims

PATENT CLAIMS

1 . Protection against the contamination of an opening (12) in an exterior surface (1 ) of an elongated machine part, the exterior surface of which forms an enclosed curve in a plane perpendicular to a longitudinal axis of the elongated machine part (2), wherein a flexible, continuous circumferential band (3) is placed over the opening (12) and against the exterior surface (1 ) along the closed curve, whereby the band (3) either covers the opening (12) itself or secures a plug in the opening or is manufactured as one piece with a plug that fits in the opening (12) in an interlocking manner.

2. Protection according to claim 1 , wherein the machine part (2) has a circumferential groove (4) in its exterior surface (1 ), whereby the groove (4) crosses over the opening (12) as the circumferential band (3) is situated in the groove (4).

3. Protection in accordance with claim 1 or claim 2, wherein the circumferential band (3) has an axial extension, a radial thickness and a diameter size relative to the machine part and the opening (12) so that there is always compressive stress in a material transition between the band material and the exterior surface (1 ) of the machine part material.

4. Protection in accordance with claim 2 and claim 3, wherein the groove (4) has an extension in an axial direction along the exterior surface (1 ) and has the same depth over its entire length because the extension in the axial direction is no smaller than the diameter of the opening (12).

5. Protection in accordance with claim 4, wherein the groove (4) is centred relative to the extension of the opening along the machine part axis, so that the piece of the groove (4) that may exceed the extension of the opening in the axial direction is equally distributed on either side of the opening (12).

6. The distance piece (10) with two ends and comprising an machine attachment or other equipment at one end (9) and a foot (7) adapted for contact pressure against a fixed part at the other end (8), where the distance between the attachment (9) and the foot (7) is adjustable with a force-transmitting mechanism comprising an exterior cylindrical machine part (2), where the exterior cylindrical machine part comprises an opening (12) in its exterior surface (1 ) wherein a flexible continuous circumferential band (3) is placed over the opening (12) and against the exterior surface of the cylindrical machine part along a closed curve, whereby the band (3) either covers the opening (12), secures a plug in the opening or has been manufactured in a single piece with an interlocking plug in the opening (12).

7. The distance piece (10) in accordance with claim 6, wherein the opening (12) is a threaded hole and that a screw (1 1 ) is screwed into the threaded hole, attaching the exterior cylindrical machine part (2) axially and rotationally against an interior part.

8. Distance piece (10) in accordance with claim 6 or 7, wherein the circumferential band (3) is manufactured using silicone with a predefined Shore A hardness of between 55 and 70 pts, preferably a hardness of 60 pts measured in accordance with D2240 and a tensile strength of no less than 4 MPa measured in accordance with D412.

9. Distance piece in accordance with one or more of claims 6-7, wherein the circumferential band (3) is manufactured from a plastic type with such a hardness and elastic expansion that its removal from the machine part (2) will result in the destruction of the band (3).

10. The approach for the prevention of contamination of an opening (12) in an exterior surface (1 ) of a cylindrical machine part (2), wherein a flexible continuous band (3) is installed around the machine part (2) and either secures a plug in the opening (12), is connected to a plug situated in the opening (12) or completely covers the opening (12), thereby establishing force-locking contact between the machine part surface (1 ) and the band (3).