GB1601732A

GB1601732A - Sealing gland

Info

Publication number: GB1601732A
Application number: GB12572/78A
Authority: GB
Original assignee: CHEM PLANT STAINLESS Ltd
Current assignee: CHEM PLANT STAINLESS Ltd
Priority date: 1978-05-31
Filing date: 1978-05-31
Publication date: 1981-11-04

Description

(54) SEALING GLAND (71) We, CHEM-PLANT STAINLESS LIMITED, a British company of Coppermill Court, West Hyde, Rickmansworth, Hertfordshire, WD3 2XS, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to sealing glands for 'U' trough mixers such as are used, for example, for mixing powders and pastes in the manufacture of medicines.

Such a 'U' trough mixer comprises a generally horizontal elongate trough, of 'U' shape in cross section accommodating mixing means carried by a rotatable driving shaft extending longitudinally along the trough and passing through end walls at opposite ends of the trough, the shaft being sealed with respect to these end walls by repective sealing glands.

In order to comply with health regulations, and in any case in the interests of hygiene and safety, it is necessary for a 'U' trough mixer for mixing powders or pastes for medicines to be so constructed that these glands can be cleaned after every batch mixed in the mixer. Whether the mixer is used to mix powders, damp mixes or pastes, if the glands were not cleaned after every batch, cross contamination might occur and micro-organisms could lodge in the glands.

Because it has not been possible, prior to the present invention to provide a gland arrangement for a 'U' trough mixer which allows the gland to be cleaned adequately with convenience, there has been a preference for mixers of the kind in which stirring members extend downwardly into a bowl or the like from a supporting and bearing structure disposed above the bowl, and therefore out of contact with the material being mixed, although there are, in other respects, significant advantages in 'U' trough mixers as compared with mixers of the above noted bowl type.

It is an object of one aspect of the present invention to provide a 'U' trough mixer, having a gland construction which can be readily dismantled for cleaning and reassembled.

According to this aspect of the present invention, there is provided a 'U' trough mixer including a shaft extending through at least one end wall of the 'U' trough perpendicular to said end wall and sealed with respect to said end wall by a gland construction including a seal of flexible material in the form of an elongate member of uniform cross section having first and second ends and extended around the shaft in a loop so that its ends meet, at least in a compressed condition of the seal, and an annular gland housing encircling the shaft and extending around the periphery of the fitted seal and over the surface of the fitted seal which faces away from the respective end wall in the axial direction of the shaft, said housing comprising a plurality of interconnected part-annular discrete segments and releasable holding means being provided whereby the housing can be retained in position with respect to the respective end wall and prevented from moving away from the respective end wall, whereby said seal can be compressed axially between the gland housing and said end wall, at least one of the connections between adjacent said segments being releasable so that the annular housing can be opened, at least when the housing is. slackened off, to allow removal of the seal for cleaning.

Preferably, each of the part-annular discrete segments of the housing has a hole therethrough to receive a bolt and is fitted on a respective bolt, received in said hole, which bolt extends generally parallel with the shaft and serves in conjnction with a corresponding internally threaded member to retain the respective segment in position with respect to the respective end wall and prevent movement of the segment away from the respective end wall, whereby by screwing movement of said internally threaded members on said bolts, or vice versa, said seal can be compressed axialy between the gland housing and said end wall, said screw-threaded bolts and said internally threaded members constituting said releasable holding means.

However, other releasable holding means such as wedges, levers or toggles may be employed instead of, or in addition to such screw-threaded bolts and internally threaded members.

According to another aspect of the invention there is provided a sealing gland construction for a 'U' trough mixer comprising a seal of flexible material in the form of an elongate member of uniform cross-section having first and second ends and extendible around a shaft of appropriate size in a loop so that its ends meet at least in a compressed condition of the seal, and an annular gland housing adapted to encircle a shaft of said appropriate size and adapted to extend around the periphery of the fitted seal and over one axially presented end face of the fitted seal, said housing comprising a plurality of interconnected or inter-connectable part-annular discrete segments, at least one of the connections between adjacent said segments being releasable so that the annular housing can be opened and releasable holding means whereby the assembled annular housing can be held in a desired position in the axial direction of such a shaft, relative to a mixer end wall.

It should be appreciated that the invention extends to such a sealing gland construction not only in the assembled condition but also in a disassembled condition and in the form of a kit of parts including the releasable holding means adapted for ready fitting to an existing mixer.

Embodiments of the invention are described below with reference to the accompanying drawings, in which: Figures 1 to 4 illustrate a first form of gland construction embodying the invention, Figures 5 to 8 illustrate a second embodiment, Figure 9 illustrates a variant of this second embodiment, Figure 10 is a perspective view of a 'U' trough mixer adapted to receive the gland construction of Figures 1 to 4, Figure 11 is a perspective view of the gland assembly of Figures 5 to 8 in a partly assembled condition, Figure 12 is a perspective view showing the gland assembly of Figures 5 to 8 in a disassembled condition, and Figure 13 is a perspective view showing the gland assembly of Figures 5 to 8 in an assembled condition.

Referring to Figures 1 to 4, a 'U' trough mixer (for the most part not shown) includes a 'U' section trough along which extends longitudinally a rotary mixing facility carried by a rotatable shaft 10 which extends through the end walls of the trough, these end walls being perpendicular to the longitudinal extent of the trough and thus perpendicular to the axis of the shaft.

Figures 1 to 3 show part of the shaft 10 and part of one of these end walls, referenced 12, of the trough.

It will be appreciated that the sealing gland arrangements at both end walls are substantially identical so that the following description of one arrangement applies also to the other.

On the outside of the end wall 12, encircling the shaft 10 is an annular seal 14 which is substantially square in half-axial section. The seal 14 is urged axially against end wall 12 and is also contained radially, by an annular gland housing 16. The housing 16, in its assembled form affords a generally cylindrical bore 18 through which the shaft 10 extends with clearance, and a coaxial counterbore 20, of greater diameter, which extends from the axial end face of the housing 16 nearer the end wall 12, the counterbore 20 receiving a major part of the axial length of the seal, the inner peripheral cylindrical wall of the counterbore 20 engaging the outer periphery of the seal 14 in use and the axially facing flat shoulder 22 formed between the bore 18 and counterbore 20 engaging, in use, the end face of the seal 14 which is furthest from the end wall 12.

The housing 16 has two lugs 24 extending outwardly therefrom on diametrically opposite sides of the housing, each lug 24 being formed with a bore 26 extending therethrough in the axial direction and receiving a respective screw threaded bolt 28 extending in the axial direction from the end wall 12 to which it is secured, for example by welding. Thus the bolts 28 are disposed diametrically opposite each other with respect to the hole in the wall 12 through which the shaft 10 extends.

The housing 16 is urged towards the wall 12, thus compressing the seal 14 and ensuring proper sealing, by nuts 30 screwed on to the bolts 28 and engaging the lugs 24. In the embodiment of Figures 1 to 4 the nuts 30 are cylindrical externally and have diametral bores therethrough to allow the nuts to be tightened using a tommy-bar.

As can be seen in Figures 1 and 4, the housing 16 is split along an axial plane and thus comprises two discrete parts, the two parts being generally semi-circular and being identical with each other except that whereas in one of the parts, generally diametrically extending lugs 32 extending in opposite directions from the extreme ends of its arc have each a respective bore 34 therethrough perpendicular to the parting face of the housing part, in the other of the parts, corresponding diametrically ex tending lugs 36 each carry a respective screw-threaded bolt 38 extending perpendicularly from the parting face of the housing part, the bolts 38, in the assembled condition of the gland assembly, extending through respective ones of the bores 34 and receiving respective cylindrical nuts 40, preferably identical with the nuts 30, by means of which nuts 40 the two housing parts are clamped together around the seal 14.

The seal 14 as shown in Figure 1 is severed at one point on its periphery by a cut 42 angled with respect to the axial direction, so that the seal is really an elongate member looped around the shaft 10 so that the end faces of the two ends of the elongate member mate with each other or approach sufficiently nearly to a position in which they mate with each other to mate sealingly with each other when the seal is placed under compression by tightening up the bolts 30.

The seal 14 can thus be readily removed from the shaft 10 for cleaning without drawing the seal off an end of the shaft, after disassembly of the housing 16.

Similarly, the housing 16 can readily be cleaned after disassembly and removal of the housing. It will be noted that the only tool required for assembly and disassembly of the whole gland assembly is a straight tommy bar.

Except in the respects set out below, the embodiment of Figures 5 to 8 is identical with that of Figures 1 to 4 and like references are used to indicate like parts.

In the embodiment of Figures 5 to 8, the housing 16a, although in the assembled state it has a form generally the same as the housing 16 in Figures 1 to 4, and has the same form internally, providing a bore 18, counterbore 20 and shoulder face 22, and although, like the housing 16 in Figures 1 to 4, it comprises two generally semicircular discrete parts together make up the annular housing, differs in the manner in which these discrete parts are held together.

Thus, whereas in the embodiment of Figures 1 to 4 there is a first pair of nuts which are used to hold the two parts of the housing together, and a second pair of nuts which are used to draw the housing towards the adjacent end wall of the trough, in the embodiment of Figures 5 to 8, a single pair of bolts with corresponding nuts are used to perform both functions.Thus, as shown in Figures 5 and 6, the housing 16a comprises two identical parts, each providing a portion of each of two lugs of the housing through which bolts 28a and 28b respectively extend, the housing 16a, intermediate these lugs being split diametrally axially so that each of the two identical parts provides a respective semi cylindrical portion of the bores 18 and 20 and a respective diametral axially extending planar parting face 50 extending on both sides of the semi cylindrical parts of the bores 18, 20, provided by the respective housing part.

Each face 50 terminates at its radially outermost region in a respective hinge formation, comprising, at one radially extreme end of the housing part, two fingers 52 and 53 spaced apart in the axial direction and having respective bores therethrough extending in, and aligned along an axis parallel with the main axis of the housing, the fingers 52 and 53 being externally of similar part cylindrical form concentric with the bores therethrough.

The hinge formation at the other radially extreme end of the housing part comprises a single finger 54, centrally disposed midway between the axial ends of the housing, the finger 54 engaging snugly between the two fingers 52 and 53 of the other housing part in the assembled condition of the housing and having a bore which, in said assembled condition is aligned with the bores in the fingers 52 and 53 of the other housing part, the bore in the finger 54 being of the same diameter and the aligned bores receiving as a free fit a respective one of the bolts 28a and 28b. As shown in Figures 5 and 6, the finger 54 also has a part cylindrical form externally, to conform with the exterior of the fingers 51 and 52.It will be noted from Figures 5, 6 and 8 that the axes of the bores in the fingers 52, 53, 54 and thus of the bolts 28a and 28b in the assembled gland lie in the plane of the parting faces 50.

As shown in Figure 7, the housing 16a is urged towards the end wall 12 by means of nuts 30a screwed on to the externally screw-threaded bolts 28a, 28b (these nuts being shown as simple hexanogal nuts although they may, if desired, have the same form as the nuts 30 in the embodiment of Figures 1 to 4), the seal 14, which has the same form as in the embodiment of Figures 1 to 4, being thereby clamped and compressed slightly between the wall 12 and housing 16a to ensure an effective seal.

The bolts 28a and 28b prevent transverse separation of the housing parts, and thus also perform the function of the bolts 38 in Figures 1 to 4.

The bolt 28a is longer than the bolt 28b so as to ensure that it is unnecessary to remove both nuts 30a from their bolts 28a, 28b to open the housing and allow access to, and removal of the seal 14. Instead it is sufficient to remove the nut from the bolts 28b and slacken the nut on the bolt 28a sufficiently to allow the housing to be withdrawn axially from the wall 12 sufficiently for the fingers 52, 53 and 54 previously engaged around the bolt 28b to clear the latter thus allowing the two parts of the housing 16a to be swung apart from each other about the bolt 28a, as shown in Figure 11, in which, however, both nuts 30a and 30b have been removed.

The embodiment of Figure 9 differs from that of Figures 5 to 8 only in the form of the fingers which engage the bolts 28a and 28b and in that a raised annular collar 60 is provided on the side of the housing 16 nearer the wall 10, the collar 60 being coaxial with the bore 18 and the major part of the counter bore 20 being within the collar 60, the collar 60 is, of course, formed in two parts, each integral with a respective one of the two parts of the remainder of the housing.

In the embodiment of Figure 9, there is only a single finger, 54a or 54b at each end of each semi-annular part of the housing, each finger 54a or 54b extending over substantially half the axial extent of the housing, the fingers 54a being offset to the side from which the collar 60 extends and the fingers 54b being offset towards the opposite side, the finger 54a of each part of the housing overlapping the finger 54b of the other part, and the fingers 54a, 54b being of course formed with bores therethrough which receive the bolts 28a and 28b, as with the embodiment of Figures 5 to 8.

Of the remaining figures, Figure 10 is a perspective view of a 'U' trough mixer provided with bolts 28, 28 extending from the wall 12 thereof to receive a gland assembly such as described hereinbefore.

It will be appreciated that not only may 'U' trough mixers be specifically designed and manufactured to receive a gland assembly according to one or other of the embodiments described, but an existing 'U' trough mixer may readily be adapted to receive such a gland assembly simply by fixing bolts 28, 28a, 28b appropriately in the respective end wall of the mixer.

The gland construction described with reference to the drawings all present the advantage of being cleanable properly without disturbance to running gear, support bearings etc.

WHAT WE CLAIM IS: 1. A 'U' trough mixer including a shaft extending through at least one end wall of the 'U' trough perpendicular to said end wall and sealed with respect to said end wall by a gland construction including a seal of flexible material in the form of an elongate member of uniform cross section having first and second ends and extended around the shaft in a loop so that its ends meet, at least in a compressed condition of the seal, and an annular gland housing encircling the shaft and extending around the periphery of the fitted seal and over the surface of the fitted seal which faces away from the respective end wall in the axial direction of the shaft, said housing comprising a plurality of inter-connected partanuular discrete segments and releasable holding means being provided whereby the housing can be retained in position with respect to the respective end wall and prevented from moving away from the respective end wall, whereby said seal can be compressed axially between the gland housing and said end wall, at least one of the connections between adjacent said segments being releasable so that the annular housing can be opened, at least when the housing is slackened off, to allow removal of the seal for cleaning.

2. A mixer according to claim 1 wherein each of the part-annular discrete segments of the housing has a hole therethrough to receive a bolt and is fitted on a respective bolt, received in said hole, which bolt extends generally parallel with the shaft and serves in conjunction with a corresponding internally threaded member to retain the respective segment in position with respect to the respective end wall and prevent movement of the segment away from the respective end wall, whereby by screwing movement of said internally threaded members on said bolts, or vice versa, said seal can be compressed axially between the gland housing and said end wall, said screw-threaded bolts and said internally threaded members constituting said releasable holding means.

3. A sealing gland construction comprising a seal of flexible material in the form of an elongate member of uniform cross-section having first and second ends and extendible around a shaft of appropriate size in a loop so that its ends meet at least in a compressed condition of the seal, and an annular gland housing adapted to encircle a shaft of said appropriate size and adapted to extend around the periphery of the fitted seal and over one axially presented end face of the fitted seal, said housing comprising a plurality of interconnected or interconnectable part-annular discrete segments, at least one of the connections between adjacent said segments being releasable so that the annular housing can be opened and releasable holding means whereby the assembled annular

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. latter thus allowing the two parts of the housing 16a to be swung apart from each other about the bolt 28a, as shown in Figure 11, in which, however, both nuts 30a and 30b have been removed. The embodiment of Figure 9 differs from that of Figures 5 to 8 only in the form of the fingers which engage the bolts 28a and 28b and in that a raised annular collar 60 is provided on the side of the housing 16 nearer the wall 10, the collar 60 being coaxial with the bore 18 and the major part of the counter bore 20 being within the collar 60, the collar 60 is, of course, formed in two parts, each integral with a respective one of the two parts of the remainder of the housing. In the embodiment of Figure 9, there is only a single finger, 54a or 54b at each end of each semi-annular part of the housing, each finger 54a or 54b extending over substantially half the axial extent of the housing, the fingers 54a being offset to the side from which the collar 60 extends and the fingers 54b being offset towards the opposite side, the finger 54a of each part of the housing overlapping the finger 54b of the other part, and the fingers 54a, 54b being of course formed with bores therethrough which receive the bolts 28a and 28b, as with the embodiment of Figures 5 to 8. Of the remaining figures, Figure 10 is a perspective view of a 'U' trough mixer provided with bolts 28, 28 extending from the wall 12 thereof to receive a gland assembly such as described hereinbefore. It will be appreciated that not only may 'U' trough mixers be specifically designed and manufactured to receive a gland assembly according to one or other of the embodiments described, but an existing 'U' trough mixer may readily be adapted to receive such a gland assembly simply by fixing bolts 28, 28a, 28b appropriately in the respective end wall of the mixer. The gland construction described with reference to the drawings all present the advantage of being cleanable properly without disturbance to running gear, support bearings etc. WHAT WE CLAIM IS:

1. A 'U' trough mixer including a shaft extending through at least one end wall of the 'U' trough perpendicular to said end wall and sealed with respect to said end wall by a gland construction including a seal of flexible material in the form of an elongate member of uniform cross section having first and second ends and extended around the shaft in a loop so that its ends meet, at least in a compressed condition of the seal, and an annular gland housing encircling the shaft and extending around the periphery of the fitted seal and over the surface of the fitted seal which faces away from the respective end wall in the axial direction of the shaft, said housing comprising a plurality of inter-connected partanuular discrete segments and releasable holding means being provided whereby the housing can be retained in position with respect to the respective end wall and prevented from moving away from the respective end wall, whereby said seal can be compressed axially between the gland housing and said end wall, at least one of the connections between adjacent said segments being releasable so that the annular housing can be opened, at least when the housing is slackened off, to allow removal of the seal for cleaning.

housing can be held in a desired position in the axial direction of such a shaft, relative to an end wall through which said shaft passes.

4. A mixer substantially as hereinbefore described with reference to and as shown in Figures 1 to 4, or Figures 5 to 8 or Figure 9 of the accompanying drawings.

5. A sealing gland construction substantially as hereinbefore described with reference to and as shown in Figures 1 to 4 or Figures 5 to 8 or Figure 9 of the accompanying drawings.