AU2005100846B4 - Locking Means for Anchors for Castable Refractory Cement - Google Patents

Description

AUSTRALIA

ORIGINAL

COMPLETE SPECIFICATION INNOVATION PATENT Invention Title: Name of Applicant: Actual Inventor: Address for service: "Locking Means for Anchors for Castable Refractory Cement" Pressform Engineering Pty Ltd John Worner WRAY ASSOCIATES Level 4, The Quadrant 1 William Street Perth, WA 6000 Attorney code: WR The following statement is a full description of this invention, including the best method of performing it known to me:- "Lockina Means for Anchors for Castable Refractory Cement" SField of the Invention The present invention relates to a device and a method for locking anchors used IDto support castable or monolithic refractory cement in a furnace shell.

00 O 5 Background Art 0 The interior of furnaces are often lined with castable or monolithic refractory c cement. A typical furnace is constructed by first erecting a furnace shell and then applying a layer of refractory cement over the surface of the shell to provide insulation. It is necessary to support the refractory cement during the application of the cement. It is also necessary to continue that support during use of the furnace. Because furnaces are raised to a very high temperature during operation and then cooled again to normal temperatures, the cement undergoes significant expansion and contraction. This causes cracking so that the cement would break away from the furnace shell if it is not adequately supported from the shell during use.

The applicant has previously developed an anchor that is now in widespread use which comprises a substantially V shaped anchor supported by a lug secured to the refractory shell. Figure 1 provides a drawing of the anchor of the applicant which is marketed as a Rod Lock refractory anchor. As shown in the drawings, the lug 11 comprises a simple metal plate usually welded to the furnace shell 12 and upstanding from the shell transversely to the surface. The lug 11 is normally formed from mild steel or stainless steel and is provided with a elongate aperture 14 adapted to receive the anchor 21 during installation. The longitudinal axis of the elongate aperture 14 runs generally parallel to the shell surface 12 in the vicinity of the lug 11. The anchor is formed from stainless steel or nickel alloy rod and comprises two opposed arms converging towards each other in a general configuration which intersect at an apex which is configured as a 'U'shaped formation 22 rather a simple apex. The arms of the rod are -3conventionally bent with a slight wave formation 23 to provide better adherence to the refractory cement. The anchor 21 is supported by passing one arm through the aperture 14 of the lug 11 with the anchor held approximately parallel to the wall (25) until the U shaped apex 22 is centred in the aperture 14. The anchor is then rotated about the lug until the anchor stands substantially transversely to the wall and the lug. Due to the curvature and deformation of the 7- rod at the base of the U shaped apex, the U shaped apex is jammed in the 00 0aperture of the lug to provide reasonably secure engagement. In general, this engagement has been satisfactory to hold anchors in place until the refractory cement is cast.

This type of anchor has been found to be extremely successful while the furnace is in use because of its ability to allow movement relative to the lug, substantially parallel to the plane of the shell at the vicinity of the lug to cope with expansion and contraction of the cement and the shell. This has been found to be particularly useful for rotatable furnaces, but is also useful in conventional stationary furnaces.

A problem experienced with this style of anchor occurs in maintaining the anchor in position prior to the cement being cast. The anchor requires only a relatively small force against it tangentially to the orientation of the slotted aperture to knock it over. Once it is dislodged a little it will tend to fall against the shell wall.

Because the original lock depends on an interference fit between the surfaces of the U shaped apex and the slotted aperture, when the anchor is first rotated into its upright position, some compression of the steel occurs at the contact point.

This can tend to deform the metal of the lug a little such that any subsequent attempt to rotate an anchor upright is not quite as effective as the initial attempt.

It then becomes easier to knock the anchor out of its upright position and this can happen even during the casting process of the cement. Where cement is cast with the anchor dislodged from its upright position, particularly against the furnace shell, the anchor no longer performs its function and therefore the cement in that area is not properly supported. This can lead to premature failure of the cement requiring an expensive maintenance repair and furnace downtime.

-4- Previously it has been attempted to prevent the anchor from being dislodged from an upright position by tack welding the anchor to the lug. The intention is that this weld will be sufficient to hold the anchor during casting of the refractory cement but that the weld will break when the furnace is in use enabling the refractory cement to move relative to the lug. However this method has given problems of its own. Firstly it is difficult to control the amount of tack welding 1 required. If too much is applied, the tack will not break in use thereby preventing the anchor from moving relative to the lug. This is likely to lead to failure of the anchor and/or the refractory cement in its vicinity. If too little tack weld is applied, the weld will still break prematurely and the original problem will not be overcome. As well, the weld may affect the strength of the anchor and in any event is very time consuming and therefore an expensive process to apply.

Disclosure of the Invention Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Accordingly the invention resides in a locking means for a refractory anchor which is used to support a refractory lining material from the wall of a furnace in which the refractory anchor is supported from a lug fixed to the wall, the lug having an aperture, the refractory anchor formed from rod-like material and comprising a pair of divergent arms, wherein in use the refractory anchor is to be supported from the lug with the junction between the arms received in the aperture and the arms extending outwardly from the wall, the locking means comprising an element adapted to be supported from the lug to lie between the arms and to engage with the arms to fix the arms in position relative to the lug, wherein the locking means is capable of being affected by the heat generated by the furnace during use to reduce the relative support provided between the refractory anchor and the lug by the locking member.

According to a preferred feature of the invention the lug comprises plate-like element extending outwardly from the wall, having a pair of opposed side edges and an end edge, the locking means configured to engage the lug to be fixedly supported from the lug, the locking means having a pair of opposed sides, the sides each formed with a recess, the spacing between the recesses and the Nconfiguration of the recesses enabling the recesses to engage the arms when ,I the locking means is supported from the lug. 00

O

According to a preferred feature of the invention the locking means comprises a pair of retention means adapted to engage the opposed side edges of the lug.

According to a preferred feature of the invention the retention means comprise a pair elements having a spacing therebetween corresponding to the width of the lug and having formations on their opposed faces which will engage with the side edges of the lug when the locking means is in position on the lug..

According to a preferred feature of the invention the locking means is formed with a pair of openings which are each configured to be engagable with a corner of the lug, the openings being positioned relative to each other to be engagable with the opposed outer most corners of the lug when the locking means is in position over the lug The invention will be more fully understood in light of the following description of several specific embodiments.

Brief Description of the Drawings The description is made with reference to the accompanying drawings, of which: Figure 1 is an isometric drawing of a refractory anchor installed within a support lug according to the prior art; -6- Figure 2 is an isometric view of a locking clip according to the first embodiment; SFigure 3 is an isometric view of the locking clip of Figure 2 showing its orientation to the anchor and lug, immediately prior to installation; Figure 4 is an isometric view of the locking clip of Figure 2 in engagement with the lug and anchor (shown by dotted lines); 00 oo Figure 5 is an isometric view of a locking clip according to the second embodiment; Figure 6 is an isometric view of the locking clip of Figure 5 showing its orientation to the anchor and lug, immediately prior to installation; and Figure 7 is an isometric view of the locking clip of Figure 5 showing its orientation to the anchor and lug, immediately after installation.

Detailed Description of Preferred Embodiments The embodiments of the invention are directed to a locking means for a refractory anchor adapted to prevent rotation of the refractory anchor relative to a support lug which engagingly supports the anchor prior to and during casting of refractory cement but which loses its ability to restrain the anchor once the heat of the furnace when in use is applied to the locking means. The first embodiment is described with reference to Figures 2, 3 and 4.

The first embodiment as shown in Figures 2 to 4 comprises a locking clip 31.

The locking clip is adapted to be positioned over a support lug 11 extending from a furnace shell 12 while a refractory anchor 21 is in place in the upright position relative to the lug 11. The lug 11 comprises a generally rectangular member of mild steel or stainless steel, typically having thickness between 8mm and 25 mm, width of between 30mm and 80 mm and length extending from the shell of to 120mm. The corners 15 of the intersection of the length and width of the lug remote from the shell 12 are rounded to facilitate the engagement of the clip with -7the lug, as discussed below. On each of the narrow sides of the lug 11 disposed somewhat from the end 17 of the lug is provided a transverse notch 18 parallel to the end face 17 of the lug, to provide for engagement by the clip 31 as is described below. An elongate aperture 14 is provided through the lug 11 to receive the anchor 21, the aperture 14 being disposed somewhat from the lug Iend 17, the elongate axis of the aperture being substantially parallel to the end face of the lug and thereby the shell wall in the vicinity of the lug 11.

00 O The clip 31 according to the first embodiment comprises a metal bracket formed Cfrom mild steel, typically of about 1mm in thickness and having a base section 32 S 10 of generally rectangular form and a pair of arms 33 extending generally transversely to the base section at either side of the base section in symmetric layout. The rectangle of the base comprises a pair of opposed sides 34 and a pair of opposed ends 35 adjacent the sides. Each end 35 of the base section 32 is provided with a cut out 36, each cut out 36 being of generally semi-circular form with the diameter of the cut out positioned mid way along the edge of the end 35. The diameter of the cut out is configured to conform to the diameter of the rod from which the anchor 21 is constructed.

The end members 33 are typically formed during construction by bending the sheet metal of the locking clip 31 at the sides of the base portion 32 so that the end members are at an acute angle of approximately 80 degrees relative to the base section, thus the end 33 members converge a little away from the base 32.

The free corners 37 of the end members 33 away form the base section 32 are bent inwardly, and are configured to loosely engage the lug 11 when the clip 31 is placed over the lug 11. A tag 41 of generally rectangular formation is formed in each of the end members 33, typically by stamping a rectangular area within the end member to cause the area to be sheared away from end member, directed inwardly, to form the tag having a tag end 42 and a pair of opposed sides 43. The tag end 42 is proximate the base section while the end of the rectangle opposed to the base section remains connected to the end member 33 to thereby support the tag 41.

-8- The distance between the end members 33 corresponds to the width of the lug 11. In use, as shown in Figure 3 and 4, the clip is placed over the lug 11 with the clip 31 oriented so that the cut-outs 36 of the base section ends are aligned with the arms of the anchor 21, the end members 33 of the clip 31 overlying the opposed narrow sides of the lug 11. As the clip 31 is pressed home, the tags 41 engage respective narrow sides 16, thereby resiliently extending the end 1 members 33 a little until the tag ends 42 engage a respective notch 18 to thereby 00 secure the clip 31 to the lug 11. At this position, the cut-outs 36 of the base section securely engage the arms and/or the U shaped apex 22 of the anchor 21.

Movement of the anchor in any direction is thereby restrained.

Once the refractory cement has been applied and cured, the use of the furnace will result in the wall and the refractory cement being heated the resultant slow heating and cooling of the locking clip will cause it to losing any temper which maintains the clip in engagement with the lug 11 and the refractory anchor. This loss of temper is sufficient to accommodate for the relative movement between the lug and the clip and the refractory anchor and the surrounding refractory cement that arises from the heating of the walls of the furnace and the resultant differential contraction and expansion between each of the elements.

A locking clip according to a second embodiment functions in substantially the same manner as that of the first embodiment although the appearance is quite different. The locking clip of the second embodiment is shown in Figures 5 to 7.

As shown in the drawings, the clip 51 has a three sided configuration comprising a central base section 52 and two symmetric arms 53. The base section 52 has a configuration similar to that of the first embodiment and so it is not described again and where like numbers they are intended to denote like features. The arms 53 comprise planar, substantially rectangular members extending from the sides 34 of the base section at an obtuse angle to the base to thereby be diverging apart from each other from the base 52. Each of the arms 53 is formed with a rectangular cut-out 55, one end edge 56 of the cut-out being substantially aligned with the respective side 34 of the base section 52. The length of each cut-out is a substantial proportion of the length of the respective -9member 53 thereby providing the arm with a pair of side members 58 having sufficient width to provide the necessary strength to the clip 51. The width of each cut-out is slightly greater than the thickness of the lug 11. A plurality of small apertures 59 are provided in the clip to enable cement to pass there through when in position over the lug thereby assisting to prevent voids in the IN cement due to the clip, while not unduly detracting from the strength of the clip.

00 0 Significantly, in comparison to the clip 31 of the first embodiment, the clip 51 of the second embodiment is formed from spring steel and heat treated to provide a

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0clip that is highly deformable with very high resilience. The clip 51 can thus be made from material that has a thickness considerably less than that of the first embodiment, 0.5mm or less. The clip 51 also has significantly less area of metal and thus is cheaper to make and is less likely to interfere with the bonding of the cement..

In use the clip 51 is placed over the lug 11 in a similar manner to the first embodiment, the cut-outs 36 of the base section 52 being aligned with the arms of the anchor 21. The arms 53 of the clip 51 overlie the narrow sides of the lug 11, the sides of the lug passing through the cut-outs of the arms, to thereby provide lateral support to the clip 51. As the clip is pressed in engagement with the lug 11, the remote edge 60 of the cut-out 55 of each arm, being the edge opposed to the edge 56 aligned with the side of the base section, engages the respective narrow side of the lug, thereby displacing the arms by resilient deformation of the side members 58 of the arms. The clip is pressed down over the lug until the remote edges 60 engage the notches on each respective side of the lug. Because of the resilient nature of the tempered spring steel and the configuration of the clip which provides a laterally inward force component, the clip provides a very positive engagement to the lug via the notch. The engagement of the sides of the cut-outs of the arms with the lug provide a very positive engagement with the lug which resists lateral displacement of the anchor.

Particularly in the case of the second embodiment, it is desirable that the lug be provided with a plurality of notches on each narrow side, as best shown in Figure 6, the notches being parallel to enable the clip to engage the lug at more than one height from the lug end 17, in ratchet style. In a further adaptation (not shown), the notches are formed with a serrated profile, each notch having an IN upper surface extending substantially normally to the side of the lug parallel to the lug end 17) to thereby provided more secure retentive engagement of the 00 clip with the lug.

Once the refractory cement has been applied and cured, the use of the furnace will result in the wall and the refractory cement being heated the resultant slow heating and cooling of the locking clip will cause it to losing any temper which maintains the clip in engagement with the lug 11 and the refractory anchor. This loss of temper is sufficient to accommodate for the relative movement between the lug and the clip and the refractory anchor and the surrounding refractory cement that arises from the heating of the walls of the furnace and the resultant differential contraction and expansion between each of the elements.

There are many adaptations possible to the embodiments described which may retain the inventive feature of the device. For example the embodiment might well be made from other materials such as plastics material that also have strength and rigidity at normal temperature but lose those characteristics when heated by the furnace. It should be appreciated that all such adaptations are to be considered within the scope of the invention.

Claims (1)

11- The claims defining the invention are as follows: 1. A locking means for a refractory anchor which is used to support a refractory lining material from the wall of a furnace in which the refractory anchor is supported from a lug fixed to the wall, the lug having an aperture, Ithe refractory anchor formed from rod-like material and comprising a pair of oo divergent arms, wherein in use the refractory anchor is to be supported from O 0 the lug with the junction between the arms received in the aperture and the n arms extending outwardly from the wall, the locking means comprising an Selement adapted to be supported from the lug to lie between the arms and to engage with the arms to fix the arms in position relative to the lug, wherein the locking means is capable of being affected by the heat generated by the furnace during use to reduce the relative support provided between the refractory anchor and the lug by the locking member. 2. A locking means as claimed at claim 1 wherein the lug comprises plate- like element extending outwardly from the wall, having a pair of opposed side edges and an end edge, the locking means configured to engage the lug to be fixedly supported from the lug, the locking means having a pair of opposed sides, the sides each formed with a recess, the spacing between the recesses and the configuration of the recesses enabling the recesses to engage the arms when the locking means is supported from the lug. 3. A locking means as claimed in claim 2 wherein the locking means comprises a pair of retention means adapted to engage the opposed side edges of the lug. 4. A locking means as claimed at claim 3 wherein the retention means comprise a pair elements having a spacing therebetween corresponding to the width of the lug and having formations on their opposed faces which will engage with the side edges of the lug when the locking means is in position on the lug.. -12- A locking means as claimed at claim 3 wherein the locking means is formed with a pair of openings which are each configured to be engagable Z with a corner of the lug, the openings being positioned relative to each other to be engagable with the opposed outer most corners of the lug when the locking means is in position over the lug 00 O Dated this 7th day of October 2005. i n Pressform Engineering Pty Ltd SApplicant Wray Associates Perth, Western Australia Patent Attorneys for the Applicant(s)