GB2152615A

GB2152615A - Anchoring refractory fibre mats and plates

Info

Publication number: GB2152615A
Application number: GB08500338A
Authority: GB
Inventors: Hans-Jurgen Steinborn
Original assignee: Didier Werke AG
Current assignee: Didier Werke AG
Priority date: 1984-01-07
Filing date: 1985-01-07
Publication date: 1985-08-07
Also published as: GB2152615B; IT8424165V0; FR2557966B1; FR2557966A1; DE8400268U1; NL8403913A

Abstract

A device for anchoring refractory fibre mats 12, 13 or plates to the refractory lining 11 of a furnace comprises a bolt 1 with a self-tapping thread 3 at one end and a head 4 at the other end for engagement by a rotary tool. Projecting from the bolt intermediate its ends are two spaced abutments 6 and 7. In use, the bolt is screwed directly into the furnace lining 11 and passes through two fibre mats 12 and 13. The inner fibre mat 12 is retained in position by a retaining disc 8 which engages it and the abutment 6 whilst the outer mat 13 is retained in position against the inner mat by a retaining disc 9 which engages both it and the abutment 7. The holes in the retaining discs 8 and 9 are provided with lobes to allow the passage of the abutments 6,7 when the angular orientation of the discs is correct. <IMAGE>

Description

SPECIFICATION Device for anchoring refractory fibre mats and plates The present invention relates to a device for anchoring refractory fibre mats and plates to the refractory lining of a furnace.

It is known that to improve the insulation of existing furnace linings refractory insulating mats or plates based on ceramic fibres may be mounted on the interior of the lining. The linings concerned may be, for example, of light refractory bricks or of fireproof concrete or of fire clay bricks.

It is known to connect fibre mats and plates to such a lining by means of adhesive. It has however been found that such an adhesive connection can fail after a short period of operation so that the fibre mats then fall off. It has also been found that the adhesive can produce damage of the surface of the lining.

A known anchoring device comprises a bolt which passes through the mat or plate and engages in a hole in the lining whose diameter is substantially larger than that of the bolt. The bolt, which has a head formed by a nut and a further screw thread at its free end is secured in the hole with adhesive or mortar.

After the fibre mat has been placed in position a retaining disc is pressed against the fibre mat by means of a nut screwed onto the thread. This procedure is complicated since it requires several working steps and is also interrupted by a waiting period while the adhesive or mortar hardens. It is also disadvantageous that the hole in the lining for the bolt must be larger than the bolt diameter since this weakens the lining.

Use of the known device requires that first of all that the bolt be positioned, the adhesive or mortar be permitted to harden and then the fibre mat is attached. If repairs are necessary the fibre mat must first of all be removed.

It is an object of the invention to provide a device of the type referred to above which is easy to use and position in a furnace lining.

According to the present invention a device for anchoring refractory fibre mats or plates to the refractory lining of a furnace comprises a bolt having a self-tapping thread at one end and a head which may be engaged by a rotary tool at the other end and at least one abutment projecting therefrom, the device further including at least one retainer adapted to engage the abutment and be thereby positionally located with respect to the bolt whilst engaging a mat or plate through which, in use, the bolt passes.

Thus when the device is in use the selftapping thread is accommodated within the furnace lining. It is not usually necessary to drill a hole in the lining but if the lining is specially hard or if it comprises fire proof concrete or fire clay bricks then a prior drilling may be desirable. The diameter of the prior drill hole should be smaller than the diameter of the bolt. The refractory lining is therefore scarcely affected by the bolt.

A refractory fibre mat or refractory plate can be anchored to a furnace lining with the device in accordance with the invention in a single work step. In particular. it is not necessary to allow periods of time to elapse between individual anchoring steps.

It is not essential that the bolt be initially screwed into the lining and that the mat or plate can then be applied since the selftapping thread can be screwed straight through the mat or plate into the lining.

Subsequent repair work therefore does not necessitate removal of the mat or plate.

In a preferred embodiment the bolt has at least two abutments projecting therefrom at positions between the thread and the head and spaced apart in the direction of the length of the bolt. This permits two mats or plates to be connected to the lining. one above the other. In the preferred embodiment the or each retainer has an aperture formed therein through which the bolt and the or each stop may pass, the or each retainer and stop being so constructed that the or each retainer may be passed over the bolt and a stop and then locked in position behind the stop. Preferably the or each retainer and stop are so constructed that merely rotating the retainer behind the stop will result in its being locked in position.

The present invention also embraces a device of the type referred to whilst in use anchoring one or more refractory fibre mats or plates to the refractory lining of a furnace.

Further details and features of the invention will be apparent from the following description of one specific embodiment which is given by way of example with reference to the accompanying drawings, in which: Figure 1 is a side elevation of an anchoring device in situ; and Figure 2 is a plan view of the anchoring device.

The anchoring device comprises a bolt or screw which terminates in a point 2. Adjacent the point 2 the bolt is provided with a selftapping thread 3. At its other end the bolt 1 has a head 4 which is formed for the application of a screwing tool. In this embodiment a slot 5 is provided on the head for this purpose. Instead of the slot 5 a cruciform slot or a phillips screw point 5a can be provided. A further possibility is to form the head 4 as a smooth cylinder and preferably a smooth frustum 5b which may be received by a screwing tool which receives the bolt 1 with the head 4 as far as an abutment 6 or 7 (each of which is formed as a laterally opposed pair of stops) and may be used to screw the bolt into the desired surface.Between the head 4 and the screw thread 3 the bolt has a substantially smooth external surface on which the two pairs of stops 6 and 7 are provided. A retaining disc 8 and 9 is associated with each pair of stops 6 and 7, respectively. Each retaining disc has a central aperture whose size is such that it will not pass over the stops 6 and 7.

Notches or apertures 10 are however provided in the edge of each central aperture whose size corresponds to that of the stops whereby the retaining discs will pass over the stops when the notches are aligned with the stops.

The anchoring device is used as follows:The bolt 1 is screwed into a light refractory brick furnace lining 11 with the thread 3 tapping its own thread in the lining. The length of the thread is substantially the same as the distance to which the bolt is screwed into the lining.

Then a first layer of a refractory fibre mat 1 2 is laid over the smooth region of the bolt 1 in contact with the lining 11. The distance between the end of the thread 3 and the stops 6 is substantially the same as the thickness of the fibre mat. Then a retaining disc 8 is pushed over the stops 6 and 7 and turned through 90 behind the stops 6 so that it is locked. The fibre mat 1 2 is thereby pressed against and retained in contact with the lining 11.

Then a second layer of a refractory fibre mat 1 3 is pushed onto the bolt 1 until it touches the fibre mat 1 2. A retaining disc 9 is pushed over the stops 7 and turned so that it is locked in position. The fibre mat 1 3 is thereby fixed in position. Instead of a refractory fibre mat a plate or a composite of fibre mat and plate can be used.

If it subsequently transpires that a further anchoring of the fibre mats or plates at any position is desired then a bolt 1 can be screwed into the lining 11 through the fibre mats or plates 1 2 and 1 3 without their having to be removed. A retaining disc is not required in this case. The retaining disc 9 presses the fibre mats 1 2 and 1 3 against the lining 11. If the bolt is to be bored directly through the fibre mats 12, 1 3 into the lining 11 then the retaining disc 9 can be connected to the bolt 1.

In the illustrated embodiment the head 4 is flush with the smooth area of the bolt 1. It is also possible to form the head 4 as a stop in which case it projects beyond the smooth area of the bolt. In this case the retaining disc 9 can be provided with a keyhole-like central aperture.

If only one layer of fibre mat is to be applied then the stops 6 and the disc 8 are not required.

With a suitable choice of materials for the bolt 1 and the retaining discs 8 and 9 the device can be used at operational temperatures of up to 11 00,C.

Claims

1. A device for anchoring refractory fibre mats or plates to the refractory lining of a furnace comprising a bolt having a self-tapping thread at one end and a head which may be engaged by a rotary tool at the other end and at least one abutment projecting therefrom, the device further including at least one retainer adapted to engage the abutment and be thereby positionally located with respect to the bolt whilst engaging a mat or plate through which, in use, the bolt passes.

2. A device as claimed in claim 1, in which the bolt has at least two abutments projecting therefrom at positions between the thread and the head and spaced apart in the direction of the length of the bolt.

3. A device as claimed in claim 1 or claim 2 in which the or each retainer has an aperture formed therein through which the bolt and the or each stop may pass, the or each retainer and stop being so constructed that the or each retainer may be passed over the bolt and a stop and then locked in position behind the stop.

4. A device as claimed in claim 3 in which the or each aperture and stop are so constructed that a retainer may be passed over a stop and then locked in position by rotating it about the bolt.

5. A device for anchoring refractory fibre mats or plates to the refractory lining of a furnace substantially as specifically herein described with reference to the accompanying drawing.

6. A device as claimed in claim 1 in use anchoring a refractory fibre mat or plate to the refractory lining of a furnace with the selftapping thread within a hole in the lining and the bolt passing through a mat or plate which is retained in contact with the lining by a retainer which is located in position with respect to the bolt by engagement with an abutment on the bolt.

7. A device as claimed in claims 3 and 6 in which the bolt passes through the aperture in the retainer which is restrained from movement away from the lining by engagement with the abutment.

8. A device as claimed in claim 7 in use anchoring two refractory fibre mats or plates which includes two spaced abutments and two retainers, one retainer engaging a first abutment and retaining a first mat or plate in contact with the lining and the other retainer engaging the other abutment and retaining the second mat or plate in contact with the first mat or plate.