SHIELDING SHOE FOR LOOP BEAM OVENS

Description

[0001] The subject of this invention is a shielding shoe for covering openings in the base of a walking beam furnace. The shielding shoe is attached to a vertical upright of the walking beam furnace in the area of ​​a semicircular recess and consists essentially of refractory cast concrete or refractory rammed concrete.

[0002] The subject matter of this invention also includes a walking beam furnace which has the shielding shoe according to the invention.

[0003] The shielding shoe is a refractory prefabricated component installed to cover the scale hoppers and slotted openings in the base of walking beam furnaces. Walking beam furnaces are used in rolling mills to heat slabs, blocks, or billets to rolling temperature. The walking beam conveyors consist of walking beams supported by vertical columns, also called uprights or support tubes, which impart their working motion in the form of a rectangular path over the uprights. The uprights are made of high-strength steel tubes with a ceramic lining and integrated pipe cooling. The uprights pass through slotted openings in the furnace base, and the drive mechanism for the walking beam conveyor, along with auxiliary equipment, can be located below the furnace base or floor.Two shielding shoes are attached above the slots on each upright to prevent or reduce energy loss from the oven through direct radiation into the water cup. The shielding shoes are subject to heavy wear and tear and therefore need to be replaced periodically.

[0004] State-of-the-art shielding shoes consist of refractory concrete with a mounting plate welded to the upright. Slotted pins of varying lengths are arranged on the plate to secure the refractory concrete to the plate. Two shielding shoes are each placed on a separate, plate-like steel bracket to support the increased weight of the prefabricated components.

[0005] Conventional shielding shoes have the following disadvantages: These shielding shoes are heavy, weighing approximately 100-120 kg depending on size and design. Furthermore, installation and removal are quite complicated due to the difficulty of using lifting equipment. In addition, installing or replacing the shielding shoe requires cutting and welding work, which poses a particular hazard and requires approval as "hot work." The fire-resistant cast concrete of the shielding shoe is "green" upon delivery and, due to the metallic components used, is therefore not heat-treated. This also results in a limited shelf life for the shielding shoe.

[0006] A shielding shoe is already known from DE 20 2019 002 656 U1, which has a steel-free shielding body and is therefore fired or sintered before assembly. However, the shielding shoe according to DE 20 2019 002 656 U1 is also a heavy, unwieldy component, the assembly of which is difficult in confined spaces such as those found in walking beam furnaces.

[0007] The invention is therefore based on the objective of providing a shielding shoe that is easier to mount.

[0008] This problem is solved by a shielding shoe according to claim 1. The shielding shoe according to the invention has a honeycomb-like structure beneath the shielding shell. The honeycomb-like structure also consists of refractory cast concrete or refractory rammed concrete. Thus, the new shielding shoe consists essentially only of cast and fired (up to 1,400°C possible) refractory cast concrete or refractory rammed concrete. Due to the honeycomb structure, the shielding shoe is considerably lighter than conventional shielding shoes. A weight saving of more than 35% is possible. The honeycomb-like structure nevertheless ensures the required stability.

[0009] Preferably, the shielding layer above the honeycomb structure has a constant thickness. This minimizes stresses in the material.

[0010] It is advantageous if the honeycomb structure, i.e., the webs of the honeycomb, has a uniform wall thickness; this also helps to reduce stress.

[0011] In a preferred embodiment, the shielding shoe has curved slots in the area of ​​the recess for the upright, which are, for example, C-shaped in plan view, so that it can be hooked onto retaining clips attached to the upright. The curved clips ensure a secure hold. Additionally, the shielding shoe can rest on a retaining ring attached to the upright. It is advantageous if each retaining clip and half of the retaining ring form a single component, making assembly on the upright particularly easy. However, these can also be separate components.

[0012] Preferably, the shielding shoe has at least one, preferably two, clamp holes on its upper side, i.e., in the shielding sleeve. Clamps can then be screwed into these clamp holes to aid assembly.

[0013] Normally, two shielding shoes are mounted on each stand. To prevent falling tinder from accumulating on the two shielding shoes, the shielding cover slopes downwards towards the edges, causing the falling tinder to slide off. The two shielding shoes thus form an umbrella-shaped structure.

[0014] The present invention also relates to a walking beam furnace with at least one upright extending through an opening in the base of the walking beam furnace. According to the invention, two shielding shoes according to one of claims 1 to 6 are attached to the upright.

[0015] The prior art and an embodiment of the invention are described below with reference to the drawings. These show: Fig. 1 a schematic cross-section through two shielding shoes attached to a stand according to the state of the art; Fig. 2 a top view of the shielding shoes made of Figure 1 ; Fig. 3 a schematic cross-section through two mounted shielding shoes according to the invention; Fig. 4 a top view of the two shielding shoes according to the invention made of Figure 3 ; Figure 1 and Figure 2 Figure 1 shows two conventional shielding shoes 2 attached to a post 1. These shielding shoes 2 typically consist of: fire-resistant cast concrete with a density of 2.5 - 3.0 kg / dm³; a sheet 3 adapted to the diameter of the post 1; slotted pins 4 (anchors); and the ceramic fiber mat 5.

[0016] The ceramic fiber mat 5 is attached to the rolled sheet metal 3 with the already welded anchors acting as slotted pins 4. The slotted pins 4 are then spread open. The entire unit, together with the refractory cast concrete poured in a mold, forms a shielding shoe 2.

[0017] A halved cast iron plate 6 (also called a plate) is used for mounting and supporting the shielding shoe 2. The two parts (left and right) of the cast iron plate 6 are placed on the stand 1 in a predetermined position, welded in place, and covered with a ceramic fiber mat 7.

[0018] To completely cover the floor slot, two shielding shoes 2 are required. During assembly, one shielding shoe 2 is placed on one half of the cast plate 6 and the other on the other half. Both shielding shoes 2 are welded to the upright 1 using the rolled sheet metal 3.

[0019] To replace a shielding shoe 2, the welded plates 3 must be cut off from the upright 1 and the plates 3 of the new shielding shoes 2 must be welded back on in the same position.

[0020] Figures 3 and 4 We now show an embodiment of the shielding shoes 1a according to the invention. The shielding shoes 1a have a semicircular recess 9a for receiving them on the upright 5a. Instead of the cast plate, two new retaining clips 2a made of highly heat-resistant stainless steel or cast stainless steel are welded to the upright 5a and covered with a ceramic fiber mat 4a on the side facing the furnace chamber. In this example, the retaining clip 2a is C-shaped. Viewed from above, it is therefore a C-shaped component, the rear of which is welded to the upright 5a.

[0021] To mount or dismount the new shielding shoe 1a, it is slid onto or removed from the new retaining clips 2a. For this purpose, the shielding shoe 1a has two curved slots 10a in the area of ​​its semicircular recess 9a, into which the two legs of the retaining clip 2a can be received. The curved shape of the slots 10a securely holds the shielding shoe 1a and minimizes the risk of stress cracks. The shielding shoe 1a also rests on a circular retaining ring 6a. The top surface of the shielding shoe 1a is formed by the shielding jacket 8a. The shielding jacket has a uniform thickness x. Below the shielding jacket is the honeycomb structure 7a, which is also made of refractory cast concrete or refractory rammed concrete.This honeycomb structure is created by pouring the concrete into a suitable mold, in which the future struts of the honeycomb are recessed. In this example, honeycomb structure 7a has a uniform wall thickness y.

[0022] To facilitate assembly / disassembly, a clamp hole 3a is provided in the shielding shoe 1a. During assembly / disassembly, a clamp with an eyelet is screwed into clamp hole 3a, into which the hook of a lifting tool can then be attached. For operational purposes, clamp hole 3a can be sealed with a fire-resistant compound.

[0023] The new shielding shoe 1a is thermally pre-treated (up to 1,400°C possible). This allows for long-term storage in dry and frost-free conditions without any loss of quality.

[0024] In this example, two identical shielding shoes 1a are attached to the upright 5a. They both have an elliptical base. Accordingly, two retaining clips 2a are attached to the upright 5a. The shielding sleeves 8a of the two shielding shoes 1a form an umbrella-like shape, allowing falling scale to slide off the shielding sleeve 8a. This prevents or minimizes disruptive deposits on the shielding shoe 1a.

[0025] The described embodiment has the following advantages: 1. Weight reduction of the shielding shoe 1a by at least 35%; 2. Easier assembly / disassembly due to the reduced weight and the use of the new clamp for handling; 3. Welding work required only once for attaching the retaining clips 2a and the retaining ring 6a; 4. Long shelf life of the manufactured and heat-treated shielding shoe 1a.

Claims

1. A shielding shoe (1a) for covering openings in the bottom of a walking beam furnace, the shielding shoe (1a) having a semi-circular recess (9a) and can thereby be taken up by a vertical support (5a) of the walking beam furnace and consisting essentially of refractory cast concrete or of refractory rammed concrete and having a shielding jacket (8a), characterised in that the shielding shoe (1a) has a honeycomb-like structure (7a) below the shielding jacket (8a).

2. Shielding shoe (1a) according to claim 1, characterised in that the shielding jacket (8a) has a constant thickness (x) above the honeycomb-like structure (7a).

3. A shielding shoe (1a) according to claim 1 or 2, characterised in that the honeycomb-like structure (7a) has a uniform wall thickness (y).

4. Shielding shoe (1a) according to one of the claims 1 to 3, characterised in that the shielding shoe (1a) has curved slots (10a) in the area of the recess (9a) so that it can be suspended on holding clamps (2a) fastened to the support (5a).

5. Shielding shoe (1a) according to claim 4, characterised in that the slots (10a) are c-shaped in top view.

6. A shielding shoe (1a) according to any one of claims 1 to 5, characterised in that the shielding shoe (1a) has at least one block hole (3a) on its upper side.

7. Walking beam furnace having at least one support (5a) projecting through an opening in the bottom of the walking beam furnace, characterised in that two shielding shoes (1a) according to any one of claims 1 to 6 are attached to the support (5a).

8. Walking beam furnace according to claim 7, characterised in that curved holding clamps (2a) are fastened to the support (5a), into which the shielding shoes (1a) are suspended.

9. Walking beam furnace according to claim 7 or 8, characterised in that a supporting ring (6a) is fastened to the support (5a), on which the two shielding shoes (1a) rest on.

10. Walking beam furnace according to claim 9, characterised in that one half of the supporting ring (6a) and a respective holding clamp (2a) are a one-piece component.