WO2011106411A2

WO2011106411A2 - Insulation apparatus

Info

Publication number: WO2011106411A2
Application number: PCT/US2011/025909
Authority: WO
Inventors: Leland Matthew Reineke
Original assignee: Americarb, Inc.
Priority date: 2010-02-24
Filing date: 2011-02-23
Publication date: 2011-09-01
Also published as: WO2011106411A3

Abstract

An insulation apparatus such as a CZ modular insulation pack for CZ-style mono-crystal pulling equipment is provided for use in the production of silicon, sapphire and other crystal materials. The apparatus may have a tubular heat shield with a generally cylindrical circumferential surface. The apparatus may include more than two fiber board segments arranged in side-by-side relation to form a continuous annular ring around the heat shield. The insulation apparatus may include two handles movable between a retracted position and an extended position relative to the heat shield.

Description

Title: Insulation apparatus

BACKGROUND

High temperature fiber board insulation products are typically used in vacuum furnace linings, Directional Solidification System (DSS) furnaces, Czochralski (CZ) crystal pullers, and other high temperature furnace applications involving

temperatures above of 1000°C. At these temperatures, thermal expansion and contraction of the insulation products may produce cracks or otherwise degrade the insulating characteristics of the products. Thus there exists a need for a cost-effective fiber board insulation product that can accommodate thermal expansion and contraction without cracking and can retain sufficient insulation and structural characteristics for longer periods of use relative the prior art.

SUMMARY

The following is a brief summary of the subject matter that is described in greater detail herein. This summary is not intended to be limiting as to the scope of the claims.

Described herein are examples of an insulation apparatus and processes for producing the insulation apparatus which are directed to overcoming one or more of the aforementioned problems with the prior art. An example insulation apparatus may correspond to a CZ modular insulation pack for CZ style mono-crystal pulling equipment that is used in the production of silicon, sapphire and other crystal materials.

In this example embodiment, an insulation apparatus may have a tubular heat shield with a generally cylindrical circumferential surface. The apparatus may include more than two fiber board segments arranged in side-by-side relation to form a continuous annular ring around the heat shield. Each fiber board segment may include a concave surface that corresponds to a portion of the generally cylindrical circumferential surface of the heat shield. Also, each side of each fiber board segment may be shiplapped to produce joints with overlapping fiber board material. The fiber board segments may be mounted to the heat shield using graphite fasteners that extend (through holes in the fiber board segments) into operatively supported connection with the heat shield. In an example embodiment, the heat shield may include a portion (such as an outer felt liner) that includes channels therein on opposed sides of the heat shield for receiving movable handles therein. In the same embodiment (or a different embodiment without channels in the heat shield), the fiber board segments mounted adjacent the handles may include channels that receive the handles therein. In embodiments with channels in at least one of the heat shield and fiber board segments, these handles are operative to be manually moved in the channels between a retracted position and an extended position. In the retracted position, the handles may be lowered sufficiently so as to not extend above the heat shield. In the extended position, portions of the handles extend above the heat shield to facilitate moving the apparatus during assembly and repairs.

Other aspects will be appreciated upon reading and understanding the attached figures and description.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a perspective view of an example insulation apparatus.

Fig. 2 shows a perspective exploded view of the example insulation apparatus. Fig. 3 shows a perspective view of examples of fiber board insulation segments.

Fig. 4 shows a side view of an example of the insulation apparatus with one fiber board segment removed from in front of a movable handle.

Fig. 5 shows a cross-sectional view of the insulation apparatus in the location of a movable handle.

Fig. 6 shows a schematic view of an upmost edge of a fiber board segment cut from a fiber board billet with a generally parallel grain.

Fig. 7 is flow diagram that illustrates an example process for producing fiber board segments for an example insulation apparatus.

Fig. 8 is flow diagram that illustrates an example process for assembling an insulation apparatus.

DETAILED DESCRIPTION

Various technologies pertaining to insulation apparatuses and processes will now be described with reference to the drawings, where like reference numerals represent like elements throughout. In addition, a flow diagram of an example process is illustrated and described herein for purposes of explanation; however, it is to be understood that alternative examples of the process may be carried out with fewer steps, additional steps, steps in a different order, and/or modified steps. Also, it is to be understood that the examples of an insulation apparatuses described herein may be typically used in CZ crystal pullers. However, it is to be understood that one or more features described herein may be used in other types of insulating processes.

With reference to Figure 1, an insulation apparatus 100 is illustrated that is in the form of a fully assembled CZ puller insulation pack 102. Such an insulation pack 102 may include a tubular heat shield 104 that has a generally cylindrical

circumferential surface. Such a heat shield may include an inner liner 150 comprised of machined graphite, carbon composite, or other material capable of maintaining its structural integrity through multiple heating and cooling cycles with temperatures reaching 1000°C. Also, the heat shield 104 may include an outer felt liner 152 comprised of a graphite felt or other high temperature compatible material that extends around the outer surface of the inner liner 150. Such a felt liner may be compressible to compensate for thermal expansion between the heat shield and other elements (described below) that are mounted to the heat shield.

In this described embodiment, the insulation pack 102 may include a plurality (e.g., two or more) of fiber board segments 130-137 arranged in side-by-side relation to form a continuous annular ring 108 around the heat shield. Figure 3 shows an example of two adjacent fiber board segments 137, 130 in which the heat shield has been removed. As illustrated in Figure 3, each fiber board segment may include a concave surface 138 that has a curvature that corresponds to the generally cylindrical circumferential curvature of the heat shield. Thus when the insulation pack 104 is assembled as shown in Figure 1 , the concave surfaces of the fiber board segments are each in contact with the heat shield 102.

The fiber board segments may be cut from billets of fiber board. Such billets may be comprised of short fiber material (e.g., fiber strands averaging on the order of 1000 microns in length) that has been carbonized into a low density non-graphitizing insulating material (e.g., densities ranging from 13g/cc to .30 g/cc).

In example embodiments, the fiber board segments may be cut from at least one billet of fiber board in which the grain of the billet of fiber board extends in generally parallel planes between opposed ends of the billet. Figure 6 shows a top plan view of a top edge 602 of an example fiber board segment 600 cut from such a fiber board billet 606 (shown in phantom) that includes grain 604 orientated in generally parallel planes. As shown in Figure 6, with a fiber board segment cut in the manner illustrated, the orientation of the grain 604 in the fiber board segment 600 extends generally perpendicular to radiant energy 608 directed radially towards the center of curvature 610 of the concave surface 614 of the fiber board segment 600. As a result, the center 610 of the fiber board segment may have the lowest thermal conductivity for heat sources directed in a radial direction from heat sources inside the heat shield.

However, it should be appreciated that positions on the concave surface 614 farther from the center 610 may have relatively higher thermal conductivity relative a radially directed heat source 608, because the grain of the fiber board is not orientated perpendicular to the radially directed heat source. Thus, to minimize the increase in thermal conductivity of the fiber board segment at points further away from the center 610, the number of segments used to assemble the annular ring may be sufficiently large (e.g., 8-12), to minimize the width of the fiber boards segments.

Referring back to Figure 1 , in this described embodiment, the insulation pack 102 includes two slideable handles 110, 168 positioned on opposed sides of the heat shield 104. These handles are each operative to slide relative to the heat shield in directions parallel to a central longitudinal axis 114 of the heat shield between a retracted position and an extended position. Figure 1 shows the handle 112 in a state in which it has been slid to the extended position. In this extended position a portion 116 of the handle extends above the heat shield and the fiber board segments 130-137. This portion 116 of the handle may include one or more horizontal sections to enable a person to firmly grasp the handle when lifting the insulation pack upwardly.

Figure 1 also shows the handle 110 in a state in which it has been moved downwardly to the retracted position. In this retracted position, the portion 116 of the handle that is capable of extending above the heat shield is now positioned in between the heat shield and a fiber board segment such that no portion of the handle extends above the heat shield and fiber board segments 106. However, it should be appreciated that in alternative embodiments, when the handle is in the retracted position, an amount of the handle may extend above at least one of the heat shield and fiber board segments provided that such a small amount does not interfere with the operation of the operation of the insulation apparatus.

Figure 2 shows a partially exploded view of the described insulation apparatus 100. As illustrated in Figure 2, the sides 126, 128 of each fiber board segment 130, 131 may be shiplapped to facilitate overlapping joints between the fiber board segments. As a result when the segments are assembled to form the annular ring 108, each side of each fiber board segment includes portions 120 which traverse (e.g., cross over or under), in an axial direction 124 with respect to the heat shield 104, portions 122 of a side of an adjacent fiber board segment included in the annular ring. In this configuration, heat energy directed in a radial direction from a heat source within the heat shield will pass through at least the outer portions 120 of the side 126 of a fiber board segment 130, even when a gap is present between the inner portions 122 of the side 128 of the fiber board segment 131 and adjacent portions 121 of the side 126 of the adjacent fiber board segment 130.

As shown in Figure 2, opposite sides of each fiber board segment may be shiplapped in an opposite manner. As a result, all of the segments may have a common configuration for their shiplapped sides. However, it is to be understood that in alternative embodiments, different fiber board segments may have different configurations of shiplapped sides. For example, one side of a fiber board segment may have a shiplapped contour that is the mirror image of the opposite side of the same fiber board segment.

Also, it is to be understood that different styles of shiplapping may be uses at the joints of adjacent fiber board segments. For example, rather than the stepped contour illustrated in Figure 2, the sides of the fiberboard segments may include tongue and grove arrangements, or any other cooperatively assembled joint that minimizes the amount of radiant energy passing therethrough while still

accommodating thermal expansion of the fiberboard segments.

In this described embodiment, the fiber board segments may be mounted to the heat shield with fasteners. For example, as shown in Figure 2, such fasteners may include studs 140 that are in operatively supported connection with the heat shield 104. For example, each stud 140 may be threaded, and may be threadebly engaged into threaded bores 142 in the inner liner of the heat shield.

As shown in Figure 3, fiber board segments may include one or more holes 148 therethrough, such that when a fiber board segment is placed against the heat shield 104, the studs extend into the holes 148. As shown in Figure 2, such holes may include counter bores 149 with diameters that are sufficiently large to receive a nut 144 in threaded engagement with each stud. In addition, the counter bores may be sufficiently deep to facilitate receiving plugs 146 adjacent the nuts. Such plugs may be comprised of fiber board (such as the same fiber board used to make the fiber board segments) or other high temperature insulating material. In this described embodiment, the studs and nuts of the fasteners may be comprised of graphite.

To facilitate movement of the described handles 110, 112 between the retracted and extended positions, either or both of the heat shield 104 and fiber board segments 133, 137 adjacent the handles, may be adapted to include sufficient space for the handle to slide therebetween. For example, as shown in Figure 2, in an embodiment, the felt liner 152 of the heat shield 104 may include a channel 160 cut therein which provides space for a handle to slide therein adjacent the inner liner 150 of the heat shield. Figure 4 illustrates a side view of the insulation apparatus 100 (with a fiber board segment 133 removed from the location of a handle 112), in order to illustrate that the channel 160 cut in the felt liner 152 has a sufficient size to accommodate receiving the handle 112, when moved from the extended position shown to a lower retracted position.

Referring back to Figures 3 in the same embodiment (or a different embodiment), the fiber board segments mounted adjacent the handles may include channels 162 (shown in phantom) cut in the concave surfaces 138 of the fiber board segments in which the handles may also slide. As shown in Figure 3, the channels 162 may extend along the concave surface to a position below the at least one hole 148 in each respective fiber board segment.

Referring back to Figure 2, each handle may include an elongated slot 118 extending therethrough. The slot may be positioned so that when the handle 112 is mounted between the heat shield and the respective fiber board segment 133, a respective one of the studs 140 of the fasteners extends through the slot 118 in the respective handle 112 and into operatively supported connection with the inner liner 150 of the heat shield 104.

Figure 5 illustrates a side cross sectional view of the insulation apparatus cut through the portion of the apparatus that includes the handle 112 mounted in this described manner with a stud 140 extending through the slot in the handle 112. As can be appreciated from Figures 2 and 5, when the handle moves relative to the heat shield between the retraced and extended positions, the stud 140 moves along the slot and prevents the handle from being pulled out of engagement with the heat shield.

Also, as shown in Figure 2, in this example embodiment, the stud 140 that extends through each handle 112 may further include a bushing 166 thereon that is positioned in the hole through the fiber board segment between the nut 144 and handle 112. In addition as shown in Figures 2 and 3, in this example, the fiber board segments 133, 137 adjacent the handles 110, 112 may include handle access pockets 168 cut into an uppermost edge and concave surface of the fiber board segment. The handle access pockets 168 may have sufficient size to enable at least one finger of a human hand to extend therein and grasp the upper portion 116 of the handle 112 when the handle 112 is in the retracted position.

The example insulation apparatus may be used with relatively thicker walled fiber board segments (relative to the prior art), which based on the described structure of the apparatus are operative to allow for thermal expansion without creating voids in the insulation or undue stress on the apparatus. As an example, a 40-inch inside diameter hot zone (within the heat shield) may be insulated using 8 to 12 fiber board segments that are 3 to 4 inches thick (in the radial direction) bolted to a heat shield with graphite studs 1.5 to 2 inches in length. Such an example insulation apparatus may be used in a CZ-style mono-crystal pulling equipment to replace the use of 3-4 concentrically positioned 1 inch thick monolithic tubes of insulating material. Also, it should be noted that the described example insulation apparatus may be produced in different diameters, sizes, and wall thicknesses, depending on the intended configuration of the CZ-style mono-crystal pulling equipment.

Referring now to Figure 7, an example process 700 that facilitates the production of fiber board segments from an insulation apparatus is illustrated. The process 700 may include a step 702 of cutting more than two (e.g., 8-12) fiber board segments from at least one billet of fiber board such that the fiber board segments are adapted to be arranged in side-by- side relation to form a continuous annular ring around a generally cylindrical circumferential surface of a tubular heat shield. In this step, each fiber board segment may be cut to include a concave surface that corresponds to a portion of the generally cylindrical circumferential surface of the heat shield. Also in this step, each side of each fiber board segment may be shiplapped, such that the each side includes portions which traverse, in an axial direction with respect to the heat shield, portions of a side of an adjacent fiber board segment that forms the annular ring (e.g., shiplapping). In example embodiments, cutting of the fiber board billet may be carried out using a CNC wire saw with a .060 inch wire blade or other suitable saw.

Continuing at step 704, in this embodiment (or an alternative embodiment) for at least two of the fiber board segments, the process may optionally include cutting a channel in the location of the concave surface. Also, in this embodiment (or an alternative embodiment) such channels may be located in the heat shield. Such channels (whether in the fiberboard segments or the heat shield or both) are operative to receive movable handles that slide respectively in the channels in directions parallel to a central longitudinal axis of the heat shield between a retracted position and an extended position. In this example embodiment, when a handle is in the extended position, a portion of the handle extends above the heat shield and fiber board segments. Also in this example, when a handle is in the retracted position, an uppermost edge of the handle may be generally flush with or lower than the uppermost edge of the heat shield and/or fiber board segments.

Continuing at step 706, the process may include cutting a handle access pocket in each of the fiber board segments that will be mounted adjacent a handle. Such a handle access pocket may have sufficient size to enable at least one finger of a human hand to extend therein and grasp a portion of a handle when the handle is in a retracted position.

Continuing at step 708, the process may include drilling at least one hole through each fiber board segment. The holes may be drilled to be sufficiently large to permit a fastener to extend therethrough and into operatively supported engagement with the heat shield. In example embodiments that include channels in the fiber board segments adjacent the handles, the channels may be cut to extend from a handle access pocket of each respective fiber board segment to a position below the at least one hole drilled through each respective fiber board segment. In addition, step 708 may include drilling a counter bore for each hole on a side of the fiber board segments that is opposite the concave surface.

Once the fiber board segments have been cut and drilled as described in the preceding steps, the process may include a step 710 of coating the fiber board segments with a graphite coating or other high temperature compatible coating. Such a graphite coating may include a graphite foil such as that made by GrafTech

International Ltd. of Cleveland, Ohio, that is applied with graphite paint as a binder such as graphite paint part number DAG 137 made by DAG 137 by HENKEL, International of Diisseldorf, Germany. Alternatively, the coating may include only graphite paint such as DAG 137. At step 712, the example process may include curing the coating by drying the coated fiber board segments on a drying rack of an oven. For example, the coating coatings may be dried at a temperate of 100°C for 24 hours.

As discussed previously, the fiber board segments in step 702 may be cut from fiber board billets in which the grain of the billet of fiber board extends in generally parallel planes between opposed ends of the billet. As a result in step 706, the holes that are drilled may extend in a direction that is generally normal to the planes of the grain in fiber board of the respective fiber board segment.

Also, it should be noted that the described grain in the fiber board billets is a result of the type of molding process used to create the fiber board billets. In example embodiments, the billets of fiber board may be produced via a drain casting process, in which layers of the slurry build up on top of each other over a flat screen in a mold. These overlapped layers form a visible grain that extends along generally parallel planes through the fiber board billet. However, in alternative embodiments the fiber board billets may be generated using other types of casting processes (e.g., vacuum casting).

The previous process 700 is operative to produce fiber board segments that are usable to assemble a new insulation apparatus. However, it should be understood that such fiber board segments may also be used to replace existing worn-out or broken fiber board segments from an existing insulation apparatus.

Referring now to Figure 8, an example process 800 that facilitates the assembly of an insulation apparatus is illustrated. In this example embodiment, the fasteners may include threaded graphite studs. Also, each handle may include an elongated slot extending therethrough. Also, the heat shield may include threaded bores in the locations at which the studs are desired to be mounted. With these features, the process 800 may include a step 802 of mounting the studs into bores in the outer surface of the heat shield. However, it should be noted that in cases where an insulation apparatus is being repaired, such studs may already be in place on the heat shield.

Continuing at step 804, the method may include mounting the fiber board segments to the heat shield to form the annular ring around the heat shield. In this step, the fiber board segments may be positioned such that the studs mounted on the heat shield pass into the respective holes in the fiber board segments. However, for at least two studs on opposed sides of the heat shield (prior to mounting the fiber board segments adjacent the handles), this method 804 may include a step 806 of mounting the handles adjacent the heat shield such that the respective stud extends through the respective slot in the respective handle. Then method step 804 may include a step 808 of mounting the fiber board segments with the handle access pockets (and/or channels) adjacent the handles such that each respective stud through the respective handle extends into the respective hole in the respective fiber board segment.

Continuing at step 810, the method may include placing graphite bushings on at least the studs that extend through slots in the handles. Then continuing at step 812, the method may include threadably engaging a graphite nut to each stud in the counter bore of each fiber board segment. Also, in a step 814, the process may include placing a fiberboard plug in each counter bore adjacent each respective nut.

In this described embodiment, the heat shield may include an inner liner comprised of carbon composite or machined graphite. Also, example embodiments of the heat shield may include a felt liner. Thus, prior to steps 802 and 804 of mounting the studs and fiber board segments, the method may include a step of mounting a graphite felt liner around the inner liner. In embodiments without channels in the fiber board segments (and optionally in embodiments with channels), such a felt liner may include at least two channels. Thus, this step may include cutting such channels (or at least orientating existing channels of the felt liner) to be positioned in the location where the handles will be mounted on the heat shield. Such a felt liner may be secured to the inner liner via the mounting of the studs or other fasteners (or via an adhesive).

These example processes with respect to Figures 7 and 8 have been explained as being segregated into separate steps. However, it should be noted that such steps could be carried out in a different order. Also portions of one or more steps could be carried out during portions of other steps. For example, when assembling the insulation apparatus, the fiber board segments and associated studs, nuts, plugs, (and handle) for one fiber board segment may be completely mounted to the heat shield before mounting another fiber board segment and its associated studs, nuts, plugs, (and handle).

It is noted that several examples have been provided for purposes of explanation. These examples are not to be construed as limiting the hereto-appended claims. For example, in alternative example embodiments, the configuration of the handles may have different shapes, styles, and sizes. Also, such handles may include more than one slot. Also such handles may use fasteners to secure the handles, which fasteners are not used to mount the fiber board segments to the heat shield. Also, alternative embodiments may not include any handles.

Also, example embodiments may employ additional elements which enhance the structural integrity and assembly of the insulation apparatus (e.g., graphite foil washers on the stud). In addition, some embodiments may include both channels in the felt liner and in the fiber board segments for receiving the handles. However in other embodiments, the insulation apparatus may include channels in one or the other of the heat shield and fiber board segments. Thus, it should be recognized that the examples provided herein may be permutated while still falling under the scope of the claims.

Claims

CLAIMS What is claimed is:

1. An insulation apparatus comprising:

A tubular heat shield having a generally cylindrical circumferential surface, wherein the heat shield includes a central longitudinal axis; more than two fiber board segments arranged in side -by-side relation to form a continuous annular ring around the heat shield, wherein each fiber board segment includes a concave surface that corresponds to a portion of the generally cylindrical circumferential surface of the heat shield, wherein each side of each fiber board segment includes portions which traverse, in an axial direction with respect to the heat shield, portions of a side of an adjacent fiber board segment included in the annular ring, wherein each fiber board segment includes at least one hole therethrough; at least one fastener extending through each hole and into operatively supported connection with the heat shield; wherein further comprising at least one of: at least two channels in portions of the heat shield respectively on opposed sides of the heat shield; and at least two channels in the concave surfaces respectively of at least two fiber board segments on opposed sides of the heat shield; and wherein the channels in at least one of the heat shield and fiberboard segments include therein movable handles, wherein each handle is movable in directions parallel to the central longitudinal axis between a retracted position and an extended position, wherein in the extended position, a portion of the handle extends above the heat shield and fiber board segments.

2. The insulation apparatus according to claim 1 , wherein each handle includes an elongated slot extending therethrough, wherein for each of the two fiber board segments, a respective one of the fasteners extends through the slot in the respective handle and into operatively supported connection with the heat shield, wherein when the handle moves relative to the heat shield between the retraced and extended positions, the fastener moves along the slot.

3. The insulation apparatus according to claim 2, wherein each hole includes a counter bore, wherein each fastener includes a threaded stud that extends through the respective hole in each fiber board segment and is threadably engaged within threaded bores in the heat shield, wherein each fastener includes a nut that is threadably engaged with the stud in the counter bore, wherein for each of the at least two fiber board segments, a respective one of the studs extends through the slot in the respective handle.

4. The insulation apparatus according to claim 3, wherein for each stud that extends through the slots in the handles, the stud includes a bushing between the nut threadably engaged with the stud and the handle through which the stud extends.

5. The insulation apparatus according to claim 4, wherein each counter bore includes a plug therein adjacent each respective nut.

6. The insulation apparatus according to claim 2, further comprising a handle access pocket in the fiber board segments mounted adjacent the handles, wherein the handle access pocket has a sufficient size to enable at least one finger of a human hand to extend therein and grasp a portion of the handle when the handle is in the retracted position.

7. The insulation apparatus according to claim 2, wherein the heat shield includes an inner liner and a felt liner extending around the inner liner, wherein the felt liner includes the channels, wherein the handles extend in the channels in the felt liner.

8. The insulation apparatus according to claim 2, wherein the fiber board segments adjacent the handles include the channels extending from an uppermost edge of each respective fiber board segment to a position below the at least one hole in each respective fiber board segment.

9. The insulation apparatus according to claim 2, wherein the plurality of fiber board segments are cut from at least one billet of fiber board, wherein a grain of the billet of fiber board extends in generally parallel planes between opposed ends of the billet, wherein the holes extend through the fiber board segments in directions that are generally normal to the planes of the grain in fiber board of the respective fiber board segment.

10. A method comprising: a) cutting more than two fiber board segments from at least one billet of fiber board such that the fiber board segments are adapted to be arranged in side-by- side relation to form a continuous annular ring around a generally cylindrical circumferential surface of a tubular heat shield, wherein the heat shield has a central longitudinal axis, wherein each fiber board segment is cut to include a concave surface that corresponds to a portion of the generally cylindrical circumferential surface of the heat shield, wherein each side of each fiber board segment is cut to include portions which traverse in an axial direction with respect to the heat shield, portions of a side of an adjacent fiber board segment that forms the annular ring; and b) drilling at least one hole through each fiber board segment, wherein the holes are sufficiently large to permit a fastener to extend therethrough and into operatively supported engagement with the heat shield.

11. The method according to claim 10, further comprising: c) coating each fiber board segment with graphite paint.

12. The method according to claim 11, wherein the fasteners include threaded studs, further comprising: d) mounting the studs into bores in the outer surface of the heat shield; e) mounting the fiber board segments to the heat shield to form the annular ring around the heat shield, wherein for at least two studs on opposed sides of the heat shield; i) mounting at least two handles on the at least two studs, such that a respective one the at least two studs extends through a respective slot in the respective handle; ii) mounting a respective fiber board segment adjacent each respective handle, such that each respective stud through the respective handle extends into the respective hole in the respective fiber board segment; wherein each handle is operative to move relative to the heat shield between a retraced position and an extended position, wherein during relative movement between a handle and the heat shield, a respective stud through the handle moves along the respective slot in the handle.

13. The method according to claim 12, wherein (c) includes drilling a counter bore for each hole, wherein each stud includes threads, wherein (d) includes threadably engaging each stud within threaded bores in the heat shield, wherein further comprising: f) threadably engaging a nut to each stud in the counter bore of each fiber board segment.

14. The method according to claim 13, wherein prior to (f), for each stud that extends through the slot of the respective handle, placing a bushing on the stud adjacent to the handle.

15. The method according to claim 14, after (f), placing a plug in each counter bore adjacent each respective nut.

16. The method according to claim 15, further comprising: sliding the handles between the retracted and extended positions, wherein in the retracted position, portion of the handle extends above the heat shield.

17. The method according to claim 12, wherein the heat shield includes an inner liner, further comprising:

prior to (d) mounting a felt liner around the inner liner, wherein the felt liner includes at least two channels, wherein in (e) the handles are placed in the channels of the felt liner.

18. The method according to claim 10, further comprising:

in at least two of the fiber board segments, cutting a channel in the location of the concave surface, wherein the channel is operative to receive a movable handle that slides in the channel in directions parallel to the central longitudinal axis between a retracted position and an extended position, wherein in the extended position, a portion of the handle extends above the heat shield and fiber board segments, wherein each channel extends from an uppermost edge of each respective fiber board segment to a position below the at least one hole in each respective fiber board segment.

19. The method according to claim 10, further comprising:

prior to (c) cutting a handle access pocket in at least two fiber board segments adjacent an uppermost edge and the concave surface of each fiberboard segment, wherein each handle access pocket has a sufficient size to enable at least one finger of a human hand to extend therein.

20. The method according to claim 10, wherein in (a) the grain of the billet of fiber board extends in generally parallel planes between opposed ends of the billet, wherein in (c) the holes are drilled in a direction that is generally normal to the planes of the grain in fiber board of the respective fiber board segment.