Straight tube basket type graphite heating element

Abstract

The application provides a straight cylinder type basket type graphite heating body, the graphite cylinder body comprises an upper heating area, a middle basket heating area and a lower heating area, the upper end of the upper heating area is provided with an upper electrode connecting ring, the lower end of the lower heating area is provided with a lower electrode connecting ring, the middle basket heating area is arranged between the upper electrode connecting ring and the lower electrode connecting ring, the middle basket heating area is provided with a plurality of interval arranged heating plate groups along the circumference, the lower end of the upper electrode connecting ring is provided with a plurality of interval arranged heating body upper connections of the hot area along the circumference, the upper end of the lower electrode connecting ring is provided with a plurality of interval arranged heating body lower connections of the hot area along the circumference, each heating body upper connection is connected with the upper end of each heating plate group, each heating body lower connection is connected with the lower end of each heating plate group, the upper end of the upper electrode connecting ring on the side wall of the graphite cylinder body is provided with a plurality of air inlet holes in communication with the inside of the graphite cylinder body along the circumference, and the problems of single heat transfer form of the straight cylinder type graphite heating body and difficult adjustment of the resistance characteristics in design are solved.

Description

Technical Field

[0001] This utility model relates to the field of optical fiber preform heating, and in particular to a straight cylindrical basket-type graphite heating body. Background Technology

[0002] Graphite is the preferred material for heating elements in wire drawing furnaces due to its high temperature resistance, excellent thermal and electrical conductivity, strong thermal stability, and good chemical inertness. Conventional graphite heating elements in wire drawing furnaces are cylindrical, hollow structures. The graphite material is either integrally molded or composed of multiple segments, with smooth inner walls and electrode connections at the top and bottom. When current is introduced into the cylindrical graphite body through the electrodes, the graphite generates Joule heat due to its resistance. This heat diffuses within the graphite material via thermal conduction, causing the temperature of the inner wall of the cylinder to rise rapidly and uniformly, forming an annular hot zone. Simultaneously, the heat source on the inner wall transfers heat to the center of the furnace cavity through thermal radiation, ultimately forming a stable cylindrical high-temperature zone in the central region of the cylinder.

[0003] The aforementioned cylindrical graphite heating element has significant limitations in practical applications: First, the heat transfer method is singular, mainly relying on the thermal radiation of the annular hot zone surface to achieve central heating, resulting in significant heat loss and low energy utilization efficiency; second, the resistance characteristics are determined by the overall cylindrical structure, making it impossible to flexibly adjust the resistance parameters according to process requirements, resulting in poor adaptability; third, the high-temperature zone range is fixed by the inner wall size of the cylindrical structure, making it difficult to achieve precise positioning and flexible control of the high-temperature zone, and thus failing to meet the manufacturing requirements of products with different specifications. Utility Model Content

[0004] This invention provides a straight-cylinder basket-type graphite heating element, which solves the problems of the single heat transfer mode and the difficulty in adjusting the resistance characteristics of straight-cylinder graphite heating elements.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows: a straight-cylinder basket-type graphite heating element, including a graphite cylinder, the graphite cylinder including an upper heating zone, a middle basket-type heating zone and a lower heating zone, an upper electrode connecting ring at the upper end of the upper heating zone, a lower electrode connecting ring at the lower end of the lower heating zone, a middle basket-type heating zone between the upper electrode connecting ring and the lower electrode connecting ring, a plurality of heating plate groups arranged at intervals along the circumference of the middle basket-type heating zone, a plurality of heating element hot zones connected at intervals along the circumference of the lower end of the upper electrode connecting ring, a plurality of heating element hot zones connected at intervals along the circumference of the upper end of the lower electrode connecting ring, each heating element hot zone connected at the upper end of each heating plate group, each heating element hot zone connected at the lower end of each heating plate group, and a plurality of air inlets communicating with the interior of the graphite cylinder are arranged at the circumference above the upper electrode connecting ring on the side wall of the graphite cylinder.

[0006] In a preferred embodiment, the heating plate assembly includes an upper horizontal connecting block and a lower horizontal connecting block. Multiple graphite plates are arranged at intervals between the upper and lower horizontal connecting blocks. The multiple graphite plates are connected end to end through the upper and lower horizontal connecting blocks and arranged in a folded manner to form the heating plate assembly.

[0007] In the preferred embodiment, the number of upper horizontal connecting blocks is one more than the number of lower horizontal connecting blocks. An extension connecting block is provided at the lower end of the upper connection of the heating element's hot zone. The extension connecting block is connected to the lower end of the graphite plate on the side. The lower connection of the heating element's hot zone is connected to the lower horizontal connecting block.

[0008] In the preferred embodiment, the number of lower horizontal connecting blocks is one more than the number of upper horizontal connecting blocks. An extension connecting block is provided at the upper end of the lower connection of the heating element's hot zone. The extension connecting block is connected to the upper end of the graphite plate on the side. The upper connection of the heating element's hot zone is connected to the upper horizontal connecting block.

[0009] In the preferred embodiment, the extension connecting block has a T-shaped structure.

[0010] In the preferred embodiment, the graphite cylinder is a hollow cylindrical structure.

[0011] In the preferred embodiment, after each heating plate group is connected in parallel, its two ends are connected to the upper electrode connecting ring and the lower electrode connecting ring, respectively.

[0012] The beneficial effects of this utility model are as follows: It is equipped with an air inlet, which allows heat to be transferred downwards through inert gas. The temperature can be further adjusted by modifying the gas channel structure, resulting in a variety of heat transfer methods. It uses multiple graphite sheets for simultaneous heating, and the three-dimensional heating can reduce heat loss. The hot zone is composed of multiple graphite sheets, and the resistance can be flexibly adjusted by changing the thickness during the design stage. The hot zone is determined by multiple graphite sheets, which can accurately determine the high-temperature zone. The upper and lower connecting parts can be connected to the electrodes of the wire drawing furnace respectively, which is more reliable than the traditional basket-type heating element and has a larger contact surface, making it less prone to arcing. Attached Figure Description

[0013] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0014] Figure 1 This is a schematic diagram of the heating element cylinder.

[0015] Figure 2 This is an enlarged schematic diagram of the heating plate assembly.

[0016] Figure 3 This is a side view of the heating element cylinder.

[0017] Figure 4 This is a cross-sectional view of the heating element cylinder.

[0018] Figure 5 This is a schematic diagram of the installation and application of the heating element.

[0019] Figure 6 This is a schematic diagram of the equivalent resistance distribution of the heating element. Figure 1 .

[0020] Figure 7 This is a schematic diagram of the equivalent resistance distribution of the heating element. Figure 2 .

[0021] Figure 8 This is a simplified diagram of the resistor connection.

[0022] In the figure: Upper heating zone 1; Upper electrode connecting ring 101; Lower electrode connecting ring 102; Graphite plate 103; Upper connection of heating element hot zone 104; Lower connection of heating element hot zone 105; Upper horizontal connecting block 106; Lower horizontal connecting block 107; Air inlet 108; Extension connecting block 109; Middle basket heating zone 2; Lower heating zone 3; Heating plate assembly 4; Graphite cylinder 5; Outer shell 6; Inner sleeve 7; Fiber optic preform 8. Detailed Implementation

[0023] Example 1: like Figure 1-8 A cylindrical basket-type graphite heating element includes a graphite cylinder 5, which comprises an upper heating zone 1, a middle basket-type heating zone 2, and a lower heating zone 3. The upper heating zone 1 has an upper electrode connecting ring 101 at its upper end, and the lower heating zone 3 has a lower electrode connecting ring 102 at its lower end. The middle basket-type heating zone 2 is located between the upper electrode connecting ring 101 and the lower electrode connecting ring 102. The middle basket-type heating zone 2 has multiple spaced heating plate assemblies 4 arranged circumferentially. The lower end of the ring 101 is provided with multiple spaced heating element hot zone upper connections 104 along the circumferential direction. The upper end of the lower electrode connecting ring 102 is provided with multiple spaced heating element hot zone lower connections 105 along the circumferential direction. Each heating element hot zone upper connection 104 is connected to the upper end of each heating plate group 4, and each heating element hot zone lower connection 105 is connected to the lower end of each heating plate group 4. The graphite cylinder 5 has multiple air inlets 108 above the electrode connecting ring 101 on the side wall, which are connected to the interior of the graphite cylinder 5.

[0024] Because graphite is conductive and has a certain resistance, the current will generate heat along the path from the upper electrode connecting ring 101 to the lower electrode connecting ring 102, thus forming three hot zones: the upper heating zone 1, the middle basket heating zone 2, and the lower heating zone 3. The middle basket heating zone 2 has a complex structure and is the main hot zone.

[0025] An outer shell 6 surrounds the graphite cylinder 5, and an inner sleeve 7 is inserted inside the graphite cylinder 5. Inert gas enters the graphite cylinder 5 through the air inlet 108. Since the inert gas is heavier than air, it carries heat and flows from top to bottom. Part of it enters the inner side of the inner sleeve 7 to heat the optical fiber preform 8, while the other part flows into the gap between the inner sleeve 7 and the graphite cylinder 5 and enters the cavity between the outer shell 6 and the graphite cylinder 5 through the hollow part in the center of the graphite cylinder 5, forming a total of three thermal layers. The two outer thermal layers can effectively insulate the thermal layer inside the inner sleeve 7. At the same time, because the inert gas is pressurized, it can prevent external air from entering the graphite furnace, thus achieving a positive pressure seal.

[0026] In a preferred embodiment, the heating plate assembly 4 includes an upper horizontal connecting block 106 and a lower horizontal connecting block 107. Multiple graphite plates 103 are arranged at intervals between the upper horizontal connecting block 106 and the lower horizontal connecting block 107. The multiple graphite plates 103 are connected end to end through the upper horizontal connecting block 106 and the lower horizontal connecting block 107 and arranged in a folded manner to form the heating plate assembly 4.

[0027] The current will bend up and down along the structure, resulting in a longer flow. The smaller the cross-sectional area of ​​the hot zone, the greater the resistance, the more heat, and the more concentrated the temperature.

[0028] In the preferred embodiment, the number of upper horizontal connecting blocks 106 is one more than the number of lower horizontal connecting blocks 107. An extension connecting block 109 is provided at the lower end of the upper connection 104 of the heating element hot zone. The extension connecting block 109 is connected to the lower end of the graphite plate 103 on the side. The lower connection 105 of the heating element hot zone is connected to the lower horizontal connecting block 107.

[0029] In the preferred embodiment, the number of lower horizontal connecting blocks 107 is one more than the number of upper horizontal connecting blocks 106. An extension connecting block 109 is provided at the upper end of the lower connection 105 of the heating element hot zone. The extension connecting block 109 is connected to the upper end of the graphite plate 103 on the side. The upper connection 104 of the heating element hot zone is connected to the upper horizontal connecting block 106.

[0030] Taking four graphite plates 103 as an example, two structures can be selected. One is two upper horizontal connecting blocks 106 at the top and one lower horizontal connecting block 107 at the bottom. After being folded back, the lower part of the graphite plate 103 on the side is the connecting end, so it needs to be connected to the lower end through an extension connecting block 109 for transition. The other is one upper horizontal connecting block 106 at the top and two lower horizontal connecting blocks 107 at the bottom. The upper part of the graphite plate 103 on the side is the connecting end, so it needs to be connected to the upper end through an extension connecting block 109 for transition.

[0031] In the preferred embodiment, the extension connecting block 109 has a T-shaped structure.

[0032] Since multiple heating plate groups 4 are arranged circumferentially, the extension connecting block 109 is T-shaped, with a connecting end on each side to connect the graphite plate 103 of the heating plate group 4 in different areas on both sides.

[0033] In the preferred embodiment, the graphite cylinder 5 is a hollow cylindrical structure.

[0034] In the preferred embodiment, after each heating plate group 4 is connected in parallel, its two ends are connected to the upper electrode connecting ring 101 and the lower electrode connecting ring 102, respectively.

[0035] If there are four or more graphite plates 103 in each heating plate group 4, they are divided into two parallel groups, and the graphite plates 103 within each group are connected in series. For example, if there are four heating plate groups 4 with four graphite plates 103 in each heating plate group 4, the graphite plates 103 in each heating plate group 4 are connected in series and then in parallel. The heating plate groups 4 are generally connected in parallel and in series with the upper electrode connecting ring 101 and the lower electrode connecting ring 102.

[0036] Example 2: A cylindrical basket-type graphite heater includes a graphite heater body, which is a cylindrical structure with open ends and a hollow interior. The graphite heater body is divided into three regions along the axial direction: an upper electrode connection region, a central basket heating region, and a lower electrode connection region. The central basket heating region is composed of several U-shaped or L-shaped slits, which divide the graphite heater body into several graphite plates. These graphite plates form eight parallel circuit structures, each of which is formed by connecting several graphite plates in series through the graphite body itself. The key feature is that the graphite plates, at a certain distance along the axial length, have a stepped resistance structure, and the rate of resistance change per unit length of each graphite plate is consistent. The resistance per unit length is the lowest in the central part of the graphite heater body, while the resistance per unit length is the highest at both ends.

[0037] The upper electrode connection area and the lower electrode connection area are cylindrical in shape, and the temperature range can be changed by adjusting the cross-sectional area.

[0038] The central flower basket heating zone is divided into eight heating zones by four equivalent resistances. Its resistance is in series with the upper electrode connection zone and in series with the lower electrode connection zone. The equivalent resistance of the central flower basket heating zone itself is in parallel.

[0039] The straight-cylinder basket-type heating element is divided into three hot zones. The temperature of each hot zone can be limited by changing the graphite resistance of each zone. The temperature of the three hot zones can be roughly adjusted by controlling the inert gas introduced through the air inlet.

[0040] The thickness of the graphite plate 13 in the central flower basket heating zone can be changed by calculating the resistivity of the graphite material, thus forming a key graphite melting zone.

[0041] The current from the wire drawing furnace is connected to the upper electrode connecting ring through the electrode, where graphite resistors are connected in series to form the temperature zone - upper electrode connecting area; then the current is connected to the upper connection of the heating element's hot zone, where graphite resistors are connected in parallel to form a zone, and through a graphite plate with a set resistance value, a central basket heating zone is formed in this area; then the current is connected to the lower connection of the heating element's hot zone through the electrode, and finally flows into the lower electrode connecting ring, ultimately forming the temperature zone - lower electrode connecting area.

[0042] This graphite heating element structure, combined with the guidance of protective airflow, can create stepped temperature zones and variable central temperature zones.

[0043] The above embodiments are merely preferred technical solutions of this utility model and should not be considered as limitations on this utility model. The protection scope of this utility model should be the technical solution described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the protection scope of this utility model.

Claims

1. A cylindrical basket-type graphite heating element, characterized in that: The system includes a graphite cylinder (5), which comprises an upper heating zone (1), a middle basket heating zone (2), and a lower heating zone (3). The upper heating zone (1) has an upper electrode connecting ring (101) at its upper end, and the lower heating zone (3) has a lower electrode connecting ring (102) at its lower end. The middle basket heating zone (2) is located between the upper electrode connecting ring (101) and the lower electrode connecting ring (102). The middle basket heating zone (2) has multiple heating plate groups (4) arranged at intervals along its circumference. The upper electrode connecting ring (101) The lower end is provided with multiple spaced heating element hot zone upper connections (104) along the circumference, and the upper end of the lower electrode connecting ring (102) is provided with multiple spaced heating element hot zone lower connections (105) along the circumference. Each heating element hot zone upper connection (104) is connected to the upper end of each heating plate group (4), and each heating element hot zone lower connection (105) is connected to the lower end of each heating plate group (4). The graphite cylinder (5) is provided with multiple air inlets (108) above the electrode connecting ring (101) on the side wall of the graphite cylinder (5) along the circumference, which communicate with the interior of the graphite cylinder (5).

2. The straight-tube basket-type graphite heating element according to claim 1, characterized in that: The heating plate assembly (4) includes an upper horizontal connecting block (106) and a lower horizontal connecting block (107). Multiple graphite plates (103) are arranged at intervals between the upper horizontal connecting block (106) and the lower horizontal connecting block (107). The multiple graphite plates (103) are connected end to end through the upper horizontal connecting block (106) and the lower horizontal connecting block (107) and arranged in a folded manner to form the heating plate assembly (4).

3. The straight-tube basket-type graphite heating element according to claim 2, characterized in that: The number of upper horizontal connecting blocks (106) is one more than the number of lower horizontal connecting blocks (107). The lower end of the upper connecting block (104) of the heating element hot zone is provided with an extension connecting block (109). The extension connecting block (109) is connected to the lower end of the graphite plate (103) on the side. The lower connecting block (105) of the heating element hot zone is connected to the lower horizontal connecting block (107).

4. The straight-tube basket-type graphite heating element according to claim 2, characterized in that: The number of lower horizontal connecting blocks (107) is one more than the number of upper horizontal connecting blocks (106). An extension connecting block (109) is provided at the upper end of the lower connection (105) of the heating element hot zone. The extension connecting block (109) is connected to the upper end of the graphite plate (103) on the side. The upper connection (104) of the heating element hot zone is connected to the upper horizontal connecting block (106).

5. The straight-tube basket-type graphite heating element according to claim 3 or 4, characterized in that: The extension connecting block (109) has a T-shaped structure.

6. The straight-tube basket-type graphite heating element according to claim 1, characterized in that: The graphite cylinder (5) is a hollow cylindrical structure.

7. The straight-cylinder basket-type graphite heating element according to claim 1, characterized in that: After each heating plate group (4) is connected in parallel, its two ends are connected to the upper electrode connecting ring (101) and the lower electrode connecting ring (102) respectively.

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