JP2012038473A - Induction heating apparatus and induction heating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction heating apparatus that supplies a heated material immediately at a normal restart of operation by retaining warmth of the heated material having been heated once to high temperature in a heating furnace while keeping energy loss small.SOLUTION: Adjacently to a cylinder type primary heating furnace 10 having a first induction heating coil 1 for primary heating, a cylinder type warmth retaining furnace 20 having a second induction heating coil 2 for warmth retainment is provided in parallel, and the overall length Lof the primary heating furnace and the overall length Lof the warmth retaining furnace 20 are set to be substantially equal to each other.

Description

  The present invention relates to an induction heating apparatus and an induction heating method.

  An induction heating device is used to supply a high-temperature metal material to a hot forging machine (equipment). That is, a continuous conveyance induction heating apparatus that heats a block-shaped metal material (material to be heated) sequentially fed into a high frequency induction heating coil is used, for example, heated to a high temperature of 1200 ° C. A block-like high-temperature metal material is supplied to a hot forging machine.

  However, when work in the next process is interrupted due to a problem with a hot forging machine, etc., the high-temperature metal material that is sequentially discharged from the induction heating device is brought to room temperature as an annealing material due to the interruption of the above work. After returning, it must be reheated and energy is wasted.

In order not to generate such an annealed material, the following methods have been conventionally performed.
The first is a method of stopping the conveyance by reducing the heating energy of the induction heating device so as to keep the temperature of the object to be heated (metal material).
The second is a method of providing a warming atmosphere furnace in the vicinity of the induction heating device (see, for example, Patent Document 1).

JP 2005-153006 A

  However, the first method has a problem that it is difficult to keep the temperature of each part in the furnace of the induction heating apparatus uniform during the heat insulation operation, and the temperature of the material to be heated varies after the operation is resumed. It was. In addition, a method has been proposed (as a slightly improved method of the first method) in which the temperature distribution of each part in the furnace is made uniform by continuing the decelerating feed without stopping the conveyance of the heated material. By decelerated conveyance, an annealed material is generated (as is the case with high-temperature metal material being discharged).

  Further, in the second method, conventionally, an atmospheric furnace such as a combustion furnace or an electric heating furnace has been used as a heat insulation furnace, and there is a large energy loss during standby, and the heating element has a short life in the electric heating furnace. On the other hand, the combustion furnace has quality problems such as adhesion of scale, and the second method is difficult to put into practical use.

  Therefore, the present invention is a heat insulation furnace that can quickly transfer a material to be heated, which has been heated to a high temperature, to a heat insulation furnace and does not require preheating, achieves energy saving, and further saves the entire apparatus. Space can be made, practicality is high, and it is easy to keep the temperature of the material to be heated even after restarting operation in particular, so that the quality of the product in the next process can be maintained uniformly and high. With the goal.

  In view of this, the induction heating apparatus according to the present invention is arranged in parallel with a cylindrical heat-retaining furnace having a second induction heating coil for heat retention, adjacent to the cylindrical main-heating furnace having a first induction heating coil for main heating. Furthermore, the full length of the main heating furnace and the temperature maintaining furnace was set to be substantially the same.

Further, traverse means capable of transporting the material to be heated by reciprocating in the horizontal direction between the discharge port of the main heating furnace and the input port of the heat insulation furnace disposed adjacent to the discharge port. It has.
Further, the second induction heating coil of the heat retaining furnace includes a plurality of heating coil single units arranged in series and one or two winding connection coils, and the heating coil unit is interposed via the connection coils. They are electrically connected in series.

  The induction heating method according to the present invention includes a cylindrical heat-retaining furnace having a second heat-reducing coil for heat insulation, in parallel with a cylindrical main-heating furnace having a first induction heating coil for main heating. In addition, the main heating furnace and the heat retaining furnace are set to have substantially the same overall length, and when the material to be heated discharged from the main heating furnace cannot be transported to the next process facility, the main heating furnace All the materials to be heated inside are stored in the above-mentioned heat insulation furnace and kept warm, and then the next process equipment is restarted, the material to be heated contained in the heat insulation furnace is At the same time as discharging from the heat insulation furnace to transport to the next process equipment, a new material to be heated is put into the main heating furnace to resume heating of the material to be heated, and the discharge from the heat retention furnace and the main heating furnace are resumed. When all the materials to be heated in the heat insulation furnace are discharged The material to be heated that is heated from the main heating furnace without interruption continued a method for transporting to the next process equipment.

According to the present invention, when the next process equipment (such as a high-temperature forging machine) is stopped for some reason, the high-temperature metal material (high-temperature heated material) can be maintained so as to immediately maintain its high-temperature state in a heat-retaining furnace, The quality of products processed in the next process equipment can be kept stable. Moreover, it is a space-saving device, does not require preheating energy and standby energy, and consumes less energy for operation.
In particular, since all the materials to be heated existing in the cylindrical main heating furnace can be stored in the heat insulation furnace, it is not necessary to generate an annealing material.

  Furthermore, when the next process equipment is restarted, the high-temperature heated material can be immediately sent out from the heat retaining furnace, and then the high-temperature heated material can be continuously supplied from the main heating material without interruption.

It is a partial cross section simplified side view which shows one Embodiment of this invention. It is a simplified plan view. It is a graph which shows an energy (electric power) provision state. It is a simplified plan view. It is a simplified top view of a normal conveyance state. It is a simplified top view explaining the condition where a to-be-heated material is traversed to a horizontal direction in a conveyance interruption state. It is a simplified top view which shows the state which accommodates the first to-be-heated material in a heat retention furnace. It is a simplified top view which shows the state which accommodates the 2nd to-be-heated material in a heat retention furnace. It is a simplified top view which shows the state which accommodates all the to-be-heated materials in a heat retention furnace. It is the simple top view which showed the state immediately after restarting an operation | movement and starting conveyance of a to-be-heated material to the next process equipment. It is the simplified top view which showed the state after that. Furthermore, it is a simplified top view which shows the subsequent state. It is the simple top view which showed the state which carries out a to-be-heated material to the next process equipment. It is a simplified top view of the state just before the last to-be-heated material is discharged | emitted from a heat retention furnace, and is transferred by a traverse means. Then, it is a simplified top view explaining the state by which the to-be-heated material (the last from a heat retention furnace) transferred to the front of the discharge port of this heating furnace by a traverse means is conveyed to the next process equipment. It is the decomposition explanatory view showing the important section composition of a heat retention furnace. It is a perspective schematic diagram of an example of a connection coil. It is an assembly drawing which showed the principal part structure of the heat retention furnace. It is an assembly drawing which shows the principal part structure of the conventional induction heating furnace.

Hereinafter, the present invention will be described in detail based on the illustrated embodiment.
1 to 15, 10 is a cylindrical main heating furnace having a first induction heating coil 1 for main heating, and 20 is a cylindrical heat insulating furnace having a second induction heating coil 2 for heat retention. , In plan view, parallel to each other and next to each other. In the illustrated example, the main heating furnace 10 and the heat retaining furnace 20 are both fixed horizontally, and the full length L ₁₀ and the full length L ₂₀ are set to be substantially the same. Although not shown, the main heating furnace 10 and the heat retaining furnace 20 may be arranged vertically in parallel.

  3 is a material supply device, and a block-shaped metal material (material to be heated) M generally called a billet is moved by a known chain conveyor, chute, robot arm or the like as indicated by an arrow A (see FIG. 2). Supply to the vicinity of the insertion port 4 of the main heating furnace 10. In FIG. 1 to FIG. 15, a cradle and a guide member for supporting the metal material (material to be heated) M are omitted, but in the vicinity of the insertion port 4 of the heating furnace 10, The to-be-heated material M held is fed into the through-hole heating path 6 from the insertion port 4 by the coil pusher 5. The heating path 6 formed of a through hole is formed of a cylindrical refractory heat insulating material, and the first induction heating coil 1 is wound around the outer periphery of the refractory heat insulating material. 4 to 15, the heating path 6 and the heating coil 1 are omitted, and the heating furnace 10 is simply expressed.

  Reference numeral 15 denotes a next process facility such as a hot forging machine, and the material to be heated (metal material) M heated to a high temperature by the induction heating device according to the present invention is used as a chute or a conveyor shown in FIG. (See arrow B in FIG. 1 and FIGS. 5, 11, 13, and 15 described later).

  By the way, the discharge port 11 (of the heating path 6) of the main heating furnace 10 and the input port 21 of the heat insulation furnace 20 are disposed side by side. The inlet 21 pushes the metal material (material to be heated) M heated in the heating furnace 10 into the heat retaining path 22 when the next process equipment 15 is stopped (interrupted) as will be described later. It means an opening to be inserted (inserted). However, the charging port 21 serves as a delivery port when discharging the metal material (heated material) M in the heat retaining path 22 that has been kept warm.

  Reference numeral 30 denotes traverse means, as indicated by arrows C and E, between the discharge port 11 and the input port 21 (described above) that are the same height and are arranged side by side in the horizontal direction. The material to be heated M is conveyed by reciprocating in the horizontal direction.

  The traverse means 30 will be described more specifically. In a plan view, in a direction orthogonal to the main heating furnace 10 and the heat retaining furnace 20, and slightly downstream from the discharge port 11 and the input port 21 (the main heating furnace 10). 2), the two parallel rails 31, 31 are laid or fixed on the floor 32 or the like. A frame 33 is attached along the rails 31 and 31 so as to be reciprocally movable left and right (as indicated by arrows C and E).

  As viewed from the side, as shown in FIG. 1, a chain conveyor 35 is suspended from rotating bodies 34, 34, 34 such as chain wheels disposed at the respective vertex positions of the inverted triangle. One of the rotating bodies 34, 34, 34 is rotationally driven by an electric motor, and as shown in FIG. 1, FIG. 5, FIG. 10, FIG. 7 and FIG. 9, the chain conveyor 35 is driven so that it can be switched between forward and reverse, when the upper horizontal portion of the chain conveyor 35 supplies the feed in the upstream direction. .

  An auxiliary roller 36 that rotates in synchronism with the chain conveyor 35 by the electric motor or another electric motor is disposed as shown in FIG. That is, when the material to be heated M tries to transfer to the chain conveyor 35 (or to be inserted into the heat insulation furnace 20 from the chain conveyor 35), the upper surface of the material to be heated M is in a pressed state, Smooth movement is possible. 2 to 15, the roller 36 and its driving means are not shown. In FIG. 1, the base frame 33, the support frame and the pivot shaft of the rotating body 34, the drive electric motor, and the like are not shown. These may be performed using known members and equipment.

  In addition, photoelectric sensor means 37 is provided as illustrated in FIGS. 1, 4, and 5. This photoelectric sensor means 37 has a light projecting part 37a and a light receiving part 37b. Install. In other words, the light beam 38 is at a height that runs near the upper horizontal portion of the chain conveyor 35 so as to detect whether or not the material to be heated M is present on the upper horizontal portion of the chain conveyor 35. 37a and light receiving part 37b are installed. (In FIG. 2 and FIGS. 5 to 15 other than that, such photoelectric sensor means 37 is not shown.)

  Next, in FIGS. 16-18, it is the Example which showed the principal parts, such as the 2nd induction heating coil 2 used for the above-mentioned heat retention furnace 20, 23 is a cylindrical refractory heat insulating material, Since it is difficult to produce the refractory heat insulating material 23 with an axial length exceeding 1000 to 1200 mm, the two refractory heat insulating materials 23a and 23a are produced (in FIGS. 16 to 18), These are assembled by joining the end faces 24 and 24 to each other. Along with this, the second induction heating coil 2 also needs to connect a plurality (two in the illustrated example) of heating coil units 2a, 2a in series.

  FIG. 19 shows a conventional heating coil 44, and an end face plate 45 is formed at a portion where the refractory heat insulating materials 23a and 23a are joined. The inner terminal 47, 47 of the heating coil 46, 46 wound around each refractory heat insulating material 23a, 23a was electrically connected by the terminal connection plate 48 beyond the end face plate 45. Accordingly, in the conventional heating coil 44 shown in FIG. 19, there is a region where no coil is wound in the vicinity of the coil end face plates 45, 45, and the coil is not wound when energized (the end face plates 45, 45). In the region (near 45), the magnetic flux density is weak. If the conventional heating coil 44 in which the magnetic flux density is locally weak is assumed to be used in the heat insulation furnace 20, in the heat insulation furnace 20, the material to be heated M in principle is not fed. Therefore, it can be seen that there is a big problem that the temperature is lowered (more than others) in the vicinity of the end face plates 45, 45.

  Therefore, in the embodiment of the present invention (FIGS. 16 to 18), in order to solve such problems, the end plate 45, 45 is omitted (straight cylindrical type) refractory heat insulation unit 23a, 23a are joined together. At the same time, one coil (or two coils, not shown) of the connection coil 25 is interposed between the end surfaces 24 and 24, and the heating coils 2a and 2a are electrically connected.

  In the embodiment of FIGS. 16 to 18, the coil pitch of the single coils 2a and 2a and the pitch of the connecting coil 25 are made the same, and terminals 27 and 26 are attached to each of them, as shown in FIG. The terminal 2 and the terminal 26 are connected, and the coil 2 is configured in a continuous manner with the same pitch as a whole. That is, the coil 2 is composed of a coil single body 2a, a connection coil 25 (1 or 2 turns) and a coil single body 2a, and the three are electrically connected in series and have a magnetic flux density in the longitudinal direction (axial direction). As a heat-retaining furnace that keeps the temperature constant, the plurality of internal materials to be heated M are kept at the same temperature. That is, the temperature of the material to be heated M that is stationary at the joining portion of the end faces 24 and 24 is maintained without being lowered, and the problem described in FIG. 19 is solved.

  3 (A) and 3 (B) are graphs showing the power consumption of the first induction heating coil 1 and the second induction heating coil 2, and accordingly the magnetic flux density, in the longitudinal coil (axial direction). is there. As can be seen from FIG. 3A, in the first induction heating coil 1 of the heating furnace 10, the power (magnetic flux density) is gradually reduced from the insertion port 4 to the discharge port 11. On the other hand, in the second induction heating coil 2 of the heat retaining furnace 20, as shown in FIG. 3B, it is evenly distributed from the charging port 21 to the opposite pressing port 29, and its electric power (magnetic flux) (Density) is set to be equal to or less than the value on the discharge port 11 side of the first induction heating coil 1.

  Next, the operation and operation of the induction heating apparatus according to the present invention described above will be described. If the next process equipment 15 is operating normally, as shown in FIGS. 2, 4 and 5 (and FIG. 1), Sequentially, the material to be heated (metal material) M was pushed from the material supply device 3 into the insertion port 4 of the heating furnace 10 by the coil pusher 5 and sufficiently heated (high temperature) from the discharge port 11. The material to be heated M is discharged, placed on the horizontal upper side of the chain conveyor 35, sent to the conveying means 7, and sent to the next process equipment 15 by this conveying means 7, where processing such as hot forging is performed. Done.

  However, in the case of interruption of conveyance that cannot be conveyed to the next process equipment 15 due to various troubles, the chain conveyor 35 is stopped in the state of FIG. 5 (the conveyance to the next process equipment 15 indicated by the arrow B is interrupted). 6) As shown in order of FIG. 6, FIG. 7, FIG. 8, and FIG. 9, all the materials to be heated M inside the main heating furnace 10 are temporarily stored in the adjacent heat insulating furnaces 20 and kept warm. .

  By the way, in addition to the main coil pusher 5 for pushing the material to be heated M in the direction of arrow G into the main heating furnace 10, the warmer furnace pusher 8 for pushing the material to be heated M in the heat insulation furnace 20 in the direction of arrow H. Also, a warming furnace pusher 9 is provided for extending (pressing) the arrow J in the direction of arrow J and for extruding the material to be heated M that has been kept warm in the heat retaining furnace 20. An actuator 12 such as an air cylinder that reciprocates the frame 33 along the rail 31 as indicated by arrows C and E is provided. The pushers 5, 8, and 9 are preferably electric reciprocating devices, and have a mechanism capable of accurately performing extension speed control and stroke position control.

  Returning to FIG. 5 to FIG. 9, when the next process equipment 15 is unexpectedly stopped for some reason, the feeding in the direction of arrow B in FIG. Is moved in the direction of arrow C. As a result, the hot material to be heated (metal material) M on the chain conveyor 35 moves to the front of the inlet 21 of the heat retaining furnace 20 and stops. Immediately, as shown in FIG. 7, the pusher 8 pushes (injects) it in the direction of the arrow H and stores it in the heat insulating furnace 20.

  As soon as the above-mentioned “interruption” occurs, energization is immediately started to the heating coil 2 of the heat retaining furnace 20. In addition, when the pusher 8 is pushed (injected) in the direction of the arrow H, it is desirable that the chain conveyor 35 and the auxiliary roller 36 are driven to rotate, contrary to the arrow (in FIG. 1).

  As shown in FIG. 7, when the introduction of the first heated material M is completed, the pusher 8 is shortened and the frame 33 is traversed along the rail 31 in the direction opposite to the arrow C. The second, third,... Heated material M is placed (stored) in the heat insulation furnace 20 as shown in FIGS. 8 and 9, and all the heated materials M in the main heating furnace 10 are It moves in the heat insulation furnace 20, and heat-retains there. Since it is the high-temperature material to be heated M that has already been heated in the main heating furnace 10, as shown in FIG.

  Further, as described in FIGS. 16 to 19, the second induction heating coil 2 includes a plurality of heating coil single bodies 2a and 2a via one or two winding connection coils 25 formed at the same coil pitch. Since they are electrically connected, the magnetic flux density is equalized in the longitudinal direction (axial direction), and all the materials to be heated M that are stored and kept warm are given the same heating energy, so that the next process equipment 15 In addition, after the cancellation of the interruption (at the time of restart), the quality of the material to be heated M supplied in the direction of the arrow B becomes stable and excellent as shown in FIGS.

As shown in FIG. 10, when the next process equipment 15 was restarted, it was stored in the heat insulation furnace 20 (
In order to transport the heated material M), which has been kept warm, to the joint process equipment 15, the pusher 9 presses the heated material M in the direction of arrow J, and discharges the heated material M from the original inlet 21 of the heat retaining furnace 20. The main heating furnace 10 is pressed in the direction of the arrow G by the pusher 5 and the operation of introducing a new material to be heated M is performed in synchronism (both the pushers 9 and 5 are simultaneously pressed to operate the main heating furnace. 10 resumes the heating of the material M to be heated.

In FIG. 10, as clearly indicated by a one-dot chain line L ₀ , the rear end surface 16 of the heated material Mb at the right end of the figure in the heat insulating furnace 20 and the front end surface of the first heated material Mf in the heating furnace 10. 17 is located on the vertical plane. 11, 12, 13, and 14, the materials to be heated M ---- Mb, Mf ---- in the heat-retaining furnace 20 and the main heating furnace 10 are sequentially sent by the pushers 9, 5. Yuku given, but the rear end face 16 and the front end surface 17, while located on the same vertical plane as shown by a chain line L _0, both the material to be heated Mb, Mf is advancing while synchronously.

  In other words, as shown in FIGS. 10 to 15, the discharge (feed) of the material to be heated M from the heat insulation furnace 20 and the input (feed) to the main heating furnace 10 are operated synchronously. When all the materials to be heated M in the heat insulating furnace 20 are discharged in this way (see FIGS. 14 and 15), the next material to be heated Mf from the main heating furnace 10 is the direction of the arrow B. It is transported without interruption.

  That is, when the last material to be heated Mb of the heat retaining furnace 20 is conveyed in the direction of arrow B, the first (frontmost) material to be heated Mf is subsequently conveyed from the main heating furnace 10. As a result, the material to be heated (metal material) heated to a predetermined high temperature can be continuously supplied to the next process equipment 15 without interruption, and the quality is not deteriorated when the operation is resumed. Therefore, a stable high quality forged product can be manufactured.

  As described above, when a forging operation or the like, which is a later process than the main heating furnace 10 that performs continuous induction heating, is interrupted due to trouble or the like, it is immediately stored (injected) into the heat insulating furnace 20 to prevent a decrease in temperature. When the next process equipment 15 is restarted, first, the heated material M that has been kept at a high temperature is sequentially transferred from the heat-retaining furnace 20, and then the high-temperature heated material M is transferred from the main heating furnace 10, No tempered material is generated and energy is not wasted.

  Further, the material to be heated M after restarting (resuming operation) is smoothly conveyed to the next process equipment 15 without variation in temperature. Moreover, since the problem of adhesion of scales and the like generated in the conventional combustion furnace does not occur, and preheating and standby energy are not required, the present invention can be said to contribute to energy saving.

Moreover, as shown in FIGS. 1-15 and demonstrated, it can be set as the whole compact apparatus, and it can contribute also to space saving.
In short, the present invention has no waiting time after the work interruption of the next process equipment 15 and can be said to be an excellent invention. Moreover, the waiting time at the time of switching from the heat insulation operation by the heat insulation furnace 20 to the normal (normal) operation for canceling the interruption can be minimized. In addition, since the heat retaining furnace 20 uses the induction heating coil 2, it does not require preheating and has a large energy saving effect.
Note that the temperature of the material M to be heated in the heat retaining furnace 20 can be managed with higher accuracy if the supplied power is corrected at the time of introduction into the second induction heating coil 2 or at the time of discharge.

According to the present invention, the cycle time before and after the work interruption can be maintained as it is in a series of flows, and there is an advantage that the work waiting time of the next process equipment 15 does not occur. As shown in FIG. 5 to FIG. 6, the operation of the next process equipment 15 is interrupted for some reason, and during the predetermined initial period from the start of energization to the induction heating coil 2 of the heat retaining furnace 20, It is desirable to add the electric power required to raise the temperature of the inner wall itself to the electric power required to keep the material to be heated M, and apply it to the induction heating coil 2. In particular, during the predetermined initial period from the start of energization described above, in order to reduce the energy required to raise the temperature of the inner wall itself, the specific gravity of the refractory heat insulating material 23 (see FIG. 18) on the inner wall of the heat retaining furnace is desirably 1.30 to 1.60.
According to the present invention, in particular, the induction heating method may be energized only when it is desired to heat the material to be heated M, and it is not necessary to preheat the heat-retaining furnace 20, so that standby energy is unnecessary and energy saving.

DESCRIPTION OF SYMBOLS 1 1st induction heating coil 2 2nd induction heating coil 2a Heating coil single-piece | unit 10 Main heating furnace 11 Outlet 15 Next process equipment (hot forging apparatus)
20 Thermal insulation furnace 21 Input port 25 Connection coil 30 Traverse means L ₁₀ , L ₂₀ full length M Heated material (metal material)

Claims (4)

Adjacent to the cylindrical main heating furnace (10) having the first induction heating coil (1) for main heating, the cylindrical heating furnace (20) having the second induction heating coil (2) for heat insulation is arranged in parallel. An induction heating apparatus characterized in that the heating furnace (10) and the heat insulation furnace (20) are arranged in parallel, and the overall lengths (L ₁₀ ) and (L ₂₀ ) of the main heating furnace ( ₂₀ ) are set substantially the same.   Between the outlet (11) of the main heating furnace (10) and the inlet (21) of the warming furnace (20) arranged adjacent to the side of the outlet (11) in the lateral direction. The induction heating apparatus according to claim 1, further comprising traverse means (30) capable of reciprocatingly moving the material to be heated (M).   The second induction heating coil (2) of the heat retaining furnace (20) includes a plurality of heating coil single bodies (2a) (2a) arranged in series and a connection coil (25) of 1 to 2 turns. The induction heating device according to claim 1, further comprising a heating coil unit (2a) (2a) electrically connected in series via the connection coil (25). Adjacent to the cylindrical main heating furnace (10) having the first induction heating coil (1) for main heating, the cylindrical heating furnace (20) having the second induction heating coil (2) for heat insulation is arranged in parallel. Further, the full lengths (L ₁₀ ) and (L ₂₀ ) of the main heating furnace (10) and the heat retaining furnace (20) are set substantially the same, and then discharged from the main heating furnace (10). When the material to be heated (M) is interrupted to the next process facility (15), all of the materials to be heated (M) inside the main heating furnace (10) are placed in the adjacent heat retaining furnace (20). When the next process equipment (15) is restarted, the material to be heated (M) stored in the heat insulation furnace (20) is transferred to the next process equipment (15). In order to do so, a new material to be heated (M) is put into the main heating furnace (10) at the same time as it is discharged from the heat insulation furnace (20). To resume the heating of the material to be heated (M),
When all the materials to be heated (M) in the heat insulation furnace (20) are discharged by synchronously operating the discharge from the heat insulation furnace (20) and the charging to the main heating furnace (10), there is no interruption. An induction heating method, wherein the heated material (M) heated from the main heating furnace (10) is continuously conveyed to the next process equipment (15).

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