CA1197094A - Apparatus and method for spot annealing tubing - Google Patents
Apparatus and method for spot annealing tubingInfo
- Publication number
- CA1197094A CA1197094A CA000427653A CA427653A CA1197094A CA 1197094 A CA1197094 A CA 1197094A CA 000427653 A CA000427653 A CA 000427653A CA 427653 A CA427653 A CA 427653A CA 1197094 A CA1197094 A CA 1197094A
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- CA
- Canada
- Prior art keywords
- chamber
- tubing
- annealing
- tube
- accordance
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
- C21D9/54—Furnaces for treating strips or wire
- C21D9/56—Continuous furnaces for strip or wire
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
ABSTRACT
In the manufacture of tubing, and particularly finned tubing, for use by the heat transfer industry in the manufacture of heat ex-changers, annealed ends and lands are desirable in certain applications to facilitate the assembly of the tubes to headers and baffles by ex-panding techniques. Such spot-annealed portions can be produced on a continuous basis by the described apparatus in which the moving tube is passed through a heating chamber which reciprocates on a carriage in the direction of tube movement. The heating chamber has a pair of spaced, power-actuated clamps which grip the tubing at the ends of a discrete length potion. The heating chamber and carriage are moved with the tube while it is clamped to provide sufficient heating time to anneal the discrete length portion. The carriage then returns to its starting position. Heating of the discrete clamped tubing portion can be by a resistance technique through the clamps or by other tech-niques such as induction heating or gas radiant heat. If desired, an inert gas can be supplied to the heating chamber to prevent oxidation and/or discoloration. Also, if desired a quench can be supplied in a secondary chamber positioned on the carriage immediately downstream of the heating chamber to prevent post-oxidation of the annealed tube.
In the manufacture of tubing, and particularly finned tubing, for use by the heat transfer industry in the manufacture of heat ex-changers, annealed ends and lands are desirable in certain applications to facilitate the assembly of the tubes to headers and baffles by ex-panding techniques. Such spot-annealed portions can be produced on a continuous basis by the described apparatus in which the moving tube is passed through a heating chamber which reciprocates on a carriage in the direction of tube movement. The heating chamber has a pair of spaced, power-actuated clamps which grip the tubing at the ends of a discrete length potion. The heating chamber and carriage are moved with the tube while it is clamped to provide sufficient heating time to anneal the discrete length portion. The carriage then returns to its starting position. Heating of the discrete clamped tubing portion can be by a resistance technique through the clamps or by other tech-niques such as induction heating or gas radiant heat. If desired, an inert gas can be supplied to the heating chamber to prevent oxidation and/or discoloration. Also, if desired a quench can be supplied in a secondary chamber positioned on the carriage immediately downstream of the heating chamber to prevent post-oxidation of the annealed tube.
Description
"APPARATUS AND METHOD FOR SPOT ANNEALING TUBING"
Back~round of the Invention The invention relates to the annealing of tubing and sim-ilar elongated products such as rods or wires. More par~icularly, it relates to the annealing of elonqated products on which it is sometimes desirable to have at leas~ selected portions of ~heir length in an annealed state. One such product is straight lengths of finned tubing to be used in heat exchangers. Such tubing has been conven-tionally processed in short lengths cut frcm a s~raightened portion of a large coil which has been annealed. The short leng~hs have a long mandrel inserted in them and are then position2d in a fin rolling apparstus which is capable sf selectively moving the finning members into and out of contact with the tubing so that unfinned lands and ends can be provided. When the unfinned portions are in an annealed state, the tubes can be more easily assembled into the tube sheet header and baffle portions of heat exchangers by internal expansion techniques.
Techniques prev~3usly used ~o anneal such tubes have in-cluded both batch and continuous techniques. In the batch technique, the entire coil or ind~vidual tube length must be placed in a furnace for an extended period. The prooess is very time-consuminy, requires very expensive capital equipment, and also utilizes a large amount of energy. Continuous annealing techniques have ~l~so been developed;
one example of which can be seen in Herren et al Patent No. 3,518,405.
In this apparatus, the tubinQ is bent partially around each of a spaced pair of current-rarrying electrode wheels which cause the por-tion of the tubing between the wheels to be heated. The electrode ~L~?76~ ~
wheels are typically made of graphite which wears relatively rapid1y, thus causing a substantial expense in maintenance9 electrode replace-ment and downtime. Another example can be seen in Judd, Paten~ No.
4,309,887 wherein the entire tube is continuously annealed by an in-duction heater. Patent 3,708,354 also shows continuous annealing.
Summary of the Invention It is among the objects of the present invention to provide an annealing apparatus which can be operated as an integral part of a high speed continuous finning operation which produces a large number of short tube lengths from a large coil. It is an additional object to provide such an apparatus which is relatively compact and simple, able to operate for extended periods with little maintenance, and very energy efficient.
These and other objects and advantages are attained by the apparatus and method of the present invention in which selective or "spot" annealing of spaced portions along the length of a continu-ously moving tube can take place at a speed which is at least suf~i-cient to accommodate a downstream finning operation. However, the ap-paratus could also be used independently of any downstream operations to spot anneal plain tube or wire or rod stock. The apparatus in-cludes an annealing chamber mounted on a reciprocating carriage whichcan move in the direction of the tube or other workpiece. The anneal-ing chamber contains a pair of spaced, automatically actuated tube engaging clamps which engage the tubing. During the limited time that the clamps engage the moving tubing, they cause the chamber and car-riage to which the are attached to be moved downstream with the tubing.Thus, the spot annealing takes place during the time the carriage is ~ ~37~
moving. Upon release of the clamps, an air cylinder or other means rapidly returns the carriage upstream to its starting position. A
quenching chamber is preferably mounted on the carriage immediately downstream of the annealing chamber so that the just-annealed portion 5 of the tubing can be rapidly cooled as th.e carriage returns upstream.
The quenching can prevent post-annealing oxidation and/or discolora-tion whi1e the injection of an inert gas atmosphere such as nitrogen into the annealing chamber prevents oxidation and/or discoloration during annealing. In many, if not most situations in which the re-sulting spot-annealed tubes are used~ such surface defects would have no effect on the tube performance. However, since a bright, shiny tube certainly is more esthetically pleasing ~o a purchaser ~han a dull, discolored one, it is usually advantageous to use an inert atmo-sphere and a quench. In order to provide annealed tube sections with the grain and hardness properties desired, the annealing time and thus the tube temperature can be selectively controlled, preferably via electrical relays in response to signals from a mini-computer.
The computer receives its signals from a counter which is actuated by a wheel encoder which is rotated by the moving tube. The aForemen-tioned elements which are conventional, ensure that only those por-tions of the tubing which are to be left unfinned in a downstream finning operation will be annealed. In a preferred embodiment wherein annealing is accomplished by resistance heating techniques through the clamps, the elements also permit arcing to be avoided by actua~
ting the clamps to contact the tube for a small time interval before and after the current is applied. In two disclosed modifications, annealing is accomplished by substituting an induction annealing tech-nique or a radiant gas technique for the resistance annealing techni-que of the preferred embodiment.
~7~
B _ ~r~ JD~IIlll Fig. 1 is an isometric view of a preferred embodiment of the improved annealing apparatus using a resistance heating techni-que and its rela~ionship to a length of tubing being positively driven through it;
Fig. 2 is a side view of the apparatus of Fig. l;
Fig. 3 is an isometric view illustrating a modified form of annealing chamber using an induction heating technique9 Fig. 4 is an isometric view illustrating a modified form of annealing chamber using a radian~ gas heating ~echnique; and Fig. 5 is a crosc-sectional view taken on line 5-5 of Fig. 4-Detailed Description of the Preferred Embodiment Referring ~o Fig. ll the annealing apparatus lO includes a base structure indicated generally at 12. The base includes an upper fixed support plate 14 and a lower fixed support plate 16. A first pair of support blocks 20 support a first guide rail member 22, while a second pair of support blocks 20 supports a second guide rail 22'.
The support blocks 20 attach to the upper support plate 14 by any suitab1e means such as fasteners. Slidably mounted on the guide ways or rails 22, 22' are a plurality of spaced guide blocks 24 which are mounted to the underside of a reciprocable support plate or carriage member 28. Mounted at the upstream end of the appara~us relative to a length of tubing 30 being driven in the dir~ction of the arrow is an annealing chamber 32 which is enclosed with a top plate 33. Im-mediately downstream of the annealing chamber 32 is a quenching cham-ber 34 which is also normally enclosed by a cover member 35.
9~
The carriage assembly 28 including the annealing and quench-ing chambers 32, 34 is adapted to be reciproca~ed in an axial direc--tion within the constraints provid2d by guide blocks 24 and guide rails 22, 22'. Movement in a downstream direction from the position shown in Fig. 1 is provided by clamping the carriage to the moving tubing 30 as will hereinafter be described. Movement in an upstrearn direction is provided by the piston shaft 38 which is anchored to the carriage by a support block 39 at its upstream or extended end and by a piston (not shown) movable within the air cylinder 40 at its down-1~ stream end. The return movement of the piston rod 38 and carriage 2B are achieved by admitting air into the cylinder 40 through hose 41 and permitting it to exit through hose 42. In the downstream direc-tion, each of the hoses 41, 42 is preferably valved to be in an ex-haust mode so as to not resist the downstream movement of the car~
riage. Since the carriage may be returned to its upstream end very rapidly by the air cylinder 40, a hydraulic spring member 44 is pref-erably provided as a cushion.
The aforementioned positively driven tubing 30 provides the force for advancing the carriage 28 in a downstream direction. This is accomplished by a pair of fixed clamp members 52, 52' and a pair of movable clamp members 54, 54' which are attached to a movable clamp plate 56 so as to clamp the tubing 30 against the fixed clamp members 52, 52' when the piston shaft 58 of an air cylinder 60 is actuated.
~hen resistance anneal;ng is employed, the fixed clamp members 52, 52' haYe conductive jaws which are each at a different electrical poten-tial so as to cause resistance heating of the segment of tubing 30 clamped between them. Also, the clamp members 52, 52' are mounted on brackets 61 which electrically isolate them from the housing portion ~L~7~
of the chamber 32. Further~ an insulating plate 62 electrically is~-lates the movable clamp members 54, 54' from each other and from the movable plate 56 to which they are attached. Electrical current is carried to the clamp members 52, 52' by water-cooled electrical cables 66 which are connected at their opposite ends to a transfDrmer assem-bly 6B. The cables 66 are quite thick and not extremely flexible, and are preferably supported for movement along with the carriage 28 by a power track assembly 72 which is rigidly attached to the carriage plate 28 at its upstream upper end and to the lower support plate 16 at its lower end. The links of the power track 72 are pivoted to each other, thus causing the movement o~ the cable 66 to be very well constrained. The power track assembly 72 has capacity to support a number of cable-like members, including the hoses 74~ 75 which supply air to the clamp cylinder 60.
An inert atmosphere is preferably provided to each of the chambers 32, 34 from a source such as a nitrogen tank 76. Through ap-propriate valving (not shown) the gas is directed to the annealing chamber inlet tube 80 and the quench chamber inlet tube 82. The inert gas exits the two chambers through the openings at their ends 32' 34' through which the tubing 30 passes. The quench chamber 34 includes a water inlet nozzle 86 which preferably is fashioned so as to direct watcr to all portions of the periphery of the tube. This quench water ls removed from the chambPr through an outlet drain opening 88.
The tubing 30 is guided for movement away from the anneal-ing apparatus 10 by a funnel-shaped exit guide 92. The downstream handling of the tubing forms no part of the present invention and could comprise appropr-iate structure for finning the spot annealed tubing on a continuous basis or simply structure to cut ~he ~ubing into short lengths or to recoil it. The tubing 30 is positively driven when it enters the annealing chamber 32 through opening 32'. It is preferably supplied in a large coil (not shown) and is passed through a series of straightening rollers 94, at least some o~ which are powered. The straightened tubing is passed thorough a wheel encoder device 96 whose wheels are rotated by the moving tube to generate counter pulses repre-sentative of tube displacement in a counter 98. A control panel 100 may contain appropriate controls to manually operate the apparatus 10.
Preferably, however, ~he counter pulses generated by the counter 98, which are representative of tube displacement9 are fed to a computer apparatus (not shown) which i5 programmed tc operate the clamp cylin-der 60, the return cylinder 40 and the application of power to the clamps. To prevent arcing when resistance annealing is employed5 power i5 not directed to fixed clamp members 52, 52' until after cyl-inder 60 has been actuated to force the movable clamp portions 54, 54' against the tube. Similarly, the power to the fixed clamps is cut before the clamp cylinder 60 is released.
The annealing apparatus of the invention can e~ploy differ ent techniques o~ annealing other than resistance such as induction an-nealing and radiant gas annealing and can be designed such that the power inputs, the travel times of the carriage and tubing while power is being applied, and the annealing temperature can be varied for various annealing requirements. In the case of resistance annealing, the power can be varied by selecting a suitable transforlner 68 which has adjustable taps. A suitable annealing temperature f~r copper tubing is 1200F which produces an annealed area between the clamps having a 15 grain size and a Rockwell 15T hardness of 57-60. Obviously, when resistance annealing at a particular tube velocity, the power ap-7~
plied must be sufficient to produce the desired tube temperature and will vary depending upon the tube density, the distance between ~he c1amps 52, 52', and the time duration of heat application. Since the time duration is limited by the tube velocity and the maximum travel S capability of the carriage member 28, it is rela~ively si~ple to ex-per;ment when setting up the apparatus for a particular ~ube, until a power tap is found which can achieve the required ~emperature in the carriage travel available and then to provide variations in ~he time of power application until an exact temperature is achieved. The quench water admitted through nozzle 86 preferably flows continuously with a variable flow rate. Similarly9 the nitrogen purge through pipes 80, 82 is atso continuous with a variable flow rate.
The foregoing description relates to a preferred embodiment of a spot annealing apparatus in which resistance annealing is accomplished by passing electrical current into the spaced clamp members 52, 52' and through the portion of the tubular workpiece 30 which is clamped by them. It should be noted, however, that other annealing techniques could be substituted for the resistance technique without substantially changing the apparatus shown in Figs. 1 and 2.
Figure 3 shows a general arrangement for an induction annealing cha~ber 132. Components of this chamber include a pair of stationary tube clamps 152, 152', a pair of power actuated mo~able tube clamps 154, 154', and a water cooled induction annealing coil 188. The clamps engage the moving tubing 130 and cause the annealing chamber and carriage to be moved downstream with the tubing while annealing is taking place via the water cooled annealing coil 188 which surrounds the portion of tube between clamps.
The tube clamps are engaged prior to applying an inductive field to the tubing and also current is removed prior to clamp release in order to assure safety and tube quality. All other construction oF the annealing chamber and the control movements of the carriage are similar to that described for the resistance spot annealer. The annealing coil is shown as comprising attached helically wound current carrying bar portions 188' which are joined to electrical cables 166 and a tubular water circulating portion 188" connected to water supply and discharge tubes ~90, 190'.
Figures 4 and 5 show a general arransement of a radiant annealing chamber 232 employing natural gas combustion to accomplish spot annealing of a tube 230. Components of this chamber include a pair of stationary tube clamps 252, 252', a pair of power actuated movable tube clamps 254, 254', and a water cooled tubular burner housing 291 located longitudinally between tube clamps, said housing having longitudinal rows of spark plug ignited gas burners 292 mounted around its reflective inner surface 293. As in the aforementioned annealing techniques, the clamps engage the moving tubing 230 and cause the annealing chamber and carriage to be moved downstream with the tubing while annealing is taking place in the radiant tube burner housing. In general, all other construction of the annealing chamber and the control movements of the carriage, are similar to that described for the resistance spot annealer. The gas burners 292 may be suitable premix burners such as those sold by North American Mfg. Co. of Cleveland, Ohio. They are preferably mounted in gas receiving manifolds 294 so as to extend through the outer wall of the housing 291 and the reflective inner wall 293. Excess heat within the walls of the housing 291 is carried _g 7o!~
away by circulating water which enters pipe 295 and leaves by pipe 269. If desired, vent hoses can be attached to the interior of the burner housing 291 to vent any fumes.
Back~round of the Invention The invention relates to the annealing of tubing and sim-ilar elongated products such as rods or wires. More par~icularly, it relates to the annealing of elonqated products on which it is sometimes desirable to have at leas~ selected portions of ~heir length in an annealed state. One such product is straight lengths of finned tubing to be used in heat exchangers. Such tubing has been conven-tionally processed in short lengths cut frcm a s~raightened portion of a large coil which has been annealed. The short leng~hs have a long mandrel inserted in them and are then position2d in a fin rolling apparstus which is capable sf selectively moving the finning members into and out of contact with the tubing so that unfinned lands and ends can be provided. When the unfinned portions are in an annealed state, the tubes can be more easily assembled into the tube sheet header and baffle portions of heat exchangers by internal expansion techniques.
Techniques prev~3usly used ~o anneal such tubes have in-cluded both batch and continuous techniques. In the batch technique, the entire coil or ind~vidual tube length must be placed in a furnace for an extended period. The prooess is very time-consuminy, requires very expensive capital equipment, and also utilizes a large amount of energy. Continuous annealing techniques have ~l~so been developed;
one example of which can be seen in Herren et al Patent No. 3,518,405.
In this apparatus, the tubinQ is bent partially around each of a spaced pair of current-rarrying electrode wheels which cause the por-tion of the tubing between the wheels to be heated. The electrode ~L~?76~ ~
wheels are typically made of graphite which wears relatively rapid1y, thus causing a substantial expense in maintenance9 electrode replace-ment and downtime. Another example can be seen in Judd, Paten~ No.
4,309,887 wherein the entire tube is continuously annealed by an in-duction heater. Patent 3,708,354 also shows continuous annealing.
Summary of the Invention It is among the objects of the present invention to provide an annealing apparatus which can be operated as an integral part of a high speed continuous finning operation which produces a large number of short tube lengths from a large coil. It is an additional object to provide such an apparatus which is relatively compact and simple, able to operate for extended periods with little maintenance, and very energy efficient.
These and other objects and advantages are attained by the apparatus and method of the present invention in which selective or "spot" annealing of spaced portions along the length of a continu-ously moving tube can take place at a speed which is at least suf~i-cient to accommodate a downstream finning operation. However, the ap-paratus could also be used independently of any downstream operations to spot anneal plain tube or wire or rod stock. The apparatus in-cludes an annealing chamber mounted on a reciprocating carriage whichcan move in the direction of the tube or other workpiece. The anneal-ing chamber contains a pair of spaced, automatically actuated tube engaging clamps which engage the tubing. During the limited time that the clamps engage the moving tubing, they cause the chamber and car-riage to which the are attached to be moved downstream with the tubing.Thus, the spot annealing takes place during the time the carriage is ~ ~37~
moving. Upon release of the clamps, an air cylinder or other means rapidly returns the carriage upstream to its starting position. A
quenching chamber is preferably mounted on the carriage immediately downstream of the annealing chamber so that the just-annealed portion 5 of the tubing can be rapidly cooled as th.e carriage returns upstream.
The quenching can prevent post-annealing oxidation and/or discolora-tion whi1e the injection of an inert gas atmosphere such as nitrogen into the annealing chamber prevents oxidation and/or discoloration during annealing. In many, if not most situations in which the re-sulting spot-annealed tubes are used~ such surface defects would have no effect on the tube performance. However, since a bright, shiny tube certainly is more esthetically pleasing ~o a purchaser ~han a dull, discolored one, it is usually advantageous to use an inert atmo-sphere and a quench. In order to provide annealed tube sections with the grain and hardness properties desired, the annealing time and thus the tube temperature can be selectively controlled, preferably via electrical relays in response to signals from a mini-computer.
The computer receives its signals from a counter which is actuated by a wheel encoder which is rotated by the moving tube. The aForemen-tioned elements which are conventional, ensure that only those por-tions of the tubing which are to be left unfinned in a downstream finning operation will be annealed. In a preferred embodiment wherein annealing is accomplished by resistance heating techniques through the clamps, the elements also permit arcing to be avoided by actua~
ting the clamps to contact the tube for a small time interval before and after the current is applied. In two disclosed modifications, annealing is accomplished by substituting an induction annealing tech-nique or a radiant gas technique for the resistance annealing techni-que of the preferred embodiment.
~7~
B _ ~r~ JD~IIlll Fig. 1 is an isometric view of a preferred embodiment of the improved annealing apparatus using a resistance heating techni-que and its rela~ionship to a length of tubing being positively driven through it;
Fig. 2 is a side view of the apparatus of Fig. l;
Fig. 3 is an isometric view illustrating a modified form of annealing chamber using an induction heating technique9 Fig. 4 is an isometric view illustrating a modified form of annealing chamber using a radian~ gas heating ~echnique; and Fig. 5 is a crosc-sectional view taken on line 5-5 of Fig. 4-Detailed Description of the Preferred Embodiment Referring ~o Fig. ll the annealing apparatus lO includes a base structure indicated generally at 12. The base includes an upper fixed support plate 14 and a lower fixed support plate 16. A first pair of support blocks 20 support a first guide rail member 22, while a second pair of support blocks 20 supports a second guide rail 22'.
The support blocks 20 attach to the upper support plate 14 by any suitab1e means such as fasteners. Slidably mounted on the guide ways or rails 22, 22' are a plurality of spaced guide blocks 24 which are mounted to the underside of a reciprocable support plate or carriage member 28. Mounted at the upstream end of the appara~us relative to a length of tubing 30 being driven in the dir~ction of the arrow is an annealing chamber 32 which is enclosed with a top plate 33. Im-mediately downstream of the annealing chamber 32 is a quenching cham-ber 34 which is also normally enclosed by a cover member 35.
9~
The carriage assembly 28 including the annealing and quench-ing chambers 32, 34 is adapted to be reciproca~ed in an axial direc--tion within the constraints provid2d by guide blocks 24 and guide rails 22, 22'. Movement in a downstream direction from the position shown in Fig. 1 is provided by clamping the carriage to the moving tubing 30 as will hereinafter be described. Movement in an upstrearn direction is provided by the piston shaft 38 which is anchored to the carriage by a support block 39 at its upstream or extended end and by a piston (not shown) movable within the air cylinder 40 at its down-1~ stream end. The return movement of the piston rod 38 and carriage 2B are achieved by admitting air into the cylinder 40 through hose 41 and permitting it to exit through hose 42. In the downstream direc-tion, each of the hoses 41, 42 is preferably valved to be in an ex-haust mode so as to not resist the downstream movement of the car~
riage. Since the carriage may be returned to its upstream end very rapidly by the air cylinder 40, a hydraulic spring member 44 is pref-erably provided as a cushion.
The aforementioned positively driven tubing 30 provides the force for advancing the carriage 28 in a downstream direction. This is accomplished by a pair of fixed clamp members 52, 52' and a pair of movable clamp members 54, 54' which are attached to a movable clamp plate 56 so as to clamp the tubing 30 against the fixed clamp members 52, 52' when the piston shaft 58 of an air cylinder 60 is actuated.
~hen resistance anneal;ng is employed, the fixed clamp members 52, 52' haYe conductive jaws which are each at a different electrical poten-tial so as to cause resistance heating of the segment of tubing 30 clamped between them. Also, the clamp members 52, 52' are mounted on brackets 61 which electrically isolate them from the housing portion ~L~7~
of the chamber 32. Further~ an insulating plate 62 electrically is~-lates the movable clamp members 54, 54' from each other and from the movable plate 56 to which they are attached. Electrical current is carried to the clamp members 52, 52' by water-cooled electrical cables 66 which are connected at their opposite ends to a transfDrmer assem-bly 6B. The cables 66 are quite thick and not extremely flexible, and are preferably supported for movement along with the carriage 28 by a power track assembly 72 which is rigidly attached to the carriage plate 28 at its upstream upper end and to the lower support plate 16 at its lower end. The links of the power track 72 are pivoted to each other, thus causing the movement o~ the cable 66 to be very well constrained. The power track assembly 72 has capacity to support a number of cable-like members, including the hoses 74~ 75 which supply air to the clamp cylinder 60.
An inert atmosphere is preferably provided to each of the chambers 32, 34 from a source such as a nitrogen tank 76. Through ap-propriate valving (not shown) the gas is directed to the annealing chamber inlet tube 80 and the quench chamber inlet tube 82. The inert gas exits the two chambers through the openings at their ends 32' 34' through which the tubing 30 passes. The quench chamber 34 includes a water inlet nozzle 86 which preferably is fashioned so as to direct watcr to all portions of the periphery of the tube. This quench water ls removed from the chambPr through an outlet drain opening 88.
The tubing 30 is guided for movement away from the anneal-ing apparatus 10 by a funnel-shaped exit guide 92. The downstream handling of the tubing forms no part of the present invention and could comprise appropr-iate structure for finning the spot annealed tubing on a continuous basis or simply structure to cut ~he ~ubing into short lengths or to recoil it. The tubing 30 is positively driven when it enters the annealing chamber 32 through opening 32'. It is preferably supplied in a large coil (not shown) and is passed through a series of straightening rollers 94, at least some o~ which are powered. The straightened tubing is passed thorough a wheel encoder device 96 whose wheels are rotated by the moving tube to generate counter pulses repre-sentative of tube displacement in a counter 98. A control panel 100 may contain appropriate controls to manually operate the apparatus 10.
Preferably, however, ~he counter pulses generated by the counter 98, which are representative of tube displacement9 are fed to a computer apparatus (not shown) which i5 programmed tc operate the clamp cylin-der 60, the return cylinder 40 and the application of power to the clamps. To prevent arcing when resistance annealing is employed5 power i5 not directed to fixed clamp members 52, 52' until after cyl-inder 60 has been actuated to force the movable clamp portions 54, 54' against the tube. Similarly, the power to the fixed clamps is cut before the clamp cylinder 60 is released.
The annealing apparatus of the invention can e~ploy differ ent techniques o~ annealing other than resistance such as induction an-nealing and radiant gas annealing and can be designed such that the power inputs, the travel times of the carriage and tubing while power is being applied, and the annealing temperature can be varied for various annealing requirements. In the case of resistance annealing, the power can be varied by selecting a suitable transforlner 68 which has adjustable taps. A suitable annealing temperature f~r copper tubing is 1200F which produces an annealed area between the clamps having a 15 grain size and a Rockwell 15T hardness of 57-60. Obviously, when resistance annealing at a particular tube velocity, the power ap-7~
plied must be sufficient to produce the desired tube temperature and will vary depending upon the tube density, the distance between ~he c1amps 52, 52', and the time duration of heat application. Since the time duration is limited by the tube velocity and the maximum travel S capability of the carriage member 28, it is rela~ively si~ple to ex-per;ment when setting up the apparatus for a particular ~ube, until a power tap is found which can achieve the required ~emperature in the carriage travel available and then to provide variations in ~he time of power application until an exact temperature is achieved. The quench water admitted through nozzle 86 preferably flows continuously with a variable flow rate. Similarly9 the nitrogen purge through pipes 80, 82 is atso continuous with a variable flow rate.
The foregoing description relates to a preferred embodiment of a spot annealing apparatus in which resistance annealing is accomplished by passing electrical current into the spaced clamp members 52, 52' and through the portion of the tubular workpiece 30 which is clamped by them. It should be noted, however, that other annealing techniques could be substituted for the resistance technique without substantially changing the apparatus shown in Figs. 1 and 2.
Figure 3 shows a general arrangement for an induction annealing cha~ber 132. Components of this chamber include a pair of stationary tube clamps 152, 152', a pair of power actuated mo~able tube clamps 154, 154', and a water cooled induction annealing coil 188. The clamps engage the moving tubing 130 and cause the annealing chamber and carriage to be moved downstream with the tubing while annealing is taking place via the water cooled annealing coil 188 which surrounds the portion of tube between clamps.
The tube clamps are engaged prior to applying an inductive field to the tubing and also current is removed prior to clamp release in order to assure safety and tube quality. All other construction oF the annealing chamber and the control movements of the carriage are similar to that described for the resistance spot annealer. The annealing coil is shown as comprising attached helically wound current carrying bar portions 188' which are joined to electrical cables 166 and a tubular water circulating portion 188" connected to water supply and discharge tubes ~90, 190'.
Figures 4 and 5 show a general arransement of a radiant annealing chamber 232 employing natural gas combustion to accomplish spot annealing of a tube 230. Components of this chamber include a pair of stationary tube clamps 252, 252', a pair of power actuated movable tube clamps 254, 254', and a water cooled tubular burner housing 291 located longitudinally between tube clamps, said housing having longitudinal rows of spark plug ignited gas burners 292 mounted around its reflective inner surface 293. As in the aforementioned annealing techniques, the clamps engage the moving tubing 230 and cause the annealing chamber and carriage to be moved downstream with the tubing while annealing is taking place in the radiant tube burner housing. In general, all other construction of the annealing chamber and the control movements of the carriage, are similar to that described for the resistance spot annealer. The gas burners 292 may be suitable premix burners such as those sold by North American Mfg. Co. of Cleveland, Ohio. They are preferably mounted in gas receiving manifolds 294 so as to extend through the outer wall of the housing 291 and the reflective inner wall 293. Excess heat within the walls of the housing 291 is carried _g 7o!~
away by circulating water which enters pipe 295 and leaves by pipe 269. If desired, vent hoses can be attached to the interior of the burner housing 291 to vent any fumes.
Claims (22)
1. An apparatus for selectively annealing a portion of a length of metallic tubing or the like while the tubing is moving com-prising a base including ways; a carriage mounted for reciprocatory movement on the ways; an elongated annealing chamber mounted on the carriage; a pair of spaced clamps mounted in the upstream end of the annealing chamber, said clamps being spaced from each other by a dis-tance which is at least as large as the axial length of a tube por-tion to be annealed; means to periodically actuate said spaced clamps to engage at least one discrete portion of a tube passing through said chamber and to cause said carriage and annealing chamber to be moved by the movement of said tube; means for heating and annealing said at least one discrete portion of tube while it is engaged by said clamps; means to release said clamps, and means to return said car-riage to the upstream end of the ways.
2. An apparatus in accordance with Claim 1 in which said annealing chamber contains an inlet opening means for receiving an inert atmosphere.
3. An apparatus in accordance with Claim 1 in which a quenching chamber is positioned immediately downstream of said an-nealing chamber, said quenching chamber containing a fluid quenching means for rapidly cooling the heated portion of the tubing after the clamps have been released.
4. An apparatus in accordance with Claim 3 in which said quenching chamber also contains an inlet opening for receiving an in-ert atmosphere.
5. An apparatus in accordance with Claim 3 in which said fluid quenching means comprises a spray nozzle for spraying water on the heated portion of the tubing.
6. An apparatus in accordance with Claim 1 in which said clamps comprise a pair of axially spaced fixed portions and a pair of movable portions which are mounted for movement normal to the axis of the tubing so as to force the tubing against the spaced fixed portions.
7. An apparatus in accordance with Claim 6 in which said movable clamp portions are moved by an air cylinder.
8. An apparatus in accordance with Claim 1 wherein said means to return said carriage comprises an air cylinder.
9. An apparatus in accordance with Claim 1 wherein said apparatus includes an upstream located driving means for moving said tubing through said annealing chamber, said chamber having apertures at its axially opposed ends for receiving said tubing.
10. An apparatus in accordance with Claim 9 wherein said annealing chamber is covered and has an inlet opening intermediate its ends for receiving an inert atmosphere, said inert atmosphere flowing out of said chamber through said apertures at its opposed ends.
11. An apparatus in accordance with Claim 6 wherein said fixed portions of said clamps are electrically connected to a pair of flexible electrical cables carried by said base which are adapted to carry current to said fixed portions for heating said at least one discrete portion of a tube, said movable portions being electrically insulated from each other.
12. An apparatus in accordance with Claim 1 wherein said means for heating and annealing comprises a pair of flexible electri-cal cables attached to said pair of clamps for resistively heating said discrete portion of tube.
13. An apparatus in accordance with Claim 1 wherein said means for heating and annealing comprises an induction heating coil mounted in said annealing chamber between said pair of spaced clamps for inductively heating said discrete portion of tube, said coil having its axis coincident with the axis of the tube.
14. An apparatus in accordance with Claim 13 wherein said induction heating coil is water cooled.
15. An apparatus in accordance with Claim 14 wherein said coil includes a solid bar portion in bonded relationship to a hollow tube portion, said solid bar portion being connected to electrical cable means and said hollow tube portion being connected to water cir-culating hoses.
16. An apparatus in accordance with Claim 1 wherein said means for heating and annealing comprises a radiant heater chamber mounted in said annealing chamber for heating said discrete portion of tube, said heater chamber having its axis coincident with the tube axis.
17. An apparatus in accordance with Claim 16 wherein said radiant heater chamber includes a plurality of gas burners directed radially toward said tube and a reflective inner wall surface.
18. An apparatus in accordance with Claim 17 wherein a cooling jacket surrounds said inner wall surface.
19. A method for selectively annealing a portion of a length of moving tubing or the like which is guided for movement in one direction of its axis comprising the steps of mounting an annealing chamber having tube receiving apertures in its ends on a carriage for reciprocable movement relative to its mounting base in the direction of the tube axis so that said portion of the length of tubing is within the chamber; clamping said portion of the tubing relative to the annealing chamber at the upstream end thereof so that said carriage and annealing chamber will move with said moving tubing in a downstream direction; heating said portion of the tubing to an annealing temperature while it is clamped; unclamping said tubing;
and returning said carriage and annealing chamber to its original upstream position relative to its mounting base.
and returning said carriage and annealing chamber to its original upstream position relative to its mounting base.
20. A method in accordance with Claim 19 and including the additional step of cooling the heated portion of the tubing after it is unclamped by passing it through a liquid spray quenching chamber located immediately downstream from said annealing chamber.
21. A method in accordance with Claim 20 wherein said cooling step is performed while said carriage and annealing chamber are being returned to their original upstream position.
22. A method in accordance with Claim 20 wherein an inert atmosphere is provided to said annealing and quenching chamber.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US37578182A | 1982-05-06 | 1982-05-06 | |
| US375,781 | 1982-05-06 | ||
| US06/460,971 US4428563A (en) | 1982-05-06 | 1983-01-26 | Apparatus for spot annealing tubing |
| US460,971 | 1983-01-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1197094A true CA1197094A (en) | 1985-11-26 |
Family
ID=27007192
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000427653A Expired CA1197094A (en) | 1982-05-06 | 1983-05-06 | Apparatus and method for spot annealing tubing |
Country Status (7)
| Country | Link |
|---|---|
| KR (1) | KR900000040B1 (en) |
| BR (1) | BR8302343A (en) |
| CA (1) | CA1197094A (en) |
| DE (1) | DE3316023A1 (en) |
| ES (1) | ES8501447A1 (en) |
| FI (1) | FI72749C (en) |
| IT (1) | IT1161599B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107974546A (en) * | 2017-12-21 | 2018-05-01 | 杭州河合电器股份有限公司 | A kind of heat-generating pipe double-station differential annealing automation equipment |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3808258A1 (en) * | 1988-03-12 | 1989-09-21 | Hoesch Ag | Continuous weld-annealing process |
| JP2002241839A (en) * | 2001-02-21 | 2002-08-28 | High Frequency Heattreat Co Ltd | Induction-heating heat treatment apparatus for v-type cylinder block |
| DE102010002531A1 (en) * | 2010-03-03 | 2011-09-08 | Eldec Schwenk Induction Gmbh | hardening device |
-
1983
- 1983-05-03 DE DE19833316023 patent/DE3316023A1/en not_active Withdrawn
- 1983-05-05 BR BR8302343A patent/BR8302343A/en unknown
- 1983-05-05 ES ES522111A patent/ES8501447A1/en not_active Expired
- 1983-05-05 FI FI831546A patent/FI72749C/en not_active IP Right Cessation
- 1983-05-06 CA CA000427653A patent/CA1197094A/en not_active Expired
- 1983-05-06 IT IT20985/83A patent/IT1161599B/en active
- 1983-05-06 KR KR1019830001938A patent/KR900000040B1/en active IP Right Grant
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107974546A (en) * | 2017-12-21 | 2018-05-01 | 杭州河合电器股份有限公司 | A kind of heat-generating pipe double-station differential annealing automation equipment |
| CN107974546B (en) * | 2017-12-21 | 2023-05-05 | 杭州热威电热科技股份有限公司 | Automatic double-station local annealing equipment for heating tube |
Also Published As
| Publication number | Publication date |
|---|---|
| ES522111A0 (en) | 1984-11-16 |
| IT8320985A1 (en) | 1984-11-06 |
| FI72749B (en) | 1987-03-31 |
| DE3316023A1 (en) | 1983-12-01 |
| BR8302343A (en) | 1984-01-10 |
| FI831546L (en) | 1983-11-07 |
| FI831546A0 (en) | 1983-05-05 |
| ES8501447A1 (en) | 1984-11-16 |
| IT1161599B (en) | 1987-03-18 |
| FI72749C (en) | 1987-07-10 |
| KR900000040B1 (en) | 1990-01-18 |
| KR840004789A (en) | 1984-10-24 |
| IT8320985A0 (en) | 1983-05-06 |
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