US3850572A

US3850572A - Gravity flow discrete article gas flow isolated thermal treatment device and method

Info

Publication number: US3850572A
Application number: US00449364A
Authority: US
Inventors: E Andrus
Original assignee: Individual
Current assignee: Individual
Priority date: 1974-03-08
Filing date: 1974-03-08
Publication date: 1974-11-26
Anticipated expiration: 1991-11-26

Abstract

Small articles such as springs are heat treated as they flow downward by gravity through a straight cylindrical tube. The tube need not be cylindrical or straight and means to assist gravity may be provided. The articles are heated by hot air or other gas introduced to said tube through apertures in its walls and which flows through portions of the tube at high velocity. Hot air thus introduced is withdrawn through other apertures in the walls of the tube in a manner to prevent heat loss by exhaust of the hot air at either end of the tube or by introduction into the tube of ambient cool air at either end of the tube.

Description

11] 3,850,572 [451 Nov. 26, 1974 United States Patent Andrus [5 1 GRAVITY FLOW DISCRETE ARTICLE GAS 3,199,854 8/1965 lpsen............ 432/134 FLO ISOLATED THERMAL TREATMENT 3,351,329 11/1967 Thomas 432/72 DEVICE AND METHOD 3,467,366 9/1969 Westeren etal................:::...

[76] Inventor: Everett Howard Andrus, Rt. No. 4, Primary Examiner-John J. Camby Watertown, Wis. 53094 Mar. 8, 1974 Attorney, Agent, or Firm-John M. Diehl 221 Filed:

ABSTRACT Small articles such as springs are heat treated as they flow downward by gravity through a straight cylindrical tube. The tube need not be cylindrical or straight and means to assist gravity may be provided. The articles are heated by hot air or other gas introduced to said tube through apertures in its walls and which 21 Appl. No.2 449,364

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flows through portions of the tube at high velocity. Hot air thus introduced is withdrawn through other apertures in the walls of the tube in a manner to prevent heat loss by exhaust of the hot air at either end of the tube or by introduction into the tube of ambient cool air at either end of the tube.

1,643,775 9/1927 Ke11eher................................ 432/64 1,725,129 8/1929 Carpenter et 432/64 2,253,897 8/1941 Doderer................................ 432/64 10 Claims, 20 Drawing Figures PAIENI nsv 2 61914 SHEET 02 0F 10 PATENTEL 3.850.572

saw on or 10 Fig. 5.

Pmmmm I I 3,850,572

SHEET 0? or 10 END PLATE TUBE LENGTH Fig. /8.

GRAVITY FLOW DISCRETE ARTICLE GAS FLOW ISOLATED THERMAL TREATMENT DEVICE AND METHOD I BACKGROUND OF THE INVENTION 1. Field This invention relates to a furnace or oven or heating apparatus and more particularly to such apparatus for heat treating small articles by passing heated air thereover.

2. Prior Art The invention is an improvement over the disclosures of the following patents:

US. Pat. Nos. 3,351,329 and 3,467,366 describe use of venturi apparatus to provide isolation of the atmosphere within the furnaces described therein from the ambient atmosphere, unlike the device of the present invention.

The other above listed patents likewise describe various means for providing isolation of the atmosphere within a furnace from the ambient atmosphere; each is distinguished from the apparatus of the instant invention as will be apparent from the following detailed description.

SUMMARY AND BACKGROUND Small articles such as springs, fasteners, twist drills and the like have traditionally and conventionally been heat treated by placing the articles in a perforated metal box and placing the box in a furnace into which heated air or other gas is introduced or by placing the articles in a rotating drum provided with heated air or other gas in the interior thereof.

Such articles or devices (especially springs and many fasteners) are often characterized by a tendency to become entangled when placed helter skelter into a container. Normally hand labor is required to separate such devices which have been heat treated in bulk in the manner of the prior art and generally an excessive and evenstupendous cost factor is thereby added to the overall cost of producing the part. For example, it has been not uncommon for the' cost of carrying out this single step in the manufacture of a spring to outweigh or be larger than the total of all other costs in the manufacture of the spring, including cost of materials, cost of original manufacture of the spring, all costs of trans-' portation and even the cost of installing the spring in the final device for which it is destined which can often be done automatically by robot-type machinery. That which is true for such springs is also true for many other metal wire parts and spring steel fasteners and fastener parts.

Generally throughout the remainder of this specification reference will be had to springs. But it is to be understood that such reference to springs is intended to include other small articles or parts to which the invention may apply, including for example but not limited to spring steel fasteners, spring steel fastener parts, twist drills, bifurcated rivets and hollow rivets, the heat treating of which is required as a step in the manufacture thereof.

The device of the present invention is normally adapted to be located immediately adjacent a spring coiler, that is, a spring manufacturing machine, so that as each spring manufactured by the spring coiler is ejected from the coiler or falls from the coiler it is introduced by gravity or by the force of the ejection from the machine into the device of the invention.

In the device of the invention a tube is provided in which the springs travel vertically downward or at an angle downwardly. The tube is preferably straight and cylindrical but for parts other than coil springs may have any other suitable configuration. Springsform a column or stack of springs within the tube of the device, the lowermost spring being supported by a release mechanism provided at the lower extremity of the device and the remainder of the springs in the column or stack being supported by one another. The release mechanism releases a spring from the bottom of the heat treating device of the invention for each spring introduced at the top of the device so that the rate of release of the springs from the heat treating device exactly corresponds to the rate of introduction of the springs to the heat treating device.

Generally the springs travel downwardly through the central tube of the device due to the force of gravity acting thereon but in certain instances, generally in those instances wherein the tube is relatively long and inclined at a relatively small angle to the horizontal, means to vibrate the tube or to vibrate the entire device and thereby vibrate the tube may be provided to assist gravitational force to cause the springs to .travel downwardly therethrough.

Objects Itis therefore an object of the invention to provide an improved heat, treating device.

Another object is such animproved device thereof.

Another object is such a device wherein the parts travel in a column through a tubular portion of the device. v Another object is such a device wherein heating of the articles to be heat treated is provided by high velocity hot gas traveling in said tubular portion.

Another object of the invention is such a device.

wherein heating of each article to the temperature of heat treatment occurs very rapidly and very near the point of entry of the article into the device.

Another object of the invention is such a device wherein the ends of said tubular portion are open to the ambient atmosphere and yet no heat loss or gain and no exchange of said heated. gas with the gas of the ambient atmosphere takes place- Another object is such .a device which maybe made relatively short.

Other objects will become apparent from the drawings and from the following detailed description.

FIG. 1 is an elevation from the front of a preferred embodiment;

FIG. 2 is an elevation from the rear of the embodiment of FIG. 1;

FIG. 3 is a cross-sectional view takenon lines 3-'3 in FIGS. 5, 6 and 7;

for heat treating small entangleable parts without entanglement FIG. 7 is a cross-sectional view taken on lines 77 in FIGS. 1, 2, 3 and 4;

FIG. 8 is a schematic view of an embodiment corresponding to the embodiment of FIGS. 1-7;

FIG. 9 is a schematic view of another embodiment;

other embodiment of release mechanism for the device;

FIG. is a partially cross-sectional elevation of a modification of the embodiment of FIG. 14;

FIG. 16 is a plot of temperatures in bayonet tubes under various circumstances;

FIG. 17 is an elevation of a spring which may be heat treated in the device of the invention;

FIG. 18 is an elevation of another spring which may.

be heat treated in the device of the invention;

FIG. 19 is a plot of the relationship between time and temperature for a certain spring traveling through the device of the invention; and

FIG. 20 is a plot of the relationship between time and temperature for another spring traveling through the device.

DESCRIPTION Referring now to FIGS. 1-7, housing 20 may have support segment 21 attached thereto. Support segment 21 may be rotatably attached to support segment 22 by means not shown and support segment 22 may be attached to collar 23 which may be slidably received on support post 24 and may be retained at any desired vertical position on post 24 by tightening set screw 25;The angle of support of housing 20 with respect to vertically extending post 24 may be selected and retained by inserting pin or bolt 26 through one of holes 27 in segment 22 and thence into one of holes 28 in segment 21. If the distance between each of holes 27 is made somewhat different than the distance between each of holes 28, a very great number of different angular positions of housing 20 with respect to post 24 may be selected by suitably judicious selection of one of holes 27 and one of holes 28 through which to place pin 26.

Housing 20 may be provided at its ends with

end plate members

30 and 31 and may be provided with interiorly extending tubular member 32 sometimes hereinafter referred to as shroud tube or housing tube 32 which may have its ends attached respectively at 33 and 34 to

end plates

31 and 30.

Disposed within and extending through housing tube 32 there may be provided bayonet tube .13 which may extend beyond upper end plate 30 at its upper end 35 and may extend below lower end plate 31 at its lower end 36 and may have attached thereto a plurality of plates and bafiles, respectively upper end plate 40, baffle 41, baffle 42, baffle 43, baffle 44 and lower end plate 45. In the event that housing tube 32 is cylindrical as in the embodiment shown, each of these end plates and bafiles may be annular in shape and may be attached at its inner peripheral edge securely to tube 13,

as by welding, and may be slidably fitted in the interior of tube 32 at its outer peripheral edge. As may be seen, bayonet 46 may readily be replaced with another bayonet having a tube with a smaller or larger internal diameter to treat objects having smaller or larger diameters respectively. This may be accomplished in only a few minutes by removing screws 49, then removing holddown plates 48 and plugs 47, then sliding out the bayonet contained in tube 32 and sliding in another bayonet and then replacing plugs 47, plates 48 and screws 49. The internal diameter of tube 13 is preferably slightly greater than that of objects to be treated therein. The assembly consisting of tube 13,

end plates

41 and 45 and baffles 42, 43 and 44 is indicated generally as bayonet or bayonet assembly 46. Bayonet 46 may be retained within housing tube 32 and housing 20 by providing an insulating plug 47 at each end and providing holddown plates 48 attached respectively to

end plates

30 and 31 with screws 49 to act against plugs 47 which in turn bear against

bayonet end plates

40 and 45. Annular insulating plugs '47 may be slidably received within the bore of tube 32 and slidably received on the exterior of tube 13 adjacent ends 36 and 36 respectively.

Also provided within housing 20 are heater tube 50 containing electric heating element 51 and tube 55 to provide for flow of air as hereinafter described.

Tube 50 may be provided with ends 57 and may be attached to tube 32 as by welding: at 58.

Tube 55 may have ends 55'. Tube 55 may be referred to as abalance tube for lack of some better term. Heating element 51 may be supported within tubes 50 by conventional means which for simplicity are not shown.

The space within housing 20 which lies outside of

tubes

32, 50 and 55, may be filed with insulation 56.

Although each of

tubes

13,32, 50 and 55 are shown as being round, that is, cylindrical, any one or more of these tubes may have any other suitable cross-sectional shape such as that of a sqaure, triangle, hexagon, octagon or any regular or irregular polygon.

Housing 60 may be attached to housing 20 and may contain fan or blower indicated generally as 61 which comprises

blades

62, 63, 64 and 65 attached to shaft 66 driven by electric motor 67 which may be mounted on base plate 68 which may be attached to housing 60 with screws 69.

Electrical heating element 51 is supplied with electricity through electrical conductors 52 from a source indicated as 53 and may be insulated or may extend through insulating bushings 54 received in walls of tube 50 and housing 20 respectively.

Device 70 which may have the fonn of a hollow cylinder or other annular form, as shown, may be disposed adjacent end 35 of bayonet 46 so that each article or spring as it enters the interior of tube 13 must pass through the center thereof. Device 70 may be suitably constructed to indicate the presence of each spring or article as it passes therethrough. For example, device 70 may provide an electrical or magnetic field, one of the properties of which, such as capacitance or inductance, may be changed by a spring or other article passing through device 70, and device 70 may generate and emit a signal in response to such change to indicate the presence of an article therein. This signal may be transmitted by conductors, not shown, to conventional apparatus, not shown, which may send another signal, in

response to such signal, to the release mechanism indicated schematically at 71 which may be attached, adjacent to bottom end 36 of bayonet 46, to plate 72 which may be attached to housing 20, for example, with screws 73. Release mechanism 71 is shown and discussed in detail in connection with FIGS. 13, 14 and 15.

Passage 80 for air to pass (as indicated by arrows 81) from housing 60 to the interior of tube 50 may comprise outlet port 82 in housing 60, inlet port 83 in housing 20, wall 84 and scroll wall 85 connected to opening 86 in the wall of tube 50.

Passages

89 and 90 respectively for air to pass from the interior of tube 50 to the interior of tube 32 (as indicated by arrows 91) may be provided by contiguous matching or registering openings in the walls of

tubes

50 and 32, as shown, supplemented with walls 92 which may be attached by welding as at 93.

Air may be withdrawn through tube 32 in the balance tube 55 (as indicated by arrows 95) through port 96 provided by matching or registering contiguous openings in the walls of

tubes

32 and 55, as shown,-and by welldments 97 as shown.

Air may be withdrawn from balance tube 55 into tube 32 as indicated by arrows 98 and thence from tube 32 into fan housing 60 as indicated by arrows 99, respectively through port 100 provided between balance tube 55 and shroud tube 32 by contiguous registering openings therein and weldments 97 and through fan inlet port 101 provided by matching contiguous openings in the walls respectively of tube 32, housing 20 and housing 60, as shown.

End plate 40 and baffle 41 define a first annular space disposed between the interior of tube 32 and the exterior of tube 13. Baffles 41 and 42 define a second annular space between the interior surface of tube 32 and the exterior surface of tube 13. Baffles 42 and 43 define a third annular space between

tubes

13 and 32. Baffles 43 and 44 define a fourth annular space between

tubes

13 and 32. Baffle 44 and end plate 45 define a fifth annular space between

tubes

13 and 32. Apertures are provided in the wall of tube 13 communicating the interior of tube with each of said five spaces and apertures are provided as shown in

baffles

42 and 43. Bayonet 46 is shown schematically in FIG. 8 wherein the air flow through said apertures and into and out of said spaces and within the interior of tube 13 is more fully described.

Referring now to FIG. 8, bayonet 46 of FIGS. 1-7 is shown schematically, comprising tube 13,

end plates

40 and 45, baffles 41, 42, 43 and 44 and having inlet end 35 and outlet end 36. Heater 51 may correspond to heater 51 of FIGS. 1-7 and blower 61' may correspond to fan or blower 61 of FIGS. l-7. For simplicity shroud tube 32 is not shown. The five annular spaces lying be tween the exterior of tube 13 and the interior of tube 32 described as defined by

end plates

40 and 45 and baffles 41, 42, 43 and 44 in connection with FIGS. 1-7 are indicated in FIG. 8 schematically by arrow 111 indicating air withdrawn from said first space, arrow 112 indicating air introduced into said second space, arrow.

correspond respectively to heater 51 and blower 61 of Y FIGS. 1-7. The tube of bayonet 146 is indicated as 147 113 indicating longitudinal air flow through said third space, arrow 114 indicating withdrawal of air from said fourth space and arrow 115 indicating introduction of air to said fifth space. Flow through balance tube 55 is indicated at line 116.

As indicated by arrows 121, air is removed from theinterior of tube 13 through apertures 131 into the first space. As indicated by arrows 122, air is introduced from the second space through apertures 132 in the wall of tube 13 and in baffle 42 from said second space into the interior of tube 13 and into the third space. As indicated by arrows 124, air is removed from the interior of tube 13 and from the third space into the fourth space through apertures 134 in the wall of tube 13 and in baffle 43. -As indicated by arrows 125, air is introduced from said fifth space into the interior of tube 13 through apertures 135.

As a critical feature of the method and device of the invention, the size of each of the first, second, third,

fourth and fifth spaces and the number of apertures and size of apertures provided in the wall of tube 13 to provide communication between each of said spaces and the interior of tube 13 and the size and number of apertures in

baffles

42 and 43 isso chosen and adjusted as to provide for zero or nil outflow of gas from the interior of tube 13 at inlet end 35 as indicated by arrow and to provide for zero or nil inflow of ambient atmospheric air into the interior of tube 13 at end 35 as indicated by arrow 141 and likewise to provide for zero or nil outflow of air from the interior of tube 13 at end 36 as indicated by arrow 142 and to provide for zero or nil inflow of ambient atmospheric air into the. interior of tube 13 at end 36 as indicated by arrow 143.

A plurality of articles such as springs 105 may be introduced into bayonet 46 atend 35 as. indicated by arrow 106 and after traveling through tube 13 and being suitably heat treated may emerge as indicated at arrow 107.

tube provided with end plates and baffles, as in the case of bayonet 46, and heater 51" and blower 61' may and is provided with end plate 148, baffles 149, 150, 151, 152 and 153 and end plate 154. Articles suchas spring 108 may enter either end of tube 147 and travel therethrough to be heat treated as indicated by arrow 109. 9

End plate 148 and baffle 149 define a first space into which air maybe introduced, as indicated by arrow 155. The air may then flow through apertures 156 into the interior of tube 147 as indicated by arrows 158. Baffles 149 and define a second space from which air may be withdrawn, as indicated by arrow 159 and into which air may be introduced from the interior of tube 147 through apertures 160 as indicated by arrows 161.

Baffles

150 and 151 define a third space into which air may flow through apertures 162 in bafile 151 as indicated by arrows 163 and travel longitudinally as indicated by arrows 164 and enter into the interior of tube 147 through apertures 165 as indicated by arrows 166.

Baffles

151 and 152 define a fourth space into which air may be introduced as'indicated by arrow 167 and from which air may flow into the interior of tube 147 through apertures 168 as indicated by arrows 169 and may flow through apertures 162 into the third space as indicated by arrows 163.

Baffles

152 and 153 define a fifth space from which air'may be withdrawn as indicated by arrows 170 and into which air may flow from the interior of tube 147 through apertures 171 as indicated by arrows 172. Baffles 153 and end plate 154 define a sixth space into which air may be introduced as indicated by arrows 173 and may flow into the interior of tube 147 through apertures 174 as indicated by arrows 175.

Nil or zero flow of ambient air into tube 147 at each end is indicated by arrows 176 and nil or zero flow of gas from the interior of tube 147 outward to the ambient atmosphere is indicated by arrows 177, the nil or zero flow indicated by

arrows

176 and 177 being accomplished by suitable choice of the size of each of the spaces defined by the end plates and baffles and provision of a suitable number of apertures of suitable size and spacing in tube 147 and in baffle 151 communicating between said spaces and the interior of tube 147.

Suitable manifolding to provide the hereinabove described flow from blower 61 and heater 51" into and out of the various defined spaces (such as is provided in the embodiment of FIGS. l-7 by balance tube 55) is indicated by lines 178.

Referring now to FIG. 10, a bayonet 246 is provided which may be similar to bayonet 146 or bayonet 46 and may comprise a tube 213 having

end plates

214 and 215 and baffles 216, 217, 218, 219 and 220 which may define spaces from which air is withdrawn as indicated by arrows 221 or introduced as indicated by arrows 222 or within which air may merely travel longitudinally as indicated by arrows 223. Heater 51" and blower 61" may correspond respectively to heater 51 and blower 61.

Communicating flows between said spaces and the interior of tube 213 and .flow through baffle 219 are indicated by arrows which (unlike those of the embodiments of FIGS. 8 and 9) are unnumbered, said flows taking place through apertures in the wall of tube 213 and in baffle 219 which (also unlike those of FIGS. 8

and 9) are unnumbered.

As with the embodiments of FIGS. 8 and 9, suitable choice of the location of the baffles with respect to each other and with respect to the end plates and suitable design of size and number and location of apertures provides nil flow from the ambient atmosphere into the interior of tube 13 as indicated by arrows 230 and nil flow outwardly from the interior of tube 13 to ambient atmosphere is indicated by arrows 231.

An object to be heat treated such as a small fastener 232 may be introduced into tube 213 of bayonet 246 through either end and may travel therethrough in either direction as indicated by arrow 233. Manifolding in the manner of balance tube 55 or such manifolds as are indicated by lines 178 in FIG. 9 may be provided as indicated by lines 234 in the embodiment of FIG. to provide suitable flow to and from the defined spaces and to and from the blower and heater.

The embodiments of FIGS. 8, 9 and 10 show that the relative positions of spaces from which air is withdrawn and spaces to which air is introduced may be varied without departing from the teaching of the invention. Thus, in the embodiment of FIG. 8 air is introduced to a space adjacent to an end plate and withdrawn from a space adjacent the other end plate whereas in the embodiment of FIG. 9 air is introduced to each of the two spaces which are adjacent to the end plates and in the embodiment of FIG. 10 air is withdrawn from each of the two spaces which are adjacent to the end plates. Likewise the embodiments of FIGS. 8, 9 and 10 show that different numbers of such spaces, defined by end plates and baffles, may be utilized in accordance with the invention.

Since in all embodiments, as has been mentioned, flow outward of gas from the ends of the bayonet tube is nil and flow of ambient air into the ends of the bayonet tube is nil, the device may be operated with a gas therein which is other than air, for example, nitrogen or hydrogen.

Referring now to FIG. 11, bayonet 250 may correspond to any one of

bayonets

46, 146 or 246 in that it comprises a tube provided with end plates and baffles attached thereto which define spaces thereinbetween and which is received in shroud tube 251 which may correspond to shroud tube 232. Tube 251 may be provided with ports 252 through which air or other gas may be introduced or withdrawn into or from the defined spaces. Other portions of the apparatus such as housing, manifolding, blower and heater are omitted for simplicity. Vibrating device 253 may be attached to shroud tube 251 or to any portion of the device such as a housing or the like whereby, by operation of the device 253 in a vibratory manner as indicated by arrow 254, it provides longitudinal vibration of shroud tube 251 and bayonet 250 as indicated by arrow 255. Such vibratory motion may serve to assist gravity in providing for travel of articles to be heat treated through the tube within bayonet 250 or may be the sole means providing for such travel if, for example, bayonet 250 and shroud tube 251 are disposed substantially horizontally.

The embodiment of FIG. 12 is provided with bayonet 250 (which may be identical with bayonet 250 of FIG.

11) and shroud tube 251'. Tube 251'. may correspond to shroud tube 251 exceptithat insteadof being cylindrical it may be provided with successively wider and narrower portions to provide spaces between the end plates and baffles which are not of the cylindrical shape described for said spaces in the embodiments of FIGS. 1-7, 8, 9, l0 and 11. Ports 252' may correspond to ports 252.

As indicated by the embodiment of FIG. 12,.spaces defined by the end plates and baffles need not be cylindrically annular but may be of any suitable shape. The embodiment of FIG. 12 of course may be provided with a vibratory device in the same manner as that of FIG. 11 and of course any one of the embodiments of FIGS. 1-10 may be provided with such a device in the event that a vibratory motion is desired either to alone provide for travel of parts through the device or to provide assistance for the force of gravity.

The apertures in

tubes

13, 147 and 213 which provide for flow of gas between spaces defined by end plates and baffles and the interior of the tubes may have any suitable shape. Thus, they may be square as shown for apertures 131 in FIG. 8; they may have the form of slots as shown for apertures and 171 in FIG. 9; or they may be oval as exemplified by apertures 132 in FIG. 8.

In FIG. 13 there is shown a release mechanism 71 which is indicated schematically in FIGS. 1-7. Mechanism 71 which may be mounted on a plate 72 which may be attached to housing 20 by screws 73. In the release mechanism, tube 270 may be mounted coaxially with and slightly spaced apart from end 36 of tube 13 and may have an inside diameter sufficiently large to receive springs emerging from ends 36. Slot 271 is provided in the wall of tube 270 near its upper end and, spaced apart downwardly therefrom, aperture 272 may be provided in the wall of tube 270. Aligned with slot 271 there may be provided a first solenoid 273 containing magnetically susceptible mass 274 attached to pis-' ton or rod 275 slidably received in guide 276. Rod 275 may terminate in an enlarged end 277 which may be attached to member 278 which is provided with a bore 279 to slidably receive rod 280 which is provided with enlarged head 281 which is received in cavity 282 in member 278. At the other end, rod 280 may be threadedly attached to shoe 283 which may extend through slot 271 which may frictionally engage spring 284 contained in tube 270 urging spring 284 against the opposite interior wall of tube 270 and thereby preventing passage of spring 284 through tube 270 due to the friction of the spring with said wall, shoe 283 being urged against spring 284 by spring 285 contained within cavity 286 in member 278 and bearing against shoulder 287 provided in member 278 at the end of cavity 286. When solenoid 274 is actuated, slot 274 occupies the position shown in dashed lines at 274' and end 277 occupies the position shown in dashed lines 277 and head 282 occupies the position shown in dashed lines at 282', being urged against shoulder 288 of cavity 282 by spring 285. The face of shoe 283 is disposed at the position indicated in dashed lines at 283 because the motion to the right of slug 274 and rod 275 as indicated at 274 and 277 is designed to be greater than the travel of rod 280 to the left. Spring 284 is thus released and may drop out of tube 270.

When solenoid 273 is de-energized, the movable portions are urged to the left into the positions shown in full lines by compression spring 289 acting against guide 276 to urge enlarged head 277 leftwards.

Solenoid 293 is attached to plate 72 in alignment with aperture 272 in the wall of 270 and is provided with magnetically susceptible slug 294 therewithin attached to rod 295 received slidably in guide 296. Needle 297 is adapted to extend through aperture 272and as attached to rod 295. The positions of slug 294, rod 95 and needle 297 shown in full lines are those occupied when solenoid 293 is energized. When solenoid 293 is de-energized, slug 294, rod 295 and needle 297 occupy the positions shown in dashed lines at 294', 295 and 297' being moved leftwards by the urging of compression spring 298 acting against guide 296 and member 299 attached to rod 295.

In operation, solenoid 273 is normally de-energized so that shoe 283 occupies the position shown in full lines to retain a spring in tube 270 and solenoid 293 is normally energized to provide needle-297 in the position shown in full lines so that a spring may pass downwardly past aperture 272 as indicated by falling spring 284'.

When a signal is received from member 70 indicating that a spring is entering end 35 of bayonet 46, a corresponding signal is transmitted by electronic means, not shown for simplicity, to each of

solenoids

273 and 293 and solenoid 273 is energized and solenoid 293 is deenergized and accordingly shoe 283 is disengaged with a spring contained in tube 270 and needle 297 is thrust through aperture 272 into tube 270 so that it interrupts and stops the downward motion of the spring released by shoe 283. In this manner the entire column of springs contained within tube 13 is allowed to drop a distance corresponding to the length of one spring and space is thus provided in the interior of tube 13 adjacent end 35 to receive the spring which caused device 70 to emit a signal indicating the presence of the spring.

Immediately thereafter solenoid 273 is again deenergized so that shoe 283 again engages the spring now opposite it in the tube and solenoid 293 is energized to withdraw needle 297 from tube 270 and allow the spring previously retained in tube 270 by needle 297 to drop from tube 270 in the manner of spring 284'. The cycle is then of course repeated each time a spring enters the-device 70.

Release mechanism 71 shown in FIG. 14 corresponds to release mechanism 71 and all parts therein and the function thereof may be as described for device 71 except that

solenoids

273 and 293 and

slugs

274 and 294 are replaced respectively with double acting air or

hydraulic cylinders

300 and 301 which contain pistons attached respectively to

rods

275 and 295. By reason of each of

cylinders

300 and 301 being double acting,

rods

275 and 295 are positively driven to the left by

cylinders

300 and 301 as well as being positively driven to the right by

cylinders

300 and 301 so that

springs

289 and 298 and member 299 may be omitted. Tubes for introducing air or hydraulic fluid to

cylinders

300 and 301 are omitted for simplicity as are valves for controlling introduction of fluid to the cylinders in response to a signal generated in response to the signal from device lielease mechanisms 71" shown in FIG. 15 is similar to the embodiment 71 of FIG. 14 in that it is operated by a double acting air or hydraulic cylinder but otherwise it is appreciably different. Tube 310, is attached to plate 272 in alignment with end 36 of tube 13. Slidably treated in tube 13. Tube 311 may be'retainedin tube 310 with thumb screw 312.

Since the bayonets may be changed to provide bayonets having tubes of different internal diameters, tube 311 may be replaced with any one of severalother tubes having greater or lesser diameter bores corresponding to the diameters of springs to be treated with different bayonets.

Upper aligned apertures 314 and 315 and lower aligned

apertures

316 and 317 are provided respectively in the walls of

tubes

310 and 311. Block 320 is attached to plate 72 and provided with a cavity 321 aligned with holes 314 and 315 and a cavity 322 aligned with

holes

316 and 317. Threadedly received in cavity 321 is guide member 323 bored at 324 to slidably receive needle 325. In like manner guide member 326 is threadedly received in cavity 322 and bored at 327 to slidably receive needle 328.

Needles

325 and 328 may extend outside the block 320 through holes .329 and 330 communicating with

cavities

321 and 322.

Needle 325 is urged leftwardly by compression spring 331 acting between guide 323 and retainer member 332 attached to needle 325.

Needle 328 is urged leftwardly by compression spring 333 acting between guide member 326 and retainer member 334 attached to needle 328.

Pivotally attached to plate 72 at 335 there may be die 328 is forced to the right by cam face 337 and projects into the interior of tube 31 1, preventing downward movement of spring 350 contained therewithin and likewise all other springs disposed above spring 350 in the-device such as spring 351, while needle 325 is withdrawn from tube 311.

Cylinder 343 may be operated to drive piston rod 342 to the position shown in dashed lines at 342; whereupon link 340 and crank member 336 occupy the positions shown in dashed lines at 340 and 336' and needles 325 and 328 occupy the positions shown in dashed lines at 325 and 328, needle 325 being forced between

springs

350 and 351 and needle 328 being withdrawn from the interior of tube 311 whereupon spring 350 is allowed to fall free from the device as indicated at 350' and spring 351 and springs thereabove are retained in their present position by needle 325.

In operation, cylinder 343 is normally operated to provide crank 336 in the position of 336' so that a spring corresponding to spring 351 is retained in the device and all springs extending upwardly through tube 13 are retained in the device and any spring corresponding to spring 350 is allowed to fall free from the device.

When a signal emitted by device 70 causes means not shown for simplicity to provide actuation of cylinder 343, cylinder 343 moves crank 336 to the position shown in full lines which moves needle 328 to the position shown in full lines and withdraws needle 325 to the position shown in full lines. The spring corresponding to spring 351 drops to the position shown for spring 350, thus allowing all springs above it in the column to drop correspondingly and thus providing space within tube 13 adjacent end 35 for the spring which has caused device 70 to emit a signal to enter tube 13.

Immediately thereafter cylinder 343 may be automatically operated to cause crank 336 to resume the position shown at 336 whereupon the spring nonnally retained in the position of spring 351 continues to be retained in place by the action of needle 325 thereunder and the spring recently allowed to fall to the position of spring 350 is allowed to fall free in the manner shown at 350.

This cycle of events if of course repeated each time a spring enters device 70.

Each of

curves

1, 2, 3 and 4 is a plot of the temperature within a bayonet tube at various distances from the ends as indicated on the abscissa.

Curves

1 and 2 show the temperature of one of the springs 360 of FIG. 17 at various points in the tube of a bayonet designed to treat such springs, with the control temperature being set at 750F. Curve No. 1 was obtained with the tube entirelyfull of springs as it would be in actual use but with the spring of which the temperature was measured being allowed (and all the other springs above and below it being allowed) to remain at each position until its temperature stabilized. Curve 2 was obtained in the same manner with the same spring but without other springs in the tube. Curves No. 3 and No. 4 are plots of the temperature of one of springs 367 of FIG. 18 in a bayonet designed to treat these springs, with the bayonet tube entirely full of springs as in the case of curve No. l but with the control set for 600F. in the case of curve No. 3 and 375F. in the case of curve No. 4.

Curve No. in FIG. 19 shows the rate of heat rise of one of springs 360 of FIG. 17 when traveling through a bayonet tube designed to heat treat said springs (with other springs thereabove and therebelow in the manner in which it travels in actual use), springs being treated per minute. The data for curve No. 5 was obtained with a bayonet tube about 30 inches long. Accordingly 25 pieces were contained in the tube at any one time, each spring being 1% inches long, and accordingly each spring remained in the tube for approximately 15 seconds. The actual timeeach spring remained in the bayonet tube is shown as 17% seconds and the approximate time each remained within the portion of the bayonet tube disposed within the housing is shown as approximately 14% seconds. Control temperature was set at 750F. and it may be noted that each spring reached its desired minimum heat treatment temperature of 700F. after about 9% seconds and was heated to approximately 750F. after about 12% seconds and remained at a temperature of between 750F. and 650F. for approximately 5% seconds or until it exited from the bayonet tube. Thus the overall time during which the spring was subjected to a temperatureabove 700F. was on the order of 7 seconds, Q.

sufficient t o ac c o mplish the heat treating desired. v

Curves No. 6 and No. 7 were obtained with one of springs 361 of FIG. 18 traveling through the tube of a bayonet designed for heat treatment of said springs at a rate of 25 per minute, the bayonet tube being about 36 inches long. The data of curve No. 6 were obtained with the controls set for the desired heat treatment temperature of 600F. The data of curve No. 7 were obtained with a control setting of 375F. for a desired heat treatment temperature of 375F. At the rate of 25 In connection with FIGS. l9'and 20, it may be noted that the time during which a spring has been subjected to heat in the device is directly proportional to its position in the device. Thus, if it remains in the device 18 seconds, after 9 seconds it has traveled 50 percent of the way through the device. Accordingly, the time shown on the abssissae of FIGS. 19 and 20 is correlated with the position of the spring in the device as indicated by the legends indicating a point or time of entry into and exit from the bayonet tube and entry into and exit 9 e hay n As mentioned above, any bayonet in any of the embodiments shown may be readily removed and replaced with another bayonet having a tube of greater or lesser internal diameter and provided with apertures to provide suitable air flow for treating articles in such bayonet having a tube of greater or lesser internal diameter It will be apparent to those skilled in the art that equivalents may be utilized.

Accordingly, the present invention may be embodied Y in other specific forms without departing from the spirit or essential attributes thereof, and accordingly, reference should be made to the appended claims rather than to the foregoing specification as indicating the scope of the invention.

It is claimed: 1. In a device for heat treating small discrete metal articles the combination of a bayonet, said bayonet comprising a tubular member having an inlet end and an outlet end, said tubular member devoid of closure means at its ends, a first end plate extending from said tubular member near its inlet end, a second end plate extending from said tubular member near its outlet end,

at least three baffle members extending from said tubular member between said first end plate and said second end plate,

a shroud tube, I

said bayonet slidably received in said shroud tube,

the outer peripheries of said end plates and said baffle members being slidably engaged with the interior of said shroud tube,

said end plates and said baffle members defining spaces between the exterior of said tubular mem-' her and the interior of said shroud tube,

apertures in the wall of said tubular member communicating its interior with a plurality of said. defined spaces,

blower means and heater means to provide heated gas having an elevated temperature and a substantial pressure and velocity,

means to introduce said heated gas into a plurality of said defined spaces, and

means to withdraw said heated gas from a plurality of said defined spaces,

duct means to cycle said withdrawn gas to said blower means and thence to said spaces into which said gas is introduced. 2. The device of claim 1 wherein first, second, third and fourth baffle members are provided and the first baffle member is the nearest baffle member to said first end plate and said fourth baffle member is the nearest baffle member to said second end plate and said first end plate and said first baffle member provide a first space between the exterior of said tubular member and the interior of said shroud tube,

said first baffle member and said second baffle mem ber provide a second space between the end of said tubular member and the interior of said shroud tube,

said second bafile member and said third baffle member provide a third space between the end of said tubular member and the interior of said shroud tube,

said third baffle member and said fourth baffle member provide a fourth space between the end of said tubular member and the interior of said shroud tube, said fourth baffle member and said second end plate provide a fifth space between the end of said tubular member and the interior of said shroud tube, and wherein duct means is attached to said shroud tube to provide for introduction of said heated gas into said second and fifth spaces, g 1

duct means is attached to said shroud tube to provide for withdrawal to said blower means of gas from said first and fourth spaces,

apertures are provided in said second and third baffle members for passage of gas from said second space M to said third space and from said third space to said fourth space, apertures are provided in the wall of said tubular member to provide for gas flow from the interior of said tubular member to said first and fourth spaces,

and apertures are provided in the wall of said tubular member to provide for gas flow from said second and fifth spaces into the interior of said tubular JE QQEE r, r, t

3. The device of claim 1 characterized by the spacing of said end plates and baffle members and the spacing and locations and size of said apertures in said tubular member being preselected to provide nil outflow of gas from said tubular member at its ends and nil inflow of 29% into sa d. t ul rmemb at its 292,

4. The device of claim 3 further characterized by means to sense the presence of a part to be heat treated adjacent to said inlet end of said tubular member and to generate and emit a signal in response to said presence of such part.

5. The apparatus of claim 4 further characterized by means adjacent to the outlet end of said tubular member to sequentially release a part fromsaid device in response to a signal generated by said signal emitted by the means of claim 3.

6. The device of claim 3 wherein first, second, third and fourth baffle members are provided and the first baffle member is 'thenearest baffle member to said first end plate and said fourth-baffle member is the nearest baffle member to said second end plate and said first end plate and said first baffle member provide a first space between the exterior of said tubular member and the interior of said shroud tube, said first baffle member and said second baffle member provide a second space between the end of said tubular member and the interior of said shroud tube, said second baffle member and said third baffle member provide a third space between the end of said tubular member and the interior of saidshroud tube, said third baffle member and said fourth baffle member provide a fourth space between the end of said tubular member and the interior of said shroud tube, said fourth baffle member and said second end plate provide a fifth space between the end of said tubular member and the interior of .said shroud tube,..

and wherein duct means is attached to said shroud tube to provide 1 for introduction of said heated gas into said second and fifth spaces,

duct means is attached to said shroud tube to provide for withdrawal to said blower means of gas from said first and fourth spaces, I apertures are provided in said second and third baffle members for passage of gas from said second space and fifth spaces into the interior of said tubular member.

7. The device of claim 6 further characterized by means to sense the presence of a part to be heat treated adjacent to said inlet end of said tubular member and to generate and emit a signal in response to said presence of such part.

8. The apparatus of claim 7 further characterized by means adjacent to the outlet end of said tubular member to sequentially release a part from said device in response to a signal generated by said signal emitted by the means of claim 3.

9. The method of heat treating a plurality of springs characterized by the combination of steps of:

orienting a plurality of springs end-to-end in a downwardly extending stack,

releasing a spring from the bottom of the stack to cause the stack to fall a distance equal to the length of one spring each time a spring is about to be added to the top of the stack, dividing the stack into a plurality of zones, introducing heated gas to a plurality of said zones, withdrawing said heated gas from a plurality of said zones, and causing said gas to flow around the springs in said stack with high velocity turbulent flow generally longitudinally with respect to said stack between each of said zones.

10. The method of claim 9 wherein said stack is enclosed, characterized by the step of providing flow rates into and out of and between said zones at preselected values to provide for nil outflow from the stack of heated gas at the ends of the stack and nil inflow to the stack of ambient air at the ends of the stack.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,850,572. Dated N VGIT BBI 26, 1974 lnventofls) Everett Howard Andrus It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below: 0

Column 5, line 23, "welldments" should read weldments Column 9, line 18, "solenoid 274" should read solenoid Q 273 Column 10, line 26, "mechanisms" should read mechanism Column 11, line 44, "if" should read is line 64, "375'P.""should read 375F. Column 14,

a line 15, "locations" should read location a, line 27,

"claim 3" should read claim 4 1. Column 15, line l2 "claim 3" should read claim 7 1-. Q En'gncd and Scaled this twenty-sixth Day 0f August 1975 [SEAL] Arrest:

RUTH c. MASON c. MARSHALL DANN Arresting Officer Commissioner uflatents and Trademarks FORM PO-IOSO (10-69) USCOMM'DC 60376-P69 U15. GOVERNMENT PRINTING OFFICE: 8 I 9- 9

Claims

1. In a device for heat treating small discrete metal articles the combination of a bayonet, said bayonet comprising a tubular member having an inlet end and an outlet end, said tubular member devoid of closure means at its ends, a first end plate extending from said tubular member near its inlet end, a second end plate extending from said tubular member near its outlet end, at least three baffle members extending from said tubular member between said first end plate and said second end plate, a shroud tube, said bayonet slidably received in said shroud tube, the outer peripheries of said end plates and said baffle members being slidably engaged with the interior of said shroud tube, said end plates and said baffle members defining spaces between the exterior of said tubular member and the interior of said shroud tube, apertures in the wall of said tubular member communicating its interior with a plurality of said defined spaces, blower means and heater means to provide heated gas having an elevated temperature and a substantial pressure and velocity, means to introduce said heated gas into a plurality of said defined spaces, and means to withdraw said heated gas from a plurality of said defined spaces, duct means to cycle said withdrawn gas to said blower means and thence to said spaces into which said gas is introduced.

2. The device of claim 1 wherein first, second, third and fourth baffle members are provided and the first baffle member is the nearest baffle member to said first end plate and said fourth baffle member is the nearest baffle member to said second end plate and said first end plate and said first baffle member provide a first space between the exterior of said tubular member and the interior of said shroud tube, said first baffle member and said second baffle member provide a second space between the end of said tubular member and the interior of said shroud tube, said second baffle member and said third baffle member provide a third space between the end of said tubular member and the interior of said shroud tube, said third baffle member and said fourth baffle member provide a fourth space between the end of said tubular member and the interior of said shroud tube, said fourth baffle member and said second end plate provide a fifth space between the end of said tubular member and the interior of said shroud tube, and wherein duct means is attached to said shroud tube to provide for introduction of said heated gas into said second and fifth spaces, duct means is attached to said shroud tube to provide for withdrawal to said blower means of gas from said first and fourth spaces, apertures are provided in said second and third baffle members for passage of gas from said second space to said third space and from said third space to said fourth space, apertures are provided in the wall of said tubular member to provide for gas flow from the interior of said tubular member to said first and fourth spaces, and apertures are provided in the wall of said tubular member to provide for gas flow from said second and fifth spaces into the interior of said tubular member.

3. The device of claim 1 characterized by the spacing of said end plates and baffle members and the spacing and location and size of said apertures in said tubular member being preselected to provide nil outflow of gas from said tubular member at its ends and nil inflow of ambient air into said tubular member at its ends.

5. The apparatus of claim 4 further characterized by means adjacent to the outlet end of said tubular member to sequentially release a part from said device in response to a signal generated by said signal emitted by the means of claim 3.

6. The device of claim 3 wherein first, second, third and fourth baffle members are provided and the first baffle member is the nearest baffle member to said first end plate and said fourth baffle member is the nearest baffle member to said second end plate and said first end plate and said first baffle member provide a first space between the exterior of said tubular member and the interior of said shroud tube, said first baffle member and said second baffle member provide a second space between the end of said tubular member and the interior of said shroud tube, said second baffle member and said third baffle member provide a third space between the end of said tubular member and the interior of said shroud tube, said third baffle member and said fourth baffle member provide a fourth space between the end of said tubular member and the interior of said shroud tube, said fourth baffle member and said second end plate provide a fifth space between the end of said tubular member and the interior of said shroud tube, and wherein duct means is attached to said shroud tube to provide for introduction of said heated gas into said second and fifth spaces, duct means is attached to said shroud tube to provide for withdrawal to said blower means of gas from said first and fourth spaces, apertures are provided in said second and third baffle members for passage of gas from said second space to said third space and from said third space to said fourth space, apertures are provided in the wall of said tubular member to provide for gas flow from the interior of said tubular member to said first and fourth spaces, and apertures are provided in the wall of said tubular member to provide for gas flow from said second and fifth spaces into the interior of said tubular member.

9. The method of heat treating a plurality of springs characterized by the combination of steps of: orienting a plurality of springs end-to-end in a downwardly extending stack, releasing a spring from the bottom of the stack to cause the stack to fall a distance equal to the length of one spring each time a spring is about to be added to the top of the stack, dividing the stack into a plurality of zones, introducing heated gas to a plurality of said zones, withdrawing said heated gas from a plurality of said zones, and causing said gas to flow around the springs in said stack with high velocity turbulent flow generally longitudinally with respect to said stack between each of said zones.