US2994168A

US2994168A - Packaging apparatus

Info

Publication number: US2994168A
Application number: US673449A
Authority: US
Inventors: William R Bercaw; Ralph L Byington
Original assignee: Western Tablet and Stationery Corp
Current assignee: Western Tablet and Stationery Corp
Priority date: 1957-07-22
Filing date: 1957-07-22
Publication date: 1961-08-01
Anticipated expiration: 1978-08-01

Description

1961 w. R. BERCAW ET AL 2,994,168

PACKAGING APPARATUS Filed July 22, 1957 6 Sheets-Sheet l INVENTORS R BERCAW BY/NG TON 9 :BY M46! ATTORNEYS Aug. 1, 1961 w. R. BERCAW ET AL 2,994,168

PACKAGING APPARATUS Filed July 22, 1957 6 Sheets-Sheet 2 INVENTORS W/LL/AM R BERG/4W BY RALPH L. BV/NG TON ATTORNEYS 1961 w. R. BERCAW ET AL 2,994,168

PACKAGING APPARATUS Filed July 22, 1957 6 Sheets-Sheet 3 A T TO/PNE VS Aug. 1, 1961 w. R. BERCAW ETAL 2,994,168

PACKAGING APPARATUS Filed July 22, 1957 6 Sheets-Sheet 4 INVENTORS R BERCAW BY/NG TON ATTORNEYS 1951 w. R. BERCAW ET AL 2,994,168

PACKAGING APPARATUS 6 Sheets-Sheet 5 Filed July 22, 1957 INVENTORS W/LL/AM R BERCAW RALPH L. BV/NGTON ATTORNEYS 1951 w. R. BERCAW ET AL 2,994,168

PACKAGING APPARATUS Filed July 22, 1957 6 Sheets-Sheet 6 40 A 4| E5145 COUNTADJUS \562 DIAL I W/LL/ M k P /w RAL H L. B iivaroiv BY ATTORNEYS United States Filed July 22, 1957, Ser. No. 673,449

15 Claims. (Cl. 53,--61) This invention relates to packaging apparatus in general. More particularly this invention relates to apparatus for counting articles to be packaged, and wrapping and sealing the packages.

An object of this invention is to provide an improved apparatus for packaging articles.

Another object of this invention is to provide an improved apparatus for counting articles fed to a package forming device and forming the package around predetermined numbers of said articles.

Still another object of this invention is to provide an improved package forming apparatus in which the articles to be packaged and the wrapping material are passed through a package shaping compartment that is pro,- vided with means for forming and sealing the tabs of the package.

A further object of this invention is to provide an improved packaging machine that automatically receives a predetermined number of articles to be wrapped and transports these articles and wrapping web into a package forming device which is provided with slotted members for forming end tabs on the package as it is passed therethrough and which is provided with plough members for forming side flaps as the package is ejected.

Other and further objects of this invention will be apparent to those skilled in the art to which it relates from the following specification, claims and drawing.

In accordance with this invention, there is provided an apparatus for selecting a predetermined number of articles that are formed into a package and completely wrapped, all of these operations being performed automatically under the control of an electropneurnatic system. While this invention has been described, particularly with reference to packaging and wrapping envelopes, it is obvious that various other articles may be packaged or wrapped thereby. The various features of this invention will be set forth in detail in the following specification, claims and drawing in which briefly:

FIG. 1 is a plan view of an embodiment of this invention;

FIG. 2 is a side view of an embodiment of this invention shown in FIG. 1;

FIG. 3 is a front view of the envelope receiving compartment and the package forming compartment therebelow;

FIG. 4 is a detail view taken along the line 4-4 of FIG. 2 to show details of the package forming cornpartment;

FIG. 5 is a detail view of the wrapping material feeder and cut-off mechanism;

FIG. 6 is a detail view of the envelope receiving compartment in which the envelopes are gathered prior to w app n FIG. 7 is a view showing the manner in which the atent 2,994,168 Patented Aug. 1, 1961 ice 2 gathered envelopes are pressed together with the wrapping into the package forming mechanism;

FIG. 7a is a detail view showing how the end tabs are formed on the package;

FIG. 8 is a detail view showing the wrapped envel pes depressed to the bottom of the package forming mechanlsm;

FIG. 9 is a view of the lower portion of the apparatus shown in FIG. 8 illustrating the package of envelopes being ejected therefrom while the top tabs of the package are being folded down;

FIG. 10 is a detail view showing the ploughs that are employed for folding down the top tabs or flaps of the package;

FIG. 11 is a schematic view of the diagram of the connections and pneumatic system employed for operating this mechanism; and Y FIG. 12 is a perspective view of a wrapped package made by the apparatus of this invention.

Referring to the drawing in detail there is shown in FIGS. 1 and 2 an envelope counting and wrapping apparatus made in accordance with this invention in which the envelopes are Wrapped in paper or similar material such as cellophane, that is provided in the roll 10 supported by the shaft 11 which is journaled in bearings 12 attached to the frame .13. A suitable strap 14 of leather or similar material is attached to the bracket 15 and is held under the tension of the spring 16 in frictional contact with one of the end portions of the shaft 11 to act as a brake and restrain rotation of the roll.

The sheet material 16 is passed over the roller 17 and between the guides 18 and from these it is passed between the driven

feed rollers

19 and 20 whichare biased by the springs 21 so that they grip. the sheet material 16 firmly therebetween and advance it into the wrapping mechanism. The tension of the springs 21 may be released by the cam mechanism 22 so that the

rollers

19 and 20 are separated slightly whereby the sheet material 16 may be advanced therethrough manually.

The shafts of the rollers \19 and 20 are provided with suitable sprocket wheels 23 and 24, respectively, which are in meshing engagement as shown in FIG. 5. The gear 23 meshes with an idler gear 25 which in turn engages another idler gear 26 that meshes with a gear .7 which is supported on the shaft 28 of the cutter mech anism. The cutter mechanism comprises a rotatable member 29 to which is attached a blade 50 that copperates with the stationary cutter blade 30a attached to'the frame. The

rollers

19 and 20 may be proper circum ference so that they gauge the length of the sheet material 16 that is to be cut off, whereby this sheet material 16 is cut into strips of proper length required for wrapping the articles.

The shaft 28 of the rotatable member 29 is connected to one side of a magnetic clutch mechanism 31, the circuit of which is closed either by the cam operated switch 39 or by the microswitch 3%. Either of these switches may be closed to energize the magnetic clutch so that the sheet cellophane is fed to the envelope wrapping mechanism by the feed and cutter mechanism driven by the motor 36.

The motor 36 is connected throngh a reduction gearing 35 to the drive shaft 350 of the magnetic clutch mechanisrn and the clutch plate 34 is connected to this drive shaft. The central member 35 of the magnetic clutch mechanism is provided with a pair of slip rings 33:: and brushes 33b that contact the slip rings, and energizing the winding in this central member 33 provides a driving coupling between the clutch member 34 and the clutch member 32 so that the shaft 28 of the cutter is rotated through one revolution. The feed rollers 19 and 2%] are rotated by the gears provided between the shafts thereof and the shaft 28. When the blade 39 is brought against the stationary blade 30a the cellophane strip 16 is severed into the proper length for packaging the envelopes. The severed piece of cellophane 16a as shown in FIG. 1 is carried forward by its own momentum until the forward end thereof engages the stop members 37 and it is in position underneath an envelope receiving compartment 38.

When the cellophane strip 16a is cut off by the rotatable knife blade 38 engaging the stationary blade 38a the cam 28a at the end of the shaft 28 operates a switch 39 associated therewith and opens the circuit of the magnetic clutch thereby interrupting'rotation of the roller 29 at this point.

While the envelope wrapping cellophane is supplied to the platform 37 underneath the envelope receiving compartment 38, envelopes are continuously transported to this compartment by means of the plate 44 that is moved back and forth by the arm 43. This plate 44 receives an envelope when it is in its right hand position shown in FIG. 2 and transports it to the compartment 38 where the envelope is received and retained by resilient catches 38b and leaf spring members 33c and 38d.

The plate 44 is provided with an aperture 44a and when there is no envelope in position on the plate, the light beam from the light source 40 passes through this aperture to the photoelectric cell 41. However, when this plate is at the right hand end of its travel as shown in FIG. 2 and an envelope is placed there, the light beam is interrupted and in this manner the number of envelopes supplied to the compartment 33 is counted by the light and photoelectric cell arrangement. The output of the photoelectric cell 41 is connected to the input of the amplifier 45 shown in the wiring diagram, FIG. 11, and amplified electric pulses are impressed by this amplifier upon a relay circuit of the Strowger type, which is advanced step by step in accordance with the envelopes presented to the envelope receiving compartment 38.

This compartment 38 is provided with a pair of resilient members 381), shown in FIG. 6, attached to the top thereof that function to latch the envelopes fed to the compartment. Also, there are provided resilient members 38c on the sides of the compartment for app-lying a slight amount of pressure on the ends of the envelopes. Additional latching members 38d are attached to the sides of the compartment and there function in cooperation with the members 380 to hold the envelopes standing erect in the compartment.

When the desired number of envelopes is placed in the compartment 38 and counted by the aforesaid counting circuit, the Strowger switch closes the circuit of the solenoid 46 of the valve 47, causing this valve to connect the prmsure supply line 47a to the pipe 48, thereby applying compressed air or other fluid to the upper ends of the

cylinders

49 and 50. This pressure functions to force the pistons in these cylinders downward, thereby carrying the piston rods associated therewith downward. The cylinder 50 being considerably smaller than the cylinder 49, functions to actuate the piston thereof first and draws the piston rod 51 downward, thereby rotating the lever 52 against the tension of the spring 55. The angular lever 53 is thus rotated and moves the pad 54 downward over the top of a group of envelopes that have been aseembled in the compartment 38.

This mechanism, including the small cylinder 50, the

levers

52, 53 and pad 54 are mounted on a bar or bracket arrangement 56 that is attached to the upper end of the piston rod 57 of the cylinder 49. Thus, after the small cylinder 50 has actuated the piston rod thereof and the pad 54 is brought into engagement with the top of the envelope group, the cylinder 49 functions to move the piston rod 57 thereof downward and the group of envelopes is forced out of the envelope compartment 38 through the hole 38c formed in the bottom of this compartment. The group of envelopes is thus pressed in upright position down upon the sheet of cellophane 16a resting on the platform 37 and further motion of the piston rod 57 downward causes this group of envelopes and the cellophane to be pushed into the package forming compartment 58 which has end

tab shaping slots

58a and 58b cut into each end thereof as shown in FIG. 7. The rear of the compartment 38 is provided with a slot 38a and the rear of the compartment 58 is provided with a slot 580 sothat the arm 53 may pass through these slots as it carries the envelope engaging pad 54 downward through these compartments.

The bottoms of the envelopes therefore engage the cellophane wrapper that is positioned on the platform 37 and press this cellophane wrapper downward into the compartment 58, drawing the wrapper around the front and back of the envelope simultaneously as they are pressed into this compartment by the pad 54 as shown in FIG. 7. The function of the cylinder 50 therefore is to bring the pad 54 into engagement with the top of the group of envelopes and thereafter the cylinder 49 draws its piston rod 57 carrying the bracket members 56 which support the

levers

52 and 53, downward.

These brackets 56 are attached at one of the ends thereof to the top end of the piston rod 57 by means of the nut 57'. The other end of the long bracket 56 is provided with an apertured guide member 570' which engages the vertical rod 570 as shown in FIGS. 1 and 8, that functions as a guide rod for this end thereof. The cyl inder 49 is substantially longer than the cylinder 50 and the piston rod 57 provided thereto is of sufficient length to carry the angular lever 53'substantially to the bottom of the compartment 58 through the slot 58a provided thereto.

As previously mentioned, the ends of compartment 58 are provided with

arcuate slots

58a and 58b which receive the ends of the cellophane wrapper and fold the end tabs of the package. The slot 58a is shorter than the slot 58b and is shaped so that it causes the tab folded thereby to be creased toward the package before the tab that is formed by the slot 58b is likewise folded against the package. After the end tabs or folds are formed on both ends of the package, the package is further depressed in the forming compartment until the bottom of the package rests upon the bottom of the compartment as shown in FIG. 8.

While the package is being pressed through the compartment 58 and after the end tabs are formed thereon as described above, the package is passed with the end tabs thereof in engagement with the heated shoes so that heat is applied thereto and the end tabs of the package are heat sealed. These shoes 80 are heated by means of suitable electric heating elements that are positioned in the housings 81 attached thereto.

When the package is pressed to the bottom of the forming compartment 58 by the operation of the cylinder 49 and the piston rod 57 associated therewith,- the cross member 56 is brought into engagement with the

switches

60 and 61, which are supported on the frame member 13 as shown in FIG. 4. The switch 60 is normally closed While the switch 61 is normally open, as shown in the wiring diagram, FIG. 11. The normally closed switch 60 is connected in series with the solenoid 46 of the valve 47 and when the cross member 56 engages this switch it is opened and the circuit to the solenoid 46 is interrupted so that the valve 47 is permitted to return to its normal position in which the pressure line 47a is conis J nec'ted to the pipe 484 connected to the lower end of the cylinder 49, and the pipe 43 is connected to the exhaust line. As a result, the piston rod of the cylinder 49 is caused to return to its upper position.

The switch 61, which is normally open, is closed by the cross member 56 when this member is in its lower position, and closing this switch causes the solenoid 62 of the valve 63 to be connected to the source of current supply and energized. As a result, air pressure from the supply line 63a is connected to the pipe 64 by the valve 63 and the piston and piston rod 68 of the cylinder 66 is moved to the right, that is, drawn into the cylinder. The outer end of the rod 68 is connected to the member 74 that projects from the slide 69 which is provided with a slidable member 70 as shown in FIG. 9. The member 74 is provided with a pair of rollers that slidably engage the channel shaped support 74a which is supported by the bracket 74b as shown in FIG. 2. This slidable member 70 is provided with a forward projection 71 and is attached to a rod 75 which is surrounded by a coil spring 72 as shown in FIGS. 3, 8 and 9. The rod 75 is lodged in the guide 690 and the coil spring 72 is positioned between this guide 69a and the member 70.

When the cylinder '66 draws the rod 68 therein, the slide 69 is moved toward the package so that the projection 71 on the member 76 engages the package and presses the end top tab over the top of the envelopes between the top side tabs. This operation takes place before the member 6912 projecting from the bottom of the forward end of the slide 69 engages the side of the package. Further movement of the piston rod 68 brings the member 6% into engagement with the side of the package and presses said package out of the forming compartment 58 as shown in FIG. 9. While this is taking place, the top side tabs of the package are formed by the

plows

83 and 84. Just before the side tabs at the top of the package are brought into engagement with the

ploughs

83 and 84, and when the ejecting of the package from the compartment 58 is started toward the right as shown in FIG. 8, the shoe 85 is brought into contact with the upper right hand corner of the package to press the end tab formed on this corner, against the package. The shoe 85 which is supported from the frame by the member 86, therefore has a function similar to the projection 71 on the member 70.

After the top side tabs are formed by the

ploughs

83 and 84, as shown in FIG. 10, these tabs are sealed by the heated shoe 87 which is attached to the heater housing 88 in which there is positioned an electrical heating element similar to that positioned in the housings 81 that are employed in conjunction with the heated shoes 81). The top of the package is passed under the heated shoe 87 and sealed as it is ejected from the machine. The member 70 is restrained by the disc member 73 that is attached to the rod 75, from following the package all the way out of the compartment 58. Said disc comes in contact with the frame member 13 and prevents the member 7 from following the member 69b near the end of the package ejecting movement of the piston rod. The package is ejected upon a conveyor, not shown, and at the same time the member 74 actuates the microswitch 67, which is normally closed and which is connected in series with the solenoid 62 of the valve 63.

This normally closed switch 67 is opened by the member 74 and the circuit to the solenoid 62 is interrupted, thereby permitting the valve 63 to return to its normal position in which the pressure supply line 63a is connected to the line 65 so that pressure is applied to the right hand end of the cylinder 66, thereby causing the piston and piston rod 68 of this cylinder to be moved toward the left, that is, to the position shown in FIG. 3. When the piston rod 68 is started on its movement to this position, the piston rod 57 of the cylinder 49 is started on its upward movement, and near the top of its upward movement, the member 56 momentarily closes the circuit of the switch 39a that is connected across the 6 switch of the cam mechanism 28, long enough to energize the clutch mechanism so that the motor 36 is connected to drive the shaft 28 and permit the cam actuated switch 39 to be closed. The motor drives the roller 29 carrying the cutter blade 30; as previously described, and at the same time also drives the

feed rollers

19 and 20 that feed the cellophane web 16 through the cutter mechanism. When a suitable length of the cellophane Web 16' is passed through the cutter mechanism, the

blades

30 and 30a cooperate to sever the web and carry it forward to the package forming mechanism, as described above, at which time the switch 39 is opened and the package forming and wrapping cycle as described is repeated.

While we have shown a preferred embodiment of the invention it will be understood that the invention is capable of variation and modification from the form shown so that its scope should be limited only by the scope of the claims appended hereto.

What we claim is:

1. Apparatus for wrapping a plurality of articles into a package comprising an open bottom article receiving compartment, means for feeding the articles to be packaged to said receiving compartment one by one until a plurality of the articles to be wrapped is positioned in said receiving compartment, resilient means. positioned on the sides of said compartment for resiliently engaging the sides of the articles fed thereto and for holding said articles suspended over said open bottom, means for passing a web of wrapping material under said open bottom compartment, a package forming compartment under said open bottom compartment and in alignment therewith, means for pressing the articles received in said receiving compartment upon said web and with said web into said forming compartment, said forming compartment having ends provided with slots for receiving the end portions of said web to form end tabs from said end portions as said articles and said web are pressed through said forming compartment, and means for forming top tabs for the package as the package is ejected from said forming compartment.

2. Apparatus for wrapping a plurality of articles into a package as set forth in claim 1, further characterized in that said feeding means includes a plate, an arm for oscillating said plate to and from said receiving compartment for feeding the articles to said receiving compartment and said resilient means in said receiving compartment comprises a plurality of fingers for frictionally engaging said articles to retain them therein suspended over said open bottom.

3. Apparatus for wrapping a plurality of articles into a package as set forth in claim 1, further characterized in that there is provided electrically controlled means for actuating said pressing means after a predetermined number of articles are placed into said receiving compartment.

4. Apparatus for wrapping a plurality of articles into a package as set forth in claim 2, further characterized in that the means for counting said articles includes a light sensitive cell positioned so that the light transmitted thereto is interrupted each time an article is fed to said receiving compartment while the article is supported by said plate.

5. Apparatus for wrapping a plurality of article .nto a package as set forth in claim 1, further characterized in that there is provided slidable means for laterally ejecting the package from the bottom of the forming compartment.

6. Apparatus for wrapping a plurality of articles into a package as set forth in claim 5, further characterized in that said slidable means includes a member for engaging a top end edge of the package to press a top end tab against the top of the package, said slidable means includes an additional member for engaging the package and laterally sliding said package out of said forming compartment, a shoe positioned to engage the other top end edge of the package and press the corresponding top end tab against the top of the package as said package is moved out of the forming compartment, and a pair of ploughs for folding the top side tabs over the package also While said package is moved out of said forming compartment.

7. Apparatus for wrapping a plurality of articles into a package as set forth in claim 6, further characterized in that there is provided heating means on walls of said forming compartment for heat sealing the end tabs of said package while the package is moved through the forming compartment, and additional heating means for heat sealing the top tabs of the package while the package is moved out of the forming compartment.

8. Apparatus for wrapping a plurality of articles into a package as set forth in claim 2, further characterized in that the means for actuating said pressing means comprises an electric control, electronic means for counting the articles fed to said receiving compartment, said control including means responsive to said counting means.

9. Apparatus for wrapping a plurality of articles into a package as set forth in claim 8, further characterized in that said control includes a normally closed switch and a normally open switch, both of said switches being adapted to be actuated by said article pressing means when the package is at the bottom of said forming compartment, said normally closed switch being connected to said control to open the circuit thereof and permit said pressing means to return to its starting position, package ejecting means for ejecting the package from said forming compartment, electrical control means for said ejecting means and means connected to said normally open switch for controlling said package ejecting means control means.

10. Apparatus for wrapping a plurality of articles into a package as set forth in claim 9, further characterized in that there is provided an additional normally closed switch connected in series with said normally open switch, said additional normally closed switch being positioned to be opened by said ejecting means when the package is ejected and means for returning said ejecting means to its starting position when said additional normally closed switch is opened.

11. Apparatus for wrapping a plurality of articles into a package as set forth in claim 1, further characterized 'in that means for passing the web of wrapping material under the receiving compartment comprises a pair of feed rollers, a motor for driving said rollers, a cutter for cutting said web into predetermined lengths a'magnetic clutch connected to said motor and means operated by said cutter for controlling the circuit of said magnetic clutch.

12. Apparatus for wrapping a plurality of articles into a package, comprising an open bottom article receiving compartment, means for feeding articles to be rapped to said receiving compartment one by one until a plurality of articles to be wrapped together is fed thereto, resilient means positioned on the sides of said compartment for resiliently engaging the sides of the articles fed thereto and for holding said articles suspended over said open bottom, a package forming compartment under said open bottom compartment and in alignment therewith, means for feeding a sheet of wrapping material between said compartments, pressing means for pressing said articles from said receiving compartment onto said wrapping material and into said forming compartment, means for actuating said pressing means through a cycle of operation including a forward pressing stroke and a return stroke, said pressing means including an article engaging pad that is carried thereby through said receiving compartment and into said forming compartment during said forward stroke, said pressing means also having means for retracting said pad when said pressing means is at the bottom of its forward stroke so that said pad is clear of said receiving compartment and does not interfere with the feeding of articles to said receiving compartment during the return stroke.

13. Apparatus for wrapping a plurality of articles into a package, comprising an article receiving compartment, means for feeding articles to be wrapped to said receiving compartment, electronic means for counting said articles fed to said compartment, a package forming compartment, pressing means for pressing said articles from said receiving compartment into said forming compartment, electrical control means responsive to said electronic counting means for controlling said pressing means after a predetermined number of articles is fed to said receiving compartment, means responsive to said control means for actuating said pressing means through a cycle of operation including a forward pressing stroke and a return stroke, said pressing means including an article engaging pad that is carried thereby through said receiving compartment and into said forming compartment during said forward stroke, said pressing means also having means for retracting said pad when said pressing means is at the bottom of its forward stroke so that said pad is clear of said receiving compartment and does not interfere with the feeding of articles to said receiving compartment during the return stroke.

14. Apparatus for wrapping a plurality of articles into a package, comprising an article receiving compartment, means for feeding articles to be wrapped to said receiving compartment, a package forming compartment, means for feeding a sheet of wrapping material between said compartments, pressing means for pressing said articles accumulated in said receiving compartment onto said wrapping material and into said forming compartment, means for reciprocating said pressing means through a cycle of operation including a forward pressing stroke and a return stroke, said pressing means including a reciprocating rod, a pad, an arm for supporting said pad, means for pivotally supporting said arm on the upper part of said rod and means for rotating said arm to bring said pad into engagement with said articles positioned in said receiving compartment for pressing said articles out of said receiving compartment into said package forming compartment during the forward stroke of said pressing means, said pad being carried through said receiving compartment and into said forming compartment during said forward stroke, said pressing means also having means for retracting said arm and said pad out of said forming compartment during the first part of the return stroke of said pressing means so that during the latter part of the return stroke said arm and said pad are clear of said receiving compartment so that they do not interfere with the feeding of articles of said receiving compartment during this latter part of the return stroke.

15. Apparatus for wrapping a plurality of articles into a package, comprising an open bottom article receiving compartment, means for feeding articles to be Wrapped to said receiving compartment one by one until a plurality of articles to be wrapped together is fed thereto, resilient means positioned in the sides of said compartment for resiliently engaging the sides of the articles fed thereto and for holding said articles suspended over said open bottom, means for counting said articles fed to said compartment, a package forming compartment under said open bottom compartment and in alignment therewith, means for pressing said articles from said receiving compartment into said forming compartment, control means responsive to said counting means for controlling said pressing means after a predetermined number of articles is fed to said receiving compartment, means for moving said pressing means through a cycle of operation including a forward stroke and a return stroke, said pressing means including a pad, an arm for supporting said pad, means for pivotally supporting said arm and means for rotating said arm to bring said pad into engagement with said articles positioned in said receiving compartment for pressing said articles out of said receiving compartment into said package forming compartment during the forward stroke of said pressing means, said pad being carried through said receiving compartment and into said forming compartment during said forward stroke, said pressing means also having means for actuating said arm rotating means when said pressing means is at the bottom of its forward stroke to tilt said arm and said pad out of said forming compartment during the first part of the return stroke of said pressing means so that during the latter part of the return stroke said arm and said pad are clear of said receiving compartment so that they do not interfere with the feeding of articles to said receiving compartment during this latter part of the return stroke.

References Cited in the file of this patent UNITED STATES PATENTS 1,221,196 Lewis Apr. 3, 1917 1,308,321 Armstrong July 1, 1919 1,839,152 Heywood Dec. 29, 1931 2,153,483 Rose Apr. 4, 1939 2,196,910 Delamere Apr. 9, 1940 2,594,337 Noe Apr. 29, 1952 2,685,157 Doepel et a1. Aug. 3, 1954 2,906,075 Vogel Sept. 29, 1959