US2621346A - Semiautomatic pipe nipple threading machine - Google Patents

Description

Dec. 16, 1952 JACOBSQN ETAL 2,621,346

SEMIAUTOMATIC PIPE NIPPLE THREADING MACHINE Filed Oct. 2?, 1948 4 Sheets-Sheet l ww F 0 R M m.

l. D. JACOBSON ET'AL 2,621,346

SEMIAUTOMATIC PIPE NIPPLE THREADING MACHINE Filed Oct. 27, 1948 Dec. 16, 1952 4 Sheets-Sheet 2 SN mm B mo VC wfimn mm m m m I m km 2 w Q i o A m7 3 PM 0 mm QM MN 5 M cm a 3 No RE 0 I mm NW @m H w a 2.

8 ICHAED F. #522 Dec. 16, 1952 D. JACOBSON EIAL 2,621,346

SEMIAUTOMATIC PIPE NIPPLE THREADING MACHINE Filed Oct. 27, 1948 4 Sheets-Sheet 3 IN V EN TORS [E v//v D. JACOBS o/v QEICHARD F HER/E w W ATTO/E/VZYS Patented Dec. 16, 1952 UNITED STATES ATENT OFFICE SEMIAUTOMATIC PIPE NIPPLE THREADING MACHINE of Ohio Application October 27, 1948, Serial No. 56,762

6 Claims. 1

This invention relates to threading machinery, particularly to production threading machinery adapted for threading short lengths of pipe to form commercial pipe nipples.

Continued efforts over a great many years to increase the speed of production of threaded pipe nipples, and consequently reduce the cost, have resulted in two basic types of machines which are employed in the trade. One type is known as a hand machine, in that feeding, loading and control of the machine carriage is done by the operator. The other typ of machine is a full automatic that threads both ends of lengths of pipe to form the nipples. It is a feature of the present invention that in comparison with the prior machines an unexpected increase in production, under safer working conditions is provided, these advantages being obtained by a novel combination and arrangement of machine elements that cooperate to form. in the preferred embodiment, a relatively simple, semi-automatic hand-controlled device, although many features of the invention may also be incorporated, with corresponding increase in production, in automatic machines. For example, one type of hand machine commonly found in the trade employs a manually reciprocable carriage carrying manuallyoperated chuck jaws or gripper for the nipples, and a rotatable self-opening die head mounted in a fixed position on the bed in the machine. With prior machines of this type, the operator must place the nipple in the chuck jaws by placing one hand between the rotating die head and the jaws (a dangerous position), and manipulate a handwheel to open and close the jaws manually with the other hand. He must then move said other hand from the jaw controlling hand wheel to a lever disposed on the carriage of the machine that permits him to advance the carriage and start the threading operation. The dies are generally self-threading, and during the threading operation the operator must retract the carriage and open the jaws of another unit disposed on the same bed, which is supplied with nipples threaded at one end. Thus, considerable manipulation is required between successive threading operations, and a substantial amount of time is consumed thereby limiting the production of the machine.

By contrast, with a machine made according to this invention, means are provided whereby the grippers on the carriage are automatically openedand closed in response to the position of the carriage relative to the threading die,

and a feeding and discharge arrangement is provided wherein a new blank or length of pipe is positioned in the gripper and the threaded blank is discharged during the retraction of the carriage. Thus, loading of the blanks in position to be picked up during the next stroke of the carriag is effected under safe conditions during the threading operation, as opposed to the prior arrangement wherein the blank must be inserted by the operator in the grippers just before the threading operation. The relationship of the carriage-controlled grippers and the blank-supporting platform is such that the grippers are opened automatically on the retract stroke, whereupon the blank previously placed on the feeding platform causes the threaded nipple to be discharged forwardly from the grippers while the grippers are moving with the carriage over the new blank. During the entire cycle the operator of the preferred embodiment of the machine need make but a simple motion of a single lever with one hand, and the other hand need only place a nipple on the blank-receiving platform during the threading operation, which does not delay initiation of the threading operation.

In a machine made according to the present invention, after a new blank is gripped in the grippers, the carriage is moved forwardly and the end of the blank yieldably pressed into the threading dies. In the illustrated embodiment, this is done by the operator moving the carriage forward manually. As soon as the threading dies start on a particular blank, the threading operation proceeds automatically, so that a minimum amount of time is required for starting each blank, and the operation is independent of the driv of the threading spindles. Thus the total handling time for loading each blank is reduced, the proportion of the loading time which necessarily intervenes between the end of one threading operation and the beginning of the next is reduced, and the time required for starting a threading operation after a blank has been loaded is maintained at a minimum, so that in normal use both threading dies are in threading operation ninety per cent of the time and the production is increased tremendously over the prior machines.

Since, in the present invention, the threaded nipple is automatically ejected forwardly upon retraction of the carriage, a chute may be provided to receive the ejected nipples and transfer them to the other side of the machine convenient to the operator for loading the platform successi ely threads bothv ends. of each blank.v

In addition to their complexity and expense, such machines do not approach the high production of the present invention because the feeding cams for the carriage are-geared in syn-- chronism with the rotating threading dies, and in order to insure that the threading of' each blank is uniformly started, and that the blank will be completely threaded before the controlling cams retract carriage, it is necessary to time the dies to make a number of extra turns over that required to carry out a normal threading operation.

Fur hermore. since the stroke of the ca riage of such machines is usually constant and is long enough to handle long nipples, when short nipples' are threaded unnecessary tir e is consumed by traversal of the carriage. With the machine of the present invention the carriage movement is independent of the die rotation, and the position of the carriage controls the opening and closing of the dies and grippers so that adjustments are readily made to reduce carriage travel to the minimum reouiredfor a nipple of given length.

Another disadvantage of prior automatic machines resides in the fact that it may take many hours to change the setup and cam arrangements to convert from one size nipple to another, whereas the machine of the invention is converted as readily as is a hand machine.

With the novel combination of elements referred to in the foregoing brief descri tion of applicants machine, it has been fo nd that with one double-bank machine controlled by a single operator, a production schedule can be maintained which equals that provided by one onerator tending two of the complex and costly double-bank automatic machines. Yet, the machine of this invention retains all the flexibility, simplicity and ease of conversion to different nipple sizes that is characteristic of the slower type hand machines of the prior art.

It is another feature of a preferred embodiment of the invention that means for controlling the opening and closing of the grippers in accordance with carriage position are interconnected with the self-opening die head mechanism so that the grippers are opened as soon as the nipple end is clear out of the die, and remain open during the back stroke of the carriage. On the other hand, the grippers are closed at the end of the back stroke and remain closed during the forward stroke so that there is no danger of the nipple changing its position with the grippers. This facilitates the rearward loading and self-ejecting operation previously referred to, in addition to providing for positive carrying of the nipples.

Other improvements and advantages incident to the invention will appear in the following detailed description of a preferred embodiment thereof.

In the drawings, the machine elements that are conventional or well known to those skilled in the art are not illustrated in detail, it being understood that such elements as the self-opening die head are standard articles of commerce in the art.

Fig. l is a rear end view of the machine made in accordance with the invention with parts broken away;

Fig. 2 is a partial side view of #1 bank of the preferred embodiment of the invention;

Fig. 3; is a view similar to Fig. 2 with parts broken away in section;

Fig. 4' is afragmentary plan view of the machine;

Fig; 5. isan enlarged view of the carriage and grippers;

Figs. 6 to 9, inclusive, are schematic diagrams showing four steps in the operation of the machine;v and,

Fig. 10 is a fragmentary side view showing a modified form.

Referring to Figs. 1 to 5 wherein a preferred embodiment of the invention is illustrated, it should be understood that details of the means for driving the die heads, die head construction and machine design elements known to this art are not illustrated in detail.

We have found that one operator can operate the doubleor two-bank machine at the maximum production of each bank, and although the invention is not limited tothe use of a two-bank machine, such is the preferred form. Each bank of the machine includes several basic elements, all cooperating to attain the advantages previously referred to. These elements include the frame or bed structure it upon which are mounted the two banks A and B. For example, bank A includes a rotatable self-feeding and selfopening die head assembly D turned to the desired threading speed by motor and gearing not shown; a manually reciprocable carriage C that is moved to and from the die head. under control of the operator; blank grippersG-for carrying the blank to and from the die head; and fluid motor means M for automatically opening and closing the grippers. The. corresponding elements in bank B are lettered similarly with a. subscript. "1 appended.

Die head mechanism The diehead D is of the type that is self-feedingonce the blank is started therein by the operators' control of the carriage. As is well known in the art, the die head maybe of the type that is self-opening after the proper length of blank has been threaded. One means of accomplishing this is by providing a shoulder or an abutment means in the die head that is engaged by the blank when the threading operation is completed or substantially so. This trips mechanismv in the die head and causes it to open so that the threaded blank can be retracted from the die head. by operation of the carriage,

Manual means are generally provided to open and. close the dies which may take the form of a lever H pivoted to a collar l in that operates the die trip mechanism, and pivoted to the machine frame as at. 52.. In the preferred form of the invention, lever i i has an extension 43 disposed in a mid-section of the machine for facilitating automatic closing of the dies when the carriage is retracted. Linkage for effecting this includes a link l4 extending from the extension I3 of the die head operatin lever. As best seen in Fig. 3, link 14 connects to a double: crank arm l6- pivottoward the fixed one.

amen

ally mounted at I! on a support line l8, the latter being pivotally fixed to the frame as at l9. This arrangement accommodates for the slightly vertical oscillation of the lower end of lever H.

In order to provide for automatic closing of the die when the carriage is retracted, we prefer to provide a shift rod 22 pivoted to the crank it as at 2|, and provide it with forward and rearward adjustable collars 23 and 24 respectively. The arrangement is such that when the carriage is retracted after the die has been opened, the abutment means 31 on the carriage is pulled against collar 24 which causes the die operating means to operate the linkage just described, and close th dies jaws, these jaws being shown in their closed position in Figs. 2 and 3.

In the broader aspects of our invention, instead of relying upon abutment means integral with the die head for openin of the die in response to engagement of the blank being threaded, we could employ equivalent structure by adjusting the collar 23 so that abutment means 31a in the carriage causes the dies to snap open when the carriage reaches a predetermined position. In either event, it can be seen that the opening and closing of the die head is automatically determined by the position of the carriage relative to the frame and die head.

Carriage Continuing with the detailed explanation of a preferred embodiment, the carriage assembly C includes a body section 30 and guides 3| for sliding on ways provided in the bed of the machine in accordance with conventional machine design practice. To cause manual reciprocation of the carriage, a rock shaft 32 is mounted in the carriage and keyed to a forked arm 33 which reacts against a pin 34 fixed to the carriage in response to manual motion of the carriage-operating lever 36.

Grippers As best seen in Fig. 5, the gripper assembly G mounted on the carriage includes adjustablymounted, fixed jaw 40 and a movable jaw 68a slidably mounted in suitable guides 4!, there being adjusting means 42 and 43 for positioning the fixed jaw 40 so that it is centered with re- "spect to the blank. Replaceable jaw members 44 are fastened by suitable means 46 and formed to grip the blank when the movable jaw is forced In order to cause reciprocation of the movable jaw 48a for gripping the blank, the fluid motor assembly M is provided. This includes 'a cylinder 5! mounted on the carriage by any suitable means 52, the cylinder being fitted with double acting piston 53.

A piston rod 54 is attached to the movable jaw member 40a by means of suitable bolt means 56.

Gripper control mechanism A carriage-mounted control assembly is provided for causing actuation of the motor means M to open and close the movable jaw or gripper 4011. Where a fluid motor, such as an air or hydraulic piston and cylinder assembly is employed,

this may take the form of a valve member 69 6 connections in the valve are reversed and fluid under pressure i admitted in front of the piston to cause the gripper to open and release the blank. 7

As seen in Fig. 2, there is a cam follower device associated with the valve and going to complete the carriage-mounted control assembly for the motor M. This may take the form of a depending block 65 attached to support means 52, slotted as at 66, for reception of a cam follower bell-crank lever 61. This lever includes a cam follower roller 68 and an arm 69 for lifting the valve plunger 65. As best seen in Fig. 2, a carriage-mounted operator for the fluid motor control device is provided. In the preferred form, an angle H may be fastened to the frame provided with a rail 12. An adjustably mounted cam member includes a base 13 and a wear plate it, integral therewith that forms a cam surface for operatin the bell-crank lever 61 under certain conditions, to be hereinafter described.

Mechanism is provided for connecting the operator cam with the die head operating means previously described. This mechanism may take the form of a clevis Tl fastened to the cam 13, link 18 pivoted to the clevis and to a crank arm 19 keyed to the shaft l'l. Adjustable stop means 8! on block 86 may be provided for limiting the motion of the cam in one direction. Shaft I1 is turned when double crank arm I6 (shown in Fi s. 2 and 3) is moved by shifting of the die operating lever ll. This causes rotation of the crank 19, and the position of the cam is changed. When the lever l I is moved to close the threading jaws of the die, the cam 13 is lowered as shown in Fig. 2, and the bell-crank lever 61 is disposed so that plunger 64 is in its lowermost position. The connections to the fluid motor are now such that the grippers or jaws are closed. If the threading jaws of the die are opened, lever H is moved so as to raise the cam. With the cam in its raised position, as the carriage is retracted roller 58 rides upon the cam and plunger $4 is lifted which adjusts the connections to the fluid motor and causes the gripper to open and release the blank, after the carriage has retracted a sufficient distance to withdraw the blank from the die head.

Loading and ejecting device A semi-automatic loading and blank ejecting means are provided and disposed rearwardly of the carriage. In the preferred form, a V-shaped trough 82 is supported on the carriage by any convenient bracket means 83 and the terminal portion of the trough is cut away (as seen in Figs. 3 and 5) to clear the grippers in both the open and closed position thereof. An adjustable stop or ejector means is supported on the frame by bracket 85, and may comprise a rod 86 slidably mounted in the bracket so that it is adjust- .able along the trough 82. A spring finger 81 may alsq beprovidglto directthe completely threaded nipples frornbank B to any convenient receptacle.

Operation Theoperation of the. preferred embodiment just. described will now be explained. Assume that the machine is being first put into operation andis unloaded, but adjusted for the length of nipple to be produced. This adjustment entails selecting the roper speed of rotation for the die head; adjustment of the stop bar BBfor, the length of nipple and adjustment of collars 23 and 2d to causeproper opening and closing of the die head. Also, suitable-receptacles containing unthreaded blanks andblanksthreaded at one end are disposedadjacent machine banksA and 3- respectively. The operator standing-behind the machine placeshis right hand on levertfi ofbank A and moves thecarriage forward. With his left hand. he. picksupan unthreaded nipple and lays it in trough 32; against the stop 88. Lever ii is pushed forward andtl e die head is opened, which lifts cam 'Mand causes the movable gripper 42a to open. The carriage and die head operating lever are set in the same manner for the other bank B; and the machine is ready for operation.

The nipple N is then laid in trough 82 against stop 88 and the carriage retracted. As this occurs, the grippers encompass the nipple and when the carriage reaches its rearward position, abutment means on the carriage 3! strikes collar 2 to close the die head. Closing of the die head operates the various linkages and causes the earn it to drop, whereupon plunger E54 controlling the valve 66 drops and the m vable gripper tta grips the blank.

With the machine set up for operation as described, the principles of the cycle may be readily understood by referring to Figs. 6 to 9. As seen in Fig; 6, with the nipple N gripped by the gripper assembly G, the operator advances the carriage with one'hand by means of lever 36 and urges the nippleinto proper engagement with the threading or-chasing dies '1, and with the carriage advanced lays a blank N1 on trough 82 with the other hand. The threading dies pick up the blank and, being self-feeding, thread it automatically.

During the threading operation, the operator transfers his attention to bank B and repeats the operations just described. The completion of the threading operation in the first bank is illustrated diagrammatically in Fig. 7 wherein the nippleN has engaged an abutment means 8 within the die and causes the die jaws to open. This also lifts cam M into the path of the cam follower, but has no effect on the grippers because the cam follower is forward of the cam.

When the operator perceives the opening of the die head in the first bank, he merely grasps with one hand thelever 36 for that bank and with one continuous motion retracts the carriage. As seen in Fig. 8, early in the retract stroke cam follower 6i rides up on the previously raised cam and causes gripper 49a to open. As retraction continues, the grippers encompass the unthreaded blank N1 which ejects the threaded blank N, as seen in Fig. 9. At the end of the retract stroke, the new blank N1 is in place between the grippers and the abutment means 31 engages its collar to close the dies. This lowers the cam causing the grippers to close. Without removing his hand fromthe lever 36 and without need for hesitation, thefoperator rapidly advances the carriage, (as seen inEig. 6) toward the now closed die head 8 and loads thetroughbehind thecarriage with a third nipple.

These operations are then repeated on the second bank while the nipple N1 is being threaded in-the firstbank.

The total loading time is reducedto a minimum, since itisonly necessary to retract and advancethe carriage and lay, a new blank on the troughv 82, which ma be done while the carriage is being advanced. The portionof, the loading time which necessarily intervenes bctween 'succes sive threading operations is only that time necessary to retract and advance the carriage and yieldably press theblank gripped, into the carriage intothe threading dies. Since thisoperation is independent of. the timing of the threading dies, the time required is reduced to the minimum so that both threading dies are actually'threading about ninety perfcentof the time. Sincethe total loading time isfreduced, a further increase in production isobt'ained on many sizes and types of nipples, particularly the smaller sizes, by increasing the cutting speed of the threading dies. In prior machines working on such sizes and types of, nipples, it was useless to increase the threading speed to the maximum speed at which threading can be accomplished, since the production was limited by the handling and loading time, and any such increase merely increased the time during which the machine was waiting for the operator.

For example, a particular prior art doublebank machine operating at one hundred per cent operating efiiciency on one-half inch spacenipp-les, at the cuttingspeed recommended bythe manufacturer, thirty-three feet per. minute, is capable of producing but three hundred finished nipples per hour. A machine of the same size embodying the present invention, operating at the same threading speed on the same nipples, is capable of producing eight hundred sixtyeight and eight-tenths finished nipples per hour, an incr ase in production of about two hundred ninety per cent. The same machine is actually operated on the same nipples at a cutting speed of forty-one and three-tenths feet per minute, and at one hundred per cent operating efficiency is capable of producing one thousand eighty-six finished nipples per hour, an increase of three hundred sixty-two per cent, without any increase in operator skill or fatigue. Even greater. incr ases ar obtained in the smaller size nipples.

It will also be apparent that in the illustrated embodiment the loading operation involves a mere dropping of a blank on the loading. trough B2 behind the carriage so that there is no danger of the operator injuring his hands as exists in a. machine wherein the blank must be inserted between the grippers from the front which is adjacent to the rapidly rotating die head.

Also, due to the fact that the movement of the carriage is independent of the rotation of the dies or other parts of the machinathe stroke of carriage travel may be made just long enough to accommodate the length of nipple being machined, which increases operating speed as nipple length decreases.

Since the operation of the die head and grippers is controlled by the position of the carriage, and the blank is yieldably pressed into the dies, no delay is required such as is required in prior automatic machinery and the output of a single dual hand machinelike, that just described equals the output of two of theprior automatic me chines.

assi n 9 Modified form Fig. 10 shows a modified form which embodies certain elements of the invention, but forms a simplified construction. The arrangement of the carriage, jaws, jaw-operating means, and worksupporting and ejecting means is like that previously described in the modified form, and details thereof will be omitted.

Frame III) mounts a pair of carriages, one of which, C2, is shown in the view. Each carriage has jaw-operating motor means, one motor M2 being visible, and a pair of die heads are provided, one of them D2 appearing in the drawing. Manu-al lever III may be provided for manipulating the die head which may be of a self-closing type as described previously. The die head is also made self-opening, either with the linkag and lever means previously described, or by means of a rod I22 (shown in the drawing) that operates the die opening lever III and causes the dies to close as the carriage reaches the rearward portion of its back stroke. A hand control lever I36 is provided for each carriage and a work-supporting platform I82 and stop rod I86 are likewise provided. The jaws are controlled by relative motion of the carriage and a fixed cam I12. The control valve I60 for the motor has an operating pin I64 which may be lifted by the bell-crank lever I61 as it rides up on the cam "2.

From the standpoint of operation, the form shown in Fig. 10 is no different from that previously described. The only major structural difference between the forms is that in the form shown in Fig. 10, the chuck jaws do not close as soon as the carriage has completed its back stroke, but remain open until the carriage is advanced to a position wherein the cam follower leaves the cam. Thus, with this form reliance is had upon the pressure of spring such as 81, seen in Fig. 5, for retaining the blank in the jaws during the portion of the forward stroke in which the jaws are open. However, the form shown in Fig. 10 has all the advantages of ease and speed of operation together with safety of the previously described embodiment.

Although the foregoing description is necessarily of a detailed character, in order that the invention may be completely set forth, it is to be understood that the specific terminology in the description is not intended to be restrictive or confining, and that various rearrangements of parts and modifications of detail may be resorted to without departing from the scope or spirit of the invention as herein claimed.

What is claimed is:

l. A threading machine comprising in combination a frame, a rotatable die head mounted on said frame, a carriage reciprocably mounted on said frame, a control for moving said carriage toward and away from said die head, non-rotatabl blank gripping means carried by said carriage, die head operating means including means arranged to open the head when engaged by means moving with the carriage at completion of threading and means to close the die head, when engaged by the carriage adjacent its rearward position, motor means connected for opening and closing said blank gripping means, a, carriage-mounted control device for said motor means, an operator for moving said control device adjustably mounted on said frame and connected to said die head operating means, said die head operating means and connections being arranged so that when the die head is open said operator is placed in one position for causing said control device to actuate 1O the motor means in order to open the blank gripping means, said die head operating means and connections being arranged so that when the die head is closed said operator is placed in another position for causing said control device to actuate the motor means in order to close the gripping means, and blank support and fixed stop means disposed rearwardly of said blank gripping means, aid blank supporting and gripping means being constructed and arranged to permit said gripping means, when open, to advance rearwardly over a supported blank to eject the blank formerly disposed in the gripping means and positions said gripping means over said supported blank.

2. A threading machine comprising in combination a frame, a rotatable die head mounted on said frame, a carriage reciprocably mounted on said frame and including abutment means, a control for moving said carriage toward and away from said die head, blank gripping meanscarried by said carriage, die head operating means including means arranged to open the head when engaged by a blank being threaded in the head after threading and means to close the die head when engaged by said carriage abutment means with the carriage adjacent its rearward position, fluid motor means connected for opening and closing said blank gripping means, a carriage-mounted control valve for said fluid motor, a cam aajustably mounted on said frame and arranged to assume two positions, a cam follower movable with said carriage for operating said valve to open the grippers when said cam is in one position and to close the grippers when said cam is in the other position, and a connection between said cam and said die head operating means, said die head operating means and connection being arranged so that when the die head is open said cam is in said one position and when the die head is closed said cam is in said other position.

3. A threading machine comprising in combination a frame, a rotatable die head mounted on said frame, a carriage reciprocably mounted on said frame and including abutment means, means associated with said carriage for moving it toward and away from said die head, blank gripping means carried by said carriage, die head operating means including means arranged to open the head when engaged by means moving with the carriage after threading and means to close the die head when engaged by said carriage abutment means with the carriage adjacent its rearward position, fluid motor means connected for opening and closing said blank gripping means, a carriage-mounted control valve for said motor means, a cam adjustably mounted on said frame and arranged to assume two positions, a cam follower movable with said carriage for operating said valve to open the grippers when said cam is in one position and to close the grippers when said cam is in the other position, and a connection between said cam and said die head operating means, said die head operating means and connection being arranged so that when the die head is open said cam is in said one position and when the die head is closed said cam is in said other position.

4, A threading machine comprising in combination a frame, a rotatable die head mounted on said frame, a carriage reciprocably mounted on said frame, a manually operable control for moving said carriage toward and away from said die head, blank gripping means carried by said carriage, die head operatingme'ans'including means arrangedto open the head when engaged by means moving withthe'carriage after threading and means to close the die head when engaged by means moving with the carriage adjacent its rearward position, means moving in synchronism with said carriage for causing said die head operating means to close when the carriage is adjacent its rearward position, fluid motor means-connected for opening and closing said blank gripping means, a carriagemounted control valve for said motor means, a cam radjustably mounted on said frame and arranged to assume two positions, a cam follower movable with said carriage for operating said valve to open the grippers when said cam is in one position and to close the grippers when said cam is in the other position, and a connection between said cam and said die head operating means, said die head operating means and connection being arranged so thatwhen the die head is open said cam is in said one position and when the die head is closed said cam is in said other position.

5. A threading machine comprising in combination a frame, a rotatable die head mounted on said frame, a carriage reciprocably mounted on said frame, a manually operable control for moving said carriage toward and away from said die head, blank gripping means carried by said carriage, a blank support and fixed stop means disposed rearwardly of said carriage, die head operating means including means arranged to open the head when engaged by means moving with the carriage after threading and means to close the die head when engaged by means moving with the carriage adjacent its rearward position, means moving in synchronism with said carriage for causing said die head operating means to close when the carriage is adjacent its rearward position, fluid motor means connected for opening and closing said blank gripping means, a carriage-mounted control valve for said motor means, a cam adjustably mounted on said frame and arranged to assume two positions, a cam follower movable with said carriage for operating said valve to open the grippers when said cam is in one position and to close the grippers when said cam is in the other position, and a connection between said cam and said die head operating means, said die head operating means and connection being arranged 12 so that when the die head is open said cam is in said one positionand when the die head is closed said cam is in said other position.

I 6. A threading machine comprising incombination a frame, a rotatable die head mounted on said frame, a carriage reciprocably mounted on said frame, manually operable control pier moving said carriagetoward and away from said die head, blank gripping means carried by said carriage, die head operating means arrangedto open the head when engaged by means moving with the carriage after threading, fluid;motor means connected for opening and closing said blank gripping means, a carriage-mounted control valve for said motor means, a follower movable with said carriage for operating said valve, a cam mounted on said frame, said cam being disposed in the path'of saidfollower for causing said control valve'to actuate the motor means in order to openthe blank gripping means as the carriage is retracted from the die head, means moving in synchronism with said carriage forcausing said die head operating means to close when the carriage is adjacent its rearward position, blank support and fixed stop means disposed rearwardly of said blank gripping means, said blank support and gripping means being constructed and arranged to permit said gripping means, when open, to advance. rearwardly over a supported blank to eject the blank formerly disposed in the gripping means'and position said gripping means over said supported blank. H

IRVIN D. JACOBSON. RICHARD F. HERR.

' REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,457,603 Rankin June 5, 1923 1,740,495 'Briese et al .Dec. 24, 1929 2,067,626 Benninghoif Jan. 12', 1937 2,360,906 7 Smith Oct. 24, 1944 2,389,556 7 Siegerist Nov. 20, 1945 FOREIGN PATENTS Number Country Date 296,088 Great Britain Mar. 14, 1927

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