US3518905A - Lathe carrier center - Google Patents

Description

G. H. RHM l LATHE CARRIER CENTER My 7 im Filed June 5, 1968 2 Shoots-Shadi l G. H. RHM

LATHE CARRIER CENTER July 7, 1970 Filed June 5, 1968 FIG. 2

United States Patent Int. c1. Bzsb 33/00 U.S. Cl. 82-40 5 Claims ABSTRACT 0F THE DISCLOSURE A lathe carrier center with spring means opposing the rearward movement of the center element within its housing and with a hydraulic transmission of this rearward movement to the work-carrier pins to move them in the opposite direction against the workpiece. These carrier pins are slidable in bores in the center element and the pins together with the center element form a structural unit which may be easily exchanged in the housing for another unit. The housing together with this unit and the hydraulic pressure chamber, in turn, form another self-contained unit which is removably secured to the tubular shank of the tool which contains the spring means and adjusting means for varying their pressure which the spring means exert upon the center element through an intermediate piston which forms a part of the center head and extends through the pressure chamber and seals the same so that no hydraulic uid can escape.

The present invention relates to a lathe carrier center of the type which comprises a housing having an open end, a center element and a plurality of Work-carrier pins slidable in the axial direction in the housing and projecting from the open end thereof, spring means acting upon the center element in the direction toward the open end of the housing, a common pressure chamber in the housing associated with the center element and the work-carrier pins and communicating with the bores in which these pins are slidable, and a hydraulic fluid lling out the pressure chamber and these bores at one side of the pins whereby when a workpiece presses against the center point on the center element, the latter is moved more deeply into the housing against the action of the spring means and thereby reduces the volume of the pressure chamber and at least partly displaces the hydraulic lluid therefrom and into the bores containing the carrier pins which are thereby pressed against the workpiece.

It is an object of the present invention to provide a lathe carrier center of the type as described above in which the bores which extend into the pressure chamber and contain the work-carrier pins are located within the center element, land in which the center element including its center point, the work-carrier pins and a part of the pressure chamber together fonm a structural unit which may be easily removed from the housing and exchanged for another of the same kind or for one with different carrier pins or a different arrangement of these pins.

It is another object of the invention to provide a lathe carrier center of the above-mentioned type in which the spring means which act upon lthe center element in the direction toward the open end of the housing and thus against the workpiece are easily exchangeable as wall as adjustable so as to vary their strength.

A further object of the invention is to design the housing so as not only to permit the center element including the work-carrier pins to be easily inserted therein and removed therefrom as a structural unit, but also to divide the housing into two separate exchangeable parts, namely, a center head and a shank for mounting the tool in a ice machine. This center head comprises the actual housing element which contains the center unit, the pressure chamber and an element which is slidable in the bottom of the housing element and seals the pressure chamber and transmits the force of the spring means to the center element. The shank is made of a tubular shape and contains the spring means and the imeans for adjusting the same.

For attaining these objects, the invention provides the housing element with an axial bore which extends centrally through its bottom and terminates into the pressure chamber, and a piston which is slidable in this bore and seals the pressure chamber and extends through the latter and abuts under the pressure of the spring means against the rear end of the center element so as to press the same in the direction toward the workpiece. By dividing the housing into two main parts, namely, the actual housing element and the tubular shank, the advantage is attained that the center head may be removed from the shank as a unit and ebe exchanged for a different unit without requiring the pressure chamber to be opened and without danger that the hydraulic fluid might leak from this chamber. This division of the housing has the further advantage that the spring means may be disposed within the tubular shank, may be rnade of a considerable length, may be easily exchanged for others, and may also be easily adjusted to different strengths without requiring the center element or any parts thereof including the mentioned piston to be removed from the housing element. For securing the housing element and the shank in accurate 'alignment to each other, they are preferably provided with corresponding flanges which may be secured to each other by bolts or similar means. Although the spring means which are disposed in the tubular shank may be of any suitable construction, it is advisable to provide them in the form of a series -of cup springs which are slipped over and `are centered on a rod the front end of which engages into the bore in the bottom of the housing element and is pressed by the cup springs against the piston which extends through the pressure chamber and then presses against the rear Wall of the center element.

The means for adjusting the strength of the cup springs so as to be in accordance with the back pressure required by different center elements and different kinds of Workpieces may be of a very simple design. According to a preferred embodiment of the invention, these means may consist of a setscrew which is screwed into the rear end of the tubular shank and presses against the cup springs. The pressure of these springs then acts upon a cylindrical guide member which is secured to the front part of the rod carrying the springs and has a larger diameter than the rod and is slidable along the the inner Well of the shank so as to guide the rod accurately in its axial direction, while the rear end of the rod is axially slidable in a bore in the setscrew. When the housing of the center element is to be secured to the shank and the anges on these two elements are -bolted together, a cylindrical stud projecting from the guide member is inserted into the bore in the bottom of the housing element and then presses under the action of the cup springs against the piston in the bottom of the housing element which, in turn, presses the center element in the forward direction. By turning the setscrew in the rear end of the shank, the pressure of the cup springs may then be easily adjusted in accordance with the requirements of the particular center unit employed and the workpiece which is to be driven by its carrier pins.

By employing the shank of the tool to hold the spring means, the further advantage is attained that the exchangeable center heads may be made of very small dimensions, even though the piston in each of these heads has to be subjected to a very strong spring pressure.

The features and advantages of the present invention will become further apparent from the following detailed description thereof which is to be read with reference to the accompanying drawings, in which:

FIG. l shows an axial section of the exchangeable head of the lathe carrier center according to the invention, while,

FIG. 2 shows an axial section of the shank part of the tool.

As illustrated in the drawings, the lathe carrier center according to the invention comprises a housing 1a which has an open front end through which a center element 2 with a center point 3 thereon is inserted which is slidable in this housing in the axial direction to an extent which is determined by the length of a slot 11 into which a stop screw 12 engages which is screwed into a bore in housing 1a. The center element 2 is provided lwith several bores 4 which extend parallel to and at equal distances from the axis of the center element and at equal distances from each other. In the particular embodiment of the invention as illustrated in FIG. 1, the center element 2 is provided with three of these bores 4, although because of their offset position only one of them is shown. Each of these bores 4 contains a work-carrier pin 5 the rear end of which forms a piston which is slidable along the wall of bore 4 and carries a sealing gasket 10. Bores 4 terminate toward the rear in a pressure chamber 7 which together with the parts of bores `4 at the rear of the carrier pins 5 is lilled with a hydraulic fluid and forms a common pressure cushion 6. Pressure chamber 7 is tightly sealed toward the outside by a gasket `8 between the center element 2 and housing 1a by a piston 9 which is slidable in a central bore 14 in the bottom 13 of housing la and is likewise provided with a gasket, by the gaskets 10 on the pistonlike ends of carrier pins S, by a gasket on the stop screw 12, and by a gasket on a screw 26 which is screwed into a bore 25 after the pressure chamber 7 and the bores 4 have been filled with hydraulic fluid through this bore. By suitable spring means as subsequently described piston 9 is adapted to be pressed through the pressure chamber 7 and against the rear wall of the center element 2 which is thereby pressed forwardly to the extent as determined by the end of slot 11 against which the stop screw 11 engages which also prevents the center element from turning relative to the housing 1a.

While according to one feature of the invention the center element 2 and the carrier pins 5 together form a structural unit which may be easily exchanged in the housing 1a for another center element of the same outer diameter, for example, for one with carrier pins which have different Work-engaging ends or are spaced at a different radial distance from the center point, it is another feature of the invention that the housing 1a also forms an element separate from the shank 1b of the tool so as to permit either of these elements to be easily exchanged for another. This shank 1b has a tubular shape and contains in its front end a cylindrical guide member 17 which is slidable in the axial direction along the inner wall of shank 1b. This guide members 17 carries a cylindrical stud which is adapted to engage into the bore 14 in the bottom 13 of housing 1a and to abut against and act upon the piston 9. Guide member 17 has a tapped bore 21 into which the threaded front end of a rod 16 is screwed which is locked to the guide member by a check nut 22. On its rear end, rod 16 has a cylindrical head which is inserted into and slidable in a bore in a setscrew 18 which is screwed into the threaded rear end of shank 1b. Between the setscrew 18 and guide member 17 a series of cup springs 19 are centrally mounted on rod 16. lf a suitable key or wrench is inserted into the square recess 20 of setscrew 18 and turned in one direction or the other, the strength of cup springs 19 and thus of the spring force may be varied which is exerted by the stud upon position 9 and by the latter upon the center element 2.

The entire center head which consists of the housing 1a, the center element 2, the carrier pins 5, the pressure cushion 6, and the piston 9 may be quickly exchanged for another on the shank 1b, for example, by providing the housing 1a. and the shank 1b with corresponding flanges 23 `which are removably secured to each other by screws 24. lf a different center head which requires a different spring pressure is then secured to the shank 1b, it is a simple matter to adjust the strength of cup springs 19 by the setscrew 18 which is easily accessible from the rear end of the shank. The center head may therefore be exchanged and the spring pressure acting upon piston 9 may be adjusted without opening the pressure chamber 7.

Although my invention has been illustrated and described with reference to the preferred embodiment thereof, Iwish to have it understood that it is in no way limited to the details of such embodiment but is capable of numerous modifications within the scope of the appended claims.

l Having thus fully disclosed my invention, what I claim 1s:

1. A lathe carrier center comprising a housing element having one open side and an opposite bottom, a center element inserted into said open side and axially movable in said housing element and having a rear wall, a pressure chamber intermediate said rear wall and said lbottom, a center point on said center element projecting through said open side to the outside, said center element having a plurality of bores extending through said rear wall and forwardly to the outside and having axes parallel to and radially spaced from the axis of said center element, a plurality of work-carrier pins each having an inner end forming a piston slidable in one of said bores and an outer end adapted to engage upon a workpiece, a hydraulic fluid filling out said pressure chamber and said bores at one side of said pistons, and spring means acting upon said center element in the direction toward said open side of said housing element, whereby when a pressure exceeding the strength of said spring means is exerted by a workpiece upon said center point, said center element will move toward said bottom and thereby reduce the volume of said pressure chamber and displace the hydraulic fluid at least partly from said pressure chamber in the opposite direction into said bores and with an equal pressure against said pistons on said carrier pins which are thereby pressed against said workpiece, wherein said bottom of said housing element has a central axial bore, a plunger slidable in said bore and sealing said pressure chamber, a tubular shank secured to said bottom and coaxial with said center element, said spring means being disposed in said shank and acting upon said plunger so as to press the same through said pressure chamber and against said rear wall of said center element, and adjusting means in the rear end of said shank for varying the strength of said spring means.

2. A lathe carrier center as delined in claim 1, wherein said housing element containing said center element, said carrier pins, and said plunger forms an element separate `from said tubular shank, and further comprising means for removably securing said housing element to said shank.

3. A lathe carrier center as defined in claim 2, wherein said securing means comprise associated lianges on said housing bottom and on the front end of said tubular shank, and removable means for securing said flanges to each other.

4. A lathe carrier center as defined in claim 2, further comprising a rod in said tubular shank and substantially coaxial therewith, a cylindrical guide member secured to said rod near the front end thereof and slidable in the axial direction along an inner wall portion of said shank, a stud coaxial with a rod projecting from said guide member and adapted to engage into said bore in said housing bottom and to abut against said plunger when said housing element is secured to said shank, said spring means be- 5 ing mounted on said rod and having a considerable length, the front end of said spring means acting upon said guide member, said adjusting means consisting of a setscrew screwed into the rear end of said shank and engaging upon the rear end of said spring means, said setscrew having a central bore, the rear end of said rod being axially slid- 5 able in said bore.

5. A lathe carrier center as dened in claim 4, wherein said spring means comprise a plurality of cup springs hav- References Cited FOREIGN PATENTS 3/ 1964 Germany. 3/ 1955 Great Britain.

U.S. Cl. X.R.

ing central bores and centered on said rod behind each lo 82- 33 other.

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