Ball actuated lock pin

A lock pin assembly used for clamping two plates together, that have aligning bores for receiving the lock pin assembly. The lock pin assembly includes radially extending pins that can be forced outwardly from the center of a lock pin housing forming a part of the lock pin assembly. The actuator pins are forced outwardly and cooperate with a tapered surface on a bottom plate to create a clamping force relative to an end of the lock pin housing supportable on a top plate. The lock pin housing has cam tracks on an outer side thereof, and an actuator ring surrounds and supports the pin and carries cam followers sliding in the cam tracks. The cam tracks are made such that relative rotation of the lock pin housing and the actuator ring changes the axial location of the actuator ring along the housing. The actuator ring rests on the top plate and when the actuator pins are released so they can retract and the lock pin housing and the actuator ring are relatively rotated, the lock pin housing is raised relative to the two plates to aid in removing the lock pin assembly.

BACKGROUND OF THE DISCLOSURE

The present disclosure relates to a lock pin assembly that will clamp two members, such as machining tool plates, together, as is desirable in certain machining operations. The lock pin assembly not only secures the plate members, but it also can be unlocked and removed easily.

At the present time, there are lock pins that will lock two flat plates together with three small balls held in radial bores in a housing. The housing extends through precisely sized bores in the plates or through insert bushings on both of the plates so that a portion of the housing extends through a first plate and into the second or lower plate. The three balls in the housing then are aligned with a groove in the second plate, and upon actuation of the balls outwardly, the plates are locked together. The lock balls will provide a force that holds the plates together, but the housing or pin may be difficult to remove when a side load is placed on the plates (vertical application), or if the bores are not exactly concentric.

SUMMARY OF THE DISCLOSURE

The present disclosure provides a lock pin assembly having a lock pin housing that extends through bores in two members, typically plates, that are clamped together with the lock pin. The lock pin housing has a rotatable actuator on its exterior, at an end of the housing on the exterior of the plate members, and a cooperating cam groove and cam follower between the lock pin housing and actuator provide an axial removal force on the housing as the actuator is rotated relative to the housing. The axial removal force also backs provided lock members carried by the lock pin housing to a retracted position. As disclosed, there is at least one cam groove on the exterior of the lock pin housing, and the rotatable actuator is a ring that has a cam follower in the cam groove. With the actuator ring resting on an outer surface of one of the plate members, (the top plate as shown) when the lock pin housing is rotated while the actuator ring is held stationary (there is relative rotation between the housing and the actuator ring), the pitch of the cam groove around the exterior of the lock pin housing causes an axial force on the lock pin housing to urge it out of the bores in the two clamped plate members. The actuator rings reacts the axial force to the outer surface of the top plate member.

As disclosed there are two cam grooves on the lock pin housing and each has a compound pitch helical configuration that has an initial fine pitch so that very little axial movement of the housing, but high axial force, is provided as the lock pin housing and actuator ring are initially relatively rotated with the lock pin housing in a seated and locked position, and then after the lock pin housing has been loosened and moved axially a short distance, the helical cam grooves increase in pitch so that with little more relative rotation the lock pin housing is moved axially a greater distance for each degree of relative rotation of the actuator ring.

The lock pin housing has three radially extending lock members, in the preferred form, lock pins, extending from a center bore of the housing. The lock members are actuated outwardly by forcing an actuator ball in the center bore of the housing against inclined or cam type surfaces at inner ends of the lock members. The inner ends of the lock members extend into the center bore when they are retracted or unlocked. When the lock pin housing is inserted through a bore in a top plate member and into an aligning bore in a bottom plate member that is to be clamped to the top plate member, a force generator, as shown a set screw mounted in the housing, is used for forcing the actuator ball against the inner end inclined surfaces of the lock members to urge the lock members, pins as disclosed, outwardly from the lock pin housing. The second or lower plate member into which the housing extends has a chamfer shoulder surface around the inner or remote end of the aligning bore in the bottom plate member, and the three lock members are provided with outer end cam surfaces that will engage the chamfer surface and urge the top and bottom plate members to clamp together as the lock members are forced outwardly.

Removing the lock housing is accomplished by releasing the force generator or set screw from the actuator ball, which will permit the lock members to be retracted by an O-ring around the periphery of the lock pin housing that urges the lock members inwardly, and then by holding the actuator ring and rotating the lock pin housing the cam action force moves the housing axially in a direction away from the top plate member, as stated, for extracting the lock pin housing. If the lock members do not retract all the way, the chamfer in the bore in the bottom plate member will act against the outer end camming surfaces of the extended lock members to urge the lock members inwardly as the lock pin housing is moved out of the bores in the plate members. The provision of the fine pitch cam grooves as the actuator ring is initially moved provides an increased retraction force to initially axially move the lock pin housing. The cam grooves on the lock pin housing for the actuator ring can be made with a continuous pitch as well.

While the lock members that are carried by the lock pin housing are disclosed as pins, the lock members can be balls in radial bores of the lock pin housing, in that the spherical surfaces of balls provide camming surfaces for extending (or retracting) ball shaped lock members

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

InFIG. 1, a plate assembly indicated generally at10is made up of a first base plate member12(also called a receiver plate), and a second top plate member14(also called a sub plate), which are locked or clamped together, using a lock pin assembly15made according to the present disclosure. The lock pin assembly15, as seen inFIGS. 4,5and other figures includes an outer lock pin housing16, that has an central end bore portion18at an inner end, and this end bore reduces to a smaller diameter threaded bore portion20. The lock pin housing16has a hex shaped socket counter bore22at an outer end. An actuator set screw24can be threaded into the threaded bore20. The hex shaped socket counter bore22is designed to receive an Allen wrench for rotating the lock pin housing, and is of size to permit a smaller Allen wrench to be placed into the socket head of the actuator set screw24for tightening or loosening the set screw. The bore portion18is, as stated, larger than the threaded bore portion20, and is of size to receive an actuator ball26which is inserted from the remote end and that is acted on by an end portion28of the set screw, as will be explained.

The lock pin housing16has three radial bores, which are indicated in dotted lines inFIG. 3at30.FIG. 4is a sectional view taken through the centers of two of the bores30. Each of the bores30mounts a lock actuator member or pin32. The lock actuator members32are slidably mounted in the bores30and each has an inner end actuator surface34against which the actuator ball26will act when the set screw24is threaded inwardly along the bore20. The outer ends of the lock actuator members32have cam surfaces36, and these cam surfaces are part cylindrical so they mate with an inwardly tapered annular chamfer surface38that surrounds a lower end of a cylindrical lock pin housing receiving alignment bore42and which joins a larger cylindrical bore40formed in the base plate12. The lock actuator members32(called pins as shown) have grooves at their outer ends and an O-ring35fits in the grooves and surrounds the lock pin housing16and the lock actuator pins32to urge the pins32inwardly in toward the central bore18of the lock pin housing16.

Bore40in the base or bottom plate12thus is shouldered by the chamfer or inclined surface38. The smaller first alignment bore portion42in plate12adjacent to the second or upper plate14is bored to be exactly the same size as a second alignment bore44formed in the upper plate14. The bores42and44closely receive the outer surface of the cylindrical lock pin housing16, and as can be seen the remote end portion of the housing16extends through the alignment bore portion42and sufficiently far into the bore40so that the lock actuator pins32and the cam surfaces36of these pins or members will engage the chamfered surface38.

The upper end of the lock pin housing16has a shoulder flange48, and an actuator collar or ring50has a center bore through which the lock pin housing16extends. The actuator ring50is positioned around the lock pin housing16at the upper end of the housing and has a groove49that receives the flange48. The actuator ring50supports the end of lock pin housing16on the upper surface of plate14. The lock pin housing16also has helical cam grooves or tracks formed into the cylindrical exterior surface as shown inFIGS. 6 and 7. There are, as shown, a pair of the helical cam grooves or tracks54, each of which, as shown, extends substantially 180° around the outer surface of the lock pin housing16. The cam grooves54may extend more of less than 180°, if desired. The actuator ring50has a pair of radial bores 180° apart that are of size to receive cam follower balls52, and these cam follower balls are held in place with cap screws56, that extend inwardly from the outer edge of the actuator ring50. The cam follower balls52are of size to fit into the respective grooves54, and they form cam actuators (one in each groove) that will create, when the ring50is resting on the top plate14and held from rotation and the lock pin housing16is rotated using an Allen wrench in socket22, an axial force along the axis of the housing16by the cam action. The number of cam follower balls can be varied, depending on the number of cam grooves provided.

The helical cam grooves54, as shown and preferably, have compound pitches or inclines and, as shown, each has a first section54A that has very little pitch, or in other words, very little change in axial position relative to the axis of the lock pin housing16for substantially 90° around the housing. Then there is a second higher pitch section54B for each of the cam grooves that has a substantial change in axial position for each degree of rotation of the actuator ring50about the lock pin housing16. The incline or angle of groove section59B relative to the longitudinal axis of the housing16changes at a greater rate than the first cam groove section54A.

This means that there is a differential in the amount of force that is exerted axially on the lock pin housing16for each degree of rotation of the ring50relative to the lock pin housing16as the ring50is rotated around the housing between the movement along first cam track section54A and movement along second cam track section54B. The cam grooves may be single pitch and extend more or less than 180°, if desired.

FIG. 4shows the set screw24threaded against the actuator ball26to force the lock actuator pins32outwardly in the bores30and against the chamfer surface38so that the lock cam surfaces36provide a force urging the plates12and14together due to the fact that the flange48bears on the collar or ring50, which in turn bears against the upper surface of the plate14.

The two plates12and14are clamped or locked tightly together, as shown inFIGS. 4 and 5. While only one lock pin assembly15is illustrated, typically two or more lock pin assemblies are used for securing the plates in use. When the plates are to be separated or released, the actuator set screw24is loosened by putting an Allen wrench through the bore22and into the socket head of set screw24, and then backing the actuator set screw away from the actuator ball26. In use, the plates12and14may shift slightly, or the plates may be positioned so the bores in the two plates that receive lock pin housing16may no longer be exactly concentric. This shifting places a side load on the lock pin housing16so removal is difficult, and when there are side loads the present invention aids in removal of the lock pin assembly.

In order to permit removal of the lock pin housing16under friction or side loads and/or retract the lock actuator pins32, and thus permit the plates12and14to be separated, a large Allen wrench is placed into the socket22of the lock pin housing16and the lock pin housing16is rotated, while the actuator ring50is held relative to the plate14and the lock pin housing. While the actuator ring can usually be held manually, if needed, a wrench can be used to hold the actuator ring50from rotating. When there is relative rotation between the lock pin housing and the actuator ring, the cam follower balls52follow along the cam track sections54A, exerting a substantial force in axial direction on the lock pin housing16relative to the plates14and12, because of the low pitch of the cam track section54A during the initial relative rotation between the lock pin housing16and the actuator ring50. This axial force will move the lock pin housing16axially upwardly, even under side loads, as the lock pin housing is lifted relative to the top of plate14. Again, the actuator ball26has been loosened, and the O-ring35will act to retract the lock pins32, but if the lock pins are not fully retraced, once the lock pin housing16starts to move axially, the pins32will also tend to be retracted by the chamfer surface38acting against the outer end camming surfaces36. Then, as the lock pin housing is rotated more, after it is initially loosened, the second higher pitch portion54B of the cam groove or track will cause a relatively rapid axial movement of the lock pin housing16as the lock pin housing is rotated with the cam follower balls52in the higher pitch cam groove section. The housing16lifts and it can be gripped or pried on to pull it out through the bore42. The plate14can then be separated from the plate12. The fine pitch of the cam grooves or tracks provides increased pull out force when it is needed most, but, again, the cam tracks can be a constant pitch or a different compound pitch.

The housing16is shown partially retracted upwardly to release the plates inFIG. 7, where it can be seen that the flange48is spaced upwardly from the bottom of the groove49in the ring50that receives the flange48, and that the balls52traveling in the cam tracks54have forced the lock pin housing16upwardly. The actuator lock members or pins32will be at least partially retracted into the bores30in this position. The lock actuator pins32, as shown inFIG. 8, will be fully retracted when the housing16and actuator ring50are rotated relative to each other so the cam follower balls52are moved to the ends of the cam track sections54B.

When two plates are to be locked or clamped together, such as the plates12and14, the aligning first and second bores are formed for receiving the lock pin housing16and one of the bores is provided with a chamfered surface surrounding the aligning bore at the remote end in one of the plates, and in this instance, the chamfered surface is at a shoulder that is formed by a larger bore40extending more remotely than the aligning bore42in plate12. The two plates are placed together, and the aligning bores42and44are aligned. The lock pin housing16is then inserted with the actuator ring50rotated to a position with the cam follower balls52at the start end of the cam track sections54A, so that the flange48is seated on recess49and the actuator ring50is resting on the upper surface of top plate14, The set screw24is backed outwardly so the actuator lock pins32may be retracted and the O-ring35has urged the pins32inwardly. Then, the lock pin housing16can be inserted into the two aligning bores in the plates12and14. The chamfered surface38is machined so that with the housing16seated in the bores, with the flange48seated on the groove49and the actuator ring50resting on the top surface of plate14to support the lock pin housing16on plate14, the pins32are at a level or at a plane perpendicular to the axis of the housing16so the surfaces36will engage the chamfered surface38. The lock pin housing16is seated with the actuator ring50resting on the top surface of plate14, to properly position the actuator lock pins32. The set screw24is then driven inwardly with an Allen wrench against the actuator ball26to force the pins32out of bores30to engage the chamfered surface38and tightly lock the two plates12and14together.

This locking arrangement or clamping arrangement using the lock pin assembly disclosed can be used for various applications in addition to use in the machine tool industry. The members that are clamped together can be any selected parts, plates or members. The removal of the lock pin housing16to release the two clamped members is done as previously described.

The drawings disclose the bores in the plates formed directly in the plate material. In practice, the plates can be bored with larger holes and inserts that have bores for receiving the lock pin housing and with one insert, for the lower plate, formed with the chamfer38, installed in the larger bores. The inserts can be secured in the larger bores, and also can be hardened.

The description and drawings show the cam groove on the lock pin housing and the cam follower carried by the actuator ring, but the cam groove or track could be formed on the inner surface of the actuator ring facing the housing, and the cam follower carried on the lock pin housing.