US3495495A - Friction pin unit,especially for quick change dies and the like - Google Patents

Description

I H. DQBE RRY Feb. 17, 1970' DIES AND. THE LIKE Filed MflTCh 25, 1968 FIG-I I I I h i m k [I O 0 0 2 Z 0 2 W 0 4! I I rl m aw. 3 8 3 4 .I NU-3 I \HIHLHHHHHH ,2 4 1| 6 24 war 3 m I o ,4 2 Z M ,M .1

FIG-3 INVE N TOR HERBERT D. BERRY ATTORNEYS United States Patent 3,495,495 FRICTION PIN UNIT, ESPECIALLY FOR QUICK CHANGE DIES AND THE LIKE Herbert D. Berry, Westboro, Mass., assignor to The Minster Machine Company, Minster, Ohio, a corporation of Ohio Filed Mar. 25, 1968, Ser. No. 715,844 Int. Cl. F16b 19/00 U.S. Cl. 855 8 Claims ABSTRACT OF THE DISCLOSURE A friction pin having a rubber-like elastomeric rod-like center portion and a U-shaped outer portion with the ends of the legs of the U-shaped outer portion bulged outwardly so that the pin, when seated small end foremost in a hole provided therefor in a member, can be employed for detachably supporting the member on a support member which is provided with a hole for receiving the bulged out end portion of the outer portion of the friction pin.

In the art of quick change fixtures and quick change die sets and the like, the device into which the fixtures or die sets are to be placed, usually a press or the like, is provided with slides for receiving the principal parts of the fixtures or die sets and clamp means for clamping the parts fixedly in place in the machine.

Particularly with die sets, it is often the case that blanking and similar operations are carried out in which a cut-out or formed workpiece is pushed outwardly through the bottom of the lower part of the die set. For this reason, the machines for receiving the fixtures or die sets include an open space which is accessible for receiving such punched out or pushed through work members. Furthermore, some die sets will have strippers and ejectors and resilient cushions, and the like, integrally connected thereto and which require space on the bottom side of the die set in the machine for receiving such auxiliaries.

The provision of the space referred to represents no difficulty and ample room is available at the side edges of the support plate of the die set to be supported for supporting and locating the die set. However, when the space is made large enough for its intended purpose there will be times when there is a long unsupported length of the part of the die set mounted thereover which is advantageously provided with supporting posts or the like to prevent bending or deflection thereof. Simple posts are ample for effecting the support in most cases, although in some cases, blocks are provided for accomplishing this supporting function.

A feature of quick change die sets and the like, according to this invention, is that they can very quickly be placed into a machine, such as a press, and clamped therein and very quickly unclamped and removed therefrom. When posts or other supporting members of the nature referred to above are required, it has been customary heretofore to insert these members manually into the space under the die set so that the die set will come down into supporting engagement therewith when put into place. It is preferable for such posts, or supporting members, to be attached to the die part concerned because they will then automatically be removed from the press when the die part is removed and also so that they can easily be inserted in the press together with the die part. For this reason, it has been proposed detachably to pin the posts or blocks to the underside of the die part as by roll-pins or by split-pins, and which pins frictionally engage a hole provided for them in the principal plate of the pertaining die part.

It has been found that such pinning arrangements are 3,495,495 Patented Feb. 17, 1970 defective because if the hole in the plate of the pertaining die set is slightly oversized or wears to an oversized condition, the posts may drop out causing difliculty in putting the pertaining die set part in place and, at times, leading to the possibility of damage and loss of operating time.

Solid split-pins and roll-pins, also, can be pried open somewhat with a screw driver or the like to fit them to oversized holes, but this sort of tampering with the pin can lead to breakage thereof and, also, has its limitations, and is time consuming.

With the foregoing in mind, the present invention proposes the provision of a friction pin unit for connecting such support posts or blocks to the underside of the plate of a die part so constructed and arranged as to prevent the supported post or block from dropping off the die part, while permitting it to be easily connected thereto or removed therefrom.

A particular object of this invention is the provision of an extremely inexpensive friction pin structure which will readily accommodate itself to a relatively wide variety of hole sizes, thereby eliminating problems previously met in connection with improperly sized or worn holes.

Another object of this invention is the provision of a friction pin of the general nature referred to and for the purpose referred to, which eliminates the need for forming holes to extremely close tolerances for receiving the pm.

It is also an object of this invention to eliminate the need for reaming holes to precisely size them and smoothly finishing them for receiving the friction pin.

It is also an object to provide a friction pin for detachably connecting the parts together which never requires any adjustment or reworking to maintain the holding power thereof.

It is also an object of the present invention to provide an extremely inexpensive friction pin of the nature referred to and which can, therefore, be a throwaway item if the pin for any reason becomes defective.

A particular object of the present invention is the provision of a friction pin of the nature referred to which eliminates the danger of a pin breaking off within a member and creating a situation in which special and expensive work is required to remove the broken-off pin part from the member.

These and other objects and advantages of the present invention will become more apparent upon reference to the accompanying drawings in which:

FIGURE 1 is a sectional view showing a typical quick change die set, according to the present invention, incorporating support post members .held in place with friction pins;

FIGURE 2 is a perspective view showing a support block embodying friction pins according to the present invention;

FIGURE 3 is a view, drawn somewhat in enlarged scale and partly broken away, showing a friction pin according to the present invention; and

FIGURE 4 is a cross sectional view indicated by line IVIV on FIGURE 3.

Referring to the drawings somewhat more in detail, FIGURE 1 illustrates, somewhat schematically, an arrangement wherein a lower fixture 10 is provided which might rest, for example, on the bed of a press. A second fixture 12 is provided which is attached to the slide or platen of the press. Each fixture has guideway means 14 for receiving a respective plate of the pertaining upper or lower part of a die set and the guideway means includes clamp elements 16 which are moveable in the vertical direction for pulling the die plates downwardly so that bushings 18 provided therein engage dowel pins 20 mounted in the fixture. Since the fixtures are precisely located on the press bolster and the press slide it follows that the parts of the die set will be precisely aligned with each other.

The particular quick change die arrangement and the fixtures for reeciving the quick change die sets, and the clamping and locating means, form no part of the present invention but are illustrated for the sake of explanation.

As will be seen in respect of the lower die set in FIG- URE 1, which comprises the plate 22, the fixture is provided with a large open space 24 underneath plate 22. Plate 22 cooperates with a die member 26 mounted thereon which cooperates with punch elements 28- carried by the plate of the upper part of the die set so that a strip of stock at 30 is operated as it passes from right to left through the die set. The right-hand punch 28 punches out a slug as indicated at 32 and the left-hand punch 28, which is of a larger diameter, punches out a member 34 which may be a washer. The particular die set shown and the work operation that is performed thereby are merely exemplary and are illustrated to indicate a particular example where the central portion of the plate 22 is unsupported and wherein there must be some space left to receive slugs and workpieces.

Due to the rather long length of plate 22 which is unsupported over the space 24, it is advisable to provide support posts 36 which extend from the bottom of plate 22 downwardly to the upper space of a wear plate 38 which is a replaceable portion of the fixture at the bottom of space 24.

It is advantageous for posts 36 to be detachable from plate 22 to simplify the construction of the die set and to permit the posts to be used in connection with other die sets and for similar reasons. To this end, each post, on its upper end, carries a friction pin 40 which is the particular subject matter of the present invention. Pins 40 frictionally engage holes 42 provided in plate 22 and detachably support the posts 36 on the plate so they can be introduced into fixture 10 with the plate and removed from fixture 10 with the plate and so that they will always remain in the proper position relative to the plate.

The support for the die plate could also take the form of a block as shown at 44 in FIGURE 2. This block has pin means as at 46 mounted therein for detachable connection of the block with the underside of a plate similar to plate 22. There would preferably be at least two of the pins 46 so that the block, when mounted on the bottom of the plate of the die set part would be properly oriented thereto and would remain in a properly oriented position.

Turning now to FIGURES 3 and 4, the nature of the pin constructed according to the present invention is more clearly illustrated. The pin is made from a strip of annealed steel formed to a U-shape by a suitable die arrangement and having the ends of the legs bowed outwardly. The strip is formed so to be arcuate in cross section so that when bent up into a U-shape the resulting member is substantially round in outline.

In FIGURES 3 and 4 the steel strip referred to is indicated by reference numeral 48. It Will be noted that th :free ends of the legs of this U-shape strip of steel are bulged outwardly at 50 to form a sort of button-like or bubble-like end on the pin which tapers inwardly on the upperside and then tapers inwardly on the lower side from an enlarged center part. It will be evident that if the botton-like end part is inserted in a hole, it will take a bearing on the hole about the greatest diameter portion thereof and will adequately support a member in which the lower substantially cylindrical portion of the pin is fixed.

As will be seen in FIGURES 3 and 4, an elastomeric, rubber-like, pin 52 is disposed between the legs of the U-shaped strip 48 and forms a spring element which con tinuously urges the free ends of the legs of the U-shaped strip apart. This pin may be, for example, a cylindrical piece of urethane or neoprene. Other materials suitable for this purpose will suggest themselves. Rubber could be used in places where there is no chance for the rubber to be contacted by oils or solvents and silicone rubber could be employed in places where oil was present and where there might be some heat developed. In any case, it has been found that it is most suitable to use a cylindrical resilient pin of the nature disclosed inserted between the legs of the U-shape strip.

The pin as shown in FIGURE 3, is pressed into the hole provided therefor in the member which it is intended to support. In FIGURE 1, the pin is pressed into a hole 54 in the upper end of post 36 so that the button-like or bubble-like end portion 50 extends upwardly where it will enter into plate 22 a substantial distance. It will be noted that post 36 will be supported with its one end squarely in engagement with plate 22 because the pin engages the hole in plate 22 only in a region spaced from the upper end of post 36.

The pins are placed in block 44 in the same manner.

Normally, the resilient pin according to the present invention, can be inserted in the member into which it is to support, such as post 36 or block 44, in such a manner that it will be retained thereon rather than sticking to the part that the member is supported on. However, it is within the purview of the present invention to provide means for retaining the pin in the part which it supports, such as by providing epoxy cement, or the like, at the lower end of the pin so as not to interfere with the free flexibility of the button-like or bubble-like head end thereof.

It will be evident that the friction pin according to the present invention is ideally adapted for the particular purpose for which it is illustrated, but that it could also be employed for other purposes. For example, the resilient friction pin assembly, according to the present invention, could be employed in connection with clip-on doors for machine tools; for clip-on guards for machine tools, and the like; for clip-on tool trays; for clip-on name plates, and the like.

It is preferable, in most cases, for the pin to exhibit a relatively high degree of wear resistance and, for this reason, it is advantageously heat-treated, after formation to the U-shape part, to a hardness of about 35 to 40 Rockwell C.

It will be appreciated that the enlarged portion near the free ends of the legs of the metal strip is substantially spherical and that the outer ends of the legs converge toward each other and thus form a tapering tip on the pin assembly which makes it easy to introduce it into a hole in a member which it is to engage.

The cylindrical rubber-like member 52 preferably extends from near the lower closed end of the U-shaped strip to near the enlarged portion at the free ends of the legs. The particular length of this member is not critical, but by making it to about the length illustrated, the maximum effectiveness thereof is obtained.

The proportions of the pin are selected so the length of the straight portion is about three to four times that of the enlarged portion.

It will be appreciated that the shank of the pin assembly, as well as the somewhat spherical enlarged head portion thereof are both substantially circular and transverse cross section and thus are readily receivable in simple drilled holes in the members to be connected to the friction pin assembly.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions; and accordingly, it is desired to comprehend such modifications within this invention.

What is claimed is:

1. A friction pin assembly for effecting the detachable interconnection of a pair of members, said members having holes therein for receiving the friction pin assembly, said friction pin assembly comprising a metal strip formed substantially to a U-shape to form a bifurcated pin-like element having a pair of legs closed at one end and open at the other end end, the free ends of the legs of said pinlike element being bulged outwardly to form an enlarged portion on the element at the said other end thereof, said legs being substantially straight from the closed end of the pin to the beginning of the enlarged portion, said legs having an exterior surface convex in transverse cross section so that when said legs are. parallel the pin assembly is substantially circular in cross section, and a cylindrical member of non-metallic resilient material disposed between the legs of said element and extending longitudinally of said legs to permit the legs to be pressed toward each other while biasing the legs away from each other, said element being adapted to have its said one closed end introduced into the said hole in one of said members and pressed into the hole so that the legs of the pin-like element will fr-ictionally secure it in the hole with the said enlarged portion of the element projecting outwardly from said one member, said enlarged portion including free ends converging inwardly and being adapted to be pressed into the hole in the other of said member so as frictionally but firmly to interconnect said members.

2. A friction pin assembly according to claim 1 in which at least said legs of said element are concave toward each other in transverse cross section so that when said legs are parallel the pin assembly is substantially circular in cross section.

3. A friction pin assembly according to claim 2 in which said enlarged portion of said element at the free ends of the legs thereof is formed by a first region of said legs at the free extremity thereof where the legs diverge in a direction away from said free extremity thereof followed by a second region Where the legs converge in a direction away from said free extremity thereof.

4. A friction pin assembly according to claim 3 in which the juncture of said regions is rounded so that the said enlarged portion of said element is generally spherical.

5. A friction pin assembly according to claim 4 in which said cylindrical member extends from near the closed end of said element to at least near said enlarged portion of the element.

6. A friction pin assembly according to claim 5 in which the axial length of said element from the closed end thereof to said enlarged portion is On the order of from about three to four times the axial length of said enlarged portion.

7. A friction pin assembly according to claim 4 in which said metal strip is steel and is heat-treated to about -40 Rockwell C.

8. A friction pin assembly according to claim 4 in which said cylindrical member is made of a rubber-like elastomeric material.

References Cited UNITED STATES PATENTS 2,100,658 11/1937 Finch 5 2,175,814 10/1939 Pender.

2,243,322 5/ 1941 Van Uurn.

2,315,211 3/1943 Kost 85-5 2,553,917 5/1951 Hartman 855 EDWARD C. ALLEN, Primary Examiner U.S. Cl. X.R. 83-698

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