US2823960A - Die sets for machine presses - Google Patents

Description

Feb. 18, 1958 w. J. BLAZEK ETAL DIE SETS FOR MACHINE PRESSES 2 Sheets-Sheet 1 Filed Aug. 26, 1955 INVENTORS Feb. 18,1958 w. J. BLAZEK Em 2, 23,960

DIE SETS FOR MACHINE PRESSES- Filed Aug. 26, 1955 2 Sheets-Sheet 2 mvsmoas WJBZaze/c JJ Sfrnad ATTORNEY United States Patent DIE SETS FOR MACHINE PRESSES William J. Blazek, New Lexington, and James J. Strnad, Bedford, Ohio, assignors, by mesne assignments, to Ltemfilco Products, Inc., Bedford, Ohio, a corporation 0 O 'o Application August 26, 1955, Serial No. 530,857 9 Claims. (Cl. 308--6) This invention relates to guiding appliances, such as those used on machine tools for maintaining registry between relatively movable parts. More specifically, this invention is concerned with punch press die sets of the type in which a bed or bolster-carried die holder and a movable ram mounted punch holder are maintained in all positions of press operation in true relative alignment. Die sets of this general character are disclosed in the prior patent of Conner, No. 2,422,775, granted June 24, 1947.

As set forth in the above patent, such a die set may comprise an upper punch holder and a lower bed or bolstermounted die holder. The upper holder is securely attached to and movable in unison with the slide or ram of an associated punch press, while the die holder is adapted for attachment to the stationary bed or bolster of a press. The upper holder carries the punch or upper section of a given die assembly while the lower holder carries normally the stationary die section of said assembly.

To maintain true alignment of the holders and die sections carried thereby, the lower bed or bolster-mounted holder has mounted thereon a plurality of fixed, relatively spaced, hollow, upright guide members, known as bushing's. The associated punch holder carries in axial registry with each of said bushings a rigid, depending, guide post or pin. Each bushing includes a relatively enlarged internal chamber, and between the spaced wall surface of each of these chambers and the movable post entering the same, antifriction bearing devices are interposed. Each of these devices includes a plurality of rolling elements having simultaneous pressure contact with spaced wall surfaces provided between the posts and bushings, whereby to provide for relative longitudinal and axial movement but precluding lateral movement of the posts.

In general, such guide appliances have been formed to include two types. The first of these is a general commercially employed type in which the guide pins or posts, the antifriction ball-bearing retainers and the bushings are round or circular in their transverse cross sections, as shown in the above Patent No. 2,422,774. in a second type, each pin or post, the bearing retainer and the receiving chamber therefor provided in each bushing is substantially square, or of other polygonal transverse configuration. When the flat-sided polygonal type of pin or post is provided, use is made in connection therewith of elongated roller hearings in each retainer cage or frame in lieu of the ball bearings employed in the round or circular pin or post construction. Both forms have certain individual advantages. The cross-sectionally round or circular pin, with correspondingly formed associated parts, enablesthe parts to be accurately machined and finished to close dimensional tolerances, which latter in a practical sense are ditficult if not impossible to obtain from a manufacturing and cost standpoint when the polygonal type of pin and its associated parts are used.

However, the round pin requires the use of a correspondingly formed bearing retainer, necessitating the use Of ball-bearing a'ntifriction elements with their limited surface area of contact while under pressure loading between associated cylindrical pin and bushing surfaces; a

condition which is apt to cause undesirable pitting and scoring of ball element-engaged surfaces. Withthe use of the square, or other polygonal, type of pin, the antifriction elements possess the form of elongated cylindrical rollers, having greatly extended areas of surface contact in comparison with ball-type elements. The roller type of antifriction bearing is used between flat, opposed, wall surfaces of a cooperative post and bushing, with the result that less Wear is present and pitting and scoring is prevented or minimized. Also, in this construction an improved stable, guiding action is obtained. However,

because of the practical difficulties in machining truly flat;

surfaces disposed in proper geometric relation to each other on the posts and bushings for bearing contact, the square or polygonal pin has not been deemed suitable for commercial employment in obtaining accurate surface;

control, and its use has been accordingly restricted.

It is an object of the present invention, therefore, toprovide die set guides of the polygonal type which are so constructed and arranged as to compensate for any absence in the true flatness or parallelism with post, axes, of its bearing-engaging surfaces, this being accomplished without sacrificing the accuracy thereof of the structurein the guidance of associated relatively movable die set parts, or in causing any shortening of the period of operating usefulness normally expected from guides of this type. r

Another object is to provide a die set in which the bush-. ing-received posts thereof present a multiplicity of sub stantially flat surfaces disposed for engagement with roller? or other bearings retained for floating movement in bush-.

ing chambers having flat surfaces complemental to those of the posts, and wherein the construction is such that each complemental pair of said surfaces is yieldable under normal operating conditions of the die set, whereby to. compensate for unevenness, or the absence of true par allelism in the roller-engaged regions of said surfaces. 3

A further object of the invention is toprovide a fiatsurfaced, substantially square guide post or pin for punch press die sets wherein the body of the guide post is slotted adjacent to the flat outer regions thereof in a manner admitting of limited resilient, inward displacement of one or more of such regions in response to roller-bearing.

pressures applied to uneven areas of said surfaces, such displacement being effected as the pin or post reciprocates" in a bushing in which associated roller-bearing means are mounted.

An additional object is to provide an alternate form of die set guide means wherein a fiat-surfaced guide pin or post, substantially polygonal in its cross section and movable with the sliding head of a punch press, has its lower portion received in a chamber provided therefor in a stationary bed or bolster-mounted bushing, and wherein parallel, segment members are provided in said chamber and disposed between the walls thereof and frame-retained roller bearings surrounding the movable lower end of the pin or post, said segment members being constructed to yield resiliently and radially of the guide means in com.-

. ,pensating for surface irregularitiescausing an absence of perfect plane conditions in the flat bearing-contacting surfaces of the pin or post. i A still further object is to improve generally the construction of die set guides employing antifriction bearings. For a further understanding ofthe invention, including additional objects and advantages thereof, reference may now be had to the following description'and accompany-s ing drawings, wherein:

Fig. l is a view partly in front elevation and in vertical 1 Pa itented Feb. 18,

section of a punch press die set formed with the guide means of the present invention;

Fig. 2 is a detail horizontal sectional view taken on the plane indicated by the line 2-2 of Fig. 1;

Fig. 3 is a vertical sectional view on the line 3 -3 of Fig. 1;.

Fig. 4 is a similar view disclosing a variation of the slotted pin or post of Fig. 2;

Fig. 5'is also a similar cross-sectional view disclosing a form of the invention in which radially slotted segments are stationarily formed in the bushing element of the guide assembly;

Fig. 6 is a similar view disclosing modified gib inserts which are interiorly slotted for limited yieldability;

Pg. 7 is a similar horizontal sectional view in which solid gib inserts are formed with convex outer surfaces of greater or flatter curvature than that of the contacting inner walls of the associated bushing to yieldably space the inserts from said walls;

Fig. 8'i's a variation of the construction of Fig. 7 wherein the convex outer surfaces of the sectional and solid gib inserts possess a curvature based on arcs of shorter radii than that of the contacting bushing wall;

Fig. 9 is a horizontal sectional view, disclosing a modification in which gib inserts are disposed between the pin or post of the guide assembly and the antifriction bearing means;

Figs. 10 and 11 are detail cross-sectional views of still further modified forms of the invention.

The present invention, as above set forth, aims to provide certain improvements in die sets having square pin and bushing constructions such as those disclosed in the Conner patent, No. 2,422,775, supra, particularly in the matter of compensating for the absence of true, flat, bearing-contacting surfaces between the pins and bushings, since such surfaces often are found to be out of parallelism with the post axis or proper geometrical relation to each other.

Therefore, the present invention provides means to maintain alignment between members which are movable toward and away from each other, the same being in the form of guide means carried by the other member and with meansinterposed between the guide means to decrease frictional resistance and control relative lateral movement therebetween. The guide means are preferably provided with flat angularly related bearing surfaces and the antifriction means interposed between such surfaces are preferably in the form of roller bearings. The space present between the relatively movable members may be such that the bearingshave a relatively close fit therein, limiting the amount of any lateral motion therebetween. In the preferred arrangement, the space between the guide members is such that the rolling bearing elements are confined therein under pressure. This pressure, as defined in said Conner patent, may vary between relatively wide limits from a point where the pressure is very light to that where it is quite heavy. In some instances it may be desirable that no pre-loading of the hearing be provided, but in most'applications the pro-loading is such that the bearing elements will move concomitantly with the associated movable member but at a higher rate of linear travel.

Referring now to the drawings, and to the specific form of'the present invention illustrated in Figs. 1' through 3 thereof, the die set illustrated is shown as including a fiat upper plate or punch holder 1 which is provided centrally with an upright stem 2, the latter enabling the plate to be secured to the traveling head or slide of a press, not shown, in a well-known manner. Cooperative with the plate 1 isa spaced, parallel, bottom plate or die holder 3 which may be bolted, or otherwise conventionally secured, to an associated press bed or bolster B.

In this instance, the plate 1 has beenshown as being provided at the end thereof with vertical openings 4 in which are tightly fitted the shouldered upper ends of a pair of rigidly depending leader pins or posts 5, the latter extending downwardly from the plate 3. in spaced parallel order toward the bottom plate 3. These pins or posts are preferably square or polygonal in cross section, presenting a multiplicity of angularly disposed flat surfaces 6, the present invention being concerned primarily with the provision of means compensating for the absence of true flatness and relative perpendicularity of these surfaces and in producing as a result of the construction uniform functioning of die sets containing such leader pins or posts.

Cooperating with said pins or posts 5 are stationary hollow guides, ordinarily referred to as bushings, and which are indicated at I in the drawings. These bushings are formed with shouldered and reduced lower ends 8 which are positioned in and maintained in tight contact with the wall surfaces of a pair of openings formed in the lower or bottom plate 3, the bushings being disposed in axial alignment with the pins 5.

In the form of the invention disclosed in Figs. 1 through 3, the bushings are provided with internal bores or chambers 9, the latter being substantially square in cross section to conform with the configuration of the pins or posts 5. However, the pins or posts are sufiiciently smaller in their cross sectional dimensions than said chambers 9 so that the flat wall surfaces 10 of the chambers will be spaced from the outer complemental surfaces 6 of the pins or posts to define rectangular bearing-receiving spaces 11 therebetween.

The bearing assembly 12, which is received in these spaces, is of such size that the roller bearing elements 12a thereof will span the spaces 11 present between the pins or posts 5 and the walls of the bushings 7. Preferably the bearing elements 12a should be of such size that they prevent lateral movement between the pins or posts and the guide bushings. This condition is known as loading or pre-loading and the amount thereof may be varied. The bearing elements 12a are preferably of the elongated roller type, the same being supported in a confining retainer frame or cage structure 13 in spaced, parallel, vertical rows with each bearing element arranged for rotation about its long axis. While ball bearings may also be used, it is advantageous to employ roller bearing elements because of their extended line contact with the associated fiat pin and bearing surfaces. The hearing assembly when pro-loaded moves with the pins or posts as the latter reciprocate vertically, but at a lower rate of linear travel, the assembly being sustained in spaced elevated relation with respect to the bottoms of the bushings by the loading pressures applied to the roller elements thereof by the opposed fiat wall surfaces of the pins and bushings and which exert squeezing forces on the roller elements. 7

In accordance with the present invention, one of its novel and distinguishing features resides in providing each of the pins or posts with corner-intersecting, radially disposed, vertical slots, as indicated at 14 in Fig. 2. It will be observed by reference to this figure that the slots open to the vertical corner edges of each pin or post and that the closed inner ends of the slots terminate in the center or axial regions of said pins or posts. By so slotting the pins or posts, each of the latter presents a plurality of outer bearing surface-containing regions or segments 15 which under predetermined pressures are inwardly and resiliently yieldable to an extent adequate to compensate for the minute surface irregularities or imperfections which'may be present in the flat bearing faces or surfaces 6 of the pins or posts 5 or 10 of the bushings 7. As stated, these surface imperfections or irregularities when present constitute but slight depar tures from theoretically perfect planes, and appear usually in but a small localized area or areas of a given surface. Therefore, the slight degree of yieldability of the regions 15 of the pins or posts, as afforded by the slots 14, will not in any way interfere with the fully guided control and alignment of the relatively separable die section's carried by the plates 1 and 3, but will greatly reduce the amount of wear between the bearings, posts and bushings.

This feature of limited yieldability may, of course, be incorporated in the die set in different ways, as, among others, those specifically illustrated in Figs. 4 through 9 of the drawings.

The pin or post disclosed in Fig. 4 is provided with a plurality of slots 16, which in the main extend parallel with the surfaces 6, but with the open end of each slot opening to a surface 6 with respect to which the slot extends at right angles. The outer fiat surface-containing regions or segments 15 produced by this arrangement of slots possesses all yieldability necessary for the overcoming of surface imperfections above noted.

In the form of the invention illustrated in Fig. 5, radial or other slots 17 are formed in a plurality of stationary inserts or segments 18 integrally formed with or carried by the bushing 7. These inserts are formed with flat bearing surfaces 19 disposed in opposed but spaced relation to the surfaces '6 of a pin or post 5. In this instance, the pin or post has been shown as being cross-sectionally solid and devoid of the slots of Fig. 2. However, a slotted pin or post may be used in conjunction With the inserts or segments 18 if desired. The usual roller bearing assembly 12 is mounted in the restricted rectangular space 11 formed between the surfaces 6 and 19, the roller bearing elements 12a of the assembly engaging the opposed surfaces under pre-load confining pressures.

Fig. 6 sets forth substantially the same arrangement as in Fig. 5, but in Fig. 6 the bushing segments 18 are each provided with a plurality of parallel slots 20 which are spaced from each other and occupy a parallel relation with respect to bearing surfaces 19.

In lieu of slotting the bushing segments or the leader pins or posts as heretofore defined in obtaining bearing element relief by preventing overloading thereof, as caused by passing the same through excessively restricted operating spaces 11, the present invention may employ the solid segments 21 and 21a of Figs. 7 and 8, respectively. These segments are in the form of inserts and, as shown, are separate from the bushings 7a and from each other. The distinguishing feature of the segments 21 of Fig. 7 is to be found in the curvature of the convex outer surfaces 22 thereof. It will be noted that the surface 22 of each segment 21 possesses a convex curvature forming a segment of a circle having a greater diameter than the circle of curvature of the inner cylindrical surface of the associated bushing 7a. As a result of these differences in curvature, a thin crescent-shaped space 23 is defined between the outer convex segment surface 22 and the associated cylindrical bushing wall, with the spaced, outer longitudinal edge 24 of each segment 21 disposed in contact with the inner wall of the bushing. The spaces 23 are so formed and disposed as to admit of resilient yielding thereof in an outward and radial direction. This action takes place, as previously explained, when bearing overloading is effected as a result of irregularities in the flat surfaces 25 of the segments, or the surfaces 6 of the pins, producing undesired overloading of the roller elements 12a of the bearing assembly.

In the construction of Fig. 8, the segments 21a have convex outer surfaces 22a, the central portions only of which bear on the cylindrical wall of the bore or chamber 9 of the bushing 7a, as contrasted with the dual bearing edges 24 of the segments 21. Such centralized contact of the segments 21a with the bushing 7a is attributable to the fact that each surface 22a constitutes a segment of a circle having a smaller diameter than the circular bore of the associated bushing 7a.

A further variation is set forth in Fig. 9 wherein the inserts or segments 26 are disposed between the pins or posts and the roller bearing assembly 12, the roller elements 12a of the assembly being disposed in preloaded, simultaneous contact with the rectangularly ar- Fig. 10, the post 5b and the retainer 712 are of triangular.

configuration. Other such variations are, of course, possible.

We claim:

1. A die set comprising relatively movable, spaced and interfitting post and bushing members adapted for straight line motion and which are substantially polygonal in cross section in providing substantially flat, opposing and relatively spaced surfaces; a retainer structure conforming to the polygonal cross-sectional configuration of the space formed between said members, said structure including a plurality of independently movable bearing elements having simultaneous preloaded pressure contact.

with said opposing surfaces; and resilient means incorporated in at least one of said members and providing yielding displacement thereof in response to abnormal pressures applied to the bearing elements upon passing of the latter between portions of said opposing surfaces which are out of true geometrical relation to each other and in parallelism with post axes.

2. A guide post for die sets comprising: an integral, elongated, polygonal body, including a plurality of recessseparated, outwardly disposed bearing regions and a solid core region; each of said bearing regions presenting a longitudinally elongated, flat, outer surface, the recesses separating said bearing regions serving to admit of inward yielding movement of the latter in response to abnormal inwardly directed forces applied to said surfaces.

3. A guide post for die sets as defined in claim 2, and wherein said recesses extend substantially inwardly of said body and open at their outer ends to corner regions of said body defining said surfaces.

4. A guide post for die sets comprising: an elongated body substantially square in cross section and formed with flat bearing faces on the outer sides thereof, said body including a central longitudinal core region integrally joined with relatively movable outer regions on which said bearing faces are formed, said outer regions including merging web portions of narrow Width with respect to the width of one of said faces.

5. A die set comprising relatively movable, spaced and interfitting post and bushing members adapted for straight line motion and which are substantially polygonal in cross section in providing substantially flat, opposing and relatively spaced surfaces; a retainer structure conforming to the polygonal cross-sectional configuration of the space formed between said members, said structure including a plurality of independently movable bearing elements having simultaneous preloaded pressure contact with said opposing surfaces; and resilient means incorporated in said post member and providing yielding displacement thereof in response to abnormal pressures applied to the bearing elements upon passing of the latter between portions of said opposing surfaces which are out of true geometrical relation to each other and in parallelism with post axes.

6. In a die set; a pair of relatively interfitting and linearly reciprocable members each provided with opposing, relatively spaced, substantially parallel flat surfaces defining therebetween a chamber of polygonal cross-sectional configuration; a bearing retainer conforming generally to the polygonal cross-sectional configuration of said chamber and positioned in said chamber for longitudinal reciprocating movement therein, said retainer supporting a plurality of independently rotatable bearing elements having simultaneous, preloaded pressure conmeans=fbrmed as a part'of one' of said members andprovidingfor-resiliently yieldable movement thereof in response toabnormal pressures applied to said bearing elements upon movement of the latter between portions of said opposing surfaces which may be spaced more closely to-one another than other portions of said surfaces.

7.;In a die set; the combination defined in claim 6, wherein said-pairof members comprise a post of polygonalacross-section and a tubular bushing of polygonal cross-section, and said last-named means comprises a plurality of longitudinal slots formed in said post and extending from the flat surfaces thereof a substantial distance inwardly of said post.

8; Ina die set, the combination defined in claim 6, whereinsaid'pair'of' members are'constituted by a bushingtandta post, andsaid lastanamed means comprises a longitudinal slot formed in said bushing and extending fromone'side of said bushing a substantial distance inwardly thereof.

9.. A. die set comprising relatively reciprocable and interfitting. post and bushing members provided with opposing, relatively spaced, substantially parallel flat surfaces: defining therebetween a chamber of polygonal cross=sectional configuration; a bearing retainer conform-f iug-generally to the polygonal cross-sectional configuretion of said chamber and positioned therein forlongitudinal reciprocating movement, said'retainer including a plurality of independently rotatable bearingelementshaw ing simultaneous, preloaded pressure contact with the opposing flat surfaces of said members, at least one of said members being provided with longitudinally coextensive, resiliently yieldable segments permitting limited displacement of the flat surfaces of said member in respouse to abnormal pressure applied to said bearing elements upon movement of the latter between portions of the opposing-flat surfaces of said members which may be spacedmore closely to one another than other portions of said surfaces.

References Cited in the file of thispatent UNITED STATES PATENTS 2,422,775 Conner June 24, 1947 2,61l',435 Jani'szewski Sept. 23, 1952 FOREIGN PATENTS t -t 205,655 Great Britain Oct. 25,1923

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