US3621534A

US3621534A - Tool set assembly for powder compacting press and the like

Info

Publication number: US3621534A
Application number: US861672A
Authority: US
Inventors: Georges D De Troyer
Original assignee: Wolverine Pentronix Inc
Current assignee: Wolverine Pentronix Inc
Priority date: 1969-09-29
Filing date: 1969-09-29
Publication date: 1971-11-23
Anticipated expiration: 1988-11-23

Abstract

A UNITARY TOOL SET ASSEMBLY FOR MOUNTING IN A POWDER COMPACTING PRESS, HAVING A DIE PLATE PROVIDED WITH ONE OR A PLURALITY OF DIE CAVITIES AND TO WHICH IS MOUNTED A HOUSING EXTENDING BELOW THE DIE PLATE AND CONTAINING ONE OR A PLURALITY OF PUNCHES INDIVIDUALLY DISPOSED IN EACH DIE CAVITY. A STATIONARY CORE ROD IS DISPOSED IN EACH PUNCH AND THE PUNCHES ARE COLLECTIVELY ACTUATED FOR RECIPROCATION BY A COMMON PUNCH HOLDER TO WHICH THEY ARE

RIDIGLY AFFIXED DURING INITIAL ASSEMBLY OF THE TOOL SET IN AN IMPROVED MANNER SUCH AS TO MAINTAIN THEIR ACCURATE ALIGNMENT RELATIVE TO THE DIE CAVITIES AND THE CORE RODS.

Description

Nov. 23, 1971 G. D. DE TRoYER 3,621,534

TOOL SET ASSEMBLY FOR POWDER COMPACTING PRESS AND TINE] LIKE INVENTOR GEORGES D' DETROYER ATTORNEYS Nov. 23, 1971 G. D. DE TROYER 3,521,534

TOOL SET ASSEMBLY FOR POWDER COMPACTING PRESS AND 'THE LIKE Filed sept. 29, 1999 2 Smets-sheet z 4M 254 g/d 4M INVENTOR FIG- 4G y GEORGES o. DETROYER ATTDRNEYS United States Patent Ofce 3,621,534 TOOL SET ASSEMBLY FOR POWDER COMPACT- lNG PRESS AND THE LIKE Georges D. De Troyer, Detroit, Mich., assignor to Wolverine Pentronix, Inc., Lincoln Park, Mich. Filed Sept. 29, 1969, Ser. No. 861,672 lut. Cl. B30b 11/02 U.S. Cl. 18--165 21 Claims ABSTRACT OF THE DISCLOSURE A unitary tool set assembly for mounting in a powder compacting press, having a die plate provided with one or a plurality of die cavities and to which is mounted a housing extending below the die plate and containing one or a plurality of punches individually disposed in each die cavity. A stationary core rod is disposed in each punch and the punches are collectively actuated for reciprocation by a common punch holder to which they are rigidly afxed during initial assembly of the tool set in an improved manner such as to maintain their accurate alignment relative to the die cavities and the core rods.

CROSS REFERENCE TO RELATED APPLICATIONS The present application is related to applications Ser. No. 767,648, now Pat. No. 3,561,056 led on Oct. 15, 1969 in the name of Joseph E. Smith, Jr. and Georges D. De Troyer, entitled Tool Set for Powder Compacting Press, and Ser. No. 794,196, now Patent No. 3,574,892 filed Jan. 27, 1969 in the name of Joseph E. Smith and entitled Powder Compacting Press. The present application lis also related to issued Patents Nos. 3,328,840, 3,328,842, 3,344,214, 3,414,940 and 3,415,142.

BACKGROUND OF THE INVENTION (I) Field of the invention The present invention relates to the eld of tool set assemblies for powder compacting presses and the like, although it will be appreciated that the particular punch and punch holder construction of the invention has also substantial usefulness in other similar arrangements where a precise alignment of members reciprocating relative to each other is of importance.

(Il) Description of the prior art Powder compacting presses and the like machines utilize one or several punch members each disposed at the bottom of and displaceable in a cavity which has been filled with loose powder material to be compacted to an appropriate shape, generally in the shape of a cylinder, disk or toroid. The loose powder material is compacted between the end of the punch member and the end of a counter-punch or, .alternately as disclosed in the hereinbefore referred to patents and applications, between the end of the punch member and an anvil arranged to bedisplaceable over the die cavity for closing the open end thereof. Each punch may be individually actuated by an actuating mechanism or the punches may be disposed in a cluster and held by a common punch holder so as to be simultaneously and jointly displaceable, each punch member being disposed within an individual die cavity. The common punch holder holding a plurality of punches has, as also disclosed in the hereinbefore mentioned patents and applications, a punch holding head provided with a circumferential groove adapted to accept an enlarged diameter end portion of the punch, the projecting body portion of the punch being disposed within a radial slot extending from the top surface of the punch holding head of 3,621,534 Patented Nov.. 23, 1971 the holder for intersection with the circumferential groove.

The working end of the punch is adapted to slidably engage the inner bore of a die bushing which defines the die cavity and both the punch member and the die bushing are preferably made of an ultra hard material, for example a cemented carbide of a metal such as tungsten, titanium or the like, to insure appropriate rigidity, sturdiness, resistance to compression, and resistance to wear of the working portions of the punch and die.

The aforementioned patents and applications show examples of construction best adapted to provide punches for compacting magnetic memory cores from ferrite powder and the like. A magnetic memory core is generally in the form of a toroid, a few thousandths of an inch in diameter, having a central aperture for the threading therethrough of wires when a plurality of nished sintered cores are disposed in an appropriate frame so as to form a magnetic memory plane or the like. Magnetic memory cores we're formerly of a substantial size, of the order of mils in diameter, but the size has been continuously and consistently decreased over the years following a trend towards miniaturization and faster response of magnetic core memory stacks. Magnetic cores of 25, 20 and 18 mils are currently being manufactured, and the trend is still toward further miniaturization aiming at magnetic core sizes of only 16, 12 and even 8 mils or less. iIt is obvious that such a trend toward miniaturization of magnetic cores renders more critical the precision with which ferrite compacting presses and tooling must be built. Hollow punches having a precise O.D. dimension of the order of ..012, .008, or .006 in., with a wall thickness from .001 to .005 in., and made of an ultra hard material, such as a carbide or the like, require precise manufacturing apparatus and techniques, and delicate and precise instrumentation for checking the nished cores. The precision of fit between the punch outer diameter and the die bushing inner diameter must be held within .0005 in., and such a precision must be maintained over the life of the punch so as to provide constant density and dimensional precision in the pressed cores.

A further complication in manufacturing punches for ferrite compacting operations is due to the substantial length of the punch which results in a slender part which may easily break due to the brittleness of the material with which it is made, when subjected to uneven or bending stresses. Consequently, the punches must be precisely mounted in an appropriate holder, and high precision is required in the fitting between the holder and the punch supporting means therein. Concentricity of the longitudinal bore through the punch and high precision in the dimension of the inner diameter of each bore, permitting passage therethrough of the core rod, are also essential.

The prior art has attempted to solve the many problems presented by the aforementioned requirement for satisfactory punch construction for ferrite compacting machines, but without too much `success to date.

As disclosed, for example, in the aforementioned patents and applications, a plurality of identical punch assemblies are mounted on the end of a common holder and are disposed preferably in a circular arrangement on the enlarged end of the holder for reciprocation in unison by such holder driven by an appropriate ram forming part of the press mechanism. A portion of the end of each punch is engaged continuously in the bore of a die bushing supported in an appropriate die plate on the press and forming the die cavity. The space in the die cavity above each punch end is filled with a predetermined amount of powder material by appropriate filling means, and an upper compacting member or anvil is disposed over the open end of the die cavity or cavities and all the punches are displaced in unison by their common punch holder so as to compress the powder material against the face of the anvil with a predetermined pressure, which may be as high as several tons. The anvil is removed from the die cavities and the compacted parts are subsequently ejected from the die cavities by further upward motion of the punches and appropriate pickup means to pick up the compacted parts.

The most important disadvantage of the prior art construction is due to the fact that under repeated pounding in the course of compacting cores or the like, which, as previously mentioned, is effected at pressures as high as several tons, the punches, since they are permitted to float radially, under the repeated pounding cause a misalignment with the result that the original precise positioning of the end of the punch engaged with the powder material is not only gradually lost but, in addition, the repeated impacting forces transmitted through the punch causes considerable wear on the end faces of the punches and the internal surfaces of the die bushings.

Although this conventional floating punch arrangement on the punch holder as exemplified, for instance, in U.S. Pat. No. 3,414,940 provides during assembly a desirable self-aligning feature for the punches and associated core rods relative to the bores of the die bushings which define the spaced die cavities, the floating arrangement of the punches on the punch holder may present some disadvantage Which is'particularly pronounced in relatively small tool sets for the compacting of minute-size tablets, memory cores or the like, which require great dimensional accuracy and consistency within any particular production run.

Additionally, in a conventional assembly, the die bushings are usually press-fitted in their respective die plate apertures so as to be substantially rigid therein. However, even in the most tightly fitted assemblies, microscopic spaces remain between the adjoining surfaces of the fitted parts, which, due to the large forces during compacting operation, eventually cause the die bushings to loosen and to move within their apertures resulting in the production of dimensionally inaccurate compacted articles. This condition, together with the relative radial floatability of the punches causes extensive wear so that the complete tool set has to be frequently renovated. In severe cases of punch misalignment and die bushing movement, fretting takes place and eventually the punches may break.

SUMMARY OF THE INVENTION Accordingly, the present invention provides an improved construction and improved means to precisely align in assembly and thereafter rigidly maintain the punch or punches on the punch holder in accurate central relation relative to the die cavities defined by the bores of the die bushings disposed in the die plate. Similarly, the die bushings are rigidly fitted within their respective apertures in the die plate such that they are prevented from loosening and subsequent movement within their apertures even when subjected to prolonged high compacting forces. Although, the die bushings and punches are rigidly retained, disassembly for renovation of the tool set is possible, after which the parts can again be rigidly reassembled.

The advantages and novel features of the present improved tool set will be more clearly apparent by reference to the following detailed description of several examples of preferred embodiments.

DESCRIPTION OF THE DRAWINGS The appended drawings illustrate the exemplary forms of the preferred embodiments in which:

FIG. 1 is a fragmentary top plan view of one example of a tool set including an improved punch and die assembly according to the present invention;

FIG. 2 is an enlarged fragmentary cross section through 4 the center portion of the tool set shown in FIG. 1 as seen along line 2-2;

FIG. 3 is a fragmentary top plan view of another eX- ample of a tool set including an improved alternate punch and die assembly according to the present invention;

FIG. 4 is a transverse cross section through the center of the tool set shown in FIG. 3 as seen along line 3-3;

FIG. 4a is an enlarged fragmentary section of the center portion of the tool set shown in FIG. 4;

FIG. 5 is a cross section through the tool housing and punch holder assembly of the tool set shown in FIG. 4 as seen along line 5-5;

FIG. 6 is an enlarged fragmentary cross section of two press-fitted adjoining surfaces of a die aperture and die bushing, for example, as seen under a microscope to more clearly illustrate the mechanics of the improved assembly method.

DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to FIG. 1 and with particular reference to FIG. 2, there is illustrated in top plan view and in cross section, a fragmentary portion of an improved tool set assembly constructed in accordance with the present invention. The improved tool set assembly 10 comprises a die plate 12, having a smooth top surface 13 and which is provided with a plurality of equally spaced circularly arranged apertures 14 each receiving a die bushing 15l provided each with an axial through bore 16 which define a die cavity.

In assembly, the die plate 12 will be mounted in the press or similar machine by means of the provision of bolt mounting apertures 17 provided inthe dieplate. A housing 18 is secured to the underside of the die plate 12 by means of a radial ange 19 adapted to receive machine screws 20 for threading engagement within apertures 11 provided in the die plate 12 to thereby secure the housing 18 to the die plate. The housing 18 is provided with an axial bore 21 which at the upper end is formed into a counter-bore 22 of enlarged diameter. The axial bore 21 of the housing 18 is centrally aligned with the center of the circle on which the die apertures 14 are disposed, and is adapted to receive the push rod 23 of the punch holder 24, which at its upper end, Within the counter-bore 22, is provided with an enlarged head portion 25 of a diameter substantially corresponding to the diameter of the counter-bore 22. The punch holder 24 is reciprocable within the axial bore 21 and is adapted to support a plurality of punch members 216y supported on the enlarged head portion 25. The punch members 26 are each constructed to provide a cylindrical shank portion 27 adapted for extension into the die cavities 16, as shown in FIG. 2, and their lower ends are provided each with an enlarged head portion 28 adapted to rest on the top surface of the enlarged head portion 25 of the punch holder 24. The punch members 26 are held on the enlarged head portion 25 of the punch holder 24 by means of an inner spacer ring 29 disposed centrally between the head portions 28 of the punch members 26', an outer spacer ring 30 extending radially around the enlarged head portions 28 of the punch members and a clamping plate 31 which, in assembly, is tightly secured by a bolt 3-2 threaded into the punch holder 24 centrally thereof and having a head 33 adapted to extend into a through bore 34 provided in the die plate 12. It Iwill be noted that the thickness of the inner spacer ring 29 and outer spacer ring 30 corresponds to the 'thickness of the enlarged head portions 28 of the punch members to permit clamping plate 31, when tightened by means of the bolt 32, to exert an equal pressure on all three members and thereby rigidly secure the punch members to the head portion 25 of the punch holder 24. The inner spacer ring 29 and the clamping plate 31 are aligned in assembly relative to each other by means of dowel pins 35 extending through both members and into the enlarged head portion 25 of the punch holder 24. A radial space 36 is provided between the enlarged head portions 28 and the inner spacer ring 29 and Outer spacer ring 30, respectively, and the clamping plate 31 is provided with a plurality of equally spaced apertures 37 through which the cylindrical shank portions 27 of the punch members 26 extend for insertion into the die cavities 16. It will be noted that the plate apertures 37 are of slightly larger diameter than the shank portions 27 of the punch members 26, which, in cooperation with the radial space 36, provides a self-aligning means for the punch members 26 relative to the die cavities 16 during assembly and prior to tightening of the bolt 32.

yCertain compacted articles are required to be provided with apertures and for this purpose core rods 38 are provided for extension axially through the punch members 26. The core rods extend out of the head portions of the punch members through aligned apertures 39 provided in the enlarged head portion 25 of the punch holder 24 and through aligned bores 40 provided in the housing 18 parallel to the axial bore 21. The lower ends of the core rods ha've enlarged shank portions 41 by means of which the core rods are adjustably secured to the housing 18 by provision of individual set screws 42 extending through the wall of the housing 18 to maintain the core rods 38 in stationary position relative to the reciprocating punch members 26.

Assembly of the improved punch holder structure 24 is as follows: the punch holder 24, having the dowel pins 35 attached to the head portion 25, is inserted from the top of the housing 18 so that the push rod 23 extends through the axial bore 21 with the enlarged head portion 25 being retained within the counter-bore 22 of the housing. The inner spacer ring 29 is then placed centrally on the head portion 25 over the dowel pins 35 and the punch members 26 are arranged around the inner spacer ring 29, whereafter the outer spacer ring 30 is placed around the punch members 26. The shank portions 27 of the punch members 26 are then placed in alignment with their respective apertures 37 of the clamping plate 31, which is then placed over the punch members for abutment upon the top surfaces of the inner spacer ring 29, outer spacer ring 30 and enlarged head portions 28 of the punch members. The clamping plate 31 and the inner ring 29 are aligned relative to the head portion 25 of the punch holder 'by means of the locating dowel pins 35. The bolt 32 is then inserted through the aligned central apertures provided in the clamping plate 31 and the inner spacer ring 29 and loosely screwed into the punch holder 24. The shank portions 27 of the punch members 26 are then aligned relative to the die cavities 16 by means of their ability to float radially within the respective top plate apertures 37 and the radial space 36 provided between the inner and outer spacer rings 29 and 30. After correct central alignment of the shank portions 27 with the die cavities 16 and threading of the shank portions 27 into the respective die cavities, the bolt 32 is tightened by means of insertion of a tool (not shown) through the central apertures 34 in the die plate 12 so as to rigidly clamp the assembly in the aligned position, which thereafter will be securely maintained during operation of the tool set.

The die bushings are rigidly retained within their respective die plate apertures 14 by the use of a quick setting bonding compound, as will be more in detail described in connection with the preferred embodiment illustrated in FIGS. 3 to 5, and -which is a particular feature of the present invention. By this method, the die bushings 15 are rigidly retained within their apertures and prevented against radial and axial movement therein during the compacting operation.

As further seen from FIG. l, the die plate 12 may be additionally provided with another set of apertures 44 corresponding in number to the die bushing apertures 14 and which are preferably arranged in the same pattern. Apertures 44 are discharge `apertures to dispose of the finish compacted parts as is known from the aforementioned U.S. patents or patent applications.

With reference to FIGS. 3-5 in the drawings, a preferred modication of an improved tool set 10a of the present invention comprises a modified die plate 12a having a relatively smooth top surface 13 which is centrally provided with a iirst group of a plurality of apertures 14 preferably arranged in a circle as best shown in FIG. 3. The die plate is further provided with a second group of apertures 44 corresponding in number to the apertures 14 which are arranged in the same circular pattern as apertures 14 and positioned closely adjacent thereto.

The first group of apertures 14 are each provided with a cylindrical die bushing 15, which each have an axial bore 16 deiining a die cavity. The second group of apertures 44 dene discharge apertures for the nished cornpacted parts and normally are connected by conduits or the like to separate containers (not shown). In normal installation, as disclosed in the aforementioned U.S. patents and applications, the die plate 12a is secured in the press by means of bolt apertures 17 and means movable above the surface 13 of the die plate 12a are provided (not shown) as disclosed in the related references to iill the die cavity or cavities 16 with powdered material for compacting of the powdered material therein.

With particular reference to FIGS. 4 and 4a, a housing 18a, forming a substantially cylindrical body, is attached to the underside 45 of the die plate 12a by means of a radial ilange 19a provided with bolts 20 threadingly retained in threaded apertures 11 in the die plate 12a. The housing 18a has an axially centered through bore 21a for the sliding extension therein of the push rod 23a of a punch holder 24a. The axial through bore 21a is axially aligned with the center of the die plate 12a which forms the center of the circle of the die cavities 16 and the upper end of the axial bore 21a forms a cylindrical counter-bore 22a of substantially larger diameter than that of the axial bore 21a. The push rod 23a, which is reciprocable within the axial through bore 21a, is provided with a radially enlarged head portion 70 disposed within the counter-bore 22a of the housing for reciprocation therein. As most clearly seen in FIG. 4a, the head portion 70 of the punch holder 24a comprises a radial ange 72 having an external diameter substantially corresponding to the internal diameter of the counterbore 22a. The upper surface of the radial flange 72 is provided with an axially extending boss portion 74 adapted to extend into a corresponding recess 76 provided in the underside 45 of the die plate 12a. The radial ange 72 of the head portion 70 is provided at two circumferentially opposite positions with semi-circular recesses 78 (FIG. 5 which are adapted, in assembly, to be engaged by a pair of dowel pins 80 each extending through appropriately aligned apertures 82 in the die plate 12a and into blind apertures 84 in the bottom 69 of the counter-bore 22a of the housing 18a to thereby axially align the head portion and prevent rotation of the same during reciprocation of the punch holder 24a 'within the housing 18a. The head portion 70 of the punch hoder 24a is further provided with a plurality of radially disposed equally angularly positioned bores 86 corresponding in number to the number of die cavities 16 in the die plate, and in axial alignment therewith. The boxes 86, which are provided at their lower end with counter-bores 87, extend through both the lange portion 72 and the boss portion 74 of the head portion and are adapted to receive each a punch member 26a rigidly secured therein, as will be explained.4

The punch members 26a are each composed of a cylindrical body having a smoothly nished outer surface and a diameter substantially corresponding to the internal diameter of the die cavities 16 into which they extend and they are each provided with :a central axial through bore for extension of a core rod 318 therethrough in axial sliding engagement relative therewith. Each of the core rods 38 extends downwardly out of the head portion parallel to the push rod 23a and into longitudinal bores 40a provided in the wall portion of the housing 18a, in which the enlarged diameter shank portions 41a of the core rods extend for rigid securement of each of the core rods against longitudinal movement by means of appropriately radially positioned set screws 42 (FIG. 4), or the like, extending radially through the wall portion of the housing 18a.

Preferably, but not exclusively, a retaining plate 100 is provided around the upper end of the push rod 23a between the underside of the head portion 70 and the bottom 69 of the counterbore 22a in the housing 18a, which is secured to the head portion 70 by means of screws 102, as seen in FIG. 5, to be reciprocably movable therewith. As further shown in FIG. 5, the circumferential portions of the retaining plate 100 opposite the dowel pins 80 are cut away along a chord line 104 in order to clear the dowel pins 80. The retaining plate 100 provides a backup and abutment member for the punches 26a. In certain instances, the retaining plate 100 can be dispensed with completely. The core rods 38 extend through the retaining plate 100 by means of suitably radially spaced apertures 106.

Generally, in the initial assembly of the tool set 10a, the die plate 12a is placed with its top surface 13 upon a smooth planar assembly surface (not shown) whereupon one die bushing 15 is inserted in each of the apertures 14 for abutment upon the planar assembly surface so as to be flush with the die plate surface 13. Each of the punches 26a is then inserted within one die bushing 15 and the punch holder 24a is then placed over the punches such that their end will be substantially flush with the underside 71 of the head portion 70 of the punch holder. Thereafter, the retaining plate 100, when used, is moved over the push rod 23a and secured to the underside 71 of the head portion 70 by means of the screws 102. The dowel pins 80 are then press-fitted in their apertures 82 in the die plate such that they extend through the semi-circular recesses 78 in the radial flange 72 of the head portion 70 and past the lateral chord surfaces 104 of the retaining plate 100.

The core rods 38 are then threaded through the apertures 106 in the retaining plate 100 into the correspondingly aligned axial bores of the punches 26a to drop downwardly upon the assembly plate. The housing 18a is positioned upside down and pushed over the push rod 23a. The housing 18a is radially positioned to permit the core rod shanks 41a to enter the respective bores 41a, and the dowel pins 80 to enter the blind bores 84 in the housing to thereby radially locate the housing relative to the die plate 17a. The housing is then fastened to the underside of the die plate by means of the bolts and the core rods 38 are secured to be stationary with the housing 18a by means of tightening of the set screws 42 to thereby complete the assembly.

In accordance with the present invention, the improvement consists in rigidly securing the die bushings 15 and punches 26a in their respective supporting apertures 14 and 86 after assembly of the parts, so that they remain at all times rigid and properly aligned relative to each other. This is accomplished herein by securing the die bushings 15 and punches 26a in their respective apertures 14 in the

die plate

12 or 12a and 86 in the head portion 70 of the punch holder 24a by means of a commercial quick-setting bonding compound, such as an anaerobic adhesive. As an exemplary example, one of such bonding compounds is known and marketed under the name of .Loctite manufactured by the Loctite Corporation, Newington, Conn. This compound, particularly useful in the bonding of cylindrical parts, is an anaerobic adhesive having an unusually high shear strength exceeding that of conventionally press-litted parts for up to five times. The Loctite retaining compound is fast curing and has excellent heat and solvent resistance characteristics, as well as providing a high shear strength between the adjoining interfaces.

The surfaces of internally and externally machined cylindrical parts are never really smooth, but have a certain roughness, the degree of which depends on the type of machining. When viewed under a microscope, the machined surfaces show valleys and peaks of microscopic dimensions, which, however, when two of these surfaces are brought close together such as in press-fitting a cylindrical part Within a cylindrical bore, cause microscopic air spaces to appear between the interfaces since the surfaces actually touch each other only at the high spots or peaks permitting the valleys of the surfaces to form air spaces or pockets. These air spaces or pockets are the source of serious problems, such as loosening under vibrating or impact forces, leakage or corrosion. The function of the anaerobic adhesive is to ll these air apaces between adjoining, preferably tightly tted surfaces with a self-hardening compound which, when hardened, rigidly joins or bonds the surfaces together.

Accordingly, and with particular reference to FIGS. 2 and 4a, during assembly of the die bushings 15, the internal surfaces of the die apertures 14 are provided with a few drops of an anaerobic adhesive indicated at 108. The surfaces are machined such as to provide an interference t. The die bushings are then pressed into their apertures and properly axially positioned relative to the surface of the die plate. This is done on a heated assembly plate which is warmed to between and 100 F. to facilitate curing of the adhesive.

Similarly, and with reference to FIG. 4a, the punch members 26a are inserted in their respective apertures 86 in the head portion 70 of the punch holder 24a and after having been axially positioned within the die bushings 15 a few drops of Loctite compound is applied to the counter-bores 87 of the apertures 86 and, due to the characteristic of the Loctite compound, the compound seeps along the interfaces between the punch 26a and the apertures 86. The characteristic of the anaerobic adhesive is such that it remains liquid in free state, that is, under free flow conditions, however, if placed under restrictive ow conditions, such as exist in a microscopic clearance occuring between the adjoining interfaces of two tightly tted members, it becomes hardened to provide a solid bond between the surfaces. As can best be seen in FIG. 6, the anaerobic adhesive 108 settles in and fills the air spaces or pockets formed by the valleys of the adjoining surfaces and thus tightly bonding the surfaces together along the peaks 112 formed on the machined surfaces, thereby preventing relative longitudinal movement between these surfaces due to the high shear strength of the adhesive even if subjected at prolonged intervals to the relatively high compacting forces during operation of the press.

If it becomes necessary to renovate either tool set 10 or 10a after a certain time of operation, the die bushings 15 are pushed outwardly of their respective apertures 14 by means of an appropriate tool, as for instance an arbor press, having a force capacity exceeding the shear strength limit of the particular anaerobic adhesive compound. The die bushings are pushed out a small distance beyond the top surface 13 of the die plate to extend an amount of about two to five-thousandths (.002-.005) of an inch. The core rods 38 are loosened and extended a distance to be level with the top surface of the die bushings and then secured again to the

housing

18 or 18a. The punches 26a are moved upwardly in the die bushings a lesser amount than the bushings to slightly extend beyond the top surface 13 of the die. plate an amount of approximately one or two thousandths of an inch (.001-.002). The die bushings 15 and punches 26a then remain solidly locked in this position once the force is removed therefrom due to the quick-setting characteristic of the anaerobic adhesive between their interfaces. The tool set is now ready for renovation by grinding on a surface grinder, or the like, by which, simultaneously, all of the worn edges of the die bushings, punches and core rods are ground off until they are liush with the surface of the die plate. Thereafter, the tool set is being lapped by movement of the top surface 13 of the die plate across an appropriate lapping plate, thereby reestablishing the necessary sharp edges on the die bushings, punches and core rods. The tool set is then again ready for use.

It will be appreciated that the tool set in itself also conveniently provides the grinding fixtures, thereby eliminating the tedious task and cost of disassembly of the tool set and reassembly and alignment of the individual parts in a properly designed grinding xture.

It will be appreciated from the foregoing description and in reference to the drawings that the improved construction and assembly method of the present invention provides an accurately aligned rigid tool set assembly providing precisely positioned punches and die bushings, although retaining fully self-aligning capability during assembly and in which all of the working parts will be rigidly locked in place after assembly and alignment and maintained in the once assembled position for any length of time, or until the tool set has to be renovated, to make compacted articles of a repeating, consistently high quality. This is of particular importance in the production of very small compacted articles of micro-size, such as memory cores, which do not permit any dimensional inconsistency, however small.

Furthermore, it can be seen that a more precise dimensional control of the finished articles is obtained with the improved tool set assembly because of the elimination of any relative movement between the working parts.

Although only two preferred embodiments of the present invention are herein described, it will be apparent to anyone skilled in the art to which the invention pertains that various changes and modifications may be made therein without departing from the spirit of the invention as expressed in the scope of the appended claims.

I claim:

1. A tool set for making articles compacted of powder material, said tool set comprising:

a die plate adapted to be mounted in an appropriate aperture in a machine base;

at least one die cavity in said die plate defined by a die bushing tted in an aperture in said die plate and having a bore open at lboth ends;

a punch having an end engaged in one end of said bore and reciprocable therewithin;

a punch holder;

a housing secured to the underside of said die plate, having an axial through bore communicating with said die cavity in said die bushing;

means to rigidly secure said die bushing in said aperture in said die plate; and

means to rigidly secure said punch to said punch holder in axially centered relationship relative to the bore of said die bushing so as to prevent any radial movement and misalignment relative to each other, said means being arranged to permit said punch to axially align itself relative to said bore during assembly of said tool set.

2. The tool set as dened in claim l, in which said punch holder has an enlarged head portion, said punch being radially and axially immovably secured to said enlarged head portion in alignment with said die cavity.

3. The tool set as defined in claim 1, in which said means to secure said die bushing in said aperture in said die plate comprises a hardenable bonding agent provided between the outer surface of said die bushing and the inner surface of said aperture in said die plate.

4. A unitary tool set for making articles compacted of powdered material, said tool set comprising:

a die plate adapted to be mounted in a machine base;

a plurality of die cavities in said die plate comprising l0 cylindrical bores open at both ends, each of said die 'cavities being formed by the axial bore of a die bushing fitted in an appropriate aperture provided in the d1e plate and rigidly secured within said aperture by means of a bonding agent;

a plurality of punches each having one end slidingly engaged in one of each of said die cavities for reciprocation therein;

a punch holder for the support of said plurality of punches, said punch holder having an enlarged head portlon;

a housing secured to the underside of said die plate, having an axial through bore communicating with said die cavities in said die bushings; and

holding means for securing said punches to said er1- larged head, said holding means being arranged to permit each of said punches to each align itself in the axial bore of each of said die bushings during assembly of said tool set and to secure each of said punches rigidly retained longitudinally and radially on said head portion in axially centered position relative to each of said die cavities prior to mounting of said tool set in said machine base.

5. The unitary tool set as defined in claim 4, in which said punches are rigidly retained within apertures in said enlarged head of said punch holder by means of a hardenable bonding agent preventing radial and longitudinal sliding movement of said punches within said enlarged head apertures after hardening of said bonding agent.

6. The unitary tool set as defined in claim 5, in which said hardenable bonding agent is a liquid adhesive adapted to fill the interstices created by the surface roughness of the adjoining interfaces of the outer surface of said punches and the inner surface of said apertures in said enlarged head.

7. The unitary tool set as defined in claim 5 in which said bonding agent for securing the die bushings in the apertures in the die plate is a liquid adhesive adapted to fill the interstices created by the surface roughness of the adjoining interfaces of the outer surface of said die blshings and inner surface of said apertures in said die p ate.

8. tool set assembly for a powder compacting press comprlsing:

a `die plate having a working surface, said die plate being provided with at least one aperture;

a die bushing having an axial through bore defining a die cavity and rigidly secured in said aperture in said die plate by means effectively preventing longitudinal and radial movement of said die bushing within said aperture in said die plate during operation of said compacting press;

said through bore in said housing extending into an enlarged diameter counter-bore at the upper end of said housing adjacent the underside of said die plate;

a punch holder reciprocably supported within said through bore of said housing and having an enlarged head portion disposed within the enlarged diameter counter-bore in said housing;

a punch member having an end attached to said head portion for reciprocation therewith and another end adapted to extend in axially aligned relationship with said die cavity in said die bushing; and

means to rigidly secure the first end of said punch member to said head portion of the punch holder to prevent misalignment of the other end of said punch member relative to said die cavity in said die bushing prior to mounting said tool set assembly to said powder compacting press.

9. The tool set assembly as defined in claim 8 in which said means rigidly securing the die bushing in the aperture in said die plate comprises a curable synthetic ad- 1 1 hesive adapted to provide a secure bond between the interfaces of said die bushing and said die plate aperture.

10. The tool set assembly as defined in claim 9, in which said curable adhesive is a liquid capable of hardening in restricted space confinement as between the interfaces of said die bushing and said aperture in said die plate.

11. The unitary tool set as defined in claim 8, wherein the enlarged head portion of said punch holder is provided with an aperture axially aligned with said die cavity in which the first mentioned end of said punch member is engaged and rigidly retained by means of a curable synthetic adhesive preventing radial and longitudinal movement of said punch member relative to said punch holder after hardening of said adhesive.

12. The tool set assembly as delined in claim 11 in which said enlarged head portion of said punch holder is of a predetermined thickness to thereby establish the extent of movement of the second mentioned end of the punch member within the die cavity in said die bushing.

13. The tool set assembly as defined in claim 12, further provided with a spacer plate mounted between said enlarged head portion of said punch holder and the top of said counter-bore of said housing to thereby selectively limit the extent of movement of the second mentioned end of said punch member within the die cavity in said die bushing according to the thickness of said spacer plate.

14. The tool set as defined in claim 2, in which said punch is provided with an enlarged head portion engaged with the end face of the enlarged head portion of said punch holder and is secured thereto by means of a clamping plate provided with an aperture for passage therethrough of the punch end engaged in the bore of said die cavity with the enlarged head portion of each punch disposed between said clamping plate and the end face of the enlarged end portion of said punch holder, and threadeded clamping boltmeans for drawing said clamping plate` toward said end face for securely and rigidly holding said punch enlarged end portion relative to said punch holder.

1S. The tool set as dened in claim 14, further comprising spacer means disposed between said clamping plate and said end face of said punch holder.

16. The tool setas defined in claim 1, wherein said punch holder is provided with an aperture in which the other end of said punch is engaged, said other end of said punch being rigidly retained within said punch holder aperture by means of a hardenable bonding agent pre- 12 venting radial and longitudinal movement of said punch Vrelative to said punch holder after hardening of said bonding agent.

17. The unitary tool set as dened in claim 4, in which each of said punches is provided with an enlarged head portion engaged with the end face of the enlarged head portion of said punch holder and in which said holding means comprises a clamping plate provided with an aperture for passage therethrough of the punch end slidingly engaged in said die cavity with theenlarged head portion of said punch holder, and threaded clamping bolt means for drawing said clamping plate toward said end face for securely and rigidly holding said punch enlarged end portion relative to said punch holder.

18. The unitary tool set as defined in claim 17, further comprising spacer means disposed 'between said clamping plate and said end face of said punch holder. 19. The unitary tool set as defined in claim 8, in which the lirst end of said punches is provided with an enlarged head portion engaged with the end face of the enlarged head portion of said punch holder, and further comprising a clamping plate provided with an aperture for passage therethrough of the punch other end with the enl larged head portion of said punch disposed between said clamping plate and the end face of the enlarged end portion of said punch holder, and threaded clamping bolt means for drawingsaid clamping plate toward said end face for securely and rigidly holding said punch enlarged end portion relative to said punch holder.

20. The unitary tool set as defined in claim 19, further comprising spacer means disposed between said clamping plate and said end face of said punch holder.

21. The unitary tool set as defined in claim 11, wherein said curable adhesive is a liquid adhesive adapted to fill the interstices created by the surface roughness of the adjoining interfaces of the outer surface of said punch member and inner surfaces of said aperture in the head portion of said punch holder.

References Cited UNITED STATES PATENTS 3,414,940 12/1968 Vinson 18--l6.5X 3,499,183 3/1970 Parsons 308-237 X ROBERT L. SPICER, J R., Primary Examiner PEN-11H* UNHED STATES PATENT @NICE CERTIFICATE F CORRECTION Patent No. 3,621, 534 Dated November 23, 1971 nventor(5 GEORGES D. DE TROYER It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

IN THE SPECIFICATION Column 2, line 53, change "each" to such Column 6, line 60, correct the spelling of "holder" line 64, correct the spelling of "bores" IN THE] CLAIMS Column 11, lines 36-37, correct the spelling of "threaded" Column 12, line 37, change "surfaces" to surface Signed and sealed this Sth day of April i92.

JRD 'f.FLETCHER, JR. ROBERT GOTTSCHLK U Attesting Officer' Commissioner* o1 Patents FORM 2o-1050 (1D-69) uscoMM-Dc eos'le Psv LLS4 GOVERNMENT PMNTONG OFFICE |969 0-366-.154