Heading slide guiding system

Clearance take up means is provided to take up the running clearance between the bed frame and slide of a progressive former at least near the end of the advance of the slide to top dead center, so that the advance is completed under essentially zero clearance conditions. A header slide system must allow a certain amount of running clearance to give room for lubricant and allow for expansion of the slide and bed due to variations in the temperature of the slide and bed. This clearance however compromises the concentricity of the work piece. The present invention enables normal running clearances to be maintained; however, near the front of the slide stroke clearances are eliminated completely by putting a side load on a system of wedges. This system reduces the side to side movement of the slide as well as the cocking about the vertical axis of the slide that occurs with offset heading loads.

FIELD OF THE INVENTION 
This invention relates generally to progressive formers, and more 
particularly to a novel and improved progressive former apparatus and 
method providing and maintaining very accurate alignment of tooling 
carried on the slide with tooling carried on the die breast as work pieces 
are formed by the tooling. 
BACKGROUND OF THE INVENTION 
Progressive formers or progressive forging machines usually provide a die 
breast forming part of or mounted on the bed frame of the machine. A slide 
is also mounted on the bed frame for reciprocation toward and away from 
the die breast. A suitable drive is provided to reciprocate the slide. 
Such drive may, for example, be a crank and pitman drive or a toggle 
drive. Dies mounted in the die breast cooperate with tools carried by the 
slide to provide work stations at which work pieces are progressively 
formed to required final shape. 
Such machines also provide transfers which progressively transport the work 
pieces to each work station, where successive forming of the work piece 
occurs. Many such machines include a cutter which cuts work pieces from 
the end of rod or wire stock. Such machines may, for example, provide two 
or more work stations. 
Progressive formers are generally designated by the diameter of the stock 
which is forged and the number of work stations provided. For example, 
machines for forming one-half inch stock are generally referred to as 
one-half inch machines even though they may provide from two to five work 
stations or more. Such machines may be cold formers which work unheated 
stock, warm formers which are supplied with stock heated to an elevated 
temperature below the recrystallization temperature of the stock, or hot 
formers which work stock heated to a temperature above the 
recrystallization temperature of the stock. 
A header slide system must allow a certain amount of running clearance to 
give room for lubricant and allow for expansion of the slide and bed due 
to variations in the temperature of the slide and bed. This clearance 
however compromises the concentricity of the work piece. 
It is known in U.S. Pat. No. 4,910,993 of common assignee to accomplish 
tracking of the slide advance with reference to a favored guide interface 
and independently of thermal expansion of the frame and of tolerance 
variations in the spacing between the side members of the bed frame. 
SUMMARY OF THE INVENTION 
The present invention enables normal running clearances to be maintained; 
however, near the front of the slide stroke clearances are eliminated 
completely by putting a side load on a system of wedges. This system 
reduces the side to side movement of the slide as well as the cocking 
about the vertical axis of the slide that occurs with offset heading 
loads. 
Thus, according to the present invention, accurate and consistent tracking 
of the reciprocating slide on the bed frame is accomplished with adequate 
lateral running clearance for efficient reciprocation of the slide, but 
with means to take up such clearance as tooling mounted on the slide 
completes its advance into working relationship with tooling on the die 
breast to thereby accomplish and maintain very accurate alignment of one 
with the other as work pieces are formed by the tooling, an accuracy of 
alignment which continues to top dead center. It is particularly 
advantageous to eliminate running clearance before the tooling on the 
slide engages work pieces at the work stations if the unformed work pieces 
are bilaterally asymmetric, or if the distribution of forming forces among 
the several work stations is uneven so as to tend to cock the slide and 
tooling supported thereon. 
In a further aspect of the invention, prior to such taking up of sliding 
clearance during completion of slide advance, the tracking of the 
advancing slide may be accomplished in the above-mentioned known manner 
with reference to a favored guide interface. When such 
favored-guide-interface tracking is thus combined with the above-mentioned 
take up of sliding clearance, accuracy of alignment during the actual 
forming operation is further enhanced. With such combination, the taking 
up of clearance does not require lateral displacement of either of the 
guide elements associated with such favored guide interface. As the slide 
advances, they remain at all times slidingly engaged with each other at 
the favored guide interface.

DETAILED DESCRIPTION 
Referring to the drawings, the invention may be embodied in a machine 
having a one-piece cast bed frame 10 (FIGS. 1, 2A, 2B). The bed frame 
includes side frame members 11 and 12 (FIGS. 2A and 2B) at the two sides 
of the machine. Alternatively, the bed frame may be formed as an assembly, 
the two side frame members comprising steel plate separated by spacers, in 
the manner shown in U.S. Pat. No. 4,910,993 to common assignee. 
At the front or working end of the machine, the stationary tooling of the 
machine is carried by a die breast 16 which is mounted either directly or 
via a back-up plate (not shown) on the bed frame or on a breast plate 
forming part of the frame or bolted thereto. The stationary tooling is not 
shown but would normally be mounted in die openings formed in the die 
breast 16. The reciprocating tooling is carried in openings formed in the 
tool holder 18 carried on the punch block 19 which in turn is mounted on 
the face of the header slide 20. 
The header slide is formed with wings 21 and 22 (FIGS. 2A and 2B). The 
header is advanced and retracted by a suitable drive such as the crank and 
pinion linkage partly seen in FIG. 1 and comprising the crankshaft 24, a 
pair of laterally spaced pitmans 25, and wrist pin 26 which connects the 
pitmans to the header slide 20. Only one of the two pitmans is seen in 
FIG. 1, the other being located on the opposite side of the machine's 
center line 28 and equidistant therefrom. 
The slide wings are supported on the bed frame by laterally spaced bearing 
assemblies 31 and 32. The bearing assembly 31 includes the steel bearing 
member 34 fixed to the bed frame 10 and the bronze bearing member 35 
bolted to the slide wing 21. The interface 38 between these bearing 
members is horizontal. The bearing assembly 32 includes the steel bearing 
member 36 fixed to the bed frame 10 and the bronze bearing member 37 
bolted to the slide wing 22. These bearing members are formed with an 
outwardly and downwardly extending interface 39, preferably at a 5 degree 
angle, so the weight of the slide supported by the bearing assembly 32 
creates a bias tending to move the slide in a direction to the right as 
illustrated in FIGS. 2A and 2B. The weight supported by the bearing 
assembly 31 does not produce any lateral bias on the slide, since the 
interface 38 is horizontal. 
The lateral position of the header slide 20 is established by a bearing 
assembly 42a which includes a stationary vertically extending steel 
bearing plate 46a bolted to the side frame member 12 and a bronze bearing 
plate 47a bolted to the slide wing 22. These two bearing plates provide an 
interface 49 which prevents movement of the slide to the right beyond the 
position illustrated in FIGS. 2A and 2B. This illustrated bearing assembly 
is associated with the leading end of the slide. A duplicate bearing 
assembly (not shown) is provided on the same side of the slide in 
association with its trailing end. 
Movement of the slide to the left is limited by guide elements at the other 
side of the machine which form a bearing assembly 41a. These elements 
include stationary steel gibs 44a and 44c which are bolted to a steel 
plate 53a which in turn is bolted to the side frame member 11, and moving 
front wedging liner 45a bolted to the slide wing 21 and made of bronze. 
The interface 59 between these elements is normally disengaged and a small 
lateral clearance or running clearance R is provided, as indicated in the 
drawings. This running clearance may also be established along the length 
of the slide stroke by additional block and plate elements located along 
the length of the machine, i.e., behind the elements 44a, 44c and 45a as 
viewed in FIG. 2A, These additional elements are identified in the 
description of means to take up the running clearance which is set forth 
several paragraphs below. 
The steel bearing plate 53a preferably has an 0.010 inch bronze cladding on 
its working face. The two surfaces of each of the gibs 44a and 44c that 
intersect at the gib's inside corner preferably comprise a 0.010 inch 
bronze cladding. 
The slide is held down at each side of the machine by the stationary caps 
51 and 52 bolted to the side frame members 11 and 12. These are positioned 
for a running clearance with nylon liners 56a and 58a which are bolted to 
the top surfaces of the slide wings 21 and 22. 
With this structure, in which a bias is provided to maintain engagement at 
the interface 49, very accurate lateral positioning of the slide is 
provided. Further, since the lateral guiding of the slide 20 is provided 
only on the side frame member 12, any tolerance variation in the spacing 
between the two side frame members 11 and 12 does not in any way adversely 
affect the lateral positioning of the slide. Also, this structure for 
laterally positioning the slide eliminates lateral positioning inaccuracy 
created by thermal expansion of the bed frame or by load-induced frame 
deflections. 
The bearing elements, plates, gibs and shoe described will be understood to 
comprise guide means including guide elements associated respectively with 
the bed frame 10 and slide 20 for guiding the slide by constraining it 
against lateral motion during its advance toward the die breast 16. The 
lateral spacing between the faces of the frame-mounted steel guide element 
46a from the frame-mounted guide elements 44a and 44c together with the 
lateral spacing between the faces of the slide-mounted bronze guide 
elements 47a and 45a provide the running clearance between the bed frame 
and slide. 
In the illustrated embodiments of the invention, this running clearance 
applies during the majority of the advance stroke of the slide toward the 
top dead center position. Means is provided to take up the running 
clearance toward the end of the advance stroke. Preferably the clearance 
is taken up before the tooling carried on the slide by the tool holder 18 
advances into working relationship with the tooling on the die breast 16. 
In the illustrated embodiments of the invention, this take-up means is 
provided at one side of the slide. As best seen in FIG. 3 taken together 
with FIGS. 4A, 4B and 4C, take-up linkages and elements are guided by the 
fixed plates 53a and 53b, rod guide member 54, and blocks 55a and 55b. 
These blocks are preferably formed of black cast nylon. Take-up of lateral 
clearance is accomplished by wedging action between front wedging liner 
45a and a front sliding wedge block 57a toward the leading end of the 
slide, and between rear wedging liner 45b and rear sliding wedge 57b 
toward the trailing end of the slide. It is to be noted that the wedging 
actions at the front and rear of the slide are independent of each other. 
The sliding wedge blocks are preferably fabricated of Delrin AF which is 
acetal resin marketed under registered trademark of Dupont. The wedging 
face of each member is preferably angled at 3 degrees. 
The illustrated take-up linkage includes spring rods 63a 63b, 63c and 63d 
each with its associated surrounding compression spring 64a, 64b, 64c or 
64d. The springs as illustrated are each divided lengthwise into four 
end-to-end segments. 
Rods 63b and 63c are tied to the front wedge block 57a, and rods 63a and 
63d are tied to a rear wedge block 57b. Since the front sliding wedge 
block 57a pulls on its associated rods 63b and 63c, as described below, a 
clamp 65 is fixed to them and is positioned to engage the ends of the 
springs 64b and 64c in order to cause such pull to compress them. The rear 
sliding wedge block 57b does not pull on its associated rods 63a and 63d 
but rather directly engages the ends of the springs 64a and 64d, and these 
rods acting merely as guides for the springs. When the slide is in 
retracted position, the wedging liners 45a and 45b are disengaged from the 
sliding wedges 57a and 57b and all the springs are in minimum-load 
condition. As the slide advances, the wedge faces of the liners 45a and 
45b contact the faces of the wedges 57a and 57b and the wedges are pulled 
in the advancing direction, compressing the springs. For springs 64b and 
64c, compression occurs via pulling forces on the rods 63b and 63c. For 
springs 64a and 64d, compression occurs by direct engagement of their ends 
by sliding wedge 57b as best seen in FIG. 4C. As the wedges advance with 
the slide, they themselves slide on the stationary plates 53a and 53b. 
The engagement and wedging action between the parts takes up the running 
clearance between the slide-carried and the frame-supported guide members. 
Preferably, the running clearance is taken up before the tooling carried 
on the slide by the tool holder 18 advances into working relationship with 
the tooling on the die breast 16, i.e., before the slide-carried tooling 
contacts the work pieces. After the running clearance is taken up, the 
parts continue their advance to top dead center position of the slide, 
during which time the tooling carried on the slide engages the work pieces 
and the work pieces are formed. 
It may be noted that throughout the advance to top dead center position, 
and both before, during and after the running clearance is taken up, 
neither guide element of the bearing assembly 42a moves laterally; rather 
they remain slidingly engaged with each other at the favored guide 
interface 49 at all times. The same is true of the bearing assembly (not 
illustrated) which duplicates assembly 42a and is associated with the 
trailing end of the slide. 
Lubricant feed is maintained through lines 67 and passages 68, and through 
additional lines and passages (not illustrated), so as to maintain the 
distribution of lubricant on all sliding interfaces. In this connection, 
although the elements of the bearing assembly 42a are shown in contact at 
the favored guide interface 49, a thin lubricant film having a thickness 
of about half a thousandth of an inch is present between the metal faces. 
After taking up of running clearance, the slide advance is completed at 
what may be referred to as zero clearance. However, this term does not 
refer to solid-to-solid contact between the parts, but rather to a 
condition where the thickness of the film of lubricant between the parts 
does not exceed about half a thousandth inch of an inch. 
The running clearance R of the machine may be about 15 thousandths of an 
inch for larger machines, varying down to about 5 thousandths for smaller 
machines. When the machines reach thermal equilibrium under running 
conditions, these clearances may reduce to only say 2 thousandths. 
The wedging interfaces between the elements 45a and 57a and between 
elements 45b and 57b are angled shallowly, a preferred angle being in the 
order of three degrees to provide a taper lock type action. Lubrication of 
the interfaces between elements 57a and 53a and between elements 57b and 
53b requires particular consideration, since the proper operation of the 
parts must represent a proper balance between two opposing tendencies. One 
of these tendencies is taper lock. If lubrication at the referenced 
interfaces (elements 57a, 53a; 57b, 53b) is reduced too far, the parts 
will effectively lock against relative sliding movement at the shallow 
angles involved. The opposing tendency can be referred to as a "watermelon 
seed effect." If the film of lubricant is too thick in dimension or too 
pressurized, the wedges may pop forwardly from their wedging interfaces 
like a squeezed watermelon seed, so that undesirably the clearance 
increases or at least fails to continue to reduce to the zero clearance 
condition. No definitive spring pressures or feed pressures are believed 
to apply, since circumstances vary widely as between machines of different 
sizes working under different operating conditions. However, a proper 
balance between these tendencies in any given installation, or for a 
prototype machine intended as model for operation under any given 
standardized circumstances, can be achieved by trial and error changes of 
lubricant feed pressure and spring loading or rate. A typical spring 
compressive force at zero clearance condition might be say 100 pounds, and 
a typical lubricant feed pressure to the referenced interfaces say 40 psi. 
On the return stroke of the slide, the wedges 57a and 57b are pushed in the 
return direction by the compressed springs until the wedging liners 45a 
and 45b move beyond the range of movement of the sliding wedge blocks, or 
until the springs reach unloaded condition. In the illustrated embodiment, 
retracting movement of the wedge block 57a is limited by contact between 
elements 57a and 55a, and retracting movement of the wedge block 57b is 
limited by contact between elements 57b and 55b. 
In some installations, particularly in smaller machines, deflection of the 
bed frame 10 and/or the slide 20 under operating loads may be sufficient 
to allow use of a fixed wedge in association with the trailing end of the 
slide, so that only a single sliding wedge is employed, associated with 
the leading end or working end of the slide. Such a clearance take up 
linkage is illustrated in FIGS. 5a and 5B. A front wedging liner 75a, 
sliding wedge block 77a, spring rod 83b, compression spring 84b and clamp 
85 correspond to the front wedging liner 45a, front sliding wedge block 
57a, spring rod 63b, compression spring 64b and clamp 65 of the 
previously-described linkage, and together with underlying elements (such 
as a second rod and spring) not visible in the drawings, operate in 
generally the same way to take up the running clearance at the front end 
of the slide, the spring reacting against a fixed rod guide member 94. 
However the rear wedge 77b is fixed to the frame, and its wedging face is 
formed at a comparatively small angle, preferably a one degree angle, as 
is the wedging face of the rear wedging liner which engages it. The 
wedging action between these parts jams the parts together and applies 
brute force to bend the frame slightly and eliminate clearance at the rear 
end of the slide. 
As disclosed above, the taking up of sliding clearance is accomplished by 
take-up means at one side of the slide, and running clearance prior to 
take-up is maintained only at the opposite side of the slide. The 
invention also contemplates maintaining and taking up a running clearance 
at each side of the slide. Thus, for example, the biasing bearing members 
36 and 37 could be replaced with the members 96 and 97 shown in FIG. 6, so 
that the slide would tend to be centered by the centering action of such 
shaped guide members, the parts could be dimensioned to provide running 
clearances at each side of the slide, and take up means similar to those 
shown in FIGS. 4A, 4B and 4C, or in FIGS. 5A and 5B, could be provided at 
each side of the slide. 
The invention is not limited to the details of the specific embodiments 
shown, many of which may be changed, added to or eliminated while still 
practicing the invention. The invention is to be determined by the scope 
of the following claims, interpreted in light of the above disclosure.