US3015292A - Heated draw die - Google Patents

Description

R. A. BRIDWELL HEATED DRAW DIE 2 Sheets-Sheet 1 Jan. 2, 1962 Filed May 13, 1957 Jan. 2, 1962 R. A. BRIDWELL 3,015,292

HEATED DRAW DIE Filed May 13, 1957 2 Sheets-Sheet 2 VM M QN 5 55 I u ZZ u Za g2 i9 fj; f

United States Patent 3,015,292 HEATED DRAW DIE Robert A. Bridwell, Lynwood, Calif., assignor to Northrop Corporation, Hawthorne, Calif., a corporation of California Filed May 13, 1957, Ser. No. 658,810 3 Claims. (Cl. 113-49) This invention relates to metal working equipment and more particularly to a draw type die assembly adapted to facilitate the forming of titanium blanks and the like.

Although the forming facility as disclosed herein is especially useful in the drawing of titanium alloy blanks it may have equal or greater utility in draw operations of other blanks constructed of other materials.

Titanium alloy blanks have well known inherent characteristics rendering them especially diicult and in some cases impossible to shape by a drawing operation unless the blanks are preheated to a very specific temperature. Accordingly titanium alloy blanks are normally heated in a furnace, oven, or some type of open flame, the latter being integrated into the die assembly. If the open flame type of heating is employed a workman is necessarily subject to hazardous and to say the least unpleasant working conditions.

Titanium blanks as used throughout this disclosure refers to titanium sheet material from which sheet metal parts are to be fabricated by a drawing operation or other processing requiring close heat control.

Accordingly it is an object of the present invention to provide a draw-type die facility including means which enable titanium alloy blanks to be preheated to a very exacting temperature prior to a drawing operation.

Another object is to provide a draw-type die facility in which titanium alloy blanks may be preheated to a predetermined temperature prior to the time a drawing operation is performed in the facility without danger or discomfort to the operator thereof.

Another object is to provide a draw-type die facility including heating means and incorporating novel means directing major portions of the heat which is given oif by the heating means in the direction of a blank which has been previously positioned in and is to be shaped by the facility.

Another object is to provide a self-heating draw-type die facility which is simple in design, economical to manufacture, and which is safe and efficient in its operation.

Although the characteristic features of the present invention arel particularly lpointed out in the appended claims, the invention itself, also the manner in which it may be carried out, will be better understood by referring to the following description taken in connection with the accompanying drawings forming a part of this application and in which:

FIGURES l and 2 are sectional views of the die facility as disclosed herein in the closed and open positions thereof, respectively, the sections being taken along the common line 1-1, 2-2 of FIGURE 4. Y

FIGURE 3 is a sectional view of the die facility similar to the section as shown in FIGURE l with respect to the section of FIGURE 1.

FIGURE 4 is a partial bottom view of the upper die of the facility as shown in FIGURES l-3 as indicated by the arrows 4--4 in FIGURE 2, the viewbeing rotated ice FIGURE 5 'is a fragmentary sectional view in detail of the instant die facility as indicated by the line 5-5 of FIGURE 4.

Referring to the drawings, the draw-type die facility of the present invention is shown in FIGURES 1 3 in its mounted and assembled attitude in a conventional press and is identified in its entirety by the numeral 11. Portions of the press on which the die facility is mounted are shown in FIGURES l-3 and include a bed plate 12, a die cushion 48, an upper clamp plate 14 secured to the holding ram 16, and a main ram 17. Power to actuate the holding and main rams is applied by conventional means (not shown).

The main parts of the die' facility 11 includes upper, lower, male, and auxiliary die members 1S, 19, 21 and 22, respectively. The upper and lower die members 18 and 19 each include a mounting plate 23, the latter plates providing means for securing the die members to the bed plate 12 and holding ram 16 and on which other components of the dies 18 and 19 are respectively mounted.

In the embodiment as shown the upper die member 18 includes three horizontally positioned plate-like backing blanks 24, a stainless'steel sheet 26, a holding plate 27, and vertically positioned plate-like side blanks 28. The blanks 24, plate 27, and sheet 26 are' formed with suitable aligned apertures 25 through which the die member 21 passes during a forming operation of the facility 11. Also the blanks 24, plate 27, and sheet 26 are secured together by bolts (not shown) or the like with the side surfaces of the plates 24 in complete contact and in juxtaposed relation, with the sheet 26 secured to an outermost major side surface of the blanks 24, and with the plate 27 secured to the outer side surface of the sheet 26 substan-` tially as shown lin FIGURES 1-3. Secured to the edges of the blanks 24, sheet 26, and plate 27, as by bolts (not shown) or the like, are the side blanks 28 which completely cover the edges of the members`24, 26 and 27 except for openings for electric leads as described presently.

The blanks` 24 and 28 are constructed of a materialV consisting of asbestos fibers and suitable aggregate which are bonded together with cement or the like. Such a material is manufactured and marketed under the trade name of Transite by Johns Manville Co. Material of this character has a very high ultimate compressive strength in the range of i2000-15,000 p.s.i. at 500 F. and also embodies exceptionally good heat insulating characteristics for heating means, located within the diel aperture 25 in a pattern substantially as indicated in4 FIGURES 4 and 5. The grooves 29 are of suicient size to receive conventional tubular electrical resistor heating elements 31 so that the outermost peripheries of the heating elements are in substantially flush relation with the inner surface of the plate 27. Also in the embodiment shown two heating elements 31 are employed which are supplied with electrical current through leads (not shown) which terminate in an outlet receptacle 32. 'Ihe side of the stainless steel plate 26 adjacent the plate 27 is highly polished and, therefore, reflects heat given off by the heating elements 31 `into the plate 27 and in the direction of a blank 33 when positioned in its forming attitude in the facility 11, as shown in FIGURE 2, or of'a finished part 35 as shown in FIGURES l and 3.

The male die 21 is similar in construction to the upper die member 18 as just described and has a cross-sectional shape allowing it to pass through the aperture 25 in the plate 27 with proper Vforming clearance provided there between. Major component parts of the die 21 include a punch plate 36, stainless steel sheet 37, and backing blanks 38 A single electrical heating element 39 is utilized which is positioned in a continuous groove 41 formed adjacent the outer periphery of Ithe punch plates 36 substantially as shown in FIGURES 4 andv 5. The leads (not shown) which extend from theA heating element 39 pass through the stainless steel plate 37 and then through the die member 18 via al passageway 43, the latter being formed by removing4 portions of the blanks 24 as best seen in FIG- URES 3 and 4 and terminates in an outlet receptacle 32. The passageway 43 supplies suicient clearance for the leads 42 at such times as relative movement occurs between the die members 18 andk 21..

. The construction of the lower die member 19 is quite Y similar to the die member 18, the same is true of the Y auxiliary die member 22 with respect to the male die member 21 and, therefore, a detailed description of the. members 19 and 22 is not believed necessary. Cornponent parts of the members 19 and 22, corresponding to similar parts of the members 18l and 21, are identified by the same reference numeral with the addition of a prime.

The upper die member 18 and the lower die member 19 are secured tothe upper clamp plate 14 and the bed plate 12, respectively, by means of hold down clamps 44. The male` die 21 is secured to the ram 17 and spaced therefrom lby spaced blocks 46 and 47 and punch plate 50, simil-arly the auxiliary die member 22 rests on the hydraulically or pneumatically actuated diev cushion 48 wln'ch allows movement thereof with respect to the die member 19 in aconventional manner. As mounted in the press all of the die members are properly aligned to effect a drawing operation.

kIn operation itis assumed that an 8% Mn titanium' alloy blank 33 is positioned in the die facility 11 substantially as shown in FIGURE 2. It is well recognized the blank should be drawn as nearly as possible to its maximum allowable temperature which in the case of an 8% Mn titanium alloy blank is 1025 F. The importance of forming (drawing) titanium blanks at their maximum allowable temperature, or as close to this temperature as possible, can readily be appreciated when it is considered an elongation loss of approximately 66% occurs therein with a temperature drop Vof 200 F.

With electrical current flowing through the resistor elements 31, 31', 39 and 39', located at positions both above and below the blank 33, the temperature of the blank is soon raised to its maximum allowable temperature. A temperature sensing device (not shown) may be utilized to determine the exact time at which the blank 33 reaches the aforementioned desired temperature.

The blank 33 having been raised to the desired ternperature the resistor elements 31, 31', 39 and 39' may or may not be rendered inactive. Inasmuch as the blank is in its forming attitude at this time the drawing operation may be effected with a minimum of delay and, therefore, only a minimum temperature change will occur prior to and during the actual drawing operation.V This would not be the case if the blank 33 had been heated in a furnace, oven, or the like. In the latter instance an extended time delay would necessarily occur-(at least seconds) between the time the blank was removed from the oven and the drawing operation is effected, this delay would result in a temperature drop of approximately 200 P. The instant facility also provides additional advan= tages. Inasmuch as thek facility is well insulated, particularly the plates 27, 27', 36 and 36', it is possible to' maintain the temperature of the plates and the blank 33 at or very close to the maximum allowable tempera# ture of the latter. Also the insulating blanks 24, 24', 2S and 28' provide a workman with good protection against heat radiation. It will therefore be apparent that a die facility providing the numerous advantages and objects as set forth above has been disclosed.

While in order to comply with the statute, the invention has been described in language more or less specific as to structural features, it is lto be understood that the invention is not limited to the specific features shown, but that the means and construction herein disclosed comprise a preferred form of putting the; invention into. effect, and the invention is therefore claimed in any of its formsk orv modifications within the legitimate and valid scope. of the appended claims.

What is claimed: Y

1. In a metal forming press having open and closed positions and including holding and main rams aligned respectively with a bed plate and a die cushion, the combination comprising: upper and lower die members each including a metallic holding plate having opposed side surfaces and outer edge surfaces and having a die receiving opening formed thereinjsaid'die members includingv insulating material mounted on said holding plates, on a side surface thereof and covering the outer edge surfaces of each of said holding plates; said insulating material being further characterized by having openings formed therein which are aligned with the die receiving openings in said holding plates when mounted on said holding plates; means mounting said upper and lower die members on said holding ram and bed plate, respectively, with the exposed side surfaces of said holding plates in spaced, opposed and aligned relation; male and auxiliary die. members each including a metallic punch plate each having opposed side surfaces; insulating material mounted on a side surface of each of said punch plates; means mounting and positioning said male and auxiliary die members in said die receiving openings and on said main ram and die cushion, respectively; said male and auxiliary die members as mounted on said main ram and die cushion being further characterized in that the exposed side surfaces of said punch plates have an opposed relation with respect to each other and a coplanar relation with respect to the exposed surface of said holding plate with which they are associated at such time as said press is in said open position; and said upper, lower, maleV and auxiliary die members including heating units having heating elements which are completely surrounded by said insulating material, holding and punch plates and are equally spaced from the exposed side surfaces of said holding and punch plates.

2. In a metal forming press the combination set forth in claim l: further characterized in that the heating elements in said upper and male die members are ypositioned in the holding and punch plates, constituting components of said upper and male die members in adjacent contiguous portions of the latter holding and punch plates and the heating elements in said lower and auxiliary die mem bers are positioned in the holding and punch plates, constituting components of said lower and auxiliary die mem bers, in adjacent contiguous portions of the latter holding and punch plates. Y

3. In a metal forming press the combination asset forth in claim l: further characterized in that said upper, lower, male and auxiliary die members each include a heat reflecting sheet positioned between the unexposedside surfaces of said holding and punch plates and the in- References Cited in the le of this patent UNITED STATES PATENTS Thurber Mar. 5, 1901 Bond Dec. 17, 1912 Coates Oct. 18, 1921 Beyer Oct. 24, 1922 m Knowlton Dec. 30, 1930 Rode Dec. 1, 1931 6 Rutledge Sept. 17, 1935 Helmstaedter Sept. 9, 1941 Selvig May 4, 1943 Rechton et al Mar. 27, 1945 Walton et al. June 11, 1946 Creighton Dec. 20, 1949 Butler Sept. 5, 1950 Lent Apr. 3, 1951 OTHER REFERENCES Plastic Working of Magnesium Alloy Sheet," The Iron Age, Mar. 18, 1943, pp. 45 to 51.

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