US3295354A - Blanking method and apparatus - Google Patents

Description

Jan. 3, 1967 J. G. F. HOTTE ETAL 3,295,354

BLANKING METHOD AND APPARATUS Filed April 16, 1964 5 Sheets-Sheet 1 2 DIE OPENING Q 1967 J. G. F. HOTTE ETAL 3,295,354

BLANKING METHOD AND APPARATUS Filed April 16, 1964 5 Sheets-Sheet 2 1967 J. a. F. HOTTE ETAL 3,295,354

BLANKING METHOD AND APPARATUS Filed April 16, 1964 5 Sheets-Sheet 5 United States Patent Ofifice Patented Jan. 3, 1967 3,295,354 BLANKING METHOD AND APPARATUS Joseph G. F. Hotte, Lasaile, and Joseph L. R. A. Thomas,

Montreal, Quebec, Canada, assignors to Northern Electric Company, Limited, Montreal, Quebec, Canada Filed Apr. 16, 1964, Ser. No. 369,298 7 Claims. (Cl. 72--468) This invention relates to a method and apparatus for producing stampings from sheet material, and has particular reference to an apparatus for blanking such stampings from metallic sheet.

While many types of machine for punching sheet mate rial have been designed and used in the past in which the sheet material is placed between cooperating male and female cutting portions, the-re is always the problem of aligning the two separate parts of the die so that they engage accurately and so that there is not excessive wear of one on the other. This is rendered particularly difficult when the part to be blanked is of unsymmetrical contour and the clearances between the male and female parts are diflicult to measure. There is also the necessity of machining both of the die parts, which becomes increasingly expensive as the contour becomes more complex.

It is an object of the invention to overcome these difficulties of the prior art by providing an apparatus in which machining of only one part of the die is required, in which very accurate alignment of the parts of the die can be secured and which by its particular structure produces very cleanly blanked stampings.

More-particularly in accordance with the invention there is provided apparatus for blanking stampings from sheet material which comprises, a punch having a shaving portion contoured to an outline of the stamping to be blanked, a blanking portion on said punch being of decreased contour with respect to the said shaving portion, means for moving said punch in an operative path, adjustable cutter means surrounding the path of travel of said punch, and conforming to the contour of said shaving portion, a die plate between said punch and said cutter means, said punch being brought down to punch out and shave an aperture in said die plate to the contour of said shaving portion by co-operation with said cutter means, said die plate subsequently forming a female portion of a punching apparatus for said sheet material, comprising said die plate and said punch blanking portion.

In accordance with the invention there is also provided the method of blanking a stamping from sheet material which comprises the steps of, shaping a punch to the contour of said stamping to be blanked to form a shaving portion, further shaping said punch before said shaving portion to a contour smaller than that of the shaving portion to form a blanking portion, mounting said punch for movement in an operative path, adjusting cutter means to conform to the contour of said shaving portion surrounding the path of travel of said punch, mounting a die plate on said cutter means, blanking and shaving said die plate by passing said punch blanking and shaving portions successively into said die plate, and placing sheet material to be punched on said die plate and passing said blanking portion into said sheet.

A description of the invention will now be made with reference to the accompanying drawings in which,

FIGURE 1 shows a plan view of a die punch bed with adjustable cutting blades,

FIGURE 2 shows a side view of the apparatus of FIGURE 1 including the male punch member and the blanked die plate,

FIGURE 3 is a partial side view of the apparatus when punching a die plate and,

FIGURE 4 is a partial side view of the apparatus when blanking from a sheet.

Having reference first to FIGURE 1 there is shown a female adjustable die comprising a bed block 1, shaped to receive strip cutters 2 (see also FIGURE 2) arranged with their broad dimensions vertically. Each set of cutters 2 is supported against its respective face 3 of block 1 under lateral pressure from a securing bolt 4. Each cutter 2 is for convenience chamfered at one end and straight cut at the other. Cutters 2 of various thickness are provided (see for instance cutters 6 and 7). The die block 1 is rigidly mounted on the working table 10 of a hydraulic or mechanical punch press by securing bolts 11. The press includes an overhead vertically reciprocating ram 13 to which is affixed a male punch 14 by a securing bolt 15.

The apparatus is first set up by accurately machining the punch member 14 so that it includes a shaving portion 17 of the exact contour and dimension of the stamping to be blanked. Below the shaving part 17 is a blanking portion 18 which is of smaller periphery to allow a suitable clearance 42 between the blanking and shaving sur' faces (as described later). With the blades 2 in retracted position, well clear of the line of travel of the punch 14, the punch is brought down into the square aperture 20 in the center of the block 1 so that the leading end 21 of its shaving portion is below the upper level of the blades 2. The blades 2 are then all brought up so that they touch the shaving portion, and as close an approximation as possible to the contour of the portion 17 is obtained by arranging for the chamfers or straight cut ends to follow the direction of the periphery of the shaving portion where it cooperates with that blade. In some instances wider blades will be called for, in others narrower. Thus, for example, a fair approximation to the contour of the shaving portion can be obtained by the use of the three blades 25, 24, and 27 in the position shown, whereas the straight cut ends would be more suitablein the area where blades 28, 29 and 3% contact their portions of the periphery of 17. When the adjustment of the blades has been made they are bolted up tightly in block 11 by the rotation of bolts 4 (such as by Allen keys). Operation of the punch 14 should now be possible so that the shaving portion 17 of the punch passes into the aperture defined by the blades 2 but is not cut by them.

A die plate 36 of an appropriate thickness is placed on top of the bed 1 and blades 2 (see FIGURE 2). The die plate is made of a material whose ductility generally embraces the range of that of tool steel, to kirksite. ()ther metals will suggest themselves to those skilled in the art but as will be seen later a tough substance which retains a well defined aperture is required even though it need not have a very long life as a die plate. The die plate 36 is clamped by bolts 49. The punch 14 is brought down, it cooperates with the cutters 2, and the die plate is blanked out by the portion 18 and finally shaved by the portion 17.

The action which takes place can be seen in more detail in FIGURE 3. As the blanking portion 18 contacts the die plate 36, a roll-off edge 45 is formed in the plate, then the slug being forced out of the plate breaks away at 46. The diameter is subsequently shaved at 47 to conform to the contour of the shaving portion 17 of the ram. The slug 48 has corresponding surfaces 49 formed during the roll-off and 44 at the break. Break 44 starts at the periphery of portion 18 and extends to the inner edges of blades 2.

Sheet material can now be blanked out accurately to produce stampings by restricting the downward movement of punch 14 and allowing the blanking portion 18 of the punch 14 and the die plate 36 to cooperate as the two halves of the cutting apparatus. The cutters 2 now form a support for the die plate and prevent distortion through bending. By having reference to FIGURE 4 the effect of the blanking portion 18 on the sheet material 50 from which the stamping 51 is to be made can be seen. The material 50 produces a roll-off portion 52, a corresponding roll 53 being formed on the leading side of stamping 51. A break then occurs at 54 diagonally and extends at its outermost periphery to follow the outer contour of the shaving portion 18. The edge quality of the stamping 51 is comparable to that generally accepted in the art for stampings produced on standard blanking machines. It can be seen in FIGURE 4 that there is some distortion of the inner periphery of the walls of the hole from which the stamping has been punched out of sheet 50. The clearance 42 between portion 18 and shaving portion 17 is chosen, by trial if necessary, so that a clean blank is made in the sheet material by the blanking portion 18 and plate 36. Since the sheet may tend to cling to the blanking portion 18, a suitable stripper 43 (see FIGURE 2) is provided so that when the punch is raised the sheet material is forced off it.

When the production run has been completed or when the die plate 36 shows wear, it may be discarded and a second die plate simply formed in the same manner as the first.

This apparatus has the great advantages that only the punch 14 need be accurately machined and retained for further use, and that the block 1 with its associated blades 2 can be adapted to many shapes of punch.

We claim:

1. Apparatus for blanking stampings from sheet material which comprises,

a punch having a shaving portion contoured to an outline of a stamping to be blanked,

a blanking portion on said punch being of smaller size with respect to said shaving portion, and defining a clearance between the blanking and shaving portion,

means for moving said punch in an operative path,

adjustable cutter means surrounding the path of travel of said punch and conforming to the contour of said shaving portion, and

a die plate between said punch and said cutter means, said punch being brought down to punch out and shave an aperture in said die plate to the contour of said shaving portion by cooperation with said cutter means, said die plate subsequently forming a female portion of a punching apparatus for said sheet material comprising said die plate and said punch blanking portion.

2. Apparatus as defined in claim 1 wherein said cutter means comprises a plurality of longitudinally extending cutters movable in a direction transverse to the axis of movement of said punch, and clamping means for fixing the position of said cutters.

3. Apparatus as defined in claim 2 comprising a block for mounting said cutters, a relief in said block for receiving said cutters and screw means for fastening said cutters within said relief.

4. Apparatus as defined in claim 3 wherein said cutters are difierently chamfered at opposite ends for conforming to the shape of said punch.

5. Ap aratus as defined in claim 2 comprising a stripper for removing sheet material adhering to said punch as said punch is returned from its operative path.

6. Apparatus as defined in claim 5 wherein said die plate is of material selected from the group consisting of tool steel.

7. Apparatus as defined in claim 5, wherein said die "=late is of kirksite.

References Cited by the Examiner UNITED STATES PATENTS 2,803,152 8/1957 Wales 76-107 3,171,319 3/1965 Kyle 76107X GRANVILLE Y. CUSTER, JR., Primary Examiner.

Claims (1)

1. APPARATUS FOR BLANKING STAMPINGS FROM SHEET MATERIAL WHICH COMPRISES, A PUNCH HAVING A SHAVING PORTION CONTOURED TO AN OUTLINE OF A STAMPING TO BE BLANKED, A BLANKING PORTION ON SAID PUNCH BEING OF SMALLER SIZE WITH RESPECT TO SAID SHAVING PORTION, AND DEFINING A CLEARANCE BETWEEN THE BLANKING AND SHAVING PORTION, MEANS FOR MOVING SAID PUNCH IN AN OPERATIVE PATH, ADJUSTABLE CUTTER MEANS SURROUNDING THE PATH OF TRAVEL OF SAID PUNCH AND CONFORMING TO THE CONTOUR OF SAID SHAVING PORTION, AND A DIE PLATE BETWEEN SAID PUNCH AND SAID CUTTER MEANS, SAID PUNCH BEING BROUGHT DOWN TO PUNCH OUT AND SHAVE AN APERTURE IN SAID DIE PLATE TO THE CONTOUR OF SAID SHAVING PORTION BY COOPERATION WITH SAID CUTTER MEANS, SAID DIE PLATE SUBSEQUENTLY FORMING A FEMALE PORTION OF A PUNCHING APPARATUS FOR SAID SHEET MATERIAL COMPRISING SAID DIE PLATE AND SAID PUNCH BLANKING PORTION.

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