Improved Method of and Appliances for the Production of Hollow Bodies from Plate Blanks.
Year: 1898

page_text: Date of Application, 31st May, 1898
Complete Specification Left, 20th Dec., 1898-Accepted, 21st Jan., 1899
PROVISIONAL SPECIFICATION.
Improved Method of and Appliances for the Production of Hollow
Bodies from Plate Blanks.
I, HERMANN PLATZ, of Karlsruhe, Baden, Germany, Engineer, do hereby
declare the nature of this invention to be as follows;-
This invention relates to a method for the production of hollow bodies from
plate blanks of special sectional form, the blanks being so formed that their
thickness increases from the periphery to the centre or the bottom of the vessel
to be formed in such manner that all concentric annular zones of equal width
shall contain the same volume of material. In making hollow bodies from the
above described plate blanks, the material thereof in being forced into the
matrix die by the pressing mandril is not to be either pressed or drawn to any
material extent, but shall be simply set up in itself to such an extent as to lie
close against the matrix and mandril in forming a hollow body of uniform
thickness.
For this production of hollow bodies however, the usual means employed in
pressing or drawing hollow bodies cannot be applied, as a tearing away of the
middle part of the plate blank directly acted upon by the mandril (i.e. the
bottom of the hollow body) would always ensue in consequence of the great
friction which occurs between the blank and matrix, as already at the commence-
ment of the action of the pressing mandril the part of the blank which is
intended to form the sides of the hollow body is pressed against the inner walls
of the matrix and remains in extended contact therewith during the entire pro-
cess of forming the hollow body.
For clearly indicating the difficulties of this method when carried out with
the matrices heretofore employed the diagrams Figs. 1 to 4 of the accompanying
drawing are shewn. Fig. I shews by way of example a circular plate blank a
and Fig. 2 a square one of such a section that the concentric annular zones I
II III &c. of equal width are of equal volume.
For the production of a hollow body from one of these plate blanks such as
that at Fig. 1, the blank a was placed in the matrix b Fig. 3 and the tubular
block c was lowered upon it. The mandril or plunger of a hammer, hydraulic
press or the like was then made to force the blank a into the matrix, so as to
produce the hollow body h attached to the plunger. This mode of proceeding
is however not successful, because the friction of the blank a against the matrix
when being forced down into the same is so great that as a rule the central
portion forming the bottom of the hollow body is generally torn off.
According to the present invention the above defect is obviated by the employ-
ment of a funnel shaped matrix, with which the plate blank to be formed into
a hollow body only comes in contact with its peripheral part from the com-
mencement and during the greater part of the pressing process; by this means
the friction is greatly reduced and the conversion of the plate blank into a
hollow body is rendered possible.

page_text: For this purpose a funnel shaped matrix is employed, such as shewn by way of
example at Fig. 5, and the blank A which is to be converted into a hollow body
is placed with its periphery upon a shoulder formed in the upper end of the
matrix.
On forcing in the blank by means of the pressing mandril or plunger, only
the periphery or a small and only slightly increasing part of the blank will
come in contact with the walls of the matrix, so that the greater part of the
blank is free from contact during the process of conversion, and consequently
only comparatively little friction will ensue.
With a comparatively slight inclination of the generatrix of the walls of the
matrix to the axis thereof, the walls can be smooth as at Fig. 5; with a greater
inclination on the other hand, it is of advantage to form the surface with
circular corrugations Fig. 6, whereby the friction will be still farther
decreased; for the same purpose the matrix can also be built up of separate
rings n as at Fig. 7.
Dated this 30th day of May 1898.
ABEL & IMRAY,
Agents for the Applicant.
Improved Method of and Appliances for the Production of Hollow
Bodies from Plate Blanks.
I, HERMANN PLATZ, of Karlsruhe, Baden, Germany, Engineer, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement-
This invention relates to a method for the production of hollow bodies from
plate blanks of special sectional form, the blanks being so formed that their
thickness increases from the periphery to the centre or the bottom of the vessel
to be formed in such manner that all concentric annular zones of equal width
shall contain the same volume of material. In making hollow bodies from the
above described plate blanks, the material thereof in being forced into the
matrix die by the pressing mandril, is not to be either pressed or drawn to any
material extent, but shall be simply set up in itself to such an extent as to lie
close against the matrix and mandril in forming a hollow body of uniform
thickness.
For this production of hollow bodies however, the usual means employed in
pressing or drawing hollow bodies cannot be applied, as a tearing away of the
middle part of the plate blank directly acted upon by the mandril (i.e. the
bottom of the hollow body) would always ensue in consequence of the great
friction which occurs between the blank and matrix, as already at the commence-
ment of the action of the pressing mandril the part of the blank which is
intended to form the sides of the hollow body is pressed against the inner walls
of the matrix and remains in extended contact therewith during the entire pro-
cess of forming the hollow body.
For clearly indicating the difficulties of this method when carried out with
the matrices heretofore employed the diagrams Figs. 1 to 4 of the drawings
accompanying my Provisional Specification are shewn. Fig. 1 shews by way
of example a circular plate blank.a and Fig. 2 a square one of such a section
that the concentric annular zones I II III. &c. of equal width are of equal
volume.

page_text: For the production of a hollow body from one of these plate blanks such as
that at Fig. 1, the blank a was placed in the matrix b Fig. 3 and the tubular
block c was lowered upon it. The mandril or plunger d of a hammer hydraulic
press or the like was then made to force the blank a into the matrix, so as to
produce the hollow body h attached to the plunger. This mode of proceeding
is however not successful, because the friction of the blank a against the matrix
when being forced down into the same is so great that as a rule the central
portion forming the bottom of the hollow body is generally torn off.
According to the present invention the above defect is obviated by the employ-
ment of a funnel shaped matrix, with which the plate blank to be formed into
a hollow body only comes in contact with its peripheral part from the com-
mencement and during the greater part of the pressing process, by this means
the friction is greatly reduced and the conversion of the plate blank into a
hollow body is rendered possible.
For this purpose a funnel shaped matrix is employed, such as shewn by way
of example at Fig. 5 of the drawings accompanying my Provisional Specification
and the blank A which is to be converted into a hollow body is placed with its
periphery upon a shoulder formed in the upper end of the matrix.
On forcing in the blank by means of the pressing mandril or plunger, only
the periphery or a small and only slightly increasing part of the blank will
come in contact with the walls of the matrix, so that the greater part of the
blank is free from contact during the process of conversion, and consequently
only comparatively little friction will ensue.
With a comparatively slight inclination of the generatrix of the walls of the
matrix to the axis thereof, the walls can be smooth as at Fig. 5 with a greater
inclination on the other hand, it is of advantage to form the surface with
circular corrugations Fig. 6, whereby the friction will be still farther
decreased, for the same purpose the matrix can also be built up of separate
rings n as at Fig. 7.
Having now particularly described and ascertained the nature of this
invention and in what manner the same is to be performed, I declare that what
I claim is:
1. Method for the manufacture of hollow bodies from plate blanks whose
concentric zones of equal width are of equal volume, which consists in the use
of a funnel shaped matrix such as shewn at Fig. 5, upon the upper edge of
which the plate blank A is so placed that from the commencement of the con-
verting operation and during its progress only a small peripheral portion of the
blank will come in contact with the walls of the matrix while the greater portion
of the blank is kept out of contact, so that only a small amount of friction can
take place between the blank and the matrix, substantially as described.
2. In the method of operating referred to in the first claim, the use of a
matrix the inner conical walls of which are formed with annular corrugations
for the purpose of still farther reducing friction, substantially as described with
reference to Fig. 6 of the drawings.
·
3. In the method of operating referred to in the first claim, the use of a
matrix built up of a series of rings », substantially as described with reference
to Fig. 7 of the drawings.
Dated this 20th day of December 1898.
ABEL & IMRAY,
Agents for the Applicant.