Process and Apparatus for the Manufacture of Tubular Bodies.
Year: 1892

page_text: Date of Application, 20th Apr., 1892
Complete Specification Left, 15th Aug., 1892-Accepted. 1st Oct.. 1892
PROVISIONAL SPECIFICATION.
Process and Apparatus for the Manufacture of Tubular Bodies.
I, HEINRICH EHRHARDT of Düsseldorf, Germany, Engineer, do hereby declare
the nature of this invention to be as follows:-
In the Specification to Patent 311601 was described a process for the manufacture
of hollow bodies according to which heated iron or steel bars had a longitudinal
passage formed through them by means of a die and mandrel.
According to one part of the present invention, in order to prevent in the said
process, the metal blank operated upon from being compressed longitudinally by
the driving in of the mandrel, the arrangement shewn at Figs. 1 to 4 of the accom-
panying drawings is employed.
a is a perforating and pressing mandrel of circular cross section. b is a die with
a cylindrical cavity. c, is the rod or blank to be operated upon, of a square cross
section; d Figs. 1 and 2 is a preparatory pressing mandrel, which, as shewn at
Fig. 2, forms a collar on the end of the heated blank.
The preparatory mandrel is removed after the formation of such collar, and the
blank then has the hole formed through it by the mandrel a as shewn at Figs. 3
and 4, while at the same time it is pressed into the die b so as to assume its
configuration.
During this operation the collar previously formed prevents any pressing together
in the longitudinal direction of the formed tube, as in the first instance it takes an
abutment on the upper end of the die, and during the finishing of the operation it
is gradually drawn into the die by the pressure of the mandrel, as shewn at Fig. 4.
At the lower end of the die is a sliding block e which, in the positions shewn at
Figs. 1 and 2 when the preliminary mandrel is operating, serves as support to the
lower end of the blank.
After this operation, the slide is pushed forward until a recess formed therein
is situated under the hole of the die. This recess serves to form a nipple g on the
end of the tubular body during the finishing operation, which nipple is required for
the further treatment of the tubular body.
As shewn in Fig. 1, the circular hollow of the die constitutes the circumscribed
circle of the rectangular section of the blank, so that the die brings the
blank at once into the central position when it is inserted. The cross section of
the mandrel or plunger is made of such a size that the material of the blank which
it displaces when forced in fills out the spaces left between the rectangular sides of
the blank and the circular wall of the die.
On pressing, such an amount of friction is produced against the walls of the die
that only a slight longitudinal compression is effected even when the above described
collar is not made to bear against the die.
The friction against the walls of the die can be increased by roughing it with file
cuts, or by forming grooves therein.
In this case the die would require to be divided longitudinally in order to remove
the finished article.
Fig. 5 shews an arrangement whereby tubular bodies can also be formed out of
bars of circular section. It is only requisite for this purpose to first form a collar
on the rod in the manner above described, and as shewn at k in this figure. m is the
die and d the pressing mandrel or plunger.
The bottom of the die is so formed as to hold the rod in the central
position.
The collar also brings the bar into the central position at the upper end.

page_text: The diameter of the blank is so chosen that the material displaced by the mandrel
fills out the annular space between it and the die.
By forming the described collar, which may be cooled before finally pressing the
tubular body, not only is the longitudinal compression of the tubular object entirely
prevented, but also the tube can be extended in length thereby.
In the foregoing the production of the hollow body by the driving in of a
mandrel has been described. Such driving in of the mandrel can however also be
utilised when using suitable devices therewith, for producing a simultaneous rolling
and drawing of the tubular body, this being effected either by pressing or by
drawing.
The apparatus for carrying out this extended process is shewn at Figs. 6 to 10
of the drawings.
The mandrel or plunger g having the same cross section as that of the blank to
he operated upon is connected to the piston i of an hydraulic press. The blank h,
which has been introduced into the die k of the same section is conveyed by the
plunger g, when acted upon by the piston of the hydraulic press, to the die / into
which projects the mandrel m. This mandrel is guided by a pair of rollers no
before passing into the die k l.
If therefore, after the perforation has commenced in the die lk, the blank is
forced farther forward by the plunger g, it will be fed forward over the mandrel m
towards the rollers no, and these being at the same time rotated at a quicker
surface speed than that of the plunger 9, they will exercise a drawing action on the
blank h.
The rollers are driven and their speed regulated by spur gearing which is
rotated by means of toothed racks actuated by the piston of the hydraulic cylinder.
Thus it will be seen that by a combined pressing and drawing operation the
object acted upon is simultaneously perforated drawn and rolled.
Figs. 11, 12 and 13 shew another construction of apparatus for producing hollow
bodies according to the above described method. Fig. 11 is the pressing cylinder,
s the piston rod thereof, to which is fixed the pressing mandrel d. A A are stay
rods which are connected at one end to the press cylinder c, and at the other end
to the abutment W. The die m Fig. 11 is carried in a moveable manner on the tie
rods A A; it has a circular bore while the blank wo is of square section. The
piston rod s is fixed to the cross head t by means of the key K. To the crosshead t
are fixed rods a¹ a²; the cross-piece f serves to guide these rods a¹ a and the
mandrel d, and, at the return motion it serves for stripping the formed object off
the mandrel.
After
On pressing the mandrel d into the blank w the die m is at the same time pressed
backwards by the rods a¹ a³, that is to say, it is pushed off the blank w.
completion of the pressing therefore the perforated object will be situated outside
the die.
In order to prevent any longitudinal compression of the object w, the rear part
of the die may also be made with the same square section as the object, the front
part in which the pressing takes place being formed with the requisite circular
section. In this case the abutment g is also made with a corresponding square
section. Lastly, both the object w and the die can have the same circular
cross section. In this case the die is made at the front part r with an enlargement
which is indicated in dotted lines in the drawing Fig. 11.
This enlargement receives the material displaced by the inward pressure of the
mandrel d, and determines the outer diameter of the pressed hollow body. The
diameters of the enlargement and of the pressing mandrel d must be so proportioned
to each other that with the given diameter of the object w the material displaced
by the mandrel will fill out the enlargement. Or, when the outer and inner
diameters of the hollow body to be formed are given, the area of the cross section
of the blank must be equal to the area of the cross section of the hollow body to be
produced.
At Fig. 12 the press is shewn provided with a preliminary die M, which in the

page_text: This die serves for
After the forming
pressing operation is made to bear against the abutments bb.
forming a collar on the object w by means of the mandrel Z.
of the collar the mandrel Z is removed and the pressing and perforating of the
object is completed by the mandrel d.
The collar of the object during this operation bears against the die M and
prevents the longitudinal compression of the object. At the moment when the
enlargement of the die is filled out by the displaced material, the rods a¹ a³ press
against the die m and press this backwards until the pressing is completed. The
collar may, if necessary, be previously cooled with water in order that it may offer
sufficient resistance to the longitudinal compression of the object.
In Fig. 13 the latter is shewn at an intermediate stage, in which the backward
pressing of the die m by the rods a' a' has already taken place to a certain extent.
After the production of the hollow body this is drawn and rolled out by means
of the apparatus shewn at Figs. 6 to 10. Such drawing and rolling to the required
section may also be effected immediately after the formation of the hollow body
during one and the same heat.
The arrangement for this purpose is shewn in longitudinal section and end view
at Figs. 14 and 15. The iron or steel bar to be perforated is introduced into the
die Fig. 14 and is there perforated in the described manner.
The bottom of the die is formed by a slides which is moved in the die b by
means of a screw spindle and hand wheel or other suitable appliance. Below the
die are situated, in the same axial line, draw rings d da of gradually
decreasing diameter. The apparatus works as follows: After the die has been
closed at bottom by the slide s, the metal blank in the die is perforated as
described. When the mandrel c, which is actuated by a hydraulic cylinder or
other suitable means, has been forced to the required depth into the material, the
pressure on the mandrel is reduced in order to enable the slides to be withdrawn.
After the slide has been withdrawn, the mandrel is moved downward together
with the tubular body, and passes together with the latter successively through
the drawing rings d¸à¹ àª……. until the tubular body has acquired the requisite
thickness. Below the last ring is placed a block e with a suitable hollow for
imparting to the end of the body, in the event of this requiring to be closed, the
requisite configuration by compressing the same between the said hollow of the
block e and the correspondingly formed end of the mandrel c.
With the described apparatus the iron or steel bar is, during one and the same
heat, converted into a hollow body and then brought to the required sectional
dimensions.
It will be evident that although I have described the said invention as applied
to the production of hollow bodies of a circular transverse section, it is equally
applicable to the production of hollow bodies of an elliptical, polygonal or other
sectional form.
Dated this 20th day of April 1892.
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Process and Apparatus for the Manufacture of Tubular Bodies.
1, HEINRICH EHRHARDT, of Düsseldorf Germany, Engineer, do hereby declare
the nature of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
In the Specification to Patent 3116" was described a process for the manufacture
of hollow bodies according to which heated iron or steel bars had a longitudinal
passage formed through them by means of a die aud mandrel.
According to one part of the present invention, in order to prevent in the said

page_text: process, the metal blank operated upon from being compressed longitudinally by
the driving in of the mandrel, the arrangement shewn at Figs. 1 to 4 of the
drawings accompanying my Provisional Specification is employed.
a is a perforating and pressing mandrel of circular cross section. b is a die with
a cylindrical cavity. e is the rod or blank to be operated upon, of a square cross
section; d Figs. 1 and 2 is a preparatory pressing mandrel, which as shewn at
Fig. 2, forms a collar on the end of the heated blank.
The preparatory mandrel is removed after the formation of such collar, and the
blank then has the hole formed through it by the mandrel a as shewn at Figs. 3
and 4, while at the same time it is pressed into the die b so as to assume its
configuration.
During this operation the collar previously formed prevents any pressing
together in the longitudinal direction of the formed tube, as in the first instance it
takes an abutment on the upper end of the die, and during the finishing of the
operation it is gradually drawn into the die by the pressure of the mandrel, as
shewn at Fig. 4.
At the lower end of the die is a sliding block e which, in the positions shewn at
Figs. 1 and 2 when the preliminary mandrel is operating, serves as support to the
lower end of the blank.
After this operation, the slide is pushed forward until a recess f formed therein
is situated under the hole of the die. This recess f serves to form a nipple g on
the end of the tubular body during the finishing operation, which nipple is required
for the further treatment of the tubular body.
As shewn in Fig. 1, the circular hollow of the die constitutes the circumscribed
circle of the rectangular section of the blank, so that the die brings the blank at
once into the central position when it is inserted. The cross section of the
mandrel or plunger is made of such a size that the material of the blank which it
displaces when forced in fills out the spaces left between the rectangular sides of
the blank and the circular wall of the die.
On pressing, such an amount of friction is produced against the walls of the die
that only a slight longitudinal compression is effected even when the above
described collar is not made to bear against the die.
The friction against the walls of the die can be increased by roughing it with file
cuts, or by forming grooves therein.
In this case the die would require to be divided longitudinally in order to
remove the finished article.
Fig. 5 shews an arrangement whereby tubular bodies can also be formed out of
bars of circular section. It is only requisite for this purpose to first form a collar
on the rod in the manner above described, and as shewn at k in this figure. in is
the die and d the pressing mandrel or plunger.
The bottom of the die is so formed as to hold the rod in the central
position.
The collar k also brings the bar into the central position at the upper end.
The diameter of the blank is so chosen that the material displaced by the mandrel
fills out the annular space between it and the die.
By forming the described collar, which may be cooled before finally pressing the
tubular body, not only is the longitudinal compression of the tubular object entirely
prevented, but also the tube can be extended in length thereby.
In the foregoing the production of the hollow body by the driving in of a
mandrel has been described. Such driving in of the mandrel can however also be
utilised when using suitable devices therewith, for producing a simultaneous rolling
and drawing of the tubular body, this being effected either by pressing or by
drawing.
The apparatus for carrying out this extended process is shewn at Figs. 6 to 10
of the drawings.
The mandrel or plunger y having the same cross section as that of the blank to
be overated upon is connected to the niston ; of an hydraulic press. The blank h.

page_text: which has been introduced into the die k of the same section is conveyed by the
plunger g, when acted upon by the piston of the hydraulic press, to the die into
which projects the mandrel m. This mandrel is guided by a pair of rollers no
before passing into the die kl.
If therefore, after the perforation has commenced in the die lk, the blank is
forced farther forward by the plunger g, it will be fed forward over the mandrel m
towards the rollers n o, and these being at the same time rotated at a quicker
surface speed than that of the plunger g, they will exercise a drawing action on the
blank h.
The rollers are driven and their speed regulated by spur gearing which is rotated
by means of toothed racks actuated by the piston of the hydraulic cylinder.
Thus it will be seen that by a combined pressing and drawing operation the
object acted upon is simultaneously perforated drawn and rolled.
Figs. 11, 12 and 13 shew another construction of apparatus for producing hollow
bodies according to the above described method. c Fig. 11 is the pressing cylinder
the piston rod thereof, to which is fixed the pressing mandrel d. A. A are stay
rods which are connected at one end to the press cylinder c, and at the other end
to the abutment W. The die m Fig. 11 is carried in a moveable manner on the
tie rods A A; it has a circular bore while the blank w is of square section. The
piston rod is fixed to the crosshead t by means of the key K. To the crosshead t
are fixed rods a¹ a²; the cross-piece f serves to guide these rods a' a² and the
mandrel d, and, at the return motion it serves for stripping the formed object off
the mandrel.
On pressing the mandrel d into the blank w the die m is at the same time pressed
backwards by the rods a¹ a², that is to say, it is pushed off the blank w. After
completion of the pressing therefore the perforated object will be situated outside
the die.
In order to prevent any longitudinal compression of the object w, the rear part
of the die may also be made with the same square section as the object, the front
part in which the pressing takes place being formed with the requisite circular
section. In this case the abutment 7 is also made with a corresponding square
section. Lastly. both the object w and the die can have the same circular
cross section. In this case the die is made at the front part with an enlargement
which is indicated in dotted lines in the drawing Fig. 11.
This enlargement receives the material displaced by the inward pressure of the
mandrel d, and determines the outer diameter of the pressed hollow body. The
diameters of the enlargement and of the pressing mandrel & must be so proportioned
to each other that with the given diameter of the object w the material displaced
by the mandrel will fill out the enlargement. Or, when the outer and inner
diameters of the hollow body to be formed are given, the area of the cross section
of the blank must be equal to the area of the cross section of the hollow body to be
produced.
At Fig. 12 the press is shewn provided with a preliminary die M, which in the
pressing operation is made to bear against the abutments 6 h. This die serves for
forming a collar on the object w by means of the mandrel Z. After the forming
of the collar the mandrel Z is removed and the pressing and perforating of the
object is completed by the mandrel d.
The collar of the object during this operation bears against the die M and
prevents the longitudinal compression of the object. At the moment when the
enlargement of the die is filled out by the displaced material, the rods a¹ a² press
against the die m and press this backwards until the pressing is completed. The
collar may, if necessary, be previously cooled with water in order that it may offer
sufficient resistance to the longitudinal compression of the object.
In Fig. 13 the latter is shewn at an intermediate stage, in which the backward
pressing of the die m by the rods a' a' has already taken place to a certain extent.
After the production of the hollow body this is drawn and rolled out by means
of the apparatus shewn at Figs. 6 to 10. Such drawing and rolling to the required

page_text: section may also be effected immediately after the formation of the hollow body
during one and the same heat.
The arrangement for this purpose is shewn in longitudinal section and end view
at Figures 14 and 15. The iron or steel bar to be perforated is introduced into the
die Fig. 14 and is there perforated in the described manner.
The bottom of the die is formed by a slides which is moved in the die b by
means of a screw spindle and hand wheel or other suitable appliance. Below the
die are situated, in the same axial line, draw rings d d¹². . . of gradually
decreasing diameter. The apparatus works as follows: After the die b has been
closed at bottom by the slides, the metal blank a in the die is perforated as
described. When the mandrel c, which is actuated by a hydraulic cylinder or
other suitable means, has been forced to the required depth into the material, the
pressure on the mandrel is reduced in order to enable the slide s to be withdrawn.
After the slide has been withdrawn, the mandrel c is moved downward together
with the tubular body, and passes together with the latter successively through
the drawing rings add until the tubular body has acquired the requisite
thickness. Below the last ring is placed a block e with a suitable hollow for
imparting to the end of the body, in the event of this requiring to be closed, the
requisite configuration by compressing the same between the said hollow of the
block e and the correspondingly formed end of the maudrel c.
With the described apparatus the iron or steel bar is, during one and the same
heat, converted into a hollow body and then brought to the required sectional
dimensions.
It will be evident that although I have described the said invention as applied
to the production of hollow bodies of a circular transverse section, it is equally
applicable to the production of hollow bodies of an elliptical, polygonal or other
sectional form.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In the process for producing tubular objects from iron or steel bars by placing
the said bars in a heated condition in a die and then forcing a mandrel through
them, the method of first forming a collar or enlargement on the front end of the
blank by means of an auxiliary mandrel d or other equivalent appliance before
effecting the perforation, whereby the longitudinal compression of the object during
such perforation is prevented, and an elongation is rendered possible, substantially
as described.
2. A machine for producing tubular objects from iron or steel bars by placing
the said bars in a heated condition in a die, and then forcing a mandrel through
them, wherein a mandrel or plunger 9 connected to the piston of a hydraulic press
is made to force the iron or steel bar forward in a die kl so as to force it over the
mandrel m projecting somewhat into the die, and thus effect its perforation, the
end of the hollow body produced projecting from the end of the die k 1 being
seized by a pair of rollers no which in being rotated at a suitable speed, both roll
and draw the object while at the same time, they give it the required sectional
form, substantially as described with reference to the drawings.
3. A machine for producing hollow bodies in the manner above referred to
wherein a mandrel or plunger å connected to the piston of a hydraulic press, and
guided by the cross piece is made to penetrate into the iron or steel bar contained
in the die m, which die is pushed off the hollow body as this is formed by the
penetration of the mandrel, by means of rods a' a' connected to the crosshead t,
substantially as described with reference to the drawings.
4. The modified construction of the machine referred to in the preceding claim,
wherein the die n is provided with an auxiliary mandrel M for forming a collar
on the object treated for the purpose set forth in the first claim.
5. A machine for producing hollow bodies and simultaneously drawing the same

page_text: to the required thickness during one and the same heat, wherein a die b fixed in a
frame is closed at its lower end by a slides and is combined with a series of
drawing rings d d³ dª of gradually decreasing diameters, arranged one behind the
other in the axial line of the die, so that after the perforation of the iron or steel
bar the slide S is withdrawn and the mandrel c is made to force the hollow body
consecutively through the said drawing rings, until the desired thickness of its sides
is attained, substantially as described with reference to the drawings.
Dated this 15th dew of Amund 1900
ABEL & IMRAY,
Agents for the Applicant.