2005 - Putzmeister

Background
High quality requirements even in the
construction of model concrete pumps
54
Background
55
These are gifts with which you can give
particular pleasure to business partners.
Some people have even collected their
exhibits, sometimes over the course of
many years, with great commitment –
above all of a financial nature. We are
talking about miniature construction
machines, which are produced to scale by
highly specialised manufacturers, such as
CONRAD GmbH (Kalchreuth).
Putzmeister too has been buying the different
models of its truck-mounted concrete
pumps since the 70s, and also the TELE-
BELT telescopic deliverer, as models produced
to a scale of 1:50 from the Franconian
specialist. A larger model scale of 1:35 has
been chosen for the PM plastering machines
and floor screed conveyors – let's not
forget the machines are actually significantly
smaller in real life. The decision to order
a model of a concrete pump with the new
placing boom, for example, must be well
thought out. For, in addition to the later
unit costs, the customer often also has to
cover the costs for the handmade model,
that is, for the prototype, as well as for the
construction of the mould.
Before the new models can be produced,
an accurate manually produced specimen
must be created. To do this, the dimensions
of the original are converted to scale, the
52
required material strengths are calculated
and the mobility – e.g. the composition of
a multi-part concrete boom – is simulated.
The handmade model is also used as a
pattern for the construction of the model
and for the subsequent mould construction.
Modern CAD/CAM computer systems and
CNC milling machines play an important
role in conveying the fine contours.
As with the "real" construction machines,
CONRAD uses metal (zinc) and highquality
plastic for its models. The relatively
heavy zinc is not only easy to handle in
liquid form, but its weight also gives the
finished model part of the "valency" and
"mass" of the actual original. The plastic
and the zinc are both pressed in injection
moulds in which the respective components
are given their later, often filigree
structure. Several components are held by
one mould carrier. The zinc is pressed at a
pressure of up to 150 t/cm 2 .
After the mould carriers are automatically
ejected from the injection moulding machines,
CONRAD employees carefully check
the individual parts. The edges are filed by
machine, but the grinding and polishing is
still often manual work. The entire production
process is organised to the last detail.
As with the original, the visual impression
of the product also plays an important role
in model construction. This includes a
smooth, notch-free surface as well as careful
painting. At CONRAD, the same undercoat
and topcoat paint is used as in the
automotive industry. The paint is applied in
up to six stages. As the colour tone of the
components consisting of different materials
must be the same, different paint compositions
are used for colouration of the
plastic components and the cast zinc parts.
A CONRAD employee operating the injection moulding
machine
53
Even the latest PM models are produced
with attention to detail.
The picture shows the SIKA-PM 500 shotcrete device
as well as the high pressure BSA 14000 HP-D
concrete pump
CONRAD was founded in 1956 and began
producing faithful model vehicles in 1971.
Today, the company presents itself as the
leading manufacturer of model vehicles,
with modern prototype and mould construction,
a pressure casting foundry, plastic
injection moulding, an environmentally
friendly painting system and a department
for screen printing. Due to the good collaboration
they have experienced over decades,
Putzmeister AG has also arranged to have
its new models, such as the BSA 14000 HP
concrete pump and the SIKA-PM 500
shotcrete device manufactured by
CONRAD GmbH.
56
57
Mould carriers with parts of the stationary pump model
The zinc raw material is delivered to model builder
CONRAD in bars
The two halves of an injection mould for the BSA model
20
PM 3723 GB
21
PM 3723 GB