Engineering
Engineering: This is how we design in the armoured glass workshop
We develop protective conversions for construction machinery as a holistic project from planning to installation. An elementary component of this service is the field of engineering. The design by our engineers is computer-aided with the highest precision. Take a look behind the scenes of our development department for construction machinery armouring.
The prerequisite for everything: What requirements does our customer have for an armoured cabin?
There is no one armour for construction machinery. Rather, the best solution is always adapted to the requirements of users and equipment. That is why the engineering process begins with a consultation phase. Together with our customers we discuss:
Which construction machine is to be armoured?
Which security classifications must be fulfilled?
Is there a separate need in terms of extras?
What is the budget?
Thanks to our experience, we are able to accompany customers through the planning phase and provide in-depth advice. This includes that we, as specialists for secured construction machinery, query all relevant points in order to then be able to start a customised development.
By the way: We not only design armoured cabins for construction equipment, we also take care of other details of the machines, such as armoured glass in combination with other protective measures.
An important topic is the integration of ROPS, FOPS and Co. in the development of a protection concept for construction machinery with armoured glass.
The decisive aspect for the later development is ultimately always the question: How high must the protection be for the construction machinery operators? Depending on the area of application, the requirements differ considerably.
Falling objects are a frequent source of danger. There is a separate classification for protective conversions according to FOPS (Falling Object Protective Structure).
A cab in accordance with FOPS I for construction machinery is secured against small objects. Many makes already fulfil this at the factory. More interesting are armoured FOPS II cabs.
According to ISO 3449, these must withstand greater impact energies. With the cooperation of the Wolf company, we are able to combine their FOPS roofs and front grids, which have been tried and tested for years, with our armour.
Wolf's products are characterised by their low overall height and their patented ability to pull the front grille up onto the roof for safe storage if required.
For higher requirements, we are able to develop armoured cabins and FOPS solutions that significantly exceed FOPS II requirements.
These designs also incorporate tried and tested methods from vehicle construction. For example, our FOPS roofs are designed to be particularly rigid and torsion-resistant at the points where it is necessary.
Elsewhere, softer crumple zones or elastic elements are integrated, so that the occurring energy can be dissipated through deformation. This relieves the load on the cabin and prevents premature failure.
A similar safety concept is ROPS.
This is about the rollover protection for cabs of construction machines. All construction machines on the market use tested ROPS cabs.
However, the existing safety can be further increased by additional bracing.
Here we benefit from the fact that we can plan the entire construction and insert reinforcements at the desired points.
The box frames of the Next Generation act like a front roll bar and protect the driver very effectively in the event of a rollover of the excavator, as well as in the event of heavy parts falling onto the roof and, of course, against explosion pressure.
In order not to overload the original cabin bearings, all Next Generation explosion-proof armour is equipped with its own cone bearings.
What else needs to be considered in the design
The new DGUV requires today's armouring to have explosion protection according to ER 4.
This means that the protective conversion must withstand an explosion pressure of up to 2.5 bar for 20ms. In order to be able to imagine the load that occurs here, let's take a simple calculation example; the attack surface of a normal cabin of a 20t excavator is approx. 100 cm in width and 160cm in height.
So 100 cm x 160cm =16,000 cm² x 2.5 kg/cm²= 40,000kg.
This force hits the cabin at supersonic speed and acts for 20ms. From this simple example calculation alone, it quickly becomes clear that effective explosion protection is not a simple matter and should not be underestimated under any circumstances.
The test parameters for ER 4 are taken from the test requirements for explosion-proof facades. This does not take into account splinter throw. However, primary as well as secondary splinters occur during the transfer of explosive ordnance.
Here, the primary shards are the ones that are most dangerous, as they can have a large dead weight and are accelerated to a high speed.
In addition, they are usually steel parts that deform very little when they hit the armour and thus release all the kinetic energy into the armour, comparable to a hard-core projectile.
These fragments are then also capable of penetrating a BR 6 armoured glass pane. Secondary fragments are all parts that are carried away by the explosion, such as soil and stones contained in it. The secondary fragments may be heavier, but they are not accelerated as much.
And this is what our solutions look like
In terms of design, the task of armouring with explosion class ER 4 is solved by the fact that we have developed a torsionally and flexurally rigid box frame.
This is supported from the floor assembly by 12 mm plates attached to the sides via elastic connections. The high weight resulting from this construction also has a positive effect. The high-speed shock wave sets the mass of the armour in motion with the cabin. It should be noted that the greater the mass, the slower the initiated movement of the armour.
The generated kinetic energy of the armour is dissipated via its own elastic suspensions as well as via the cabin suspension. In addition, energy is absorbed by deformation of the side connection plates as well as by deformation of the cabin. Due to the achieved deceleration of the armour/cabin unit relative to the pressure wave, the pressure wave is already over before the cabin can possibly release openings to the interior through deformation.
Especially for use in explosive ordnance disposal or in the military sector, the topics of explosion safety and bullet resistance are also extremely relevant. Here, too, we offer you a full range of services. For maximum safety, we develop explosion-proof driver's cabs larger than ER4.
In addition, we develop armour for increased requirements, which reach the firing class BR7 or greater. Furthermore, the explosion-proof armour of the Next Generation are designed in such a way that they are pre-equipped for all-round armouring and can be easily extended with just a few modifications. This gives you a construction machine that can withstand even extreme loads.
Constructive handling of bullet-proof glass
Contrary to what many people think, bullet-proof glass panes are very sensitive to bending and torsion.
Even small bending angles immediately cause cracks to form in the laminate, which greatly reduce the mechanical load-bearing capacity of the bullet-proof glass.
To avoid this, we place great emphasis on the rigidity of the frame structure in the design.
We achieve this with a sophisticated strategy of how the individual sheets interlock and the way in which, with as many bends as possible, unnecessary welding seams are avoided.
Among other things, the bevelled corners of the bullet-proof glass pane are also decisive for the increase in torsional rigidity; these are ultimately also responsible for the unmistakable design of our bullet-proof glazing.
Only stable, usually milled T-profiles are used for disc joints.
In the event of an explosion, these prevent the panes from collapsing due to their high load-bearing capacity and therefore make a considerable contribution to the safety of the armour.
Special CAD programmes are used for the design of sheet metal parts, enabling us to go to the limits of what is technically feasible.
In these cases, the planned developments are tested for their feasibility with the help of special simulation programmes before they are taken over into the design.
These developments can then often only be accomplished with special tools and great skill on the part of the employees. CNC press brakes with press forces of up to 500 t are used.
From the field: Are you looking for an armoured construction machine for military or civilian use?
The resulting safety requirements differ greatly. As a leading supplier of cabin conversions with bulletproof glass, we offer both.
In military applications, bullet resistance is a priority in addition to explosion resistance.
This is why armour steels are primarily used in military applications.
These are more expensive than normal structural steel, but essentially much more complex to process.
Furthermore, in particularly exposed areas, additional special armour only available to the military is installed.
Bulletproof glass or polycarbonate for construction machinery?
An interesting question of detail is whether bullet-proof glass or polycarbonate is more suitable for your construction machine. Polycarbonate, for example, is characterised by a particularly high impact resistance. There are also laminates made of glass laminate and a polycarbonate pane on the back. Here, both positive properties are combined. With these composites, thinner and non-splintering bullet-proof glass panes can be produced with the same bullet resistance as pure glass laminates. However, the different coefficients of thermal expansion between glass and polycarbonate always cause problems. The coefficient of thermal expansion of polycarbonate is ten times greater than that of glass. This in turn leads to great tensions between the two materials when the temperature changes. For this reason, some glass manufacturers repeatedly experience delamination or cracking in the polycarbonate pane. Panzerglaserei only uses bullet-proof glass panes from manufacturers with extensive experience in this field and who demonstrably meet very high quality standards. We are in constant contact with our suppliers in order to always be at the cutting edge of technology, or to develop the state of the art of tomorrow together with them. We are therefore very familiar with all materials and then decide which variant best meets your requirements, taking safety and technical aspects into account.
It doesn't always have to be maximum armour
We are also able to design ingenious, simple solutions wherever a cost-effective protective conversion is required that is also easy to install.
Regardless of whether it is armour for the search for explosive ordnance, or protection against broken chain links in forestry.
Even with these tasks, the focus of our designs is always on safety, functionality and integration into the design of the machine
Planning and designing: Complete armoured glazing service
Once all questions have been clarified, the development of the concept begins.
The entire project is handled in-house.
This increases efficiency and you benefit from fast but equally professional planning and construction.
The engineering is then computer-aided on the basis of CAD data from the laser measurement.
The entire development step takes place digitally, so that you can see a visualisation of your armoured cabin in advance, giving you the opportunity to make changes at any time until exactly the solution you wanted has been found.
Quality assurance and release for production
Have all your customer specifications been met?
If so, the plans from the design department go on to work preparation and final production.
In close consultation with the designers, the prototype of the armour is created there, exactly according to your specifications.