Machine tools abstract
It is provided a support and guide device for small machine tools,
in particular for rotating-mass balancing machines, comprising:
a base element (2), at least one moving element (3) in engagement
with the base element (2), support elements (4) for the moving element
(3), and drive members (5) controlling shiftings of the moving element
(3), the support elements (4) comprising at least one elastically
deformable thin sheet (7) oscillatably supporting the moving element
(3), and the drive members (5) being active on the moving element
(3) to shaft the latter against the action of the elastically deformable
thin sheet (7).
Machine tools claims
What is claimed is:
1. A support and guide device for machine tools, comprising: a
base element, at least one moving element being offset from the
base element in a first direction and extending substantially parallel
to the base element in a second direction substantially perpendicular
to the first direction and being adapted to support a tool, support
means between said base element and said at least one moving element
for movably supporting said at least one moving element, drive members
for controlling shifting of said at least one moving element relative
to said base element, wherein said support means comprise at least
one elastically deformable sheet element oscillatably supporting
said at least one moving element, said at least one sheet element
extending in the second direction and being located at one end of
the at least one moving element, and wherein the drive members act
to move said at least one moving element in the first direction
at a portion thereof spaced from said one end.
2. A device as claimed in claim 1 wherein said support means further
comprise a pair of stiffening plates sandwiching a first region
of said at least one sheet element, and wherein said at least one
sheet element comprises second regions adjacent said first region
and free from said stiffening plates, whereby the elasticity of
said at least one sheet element is substantially proportional to
the extent of said second regions.
3. A device as claimed in claim 1 further comprising at least
one spring interposed between said at least one moving element and
said base element for holding said at least one moving element in
engagement with said drive members.
4. A device as claimed in claim 1 wherein said drive members comprise
a motor and a cam-follower assembly operated by said motor, the
cam follower being directly in engagement with said at least one
5. A device as claimed in claim 1 wherein said drive members are
arranged between said base element and said at least one moving
6. A device as claimed in claim 1 wherein said at least one moving
element comprises a first moving element and a second moving element
arranged in overlying relationship, and said at least one elastically
deformable sheet element comprises a plurality of elastically deformable
sheet elements, said first moving element extending in said second
direction and being oscillatably supported by a pair of said elastically
deformable sheet elements extending in said first direction and
spaced apart from one another, said pair of sheet elements each
having one end fastened to said base element and another end fastened
to a respective end of said first moving element, said second moving
element extending in said second direction and being oscillatably
supported by one of said elastically deformable sheet elements extending
in said second direction and fastened to a support member for supporting
a tool rigid with said first moving element, and wherein said drive
members comprise a first drive member arranged to act on said first
moving element and a second drive member arranged to act on said
second moving element, said first and second drive members being
actuatable selectively to cause shifting of said first and second
moving elements selectively according to directions substantially
perpendicular to one another.
7. A device as claimed in claim 6 wherein said first drive member
is arranged between said base element and said first moving element,
and wherein said second drive member is arranged between said first
moving element and said second moving element.
Machine tools description
FIELD OF THE INVENTION
The invention relates to a support and guide device for small machine
tools, in particular for rotating-mass balancing machines, of the
type comprising a base element, at least one moving element in engagement
with the base element, support means for the moving element, and
drive members controlling shifting of the moving element.
DESCRIPTION OF THE PRIOR ART
It is known that all machine tools are provided, in addition to
a work or cutting motion, with an advance or feed motion causing
relative shiftings between the tool and the workpiece.
These relative shiftings take place following a great variety of
modalities and among other things involve use of different mechanical
members for support and guide. For instance, generally used are
slides that, as known, are supports provided with guides and movable
along predetermined directions.
Depending on the situations, slides can movably support the workpiece
or the tool and each slide is provided for carrying out shifting
in a given direction. Slides are important and expensive components
in machine tools because accuracy in workings also relies on stability
and movement precision of same and because often very precise workings
For instance, in milling machines used as balancing machines for
rotating masses, accuracy in the relative shiftings between tool
and workpiece must be rather high: in the order of one hundredth
of a millimeter.
Balancing machines intervene in some rotors, such as armatures
of small electric motors used in cars, household electrical appliances,
electrical tooling, to remove small amounts of material at each
In order to achieve a final true accuracy of one or two hundredths
of one millimeter in these balancing machines, slides therein used
are relatively complicated and expensive, even if traditional in
Typically, in the concerned slides it is provided that at least
two guides with at least two or four ball runners, one ballscrew
with the related supports and bearings, a servo-motor operating
it and limit sensors, should be mounted on a base. The final cost
of these controlled-motion slides is high and setting of same is
also very demanding and expensive.
The foregoing is valid in spite of the fact that in this specific
case the requested relative shiftings between the workpiece to be
balanced during working and the milling tool are of minimum amount.
In fact, as already pointed out, material removal is very reduced
and the maximum length of a single milling operation to balance
a rotor can be quantified in an amount of about fifteen millimeters.
In addition, a maximum milling depth in a balancing machine is
in the order of only three millimeters, although in order to cover
the wide variety of diameters of the different pieces that may be
submitted to working, an overall maximum stroke of about forty millimeters
in the approaching direction between milling tool and rotor is to
In short, the present art teaches how to manufacture support and
guide devices for machine tools having a structure that takes into
account the amount of the shiftings to be made only as a marginal
question and that, if precision shiftings are required, needs complicated
and expensive devices.
This hinders diffusion of small precision machine tools, in particular
of said balancing machines.
SUMMARY OF THE INVENTION
Under this situation the technical task of the present invention
is to conceive a support and guide device capable of obviating the
mentioned drawbacks. Within the scope of this technical task it
is an important aim of the invention to conceive a device particularly
adapted for small shiftings in small machine tools and capable of
enabling both high accuracy and minimum costs.
Another important aim of the invention is to conceive a device
of simple structure, formed of a minimum number of pieces and of
The technical task mentioned and the aims specified are achieved
by a support and guide device for small machine tools, in particular
for rotating-mass balancing machines, comprising: a base element,
at least one moving element in engagement with said base element,
support means for said moving element, and drive members for controlling
shifting of same, said support means comprising at least one elastically
deformable thin sheet oscillatably supporting said moving element.
BRIEF DESCRIPTION OF THE DRAWINGS
Description of some embodiments of the device of the invention
is now given hereinafter, with reference to the accompanying drawings,
FIG. 1 shows the device arranged for shiftings of the horizontal
FIG. 2 shows the device in FIG. 1 arranged for shiftings of the
FIG. 3 shows a device consisting of the sum of the structures shown
in the preceding two figures, so as to obtain shiftings both in
the horizontal and in the vertical direction;
FIG. 4 is a perspective view of a portion in FIG. 1;
FIGS. 5 and 6 show an elastic thin sheet of the embodiment in FIG.
1 in a rest position and in an elastically deformed position, respectively;
FIG. 7 is a perspective view of a portion in FIG. 2; and
FIG. 8 shows an elastic thin sheet of the embodiment in FIG. 2
in a rest position.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
With reference to the drawings, the device of the invention has
been identified by reference numeral 1.
It generally comprises a base element 2 at least one moving element
3 in engagement with the base element 2 and shiftable relative to
the latter, and support means 4 for shiftings of the moving element
Also provided are drive members 5 controlling shiftings of each
moving element 3 relative to the base element 2.
The base element 2 in the simplest embodiment is the base of a
small machine tool, whereas the moving element 3 is the support
of operating members of the machine tool itself.
In the preferred instance of small machine tools such as small
milling machines for balancing rotors, elements 2 and 3 are plate-like
bodies of rectangular shapes seen in plan view and of a bulkiness
involving sides of some ten centimeters.
The moving element 3 at least at a suitably-positioned work region
is in engagement with at least one attachment piece 6 or support
for the tool to be used. For instance, the moving element 3 has
an attachment piece 6 at one end thereof. The attachment piece 6
can be embodied by supports with bearings for a milling spindle.
The support means 4 of the moving element 3 comprises at least
one elastically deformable thin sheet element 7 which engages the
moving element 3 like an oscillatable support wall.
The thin sheets 7 extend at the ends of elements 2 and 3 to which
they are merely screwed up, and have a thickness of about one or
two millimeters, for example.
Each elastically deformable thin sheet 7 is substantially flat
in a rest condition and is preferably made of high-tensile steel,
or spring steel, in order to ensure the greatest flexibility and
The thin sheet sizes are imposed by the overall structure of the
machine tools: for instance, the thin sheets 7 have square or rectangular
shapes and maximum linear sizes in the order of about ten centimeters.
Control of elasticity of the thin sheets 7 is obtained, once thickness
has been established, by applying rigid stiffening plates 9 fastened
by bolting and sandwiching the thin sheets 7 on opposite sides.
In addition, the stiffening plates 9 preferably engage a median
portion of the thin sheets 7 so as to form flexibility regions spaced
apart from each other. Practically, for each thin sheet 7 two stiffening
plates 9 in contact with opposite faces of the thin sheet 7 are
provided so as to sandwich and stiffen a first central region 7a
of each thin sheet.
The first region 7a has smaller sizes than those of the thin sheet
7: free regions 7b adjacent the first region 7a and spaced apart
from each other are always present to ensure the necessary elasticity.
Said elasticity is thus proportionate to the width of the second
free regions 7b and can therefore be adjusted at will by giving
appropriate sizes to the stiffening plates 9. Obviously the stiffening
plates 9 can be positioned on the thin sheets 7 no matter how and
even omitted when the device is formed with thin sheets 7 of very
reduced sizes or the elasticity of which is already adjusted based
on the particular needs.
The device can be made for carrying out shiftings--between the
base element 2 and the moving element 3--parallel or transverse
to each other, or preferably in both directions simultaneously.
In the first case shown in FIG. 1 the base and moving elements,
2 and 3 define a four-bar linkage together with the support means
In the second case shown in FIG. 2 the moving element together
with the related support means 4 defines a bracket body provided
with a tilting motion with respect to the base element 2 and having
an attachment piece 6 at its free end. In fact, as shown in FIG.
2 the sheet element 7 extends in a direction substantially parallel
to the moving element 3 at one end thereof, and the drive members
5 act on the moving element 3 in a direction substantially transverse
to the moving element 3 at a portion spaced from said end. In particular,
the technical solution in FIG. 2 where the stiffening plates 9
only consist of strips, can be simplified by omitting the stiffening
plates 9 and suitably reducing the available space for the thin
sheet element 7.
In the third case, which is the sum of the preceding two cases
and is shown in FIG. 3 two moving elements 3 are mounted in overlying
relationship on a single base element 2 i.e. a first moving element
3a forming a four-bar linkage with the underlying base element 2
and a second moving element 3b overlying the first moving element
and the base element 2 so as to form a body in the form of a bracket.
As shown, a first and a second drive member respectively act on
the first and the second moving element 3a, 3b, so causing shifting
of the moving elements 3a, 3b selectively according to directions
substantially perpendicular to each other.
It is also pointed out that the drive members 5 are preferably
fitted between a moving element 3 and the base element 2 and they
directly act on the moving element 3.
In other words, the drive members 5 do not act on the support means
4 but directly on the moving elements 3 so that they operate with
the greatest accuracy without intermediate members.
In detail, the drive members 5 comprise a motor, preferably an
electric motor, and a connecting rod-crank mechanism or a cam-cam
follower assembly operated by the motor.
Where a motor operates a connecting rod-crank mechanism, the connecting
rod is in engagement with a moving element 3 and the crank is supported
by a respective base element 2.
In the preferred case of a motor operating a cam-cam follower assembly,
as shown in the figures, provision is made for a cam 10 which has
a rotation axis 10a substantially parallel to the base element 2
an electric motor 11 adapted to rotate the cam 10 and coaxial with
the rotation axis 10a, and a cam follower 12 engaging the cam 10
by acting against the action of same.
The cam follower 12 consists of a roller linked to a moving element
3 and the cam is linked to the underlying element.
To enable horizontal shiftings, in FIG. 1 the cam follower 12 is
substantially at the same height as the rotation axis 10a of cam
10 whereas to enable vertical shiftings, in FIG. 2 the cam follower
12 is substantially above the rotation axis 10a. Also provided are
helical springs 8 active on each moving element 3 and interposed
between the moving element 3 and the underlying element, so as to
keep the cam followers 12 at a position at which they closely counteract
the action of cam 10. In the case shown in FIG. 1 compression springs
are present and in the case shown in FIG. 2 draw-springs are present.
Since the drive members 5 are also active against the action of
the elastically deformable thin sheets 7 springs 8 can optionally
be omitted. Cam 10 can also be of a type having one degree of freedom
only and therefore directly connected with the cam follower 12
by a shaped groove in which the cam follower runs, for example.
In this way the helical springs 8 are not required. In fact in the
last-mentioned case a complete-constraint system is concerned, with
only one degree of freedom as said, like the already discussed connecting
The electric motor 11 is preferably of the brushless type and it
is provided adapted to angularly position the cam 10 in a very precise
Operation of the device is as follows.
The device is placed at the base of small machine tools for which
relative shiftings of small amount between the workpiece and the
tool are required. As already pointed out, in small balancing machines
operating by material removal, these shiftings are of about fifteen
millimeters in a horizontal direction and forty millimeters in a
Shiftings of the moving element or upper plate-like body 3 are
obtained by starting the electric motor 11 and therefore starting
the connecting rod-crank mechanism or the cam-cam follower assembly.
For instance, with a cam-cam follower assembly of the type shown,
cam 10 can impose small shiftings to the cam follower 12 and therefore
to the moving element 3 since cam 10 is in engagement with the
base element 2 and the cam follower 12 is directly in engagement
with the moving element 3 in turn supported by one or more thin
sheets 7 in an oscillatable manner.
The thin sheets 7 perform different functions, i.e. they act as
a support for the moving element 3 as a moving guide for the same,
and as a stabilising elastic member active against the action of
the drive members 5.
As a support element they must have sufficient dimensions to place
the moving element 3 at correctly raised positions and as a guide
element they must have wide dimensions, so as to enable the moving
element 3 itself to carry out shiftings of sufficient width.
In addition, should a four-bar linkage be formed as in FIG. 1
the relatively wide sizes enable the intended longitudinal shiftings
to be achieved without an important lowering in the vertical direction.
The above can possibly lead to an excessive flexibility and yielding
in the vertical direction, but this drawback is completely overcome
and obviated by arranging sandwiching stiffening plates 9 on the
thin sheets 7.
Said stiffening plates limit the thin sheet yielding in a simple
and efficient manner, even in the presence of important weights
and of thin sheets of very reduced thickness, and in addition they
stiffen the thin sheets themselves to such an extent that, on deflection,
a sufficiently high elastic reaction is obtained.
The invention achieves important advantages.
In fact, a device of very simple structure and low cost has been
obtained which enables achievement of small and highly-precise shiftings.
Accuracy is in particular connected with the direct control of
the moving elements and the substantial absence of plays.
The support means 4 and drive members 5 by themselves enable shiftings
having an accuracy in the order of thousandths of a millimeter.
In addition, the device, due to the presence of the stiffening
plates 9 is very versatile, cheap and of easy setting in fact, one
and the same elastic thin sheet can take different elasticity values
that can be adjusted with great accuracy, and also thin sheets of
very reduced thickness and wide sizes can be utilized.