Background of the invention
[0001] The present invention concerns the field of cutting tools and more particularly the
field of portable tools for cutting various materials, e.g. wood, metal or plastic,
and particularly relates to a measurement device for use with such tools.
Description of the Prior Art
[0002] Cutting tools are commonly used to reduce large-sized products into smaller pieces.
[0003] Products must be often cut on site, using relatively small tools that can be easily
carried by the operator to the working site.
[0004] By way of example only, this class of tools includes circular saws, chain saws, electric
blades or other similar devices specially designed for cutting wood, plastic, metal
or other composite materials.
[0005] The operator that uses these tools is often confronted with the need to cut a large
piece into multiple smaller pieces of the same size.
[0006] It will be clear for everyone that cutting to constant sizes is rather simple when
tools are stationary, i.e. when they have their own support base or are stably anchored
to a workbench, but it is quite difficult when it is carried out on site using a portable
tool.
[0007] Nevertheless, referring to a particular tool, such as a chain saw, an attempt to
solve this problem has been made by providing a measurement devices that are designed
to be removably applied to the rigid guide of the chain.
[0008] Patent
US 7,861,416 discloses a measurement device for a chain saw which consists of a resilient rod
having one end fitted with a powerful magnet and a stud that is designed to be introduced
into a hole formed in the chain guide bar.
[0009] The rod extends perpendicular to the cutting plane and has a disk on the other end,
indicating the right measured length of the cut to the operator.
[0010] Furthermore, the rod may be formed of one piece, to thereby define a fixed cutting
length, or may be composed of two sliding rods, allowing the cutting length to be
adjusted from minimum to maximum preset values.
[0011] The rod is fixed to the chain saw by a pin, which is nevertheless an obstacle to
the use of this device as it requires a corresponding receiving bore to be formed
in the chain guide.
[0012] Furthermore, with this connection the rod will be rigidly connected to the chain
saw, and this will affect ease of handling of the tool because, even when the rod
is made of a resilient material, it cannot effectively absorb the shock of impacts
with the material to be cut.
[0013] Therefore, the device as disclosed in the aforementioned US patent is apparently
not easy to use and is very rigid, which will be an obstacle to handling of the tool.
[0014] It should be further noted that the measurement device with the adjustable rod is
configured to only be able to change the cutting length by discrete multiples of a
base value, typically 2", and does not allow continuous adjustments.
[0015] Due to the above, the above discussed device is found to be poorly practical and
versatile in use.
[0016] In light of these apparent limits of the prior art, it would be desirable to provide
an adjustment device that can be very easily applied to the tool, without requiring
the latter to feature particular arrangements therefor, that absorbs almost all the
vibrations generated during cutting, that is simple and inexpensive and affords very
easy handling of the tool by the user.
Summary of the invention
[0017] The present invention is based on the problem of providing a measurement device that
can obviate the aforementioned prior art drawbacks and has the features as discussed
hereinabove.
[0018] Also, there is disclosed herein a measurement device that can be easily assembled
and may be installed in a cutting tool without requiring special skills on the part
of the user.
[0019] A non-incidental object fulfilled by the present invention is to provide a sturdy
and handleable measurement device, that can be used under any possible work conditions,
due to its high stability and shock-absorbing capacity.
[0020] A similar problem has been solved, according to the invention, by a measurement device
for portable cutting tools as defined in claim 1.
[0021] Further embodiments of the present invention will be provided in accordance with
the dependent claims.
Brief description of the drawings
[0022] Additional features and advantages of the present invention will become apparent
through one embodiment of a measurement device for portable cutting tools that is
preferred but shall be intended without limitation. It will be illustrated with the
help of the following drawings annexed hereto:
Figures 1 and 2 show a perspective view of a particular cutting tool with the inventive
object applied thereto;
Figure 3 is a perspective view of the measurement device as claimed in the present
application;
Figure 4 is a side view of the device of Figure 2;
Figure 5 is a cross-section side view of the device of Figure 4;
Figure 6 is an exploded side view of the device of Figure 5;
Figure 7 is a perspective view of the device of Figure 2, installed on a portable
cutting tool, showing its versatile use.
Description of the preferred embodiments
[0023] While the following specification relates to a first embodiment of the invention,
as shown in the accompanying figures, this shall not be construed as limiting, as
the device of the invention can be provided in a form other than that disclosed herein,
and still fall within the scope defined by the main independent claim.
[0024] The measurement device, which is referenced
1 in the drawings, can be applied to a variety of cutting tools
U, e.g. an electric blade or a wheel cutter, but it will be preferably installed on
a chain saw, as schematically shown in the drawings of Figure 1.
[0025] It shall be noted that the measurement device
1 can be applied to the tool
U if the latter is equipped with both a cutting member
T designed to cut the object
O, and a stationary guide
G, which is generally fixed to a handle
I and is adapted to support the cutting tool
T.
[0026] In a chain saw, the cutting member
T is a chain that slides on an elongate guide
G defined by a thin flat metal plate
P having a rounded end
P'.
[0027] The measurement device
1 comprises a support base
2 that is adapted to be positioned on the stationary guide
G, i.e. a flat plate, in an area proximate to the cutting tool
T.
[0028] The support base
2 may be preferably applied to the flat plat
P in correspondence of the rounded end
P'.
[0029] Generally, the base
2 is made of metal and has a circular shape, as it is formed by turning. For example,
the diameter
D1 of the base
2 may range from 60mm to 30mm, and is preferably a diameter of about 40mm.
[0030] Means
3 are also provided for removably connecting the support base
2 to the stationary guide
G.
[0031] As more clearly described hereinafter, these connecting means
3 may comprise at least one screw or threaded pin, or alternatively a plurality of
magnets
4 designed to be attached to the metal plate
P whose attractive force is sufficient to keep the support base
2 in stable contact therewith.
[0032] Firstly, as best shown in Figures 5 and 6, the support base
2 may consist of a disk-shaped first end portion
5 having a flat, circular outer surface
6.
[0033] This first disk-shaped portion
5 may further have an inner surface
7 opposite and parallel to the outer surface
6. Nevertheless, the base
2 also comprises an annular second end portion
8 with a cylindrical inner wall
9, as most clearly shown in Figures 5 and 6, having a transverse end edge
10 which contacts or is more precisely joined to the inner surface
7 of the disk-shaped first end portion
5.
[0034] On the other side, an open transverse end edge
11 is provided such that an annular cavity
12 is obtained by joining the two portions, the cavity
12 being delimited by the cylindrical inner wall
9 of the second portion
8 and the circular inner wall
7 of the first portion
5.
[0035] A cylindrical pin
13 having a predetermined diameter, typically about 6mm, may extend from the center
of the cavity
12 and particularly from the circular inner surface
7, and project out of the open edge
11 of the second end portion
8 of the base
2 to fit into a corresponding hole formed in the guide element
G of the tool
U.
[0036] The cylindrical pin
13 is provided as an option, although in the particular device as described herein it
is shown in Figures 3 to 6 because, while its presence assists application of the
device
1 to the tool
U, it can be only used if the stationary guide
G of the latter has been formed with a through hole.
[0037] If the base
2 has the pin
13, then the connecting means
3 may comprise threads formed on the pin itself, so that the entire device
1 may be removably fastened to the tool
U by a nut that will be screwed down against the face
F' of the stationary guide
G opposite to the face that contacts the base
2.
[0038] Nevertheless, as an alternative to the threaded pin, the connecting means
3 may be of magnetic type and comprise at least one magnet
4 accommodated in the cavity
12 and projecting out of it to interact with the metal face
F of the metal guide
G.
[0039] For example, as shown in Figures 3 and 6, four cylindrical neodymium magnets may
be used, each having a diameter
D2 of about 14mm and a depth of about 5mm.
[0040] The cavity
12 will obviously have a depth
p that is smaller than the length
L1 of the magnets
4, i.e. smaller than 5mm and typically of about 3mm.
[0041] A substantially cylindrical straight rod-like member
14 is also provided, having a first end 15 operably connected to the support base
2 and a second free end
16 opposite thereto.
[0042] As more clearly shown in the figures, the rod-like member
14 may have a preset length L
2 selected to define a given cutting length.
[0043] In order to assist the operator during cutting, the free end of the rod may be joined
to a washer or a disk
17, as shown in figures 1 to 5, which has a very small thickness
s, so that it may partially fit into a recess formed by the cutting tool
T on the object
O during a previous scribing step performed by the operator.
[0044] In a particularly advantageous aspect, the length
L2 of the rod-like member
14 may be adjusted within a range from predetermined minimum to maximum values.
[0045] In order to do this, as shown in Figures 4 to 6, the rod-like member
14 will comprise a first tubular rod
18 stably connected to the support base
2. Therefore, the end of the first rod
18 connected to the base
2 will define the first end
15 of the rod-like member
14.
[0046] The first rod
18 may be a section of a metal tube having an outside diameter
D3 ranging from 8mm to 20mm, although a tubular section with an outside diameter of
12mm and a hole of 10mm may be preferably used.
[0047] The length
L3 of the first rod
18 may be obviously selected as desired, but for practical use it does not exceed 200mm
and is often of about 170mm.
[0048] An end opening
19 is provided at the end of the first rod
18, for a second tubular rod
20 to be slidingly introduced therein.
[0049] Therefore, the latter will have one end
21 designed to be introduced into the first rod
18 and an opposite end that will coincide with the second free end
16 of the rod-like member
14 and will be joined to the washer or disk
17.
[0050] The second rod
20 may also be a section of a tubular section having an outside diameter
D4 of about 10mm and a length
L4 of about 150mm.
[0051] Therefore, the second rod
20 will slide within the first rod
18 to adjust the position of the second free end
16 within the corresponding range from minimum to maximum values which, considering
the above mentioned dimensions, may be of about 170mm and 320mm.
[0052] Nevertheless, in order to maintain a fixed cutting length during use, the device
1 will use appropriate selective locking means
22, for blocking the second rod
20 relative to the first rod
18.
[0053] As clearly shown in the cross-section view of Figure 5 and the exploded view of Figure
6, the second rod
20 may have a transverse wall
24 and an inwardly tapered outer surface
25 in the end portion
23 that is designed to be introduced into the first rod
18.
[0054] The end portion
23 may be also formed with a blind hole
26 that ends before the transverse wall
24.
[0055] The entire end portion
23 may be either integrally formed on the second rod
20, as schematically shown in Figure 5, or consist of a suitably shaped plug
27 adapted to be fitted into or applied to the end
21 of the second rod
20 that is designed to be slidingly introduced into the first rod
18, as shown in Figure 6.
[0056] A threaded pin
28 is also provided, which is designed to be screwed down and locked in the blind hole
26 of the end portion
23 to form one piece with the second rod
20.
[0057] By way of example, the tapered surface
25 of the end portion
23 may have a length of about 5 mm, whereas the threaded pin
28 may be as long as 15 mm and have a diameter of 5 mm and M5 threads, these features
will match those of the blind hole
26.
[0058] As clearly shown in Figures 5 and 6, the locking means
22 comprise a cylindrical body
29 which is adapted for tight fitting in the first rod
18 and is made of a metal or plastic material.
[0059] This cylindrical body
29 has a threaded through hole
30 formed therein, for the end portion
31 of the pin
28 that axially projects out of the end portion
23 of the second rod
20 to be screwed in and out of it.
[0060] It should be noted that the pin
28 will be screwed in and out of the through hole
30 of the body
29 when the user imparts a clockwise or anticlockwise rotation to the second rod
20 about its axis
X.
[0061] The body
29 also has a front portion
32 that faces the end portion
23 of the second rod
20 and has a plurality of radial cuts
33 formed therein, only sketched in the perspective view of Figure 6, which will inevitably
divide this portion
33 of the cylindrical body
29 into respective distinct and angularly contiguous circular sectors
34.
[0062] Therefore, as the threaded pin
28 is screwed into the central hole
30 of the body
29, the tapered surface
25 will move toward and contact the front portion
32 of the body
29.
[0063] Namely, the tip
35 of the tapered surface
25 will fit into the through hole
30 of the body
29 and interact with the inner surface
36 of the hole
30 to outwardly expand all the circular sectors
34 along corresponding radial directions, thereby ensuring a firm hold thereof against
the inner surface
37 of the first rod
18.
[0064] Such firm hold will safely block the second rod
20 relative to the first rod
18 in the axial direction
X.
[0065] It will be appreciated that, as the threaded pin
28 is unscrewed, the tapered surface
25 will move away from the through hole
30 and all the circular sectors will be retracted
34, such that they will no longer exert a firm hold on the inner surface
37 of the first rod
18 and the second rod
20 will be free to slide relative to the first rod
18.
[0066] As compared with prior art measurement devices, the present invention is characterized
in that it has vibration damping means
38 interposed between the support base
2 and the first end
15 of the rod-like member
14 or, more precisely, between the support base
2 and the first end
15 of the first rod
18, as clearly shown in Figures 2 to 7.
[0067] It will be appreciated that the addition of the vibration damping means
38 can damp the propagation of vibrations generated on the rod-like member
14, e.g. due to shocks exerted thereon by the object O being cut or other elements that
may be found in the work environment.
[0068] Such damping only allows a small amount of the vibrations imparted by the rod-like
member
14 to reach the support base
2, and actually improves handling of the tool U by its user.
[0069] An effective implementation of the damping means
38 consists in the use of a spring
39 having one end
40 stably connected to the support base
2, and an opposite end
41 stably connected to the first end
15 of the rod-like member
14 or, in other words, stably connected to the first tubular rod
18.
[0070] Such spring
39 may be formed with steel music wire, e.g. having a diameter of 3mm, and as many turns
as to be about 20mm long.
[0071] The outside diameter D
5 of the spring
39 may be of about 15mm, to thereby define a helical spring with an elastic constant
approximately ranging from 10 kg/mm to 20 kg/mm.
[0072] Figure 7 schematically shows the function of such damping means
38, as the presence of the spring
39 allows the rod-like element
14 to oscillate about the center axis
X' of the device in all directions.
[0073] The device of the present invention may be implemented through any change or variant
that may fall within the scope defined in the annexed claims, and all the above discussed
elements may be replaced by equivalents, made of the same or a different material
and possibly in a form other than that described herein, provided it falls within
the disclosed scope.
1. A measurement device for portable cutting tools (U) such as chainsaws or similar apparatus,
wherein the cutting tool (U) has a cutting member (T) adapted to cut an object (O)
and a stationary guide (G) adapted to support the cutting member (T), wherein the
device comprises:
- a support base (2) adapted to be positioned on the stationary guide (G) of the tool
(U) close to the cutting member (T);
- means (3) for removably connecting said support base (2) to the stationary guide
(G) of the tool (U);
- a rod-like member (14) substantially cylindrical and rectilinear with a first end
(15) operatively connected to said support base (2) and a second free end (16), said
rod-like member (14) having a preset length (L2) to define a predetermined cutting length;
characterized by comprising damping means (38) interposed between said support base (2) and said first end (15)
of said rod-like member (14), said damping means (38) being adapted to reduce the
propagation of the vibrations of said rod-like member (14) to said support base (2)
to increase the handling of the tool (U) by a user.
2. Device as claimed in claim 1, characterized in that said damping means (38) comprise a spring (39) having an end (40) stably connected
to said support base (2), and an opposite end (41) stably connected to said first
end (15) of said rod-like member (14).
3. Device as claimed in claim 1, characterized in that said support base (2) has a substantially disk-like first end portion (5) provided
of a substantially planar circular outer surface (6) to which is connected the correspondent
end (40) of said spring (39), and an inner surface (7) opposite with respect said
outer surface (6) and substantially parallel thereof.
4. Device as claimed in clam 3, characterized in that said support base (2) comprises a substantially annular second end portion (8) with
a cylindrical inner wall (9) having an end edge (10) joined to said inner surface
(7) of said first end portion (5), and an open end edge (11) to define an annular
cavity (12) delimited by said cylindrical wall (9) of said second end portion (8)
and said inner surface (7) of said first end portion (5).
5. Device as claimed in claim 1, wherein the stationary guide (G) is made in a metallic
material, characterized in that said connecting means (2) are of the magnetic type and comprise at least one magnet
(4) housed into said cavity (12) and projected from said open end edge (11) to interact
with the metal face (F) of the guide (G) of the tool (U).
6. Device as claimed in claim 1, characterized in that said preset length (L2) of said rod-like member (14) is variable between a minimum predetermined value and
a maximum predetermined value.
7. Device as claimed in claim 6, characterized in that said rod-like member (14) comprises a first tubular rod (18) stably connected to
said support base (12) and having an opening end (19) to allow insertion of a second
tubular rod (20) provided with said second free end (16), said second rod (20) being
slidably movable into said first rod (18) to adjust the position of said second free
end (16) between said minimum and maximum values.
8. Device as claimed in claim 7, characterized by comprising means (22) for selectively locking said second rod (20) with respect said
first rod (18).
9. Device as claimed in claim 8, characterized in that said second rod (20) has an end portion (23) adapted to be inserted into said end
opening (19) of said first rod (18), said end portion (23) having a transversal wall
(24) with a peripheral outer surface (25) tapered inwardly and a blind threaded hole
(26) for allowing screwing of a correspondent threaded pin (28).
10. Device as claimed in claim 9, characterized in that said locking means (22) comprise a cylindrical body (29) adapted to be inserted into
said first tubular rod (18) and having a threaded through hole (30) to allow screwing
of said threaded pin (28) upon rotation of said second rod (20) around its extension
axes (X), said cylindrical body (29) having a front portion (32) faced to said end
portion (23) of said second rod (20) on which are formed a plurality of radial cuts
(33) to form respective circular sectors (34) distinct to each other, said tapered
outer surface (25) being adapted to interact with said front portion (32) upon screwing
of said pin (28) to promote the outwardly selective expansion of said circular sectors
(34) and forming a seal against the inner surface (37) of said first rod (18) for
blocking said second rod (20) with respect said first rod (18).