Transmission unit, punching unit comprising this transmission unit and creasing machine comprising this punching unit

Abstract

The present invention relates to a transmission unit (10) comprising: - a moving unit (20) comprising a drive shaft (21) rotatably supported by a frame (11) along a rotation axis (X), wherein this moving unit (20) comprises at least one cam (22) attached to the drive shaft (21) on a plane orthogonal to the rotation axis (X); - a yielding unit (30) comprising a translating body (31) slidably supported by the frame (11) along a translation axis (Y), wherein this translating body (31) defines at least a first contact surface (31a) kinematically coupled to said cam (22) by sliding such that rotation of the head (22a) of the cam (22) towards the first surface (31a) causes a translation of the translating body (31) along the translation axis (Y), in a direction opposite to the rotation axis (X). It should be noted that the yielding unit (30) comprises at least one recall profile (32) attached to the translating body (31), wherein this profile (32) defines at least a second contact surface (32a) opposed to the first surface (31a) and kinematically coupled to the cam (22) by sliding such that rotation of the head (22a) of the cam (22) towards the second surface (32a) causes a translation of the translating body (31) along the translation axis (Y) towards the rotation axis (X).

Description

[0001] The invention concerns a transmission unit, particularly for the transformation of rotary motion into reciprocating rectilinear motion.

[0002] A punching unit comprising this transmission unit is also subject matter of the present invention.

[0003] The invention also relates to a creasing machine, particularly for folding sheets, comprising this punching unit.

[0004] Nowadays transmission units are known that are capable of converting rotary motion into reciprocating rectilinear motion.

[0005] A similar known transmission unit comprises: a moving unit comprising a drive shaft rotatably supported by a frame along a rotation axis and at least one cam attached to that drive shaft on a plane orthogonal to said rotation axis; a yielding unit comprising a translating body slidably supported by said frame along a translation axis, wherein said translating body defines at least a first contact surface kinematically coupled to the cam by sliding, such that rotation of the cam head towards said first surface causes a translation of the translating body along the translation axis in the opposite direction to said rotation axis; elastic means configured to act on the translating body in such a way as to maintain contact between the moving unit and the yielding unit during the rotation of the aforementioned cam.

[0006] Although well known and appreciated, this transmission unit however has some important limitations.

[0007] In particular, the speed of the rotary motion that this transmission unit is capable of handling without loss of contact between the moving unit and the yielding unit during rotation of the cam is limited by the elastic constant of the elastic means used.

[0008] In addition, the dynamics of the reciprocating rectilinear motion transmitted by this transmission unit suffers a strong variation over time due to the loss of elasticity of the aforementioned elastic means.

[0009] The task of the present invention is to develop a transmission unit capable of overcoming the aforementioned drawbacks and limitations of the prior art.

[0010] In particular, it is the object of the present invention to provide a transmission unit whose maximum speed of rotary motion that it is able to handle without loss of contact between the moving unit and the yielding unit during cam rotation is greater than similar transmission units of known type.

[0011] Again, an object of the invention is to develop a transmission unit in which the dynamics of the reciprocating rectilinear motion transmitted is affected by less variation over time than similar transmission units of known type.

[0012] The above-mentioned task and objects are achieved by a transmission unit according to claim 1.

[0013] Further characteristics of the transmission unit according to claim 1 are described in the dependent claims.

[0014] The task and the aforesaid objects, together with the advantages that will be mentioned hereinafter, are indicated by the description of an embodiment of the invention, which is given by way of non-limiting example with reference to the accompanying drawings, where: Figure 1 represents a perspective view of a creasing machine according to the invention; Figure 2 represents a side sectional view of the creasing machine of Figure 1; Figure 3 represents a detail of Figure 2.

[0015] With reference to the above-mentioned figures, a transmission unit according to the invention is indicated as a whole by the number 10 and clearly visible in Figures 1, 2 and 3.

[0016] This transmission unit 10, particularly for the transformation of rotary motion into reciprocating rectilinear motion, comprises: a moving unit 20, clearly visible in its entirety in Figures 1, 2 and 3, comprising a drive shaft 21, also clearly visible in Figures 1, 2 and 3, rotatably supported by a frame 11 along a rotation axis X; this moving unit 20 also comprises at least one cam 22, clearly visible in Figures 1, 2 and 3, attached to the drive shaft 21 on a plane orthogonal to said rotation axis X; a yielding unit 30, clearly visible as a whole in Figures 1, 2 and 3, comprising a translating body 31, also clearly visible in Figures 1, 2 and 3, supported smoothly by the frame 11 along a translation axis Y; this translating body 31 defines at least a first contact surface 31a, shown in Figures 1, 2 and 3, kinematically coupled to the cam 22 by sliding in such a way that the rotation of the head 22a of the cam 22 towards this first surface 31a causes a translation of the translating body 31 along the translation axis Y in the opposite direction to the rotation axis X.

[0017] It should be emphasised that the yielding unit 30 comprises at least one recall profile 32, clearly visible in Figures 1, 2 and 3, attached to the translating body 31.

[0018] Furthermore, as is clear from Figures 2 and 3, this profile 32 defines at least a second contact surface 32a opposed to the first surface 31a and kinematically coupled to said cam 22 by sliding such that the rotation of the head 22a of the cam 22 towards the second surface 32a causes a translation of the translating body 31 along the translation axis Y towards the rotation axis X.

[0019] The presence of the aforementioned profile 32 makes it advantageous to maintain contact between the moving unit 20 and the yielding unit 30 irrespective of the rotation speed of the cam 22.

[0020] In addition, the dynamics of the reciprocating rectilinear motion transmitted by the instant transmission unit 10 is affected by changes related almost exclusively to wear of the first surface 31a and the second surface 32a, which impacts the aforementioned reciprocating rectilinear motion considerably less than the loss of elasticity of the elastic means to which transmission units of known type are subjected.

[0021] In the present embodiment of the invention, the rotation axis X and the translation axis Y are orthogonal to each other and incidental.

[0022] This means that the first surface 31a, which can be assimilated to a plate in a flat-cam mechanism, is a centred, non-eccentric tappet element.

[0023] However, it cannot be ruled out that the rotation axis X and the translation axis Y are skewed to each other.

[0024] Again with reference to the present embodiment of the invention, the first surface 31a and the second surface 32a are spaced apart from each other parallel to the translation axis Y by a distance d, clearly depicted in Figure 3, equal to the length of the segment joining said head 22a and the base 22b of the cam 22.

[0025] Furthermore, the cam 22 is circular and the distance d is equal to the diameter of the cam 22.

[0026] The aforementioned distance d between the first surface 31a and the second surface 32a, as well as the circular shape of the cam 22, promote the maintenance of contact between the moving unit 20 and the yielding unit 30 during the rotation of the cam 22.

[0027] However, it cannot be ruled out that the aforementioned distance d, as well as the shape of the cam 22, may be different from what has just been described.

[0028] In the present embodiment of the invention, the profile 32 is C-shaped, as is clearly shown in Figures 1, 2 and 3, with a base 32b on which the second surface 32a is defined and a pair of wings 32c and 32d whose free ends 33 are attached to the translating body 31 at the first surface 31a .

[0029] In particular, said free ends 33, in accordance with the preferred embodiment of the invention, are shaped like an inverted "L", so as to be recessed with respect to said wings 32c and 32d and so as to have two sections 33a of the "L" facing each other and spaced apart by a distance I equal to the width w of the translating body 31.

[0030] In this way, said two sections 33a are coupled to the translating body 31, at the two lateral faces 31b and 31c, which are opposite to each other, of this translating body 31, as observed in Figures 2 and 3, and are attached to this translating body 31 by means of attaching means, in particular a screw 34 and a bolt 35 inserted in an insertion direction, orthogonal to the rotation axis X and to the translation axis Y, through holes, not visible in the figures, drilled on the same two sections 33a and on the translating body 31.

[0031] This configuration, advantageously, facilitates the assembly and maintenance of the transmission unit 10, in particular it facilitates the arrangement of the profile 32 along the drive shaft 21 and along the cams 22, or vice versa, and finally it facilitates the coupling of the same profile 32 to the translating body 31.

[0032] Again with reference to the present embodiment of the invention, the transmission unit 10 comprises three cams 22, each of which is clearly visible in Figures 1, 2 and 3 and helps to define the coupling between the moving unit 20 and the yielding unit 30.

[0033] Further, each of these three cams 22 is attached to the drive shaft 21 at the same angle about the rotation axis X.

[0034] However, it cannot be ruled out that the cams 22 are present in a different number from what has been described above and are arranged on the drive shaft 21 at a different angle about the rotation axis X.

[0035] Obviously, each cam 22 is associated with one of the above-mentioned profiles 32.

[0036] As previously mentioned, a punching unit, shown as a whole in Figure 2, also forms the subject matter of the present invention, comprising: a transmission unit 10 according to any one of the preceding claims; a punch 40, clearly visible in Figure 2, attached to the translating body 31 and configured to translate parallel to the translation axis Y between a retracted position and an operating position, and vice versa; a die 50, clearly visible in Figure 2, opposed to the punch 40 and shaped to accommodate this punch 40 in the above operating position.

[0037] It is also subject matter of the present invention a creasing machine particularly for folding sheets, clearly shown as a whole in Figure 1 and indicated by number 100, comprising the punching unit as described above.

[0038] Practically, it has been established that the invention achieves the intended task and objects.

[0039] Specifically, with the invention, a transmission unit has been developed whose maximum speed of rotary motion that it is able to handle without loss of contact between the moving unit and the yielding unit during cam rotation is greater than similar transmission units of known type.

[0040] In addition, a transmission unit was developed in which the dynamics of the transmitted reciprocating rectilinear motion is affected by less variation over time than similar transmission units of a known type.

Claims

1. Transmission unit (10), comprising: - a moving unit (20) comprising a drive shaft (21) rotatably supported by a frame (11) along a rotation axis (X), said moving unit (20) comprising at least one cam (22) attached to said drive shaft (21) on a plane orthogonal to said rotation axis (X); - a yielding unit (30) comprising a translating body (31) slidably supported by said frame (11) along a translation axis (Y), said translating body (31) defining at least a first contact surface (31a) kinematically coupled to said cam (22) by sliding in such a way that rotation of the head (22a) of said cam (22) towards said first surface (31a) causes a translation of said translating body (31) along said translation axis (Y), in a direction opposite to said rotation axis (X); said yielding unit (30) comprising at least one recall profile (32) attached to said translating body (31), said profile (32) defining at least a second contact surface (32a) opposed to said first surface (31a) and kinematically coupled to said cam (22) by sliding in such a way that the rotation of the head (22a) of said cam (22) towards said second surface (32a) causes a translation of said translating body (31) along said translation axis (Y) towards said rotation axis (X); characterised in that said profile (32) is C-shaped with a base (32b) on which said second surface (32a) is defined and a pair of wings (32c, 32d) whose free ends (33) are attached to said translating body (31) at said first surface (31a).

2. Transmission unit (10) according to claim 1, characterised in that said rotation axis (X) and said translation axis (Y) are orthogonal to each other and incidental.

3. Transmission unit (10) according to claim 1 or 2, characterised in that said first surface (31a) and said second surface (32a) are spaced apart from each other parallel to said translation axis (Y) by a distance (d) equal to the length of the segment joining said head (22a) and the base (22b) of said cam (22).

4. Transmission unit (10) according to any one of the preceding claims, characterised in that said cam (22) is circular.

5. Transmission unit (10) according to claim 4, characterised in that said distance (d) is equal to the diameter of said cam (22).

6. Transmission unit (10) according to any one of the preceding claims, characterised in that it comprises a plurality of cams (22).

7. Transmission unit (10) according to claim 6, characterised in that each of said plurality of cams (22) is attached to said drive shaft (21) at the same angle about said rotation axis (X).

8. Punching unit, characterised in that it comprises: - a transmission unit (10) according to any one of the preceding claims; - a punch (40) attached to said translating body (31) and configured to translate parallel to said translation axis (Y) between a retracted position and an operating position, and vice versa; - a die (50) opposed to said punch (40) and shaped to accommodate said punch (40) in said operating position.

9. Creasing machine (100), characterised in that it comprises the punching unit according to claim 8.

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