Self-centering device for supporting and guiding a bar

Abstract

A self-centering device (10) for supporting and guiding a bar (B) to be fed to a machine tool, comprising: - a guide body (20) having a through hole (22), rotatably supported and rotating in a controlled manner about an axis (X) perpendicular to the direction of travel (D) of the bar (B) to be guided, to vary its angular orientation about the axis (X); the guide body (20) being configured for receiving and holding in position the rotating and travelling bar (B), - a return member (40) configured for an appropriate preselectable resistance to the rotation of the guide body (20) about said axis (X), so as to maintain the solid coupling and contact of the guide body (20) with the travelling bar (B), - a manual selector member (60; 90) configured for adjusting the position of the guide body (20) and controlling the angular movement thereof. The manual selector member (60; 90) comprises a screw device (66, 70; 92) cooperating with a vibration limiting element (62; 94) to set the angular rest position (36) of the guide body (20) according to the geometry of the bar (B) to be received and guided to said machine tool.

Description

Technical Field

[0001] The present invention relates to a self-centering device for supporting and guiding a bar stock that must be fed into the spindle of a machine tool (single-spindle and multi-spindle types). Background Technology

[0002] In the machine tool industry, it is known to use devices to center, support, and guide bar stock to be processed. These bar stock are subjected to vibration and impact during feeding (e.g., on the spindle of a lathe).

[0003] The function of a centering device is to attempt to reduce the vibration of these bars and correct their positioning, or it is often used for metal semi-finished products with slender shapes (such as tubes).

[0004] Some embodiments of the centering device are known from EP0213659 and EP0485902 in the name of the applicant.

[0005] The high rotational speeds of modern lathes (which can reach tens of thousands of revolutions per minute or higher) mean that current centering devices are not particularly effective in guiding and keeping the bar stock in an axially aligned position, as the bar stock also rotates around its longitudinal axis during the feed process.

[0006] In other words, the static centering effect provided by the aforementioned known devices appears to be very mild and insufficient to compare with the significant stresses experienced by the bar due to minor eccentricity or bending.

[0007] Improper guidance and centering can lead to bar impacts, often causing surface damage, as well as significant wear and noise in the feed system. Some solutions include guide bushings, which internally house the traveling bar.

[0008] The bar stock typically rotates around its own longitudinal axis and contacts the cylindrical surface of the bushing, which attempts to hold the bar stock in place and axially aligned on the spindle of the machine tool.

[0009] The centering device, especially the aforementioned bushing, must be able to support and guide bars of different diameters. For various reasons, it is inconvenient and expensive to change the bushing each time it is fed according to the diameter of the bar.

[0010] In order to meet this need, the applicant has previously proposed a centering device disclosed in EP0689890.

[0011] The known centering device includes an idle rotating annular guide element that is oriented at an angle relative to the bar.

[0012] The annular guide element is pushed to adhere to the rod at a point with opposite diameters. The rod is oriented and rotated by a suitable actuator, thus applying a dynamic centering effect to the rod.

[0013] Due to the dynamic centering effect on the bar, similar centering devices can significantly reduce wear and noise problems caused by the impact of the bar; however, the angle orientation of the annular guide element needs to be adjusted according to the diameter of the bar to be centered each time, thus requiring operator intervention. Furthermore, the device has a rather complex structure and requires connection to a suitable power source for the operation of the actuator of the centering device.

[0014] Furthermore, the large size of the device described above, which makes the structure it is paired with heavy, also negatively impacts the overall operation of the loading and supply system.

[0015] The enormous structural and functional complexity of the device inevitably implies an unsatisfactory level of mechanical reliability and an increase in overall cost.

[0016] An example of a centering device is known from EP0689890.

[0017] Based on the above description and taking into account the aforementioned limitations, sufficient reasons have been found to improve the existing bar centering device. Summary of the Invention

[0018] One object of the present invention is to improve the current centering device for feeding bars into machine tools.

[0019] Another object of the present invention is to improve upon current centering devices by providing a self-centering device that is highly versatile and easily adaptable to and compatible with available loading systems.

[0020] Another object of the present invention is to provide a lighter and more compact self-centering device.

[0021] Another object of the present invention is to provide a self-centering device that is much simpler in structure and function than current centering devices, and therefore has greater mechanical reliability.

[0022] The above is achieved by the self-centering device as defined in the claims.

[0023] The present invention overcomes the above-mentioned disadvantages.

[0024] In particular, the device according to the invention has a very simple structural configuration, enabling great versatility and improving the adaptability and effectiveness of the device. Attached Figure Description

[0025] Referring to the accompanying drawings, further features and advantages will become clear from the following description, wherein:

[0026] Figure 1 This is an exploded perspective view of the device according to the present invention;

[0027] Figure 2 It shows Figure 1 Details;

[0028] Figure 3 This is a rear view of the device according to the present invention;

[0029] Figure 4 A longitudinal section of the device according to the invention is shown;

[0030] Figure 5 This is a longitudinal section of the device according to the present invention in a stationary position;

[0031] Figure 6 It is a longitudinal section of the device in the operating position, wherein the device is connected to the bar.

[0032] Figure 7 It is another longitudinal section of the device in another operating position, wherein the device is smaller than a certain diameter. Figure 6 Bar connection under certain conditions;

[0033] Figure 8 This is a side view of the device in its working state;

[0034] Figure 9 This is a side view of another embodiment of the device according to the present invention;

[0035] Figure 10 yes Figure 9 A bottom view of the device shown;

[0036] Figure 11 They are in different operating positions. Figure 9 An enlarged side view of a part of the device;

[0037] Figure 12 Is with Figure 11 Same view, but the device is in a different operating position corresponding to a bar with a larger diameter. Detailed Implementation

[0038] Referring to the accompanying drawings, a self-centering device 10 for supporting and guiding bar stock B, third bar stock B1, and fourth bar stock B2 to be fed into a machine tool (e.g., a lathe) is disclosed in more detail below. In this text, we distinguish between general bar stock B and third bar stock B1 and fourth bar stock B2, wherein third bar stock B1 has a smaller diameter than fourth bar stock B2.

[0039] The self-centering device 10 is suitable for installation on a bar loading device, and its function is to supply bars to the lathe.

[0040] The self-centering device 10 according to the invention includes a guide body 20 having a through hole 22 configured to receive and hold rods B, B1, and B2 in place, which rotate and move along a travel direction D to the lathe. The supported guide body 20 is rotatably supported and rotates in a controlled manner about an axis X perpendicular to the travel direction D of the rods B, B1, and B2, thereby achieving an appropriate angular orientation based on the diameter of the latter rods.

[0041] More precisely, the guide body 20 includes a support portion 24, which is shaped to define a through hole 22 for allowing the passage of the bar B, the third bar B1, and the fourth bar B2, which move along the direction of travel D.

[0042] The through-hole 22 is defined by an expanded surface 28 obtained at one end E of the guide body 20; the rods B, the third rod B1, and the fourth rod B2 penetrate the end E inside the through-hole 22. The expanded surface 28 is shaped to facilitate the entry and reception of the rods B, the third rod B1, and the fourth rod B2.

[0043] The guide body 20 also includes an anti-friction element 26, which defines at least a portion of the inner surface of the through hole 22. The anti-friction element 26, together with the ball bearing 27, functions to reduce friction in the reciprocating contact between the rods B, the third rod B1, the fourth rod B2 and the guide body 20.

[0044] The self-centering device 10 also includes a return member 40, a first manual selector member 60, and a second manual selector member 90, which control the angular movement of the guide body 20 around the aforementioned rotation axis X.

[0045] Specifically, the return component 40 performs the function of moving the guide body 20 to the angular rest position before receiving bar B, the third bar B1, and the fourth bar B2. As will be explained in more detail below, this process is necessary to perform holding and centering functions on the bar B, the third bar B1, and the fourth bar B2 to be fed to the machine tool.

[0046] The return component 40 and the first manual selector component 60 and the second manual selector component 90 mate with the support structures 14 and 16, which are adapted to mate sequentially with the bar feed device. The support structures 14 and 16 are formed by a first bracket and a second bracket. Both the first and second brackets are provided with connecting elements 17, which, once the brackets are fixed to each other, cooperate to define tubular travel paths for bar B, the third bar B1, and the fourth bar B2. The first bracket is fixed to the second bracket by inserting a fixing screw device 18 into a connecting hole 19 formed in the connecting element 17 of the second bracket. Once inserted, the fixing screw device 18 is fixed in a seat 13 obtained on the connecting element 17 of the first bracket.

[0047] In one possible embodiment, as seen in the accompanying drawings, the return member 40 is fitted to the first bracket, while the first manual selector member 60 and the second manual selector member 90 are fitted to the second bracket.

[0048] The return member 40 is configured to resist rotation of the guide body 20 about axis X with suitable preselectable resistance, thereby maintaining the connection and contact between the guide body 20 and the traveling bars B, the third bar B1, and the fourth bar B2.

[0049] The return member 40 includes an elastic element 42 configured to resist a reverse rotational force on the guide body 20 to keep the rod B, the third rod B1, and the fourth rod B2 rotating in the correct position.

[0050] Specifically, the elastic element 42 includes a helical torsion spring having a first end 43 and a second end 44. The first end 43 is fixedly engaged with the support structures 14, 16, particularly with the first bracket, while the second end 44 is operably connected to the guide 20 via coupling and adjusting devices 46, 56, 58.

[0051] The connecting and adjusting devices 46, 56, and 58 include a hollow connecting element 56 and an adjusting arm 46 mating with the hollow connecting element 56. The adjusting arm 46 is configured to select the magnitude of the elastic return force applied by the torsion spring. On the adjusting arm 46, a connecting seat 48 for the second end 44 of the spring and a seat 52 accommodating a releasable fixing and adjusting screw 54 are provided, through which the position of the adjusting arm 46 around the hollow connecting element 56 can be adjusted to increase or decrease the return force applied by the torsion spring in a desired manner.

[0052] Hollow connecting element 56 extends through a through-hole obtained in adjusting arm 46 and through a torsion spring. Hollow connecting element 56 is shaped to be integrally connected to a protrusion 30 of guide body 20 by a screw device, which engages with seat 15 of support structures 14, 16.

[0053] The first manual selector component 60 and the second manual selector component 90 are configured to adjust the position and control the angular movement of the guide body 20. More precisely, the first manual selector component 60 and the second manual selector component 90 include screw devices that cooperate with vibration limiting elements to set the angular rest position 36 of the guide body 20 according to the geometry of the bars B, the third bar B1, and the fourth bar B2 to be received and guided to the machine tool.

[0054] According to the first embodiment, the limiting element included in the first manual selector member 60 includes an adjustment plate 62, which is applied to the support structures 14, 16, particularly the second bracket. The plate 62 is configured to limit the vibration of the guide 20 about the axis X.

[0055] The adjusting plate 62 is also hinged to the support structures 14, 16 by means of screw devices 74 that engage with the corresponding holes 72.

[0056] The first manual selector component 60 includes positioning devices 64, 66 to adjust the position of the adjustment plate 62 relative to the support structures 14, 16 and to releasably fix the adjustment plate 62.

[0057] The positioning device includes a mounting screw adapted to be fixedly engaged with holes obtained in the support structures 14, 16. The screw engages with an arched mounting groove obtained in the adjusting plate 62. Once the mounting screw is loosened, the mounting groove allows the position of the adjusting plate to be adjusted relative to the support structures 14, 16.

[0058] Furthermore, a sliding and limiting groove 68 is provided on the adjusting plate 62, which cooperates with the cursor screw 70 connected to and movable with the guide body 20. The positioning of the adjusting plate 62 functions to set the angular rest position 36 of the guide body 20 to the geometry of the bar stock B, the third bar stock B1, and the fourth bar stock B2 to be received and guided to the machine tool. Furthermore, the sliding and limiting groove 68 applies an end-stroke position to the cursor screw 70. The end-stroke position can be changed by altering the position of the adjusting plate 62 acting on the positioning devices 64, 66 relative to the support structures 14, 16.

[0059] The cursor screw 70 is screwed into the receiving seat 34 obtained on the guide body 20 and can slide along the sliding and limiting groove 68. When bar B, third bar B1, and fourth bar B2 are received in the guide body 20, the cursor screw 70 is intended to slide along the sliding and limiting groove 68 between the initial position and the working positions 37, 38, the initial position corresponding to the angular rest position 36, as shown. Figure 5 As shown, working positions 37 and 38 are as follows: Figure 6 and Figure 7As shown, the guide body 20 contacts the rod B, the third rod B1, and the fourth rod B2 from both sides through the elastic force of the return member 40, so as to exert a guiding and centering effect on the latter. Figure 6 and Figure 7 The example illustrates two different operating conditions for the self-centering device 10, corresponding to the different diameters of the third bar B1 and the fourth bar B2. Appropriately positioned spring elements cooperate with a properly positioned adjusting plate 62 to adapt the self-centering device 10 to different operating conditions, particularly the dimensions of the bars B, the third bar B1, and the fourth bar B2, thereby firmly holding the bars B, the third bar B1, and the fourth bar B2 in the correct position during feeding.

[0060] In the case of the third bar B1 with a smaller diameter, the adjusting plate 62 must be positioned to allow for a larger sliding space for the cursor screw 70 within the sliding groove 68. In the case of the fourth bar B2 with a larger diameter, the adjusting plate 62 must be positioned to allow for a smaller sliding space for the cursor screw 70 within the sliding groove 68.

[0061] exist Figure 9-12 In the second embodiment shown, the second manual selector component 90 includes a screw device 92 that engages with a nut element 94, which is integrally connected to and movable together with the guide body 20. The screw device 92 includes an abutment head 91 adapted to rest on a stop portion 95 obtained on the support structures 14, 16. Loosening rotation of the screw device 92 relative to the nut element 94 results in a reduction in the vibration of the guide body 20 about axis X and a reduction in the tilt of the guide body 20 relative to the direction of travel D, to accommodate a fourth bar B2 with a larger diameter, such as... Figure 12 As shown. On the other hand, the turning rotation of the screw device 92 relative to the nut element 94 results in increased vibration of the guide body 20 about the axis X and increased tilting of the guide body 20 relative to the direction of travel D, to accommodate the smaller diameter third rod B1, as shown. Figure 11 As shown.

[0062] The operation of the self-centering device 10 is now disclosed, particularly regarding the feeding of bar B, the third bar B1, and the fourth bar B2 onto the machine tool. Of particular note is the versatility of the self-centering device 10, whose structure has just been disclosed, resulting in numerous advantages over prior art devices.

[0063] Bar B, the third bar B1, and the fourth bar B2 travel along a tubular travel path defined by support structures 14 and 16, while being pushed and held in place by the loading equipment.

[0064] Before rods B, B1, and B2 are received within the through hole 22, the guide body 20 is positioned at an angle α relative to the direction of travel D, such as... Figure 5As shown. The initial tilt of the guide body 20 allows a first contact point to be established between the bar B, the third bar B1, the fourth bar B2, and the guide body 20. Due to this configuration, the self-centering device 10 is also prepared to receive very thin bars, i.e., bars with very small diameters; thus avoiding any risk that bars with very small cross-sections could pass through the guide body 20 without intercepting the inner surface of the guide body 20. In this case, the bar would actually travel into the machine tool without receiving any control action, with undesirable consequences.

[0065] Since the correct initial tilt of the guide body 20 relative to the travel direction D can be set based on the diameter of the bar stock B to be fed to the machine tool, the operating conditions are met every time.

[0066] For example, to better understand how the dimensions of bar B affect the operation of device 10, Figure 6-7 Examples of third bars B1 and fourth bars B2 with different diameters are shown. The inclination of the guide body 20 when feeding the third bar B1 must be greater than that when feeding the fourth bar B2.

[0067] Once a first contact point is established between the surfaces of bar B, third bar B1, fourth bar B2, and through hole 22, guide body 20 rotates about axis X until a second contact point is established between bar B, third bar B1, and fourth bar B2. In this way, self-centering device 10 performs the function of guiding and centering the bars B, third bar B1, and fourth bar B2 to be fed to the machine tool, holding them in the correct axial position. The angular position of guide body 20 relative to the travel direction D varies with the diameter of the supplied bars B, third bar B1, and fourth bar B2. Figure 6 and Figure 7 The comparison shows that when the third bar B1 has a smaller diameter, the guide body 20 has an inclination angle α1, while when the fourth bar B2 has a larger diameter, α1 is greater than angle α2. Therefore, the larger the diameter of the bar B, the closer it is to the diameter of the through hole 22, and the smaller the inclination of the guide body 20 relative to the direction of travel D. In other words, in the case of the fourth bar B2, the guide body 20 is arranged almost parallel to the direction of travel D.

[0068] As can be seen from the description already provided, the self-centering device 10 enables the realization of the objects stated above. In particular, since the present invention provides a universal and easy-to-use self-centering device 10, it can adapt to different operating conditions caused by production settings without slowing down production.

[0069] Due to the synergistic effect of the return member 40 and the first manual selector member 60 and the second manual selector member 90, the self-centering device according to the invention can adapt to different operating conditions, particularly based on the characteristics of the bar stock to be loaded onto the machine tool. Specifically, from a structural and functional perspective, the return member 40 and the first manual selector member 60 and the second manual selector member 90 for controlling the angular movement of the guide body 20 are simple and involve an overall reduction in weight and size. Furthermore, the manual selection methods for preloading the elastic element and for positioning the selective member are highly intuitive and easy to set up.

[0070] Due to the extremely simplified structural configuration of the self-centering device according to the present invention, the mechanical reliability of the entire feeding device is also improved.

[0071] The device 10 can be configured and its dimensions determined in a desired manner according to the application it may be intended for, and the materials used for the device 10 can be selected as needed, provided they are suitable for the specific purpose for which they are intended. Finally, versions and / or additions to the content disclosed and illustrated in the accompanying drawings are possible.

Claims

1. A self-centering device (10) for supporting and guiding a bar stock (B) to be fed into a machine tool, comprising: - A guide body (20), having a through hole (22), is rotatably supported and rotates in a controlled manner about an axis (X) perpendicular to the direction of travel (D) of the rod (B) to be guided, to change its angular orientation about the axis (X), the guide body (20) being configured to receive the rotating and traveling rod (B) and hold it in place. - The return member (40) is configured to provide suitable preselectable resistance to the rotation of the guide (20) about the axis (X), thereby maintaining a firm connection and contact between the guide (20) and the traveling rod (B). - A first manual selector component (60) configured to adjust the position of the guide (20) and control the angular movement of the guide (20), wherein the return component (40) and the first manual selector component (60) are fitted to a support structure (14, 16) suitable for fixing to the bar feed device, and wherein the first manual selector component (60) includes a screw device cooperating with a vibration limiting element to set the angular rest position (36) of the guide (20) according to the geometry of the bar (B) to be received and guided to the machine tool, wherein the limiting element included in the first manual selector component (60) includes an adjusting plate (62) applied to the support. The support structure (14, 16) is configured to limit the vibration of the guide (20) about the axis (X). The first manual selector component (60) includes positioning devices (64, 66) and a sliding and limiting groove (68) obtained on the adjusting plate (62). The positioning devices (64, 66) are used to adjust the position of the adjusting plate (62) relative to the support structure (14, 16) and to releasably fix the adjusting plate (62). The sliding and limiting groove (68) cooperates with a cursor screw (70) connected to the guide (20) and movable with the guide (20) to set the guide (20) according to the geometry of the bar stock (B) to be received and guided to the machine tool. The sliding and limiting groove (68) sets the end travel position of the cursor screw (70) at the angular rest position (36), the end travel position is changed by acting on the positioning device (64, 66) to change the position of the adjusting plate (62) relative to the support structure (14, 16), wherein the return member (40) includes an elastic element (42) configured to resist the reverse rotational force of the guide body to keep the rod (B) in the correct position, the elastic element (42) including a helical torsion spring having a first end (43) and a second end (44), the first end (43) being fixedly engaged with the support structure, and the second end (44) being connected by a coupling A connection and adjustment device (46, 56, 58) is operably connected to the guide (20). The connection and adjustment device (46, 56, 58) includes a hollow connecting element (56) and an adjustment arm (46). The adjustment arm (46) is fitted to the hollow connecting element (56) and configured to select the magnitude of the elastic return force applied by the torsion spring. On the adjustment arm (46), a connecting seat (48) for the second end (44) of the torsion spring and a seat (52) for receiving a releasable fixing and adjusting screw (54) are obtained, through which the position of the adjustment arm (46) around the hollow connecting element (56) can be adjusted to increase or decrease the return force applied by the torsion spring in a desired manner.

2. The self-centering device (10) according to claim 1, wherein, The guide (20) includes a support portion (24) shaped to define the through-hole (22) designed to allow the conveying and receiving of a rod (B) along the direction of travel (D). The through-hole (22) is defined by an expanded surface (28) obtained at an end (E) of the guide (20) adapted to receive the rod (B), the expanded surface (28) being confirmed to facilitate the entry and reception of the rod (B). The guide (20) also includes an anti-friction element (26) defining at least a portion of the inner surface defining the through-hole (22) and configured to reduce friction in reciprocating contact between the rod (B) and the guide (20).

3. The self-centering device (10) according to claim 1, wherein, The hollow connecting element (56) extends through a through hole obtained in the adjusting arm (46) and through the torsion spring. The hollow connecting element (56) is shaped to be integrally connected to the protrusion (30) of the guide (20) by means of a connecting thread, the protrusion (30) engaging the seat (15) of the support structure (14, 16).

4. The self-centering device (10) according to claim 1, wherein, The positioning device includes a setting screw adapted to be fixedly connected to a hole obtained on the support structure (14, 16) and to engage with an arched setting groove obtained on the adjusting plate (62), wherein once the setting screw is loosened, the setting groove allows the position of the adjusting plate (62) to be released relative to the support structure (14, 16).

5. The self-centering device (10) according to claim 1, wherein, The cursor screw (70), which slides along the sliding and limiting groove (68), is screwed into the receiving seat (34) obtained on the guide (20). When the rod (B) is received in the guide (20), the cursor screw (70) is intended to slide along the sliding and limiting groove (68) between an initial position and a working position (37, 38), the initial position corresponding to the angular rest position (36), in which the guide (20) contacts the rod (B) on both sides by the elastic force of the return member (40) to apply a guiding and centering effect on the latter.

6. The self-centering device (10) according to claim 1, wherein, The adjusting plate (62) is hinged to the support structure (14, 16) by a screw device (74) engaging the corresponding hole (72).

7. The self-centering device (10) according to any one of claims 1 to 6, wherein, The guide (20), the return member (40), and the first manual selector member (60) cooperate to form the support structure (14, 16), which consists of a first rod and a second rod configured to be reciprocally connected by a fixed screw device (18) with corresponding connecting holes (19). The first and second rods are semi-circular to define a tubular region, and the rod (B) is designed to travel along the tubular region.

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