SE540328C2

SE540328C2 - A guide roller assembly and a roller guide

Info

Publication number: SE540328C2
Application number: SE1651367A
Authority: SE
Inventors: Mårstedt Peter; Sachse Sebastian; Sahlin Carl
Original assignee: Morgaardshammar Ab
Priority date: 2016-10-19
Filing date: 2016-10-19
Publication date: 2018-06-26
Also published as: SE1651367A1; WO2018074968A1

Description

A guide roller assembly and a roller guide TECHNICAL FIELD The invention relates to a guide roller assembly for a roller guide configured to guide stock in a longitudinal feeding direction toward a pair of rolls for shaping the stock according to the preamble of claim 1 , and to a roller guide comprising a pair of such guide roller assemblies. In particular, the invention relates to a guide roller assembly and a roller guide for use in the production of wire, rods and beams.

BACKGROUND AND PRIOR ART Roller guides are commonly used for guiding hot stock, such as wire stock or rod stock, in rolling mills. Primarily, roller guides are placed before a pair of rolls used to shape the stock, so called entry roller guides. These roller guides guide the stock which is to be rolled toward a particular rolling groove. The use of roller guides reduces the risk of damaging the stock upon entry between the pair of rolls and enables feeding the stock at high feeding rates.

A roller guide comprises a pair of guide roller assemblies, each having an axle configured to be supported at its ends in a frame arrangement, and a roller rotationally mounted on the axle. The roller has an outer surface engagable with the stock, and is mounted on the axle by means of one or more bearing assembly/assemblies located between the roller and the axle. Typically, the outer surface of the roller is rounded and concave, such that it contacts the stock along a curved line. The roller is made from a thick piece of metal, typically steel, by means of e.g. powder metallurgy and/or machining. Since the guide roller assemblies are subjected to large forces when the stock enters between them, the rollers have to be robust and resistant to wear.

Recent efforts have been made to reduce the impact forces acting on the guide roller assemblies as stock enters between the rollers, as described in the co-pending patent application with publication number WO 2016/099370. The roller guide for this purpose comprises means for adjusting the distance between the rollers as it is detected that a piece of stock is approaching, putting the rollers in a favourable position for receiving the stock. However, even though the impact forces acting on the guide roller assembly are thereby reduced, the tool life is still limited by the heavy loads on the bearing assembly or assemblies caused by the large moment of inertia of the rollers.

SUMMARY OF THE INVENTION An objective of the present invention is to provide a guide roller assembly which is in at least some aspect improved with respect to previous guide roller assemblies. In particular, it is an objective to provide a guide roller assembly with an improved tool life. Another objective is to provide an in at least some aspect improved roller guide.

At least the first objective is achieved by means of the initially defined guide roller assembly, wherein an annular empty space extends between the bearing assemblies, delimited in a radial direction by on one hand the axle and on the other hand an inner surface of the roller, said empty space having a radial extension which is at least as large as a wall thickness of the roller.

The guide roller assembly according to the invention has a roller with a relatively thin wall and an annular empty space extending between the roller and the axle. Moving from any point on the axle and outward in the radial direction, the extension of the empty space traversed is at least as large as the wall thickness. The guide roller assembly is thus partly hollow. This reduces the total weight of the guide roller assembly and the amount of material needed to form the roller significantly in comparison with known guide roller assemblies having thick-walled rollers. The moment of inertia of the roller is thereby reduced, so that the roller can be more easily accelerated. The acceleration is therefore faster than for conventional rollers, which minimizes wear on the guide roller assembly as well as damages caused on that part of the stock that is in contact with the rollers during acceleration, i.e. the first end of the stock. The reduced moment of inertia also makes the guide roller assembly respond faster to changes in applied forces.

The relatively thin wall makes the guide roller assembly particularly useful in roller guides having means for reducing the impact force exerted on the guide roller assemblies as stock enters between the rollers, such as described in WO 2016/099370. However, the guide roller assembly can also be useful in other types of roller guides, in which the roller guides do not comprise means for reducing the impact force from the stock, depending on e.g. the dimension of the stock.

Each bearing assembly comprises a set of rolling elements arranged between an inner race fixed for common rotation with the axle and an outer race fixed for common rotation with the inner surface of the roller. The rolling elements can be e.g. rollers or balls.

The roller can be manufactured by means of e.g. additive manufacturing or hydroforming. Hydroforming is suitable for production of large series, in which case cost efficient manufacturing can be achieved. If instead additive manufacturing is used, the roller can be made with tailored walls having an internal structure such as e.g. a honeycomb structure or similar. The roller can also be made with walls of at least two different materials, such as with an inner layer of a first material and an outer layer of a second material, or with a portion holding the bearing assemblies made of a first material and a portion for guiding stock made of a second material. The roller can be constructed such that it has properties that vary along the roller. For example, by creating a non-homogeneous internal structure and/or by using different wall materials within roller, the wear resistance and hardness of the roller can be tailored. The roller can also be hardened during the additive manufacturing process.

The roller can also be provided with a coating of a different material than a base material of the roller, such as a wear resistant coating applied on a tough base material.

According to one embodiment of the invention, the wall thickness of the roller is less than 15 % of a largest outer diameter of the roller, preferably less than 10 %. The largest outer diameter is typically measured at an end of the roller.

According to one embodiment of the invention, the wall thickness of the roller is less than 20 % of a smallest outer diameter of the roller, preferably less than 15 %. The smallest outer diameter of the roller is measured at a waist of the roller.

According to one embodiment of the invention, the radial extension of the empty space increases from an axial midpoint of the guide roller assembly and toward its ends. The inner surface of the roller thus roughly follows the outer surface, since the outer surface is formed with a waist so as to receive the guided stock. The wall thickness may vary slightly along the roller, but is preferably relatively homogenous.

According to one embodiment of the invention, an inner ring formed with an inner race of said at least one bearing assembly is mounted around the axle. The inner ring can be suitably formed so as to achieve desired properties of the bearing assembly. Preferably, the guide roller assembly comprises such an inner ring on each opposite end of the guide roller assembly, so that the guide roller assembly is mirror symmetric with respect to an axial midplane of the roller.

According to one embodiment of the invention, the inner surface of the roller comprises a contact surface configured as an outer race of one of said bearing assemblies. Preferably, the inner surface is formed with such a contact surface on each opposite end of the guide roller, so that the guide roller is mirror symmetric with respect to an axial midplane. By including the outer races in the inner surface of the roller, the need for a separate outer ring is eliminated, thus reducing the complexity of the guide roller assembly and making it more robust.

According to one embodiment of the invention, an outer ring formed with an outer race of said at least one bearing assembly is mounted on the inner surface of the roller. Pre-fabricated bearing assemblies can thus be used, comprising both an inner ring, an outer ring and a set of rolling elements.

According to one embodiment of the invention, the bearing assemblies are in the form of angular contact ball bearing assemblies, groove ball bearing assemblies, or tapered roller bearing assemblies. These bearing assemblies are designed to accommodate combined loads, i.e. simultaneously acting radial and axial loads and are therefore suitable for this application. Alternatively, other types of bearing assemblies that can accommodate combined loads can be used.

According to one embodiment of the invention, the outer surface of the roller is V-shaped. Thus, the roller has the appearance of an upper and a lower truncated cone, wherein the lower truncated cone is a mirror image of the upper. The V-shape enables use of the same guide roller assembly to guide stock of different dimensions, since two points of contact between the stock and the outer surface will always be provided. If instead a rounded concave outer surface is provided, the roller is adapted to guide stock of a particular dimension.

According to one embodiment of the invention, the guide roller assembly further comprising at least one compression spring means acting in the axial direction. The spring means provides preloading for the bearing assemblies and can be in the form of a spring washer or similar.

According to one embodiment of the invention, the axle comprises two parts which are releasably connected and which extend away from each other in the axial direction. The two parts can e.g. be connected by means of a threaded joint or by another suitable connection.

The other objective mentioned above is achieved by means of a roller guide configured to guide stock in a longitudinal feeding direction toward a pair of rolls for shaping the stock, comprising: - a pair of the proposed guide roller assemblies, wherein the rollers are configured to, in a closed position, engage opposite surface portions of the stock, and - a frame arrangement in which the axles of the guide roller assemblies are supported at their ends.

Advantages and advantageous features of such a roller guide appear from the above description of the proposed guide roller assembly.

According to one embodiment of the invention, the roller guide further comprises force adjustment means for adjusting a force exerted on the guided stock during operation of the roller guide. The force exerted on the stock by the rollers can thereby be varied during operation, e.g. so as to apply a larger force as the stock enters between the rollers, and thereafter reduce the applied force. This reduces the wear on the roller guide and improves its tool life.

According to one embodiment of the invention, the roller guide further comprises detection means configured to detect a longitudinal position of a piece of stock with respect to the guide roller assemblies, and a positioning means configured to adjust a lateral distance between the guide roller assemblies in response to said detection. It is thus possible to automatically adjust the distance between the guide rollers during operation of the roller guide. This enables a reduction of the forces applied to the guide roller assemblies as the stock enters there between. The tool life of the guide roller assemblies can thereby be increased. Since the guide roller assemblies are partly hollow, the total weight of the guide roller assemblies is significantly reduced in comparison with known guide roller assemblies having thick-walled rollers. The moment of inertia of the roller is also reduced, and thereby the load exerted on the bearing assembly upon acceleration of the roller, which improves the tool life of the bearing assemblies. By the combination of the light-weight guide roller assemblies and the possibility to adjust the distance between the guide roller assemblies as a piece of stock is detected, an energy efficient guiding of stock can be achieved. Moreover, the low weight and the low moment of inertia of the guide roller assemblies allows quick adjustments of the position of the guide roller assemblies in response to the detection of a piece of stock. The roller guide thus enables cost and energy savings.

Other advantageous features as well as advantages of the present invention will appear from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will in the following be further described by means of example with reference to the appended drawings, wherein Fig. 1 schematically shows a guide roller assembly according to a first embodiment of the invention, Fig. 2 shows a cross section of the guide roller assembly in fig. 1 , Fig. 3 shows an exploded view of the guide roller assembly in fig. 1 , Fig. 4 shows a partial cross section of a guide roller assembly according to a second embodiment, Fig. 5 shows a cross section of a guide roller assembly according to a third embodiment, Fig. 6 shows a cross section of a guide roller assembly according to a fourth embodiment, and Fig. 7 shows a roller guide according to an embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION A guide roller assembly 101 for guiding stock according to a first embodiment of the invention is schematically shown in figs. 1-3 and a guide roller assembly 201 according to a second embodiment on the invention is schematically shown in fig. 4. In both embodiments, the guide roller assembly 101 , 102 has an axle 102, 202 extending in an axial direction along an axis of rotation C. The axle 102, 202 has a first end 103, 203 and a second end 104, 204 at which the axle 102, 202 is configured to be supported in a frame arrangement 2 of a roller guide 1 such as shown in fig.

. A roller 105, 205 is rotationally mounted on the axle 102, 202. The roller 105, 205 has an outer surface 106, 206 which is to be engaged with a surface portion of stock being guided. The roller 105, 205 further has an inner surface 107, 207 so that the roller is formed with a wall thickness t. An empty space is provided between the axle 102, 202 and the inner surface 107, 207 of the roller 105, 205. The radial extension of the empty space is at least as large as the wall thickness t of the roller 105, 205. In the axial direction, the empty space extends between two axially separated bearing assemblies 108, 208 located between the roller 105, 205 and the axle 102, 202. The bearing assemblies 108, 208 are positioned near opposite ends 103, 104, 203, 204 of the axle 102, 202. The radial extension of the empty space is largest near the bearing assemblies 108, 208 and is smaller at an axial midpoint of the guide roller assembly 101 , 201.

The outer surface 106, 206 of the roller 105, 205 is V-shaped, so that the roller 105, 205 has the appearance of an upper and a lower truncated cone, wherein the lower truncated cone is a mirror image of the upper one. In the shown embodiments, an upper part of the outer surface 106, 206 and a lower part of the outer surface 106, 206 form an angle a of 140° with each other. This angle a may of course vary depending on the intended application of the guide roller assembly 101 , 201. It is also possible to make the outer surface concave with a rounded shape. The guide roller assembly 101 , 201 has a height h in the axial direction and a largest outer diameter D in the radial direction, as measured at an end 103, 104, 203, 204 of the roller 105, 205. The guide roller assembly further has a smallest outer diameter d as measured at the axial midpoint of the roller 105, 205.

In the embodiment shown in figs. 1-3, each bearing assembly 108 is in the form of a ball bearing assembly having an inner ring 109 attached to the axle 102 and a tapered outer ring 110 attached to the roller 105. Rolling elements 111 , here in the form of balls, are provided between the rings 109, 110. The rolling elements 111 are in contact with on one hand an inner race 112 provided on the inner ring 109, and on the other hand with an outer race 113 provided on the outer ring 1 10. Other types of bearing assemblies can be used, such as tapered roller bearing assemblies or angular contact ball bearing assemblies.

At each end 103, 104 of the axle 102, an annular recess 114 is formed in the axle 102. In each recess 114, a spring washer 115 is provided which is in contact with on one hand a protruding surface of the axle 102, and on the other hand with an end surface of the inner ring 109. The spring washer 115 thereby acts as a compression spring means preloading the bearing assembly 108.

In the guide roller assembly 201 according to the second embodiment of the invention, each of the bearing assemblies 208 comprises an inner ring 209 on which an inner race 212 of the bearing assembly 208 is provided. However, the guide roller assembly 201 according to this embodiment does not comprise an outer ring. Instead, an outer race 213 in the form of an annular and rounded contact surface is provided directly on the inner surface 207 of the roller 205. Rolling elements 211 in the form of balls are provided between the inner race 212 and the outer race 213. The all thickness t varies slightly along the roller such as to form the outer race 213 and accommodate the rolling elements 211. The bearing assemblies 208 are in the form of angular contact ball bearing assemblies. The inner race 212 is therefore axially slightly displaced with respect to the outer race 213 and is positioned closer to the respective proximate end 203, 204 of the guide roller assembly 201 than the outer race 213.

In the second embodiment, the axle 202 is formed from a first part 202a and a second part 202b which are releasably connected by means of e.g. a threaded joint 214 formed at a midpoint of the axle 202 in the axial direction. Each part 202a, 202b extends away from the threaded joint 214 in the axial direction toward the ends 203, 204 of the axle 202. At each end 203, 204, an annular seal 215 is provided. A spring washer similar to the spring washer 115 used in the first embodiment may be provided to preload the bearing assembly, either combined with the seal 215 or mounted between the seal 215 and the end 203, 204.

A guide roller assembly 201 according to a third embodiment is shown in fig. 5. The guide roller 201 assembly is similar to the second embodiment and similar reference numerals have therefore been used. The guide roller assembly according to the third embodiment differs from the second embodiment in that the rolling elements 211 are rollers, so that the rolling bearing assembly 208 is a tapered roller bearing assembly. The outer race 213 is here provided on the inner surface 207 of the roller 205, but may also be provided on a separate outer ring similar to that in the first embodiment. In case the outer race 213 is provided on the inner surface 207 of the roller 205, a small indentation may be formed in the inner surface 207 for this purpose. The guide roller assembly further differs in the design of the axle 202. At each end 203, 204, a cavity 216 having the shape of a truncated cone is provided for mounting the guide roller assembly 201 as will be further described below. The axle 202 is further provided with conduits 219 for conducting or holding lubricant during operation.

A guide roller assembly 201 according to a fourth embodiment is shown in fig. 6. The guide roller assembly 201 is similar to the second embodiment and similar reference numerals have therefore been used. The guide roller assembly according to the fourth embodiment differs from the second embodiment in that the axle 202 has a design similar to that of the third embodiment, with a cavity 216 provided at each end 203, 204 of the axle 202. A mounting member 217 is provided at each end, which mounting member 217 has a truncated conical part 218 adapted to engage with the cavity 216 such as to hold the axle 202. The mounting member 217 is configured to be screwed onto an arm holding the guide roller assembly 201. By untightening the screws at each end 203, 204, the parts 218 are brought out of engagement with the cavities 216 and the guide roller assembly 201 can be removed from the arm. Conduits 219 for conducting or holding lubricant during operation are provided in the axle 202.

As stock enters between a pair of guide roller assemblies 101 , 201 as described with reference to fig. 1-6 above, the stock may impart both radial and axial forces to the guide roller assemblies 101 , 201 depending on the movement of the stock. For example, if the stock tends to move in an upward direction, an axial force is imparted to the roller 105, 205 and is via the bearing assemblies 108, 208 transmitted to the axle 102, 202 and therefrom to a frame arrangement holding the guide roller assembly 101 , 201.

A schematic illustration of a roller guide 1 according to an embodiment of the present invention is shown in fig. 7. The roller guide 1 is intended for guiding stock 20 in a longitudinal feeding direction A in a rolling mill, primarily toward a pair of rolls for shaping the stock 20. The roller guide 1 comprises a frame arrangement 2 and a pair of guide roller assemblies 3, 4 according to the invention, each guide roller assembly 3, 4 being mounted on an arm 5, 6 of the frame arrangement 2. The arms 5, 6 are pivotable and movable such that a lateral distance, i.e. the distance as measured in a direction perpendicular to the feeding direction A, between the guide roller assemblies 3, 4 can be adjusted. The rollers of the guide roller assemblies 3, 4 are rotatable about parallel axes of rotation perpendicular to the longitudinal feeding direction A and to the lateral direction. In this embodiment, the rollers of the guide roller assemblies 3, 4 are formed with a rounded concave outer surface. A control unit 7 is provided, in which positioning means for adjusting the lateral distance between the guide roller assemblies 3, 4 by means of moving and pivoting the arms 5, 6 can be provided, as well as force adjustment means for adjusting the force exerted by the rollers on the stock 20. The roller guide further comprises a primary guiding means configured to guide the stock 20 toward the guide roller assemblies 3, 4. In the shown embodiment, the primary guiding means comprises an entry funnel 9 and two laterally adjustable guiding parts 10, 11. The control unit 7 may be used to control also the primary guiding means.

Detection means (not shown) for detecting that a first end 20a of the stock 20 is approaching the guide roller assemblies 3, 4 can be provided on the inside of one of the guiding parts 10, 11. The guide roller assemblies 3, 4 are positioned after the primary guiding means in the longitudinal feeding direction A. The control unit 7 may comprise positioning means (not shown) for moving the guide roller assemblies 3, 4 and adjustment means (not shown) for adjusting the position of the guiding parts 10, 11 of the primary guiding means.

As long as no stock is detected between the guide roller assemblies 3, 4, the guide roller assemblies 3, 4 may be held in an open position in which the lateral distance between the rollers is sufficiently large to allow free passage of the first end 20a of the stock 20 between the guide roller assemblies 3, 4 without physical interaction with the rollers. If the roller guide comprises detection means, the guide roller assemblies 3, 4 are moved from the open position to a closed position as it is detected that the first end 20a of the stock 20 has entered between the rollers. In the closed position, the lateral distance between the rollers has been reduced so that the rollers press on opposite surface portions of the stock 20 and thereby guide it toward the pair of rolls. When the detection means does no longer detect the stock 20 between the guide roller assemblies 3, 4, the guide roller assemblies 3, 4 are again moved to the open position, ready to receive and guide another piece of stock.

If the roller guide does not comprise detection means, the guide roller assemblies 3, 4 may be held in the closed position before entry of the first end 20a of the stock 20 between the rollers. As the stock has entered between the rollers, the force adjustment means can be used to adapt the force applied by the rollers.

The invention is of course not in any way restricted to the embodiments described above, but many possibilities to modifications thereof would be apparent to a person with skill in the art without departing from the scope of the invention as defined in the appended claims. For example, the guide roller assembly may have any combination of the shown axles and bearing assemblies.

Claims

1. . A guide roller assembly (3, 4, 101 , 201 ) for a roller guide (1 ) configured to guide stock (20) in a longitudinal feeding direction (A) toward a pair of rolls for shaping the stock (20), the guide roller assembly (3, 4, 101 , 201 ) comprising: - an axle (102, 202) extending in an axial direction perpendicular to the longitudinal feeding direction, configured to be supported at its ends (103, 104, 203, 204), - a roller (105, 205) rotationally mounted on the axle (102, 202) and having an outer surface (106, 206) engagable with a surface portion of the stock (20), - two axially separated bearing assemblies (108, 208) located between the roller (105, 205) and the axle (102, 202), characterised in that an annular empty space extends between the bearing assemblies (108, 208), delimited in a radial direction by on one hand the axle (102, 202) and on the other hand an inner surface (107, 207) of the roller (105, 205), said empty space having a radial extension which is at least as large as a wall thickness (t) of the roller (105, 205).

2. The guide roller assembly according to claim 1 , wherein the wall thickness (t) of the roller (105, 205) is less than 15 % of a largest outer diameter (D) of the roller (105, 205), preferably less than 10 %.

3. The guide roller assembly according to claim 1 or 2, wherein the wall thickness (t) of the roller (105, 205) is less than 20 % of a smallest outer diameter (d) of the roller (105, 205), preferably less than 15 %.

4. The guide roller assembly according to any one of the preceding claims, wherein the radial extension of the empty space increases from an axial midpoint of the guide roller assembly (3, 4, 101 , 201 ) and toward its ends (103, 104, 203, 204).

5. The guide roller assembly according to any one of the preceding claims, wherein an inner ring (109, 209) formed with an inner race (112, 212) of said at least one bearing assembly (108, 208) is mounted around the axle (102, 202).

6. The guide roller assembly according to any one of the preceding claims, wherein the inner surface (207) of the roller (205) comprises a contact surface configured as an outer race (213) of one of said bearing assemblies (208).

7. The guide roller assembly according to any one of claims 1-5, wherein an outer ring (110) formed with an outer race (113) of said at least one bearing assembly (108) is mounted on the inner surface (107) of the roller (105).

8. The guide roller assembly according to any one of the preceding claims, wherein the bearing assemblies (108, 208) are in the form of angular contact ball bearing assemblies, groove ball bearing assemblies, or tapered roller bearing assemblies.

9. The guide roller assembly according to any one of the preceding claims, wherein the outer surface (106, 206) of the roller (105, 205) is V-shaped.

10. The guide roller assembly according to any one of the preceding claims, further comprising at least one compression spring means (115) acting in the axial direction.

11. The guide roller assembly according to any one of the preceding claims, wherein the axle (202) comprises two parts (202a, 202b) which are releasably connected and which extend away from each other in the axial direction.

12. A roller guide (1 ) configured to guide stock (20) in a longitudinal feeding direction (A) toward a pair of rolls for shaping the stock (20), comprising: - a pair of guide roller assemblies (3, 4, 101 , 201 ) according to any one of the preceding claims, wherein the rollers (105, 205) are configured to, in a closed position, engage opposite surface portions of the stock (20), and - a frame arrangement (2) in which the axles (102, 202) of the guide roller assemblies (3, 4, 101 , 201 ) are supported at their ends (103, 104, 203, 204).

13. The roller guide according to claim 12, further comprising force adjustment means for adjusting a force exerted on the guided stock (20) during operation of the roller guide (1 ).

14. The roller guide according to claim 13, wherein the roller guide (1 ) further comprises detection means configured to detect a longitudinal position of a piece of stock (20) with respect to the guide roller assemblies (3, 4, 101 , 201 ), and a positioning means configured to adjust the lateral distance between the guide roller assemblies (3, 4, 101 , 201 ) in response to said detection.