A method and an apparatus for grinding metallic materials

Abstract

The embodiments relate to an apparatus for sharpening metallic objects. The apparatus comprises means for holding an object having an actual profile; a grinding tool for grinding the profile of the object; means for providing at least two-dimensional movement for the grinding tool; means for receiving control instructions for moving the grinding tool at least two-dimensionally and for applying grinding force to the grinding tool towards the object, which control instructions have been generated according to a desired profile for the object, wherein the control instructions define grinding paths for the grinding tool to grind the object from the actual profile to the desired profile; and means for controlling the grinding tool according to the control instructions. The embodiments also concern a method.

Description

Technical Field

[0001] The present solution generally relates to grinding of metallic materials. The present solution is applicable for example for sharpening skate blades.Background

[0002] Grinding tools are used for example for grinding metallic, e.g. steel, objects, such as for sharpening skate blades. Skate blade sharpening tools may be manual or partly automatic. In the partly automatic sharpening tools, the user should hold the object to be sharpened, and the automatic grinding is applied to the object under manual monitoring of the progression of the grinding process. This means that the user determines, when the desired profile has been obtained due to grinding.

[0003] Existing sharpening apparatuses use a mechanical copying method to define a profile of a skate blade. Such a method is not flexible when a profile of the blade has to be changed according to different users. Each user has his / her own blade profile in order to get the best performance. Most of the machines on the market are mechanically automated machines where accuracy of sharpening is related to the machine's user (sharpener).

[0004] From WO 2016 / 183663 A1 there is known an apparatus and a method for sharpening metallic blade-like objects as defined in the preambles of the independent claims.Summary

[0005] Various aspects of the present solution include an improved method and an improved apparatus for grinding metallic objects. The present solution is usable for sharpening ice skate blades. The apparatus according to embodiment is able to sharpen skate blades into any pre-defined profile, and thus to give skaters more freedom and eventually better performance on the ice. By making the sharpening and profiling process fully automatic and digital, sharpener's expertise and experience is not a necessity any longer.

[0006] Various aspects concerns a method, an apparatus and a computer readable medium comprising a computer program stored therein, which are characterized by what is stated in the independent claims. Various embodiments are disclosed in the dependent claims.

[0007] According to a first aspect, there is provided an apparatus as defined in claim 1.

[0008] According to an embodiment, the control instructions have been generated by taking into account data concerning a size and / or a deterioration of the grinding tool.

[0009] According to an embodiment, the desired profile indicates more than one zones on the object that are to be grinded differently.

[0010] According to an embodiment, the apparatus further comprises means for determining which zone is to be sharpened and for adjusting grinding force for the grinding tool and for controlling vertical movement of the grinding tool accordingly According to an embodiment, the apparatus further comprises means to control the grinding force.

[0011] According to an embodiment, the apparatus further comprises means for determining the profile of the object.

[0012] According to an embodiment, the apparatus further comprises for comparing the determined profile to the desired profile, and means for generating the control instructions based on the result of the comparison.

[0013] According to an embodiment, the apparatus further comprises means for determining the desired profile from a memory.

[0014] According to an embodiment, the apparatus further comprises means for data transfer.

[0015] According to an embodiment, the apparatus further comprises a processor, a memory and a computer program product stored in said memory, wherein the computer program product comprises code to cause the apparatus to perform a method according to various embodiments.

[0016] According to a second aspect, there is provided a method as defined in claim 11.

[0017] According to an embodiment, the method further comprises determining a size and / or a deterioration of the grinding tool, and generating the control instructions by taking into account the determined size and / or deterioration.

[0018] According to an embodiment, the desired profile indicates more than one zone on the object that are to be grinded differently, whereupon the method comprises determining which zone is to be grinded and adjusting the grinding force of the grinding tool and for controlling the vertical movement of the grinding tool accordingly.Description of the Drawings

[0019] In the following, various embodiments will be described in more detail with reference to the appended drawings, in which Fig. 1shows an example of an ice skate; Fig. 2shows an example of a skate blade as a cross section view; Fig. 3shows an example of a principle of operation of a skate blade; Fig. 4shows a side view of a ice hockey skate blade; Fig. 5shows an example of a two-radius profile; Fig. 6shows different zones of an ice-hockey skate blade; Fig. 7ashows an example of wheel after truing; Fig. 7bshows an example of wheel after dressing; Fig. 8shows a workflow of machine according to an embodiment; Figure 9illustrates an example of creation of data points with a laser; Fig. 10shows an example of a profiling under constant feeding; Fig. 11shows an example of profiling with maximum feeding under force control; Fig. 12shows an idea of the present solution in a simplified manner; Fig. 13shows an example of an implementation of an apparatus according to an embodiment; and Fig. 14is a flowchart illustrating a method according to an embodiment; Fig. 15is an example of sharpening a skate blade with a grinding apparatus; Fig. 16is a flowchart illustrating a method according to an embodiment; and Fig. 17shows a system according to an embodiment. Description of Example Embodiments

[0020] In the following, several embodiments will be described in the context of sharpening skate blades. It is to be noted, however, that the invention is not limited only to sharpening skate blades. In addition to skate blades, other blades acting as a contact point between a person and an ice surface can utilize the present solution. Examples of such blades are blades for speed skating, hockey skating, figure skating, luge, skeleton and bobsled running blades. Yet, in addition, any other blade or head that needs sharpening can be worked by the present solution. Examples of such blades or heads comprise, a knife blade, axe head, etc. In fact, the different embodiments have applications in any solution where grinding of metallic objects is required.

[0021] The present embodiments relate to a grinding apparatus producing accurate two-dimensional profiles on objects by controlling the trajectory of a grinding tool under a passive grinding force control. The passive force control is implemented by a mechanism that controls the grinding force.

[0022] An example of an object is a skate blade, the profile of which is to be grinded by means of the present solution. Figure 1 illustrates an example of an ice skate 100. Ice skates comprise a blade 101 under each foot of the skater. The blade 101 can be removably attached to a shoe of the skater, or the blade 101 can be fixedly attached to a shoe part 102 of the ice skate, as shown in Figure 1. The blade may be formed from metallic material, such as steel, and have a specific shape to facilitate skating.

[0023] In ice-hockey skates, the sharpening creates a concave surface on the blade. This has been illustrated in Figure 2 showing a blade 201 on the ice 200 and the concave hollow 203 (later referred to as "a hollow") that is formed by blade edges 202. When the blade 201 is set perpendicular to the ice 200, a hollow 203 is created between the blade 201 and the ice 200. Sharpening of the blade is done with a grinding tool, such as a grinding wheel. Sharpening of the ice-skate blades refers to a method of creating the hollow for the blade. By changing the side radius of the grinding wheel, a different radius of the hollow 203 can be created on the blade 201. The radius of the hollow 203 is defined as a depth of the groove relative to the bottom of the blade 201. The sharpening process creates two sharp edges 202 on the blade 201. These edges 202 touch the ice 200 during skating, and are called inner and outer edges. These sharp edges 202 tend to wear down or to get damaged in the long run. Thus, sharpening should be done regularly to maintain the quality of the skate blade 201. Figure 15 illustrates an example of sharpening a skate blade with a grinding wheel. Figure 15 shows the blade 1500 and grinding wheel 1510.

[0024] Figure 3 illustrates an example of principle of skating. The blade 301 glides on the ice 300 due to friction and pressure. The sharp edge 302 melts the ice 300 and makes a tiny water layer 303 between the blade 301 and the ice 300. This makes the gliding possible.

[0025] As mentioned, the skate blades wear over time, and therefore sharpening is expected. Ice-hockey players and figure skaters expect sharp enough skate blades, and desire sharpening that is tailored for a specific activity. In addition, the skate blades should be sharpened to match the individual requirements of the skater. For example, ice-hockey players prefer blades that are sharpened and shaped in a certain way to suite their style of play or their playing position as well as their physique. The blade profiles need to be produced quickly onsite and need to be customized according to individual's requirements and preferences.

[0026] Each user has a different need for the blade profile which depends on the different levels they are at. For example, weight, height, skill, and the type of the sport affect what kind of radius of the hollow the user needs. Another important factor is the state of the ice. Fast, hard ice refers to a low-temperature ice. The blade glides better because the blade does not go very deep into the ice. Skating on slow ice or soft ice means it is better to have a large radius of hollow or a hollow that is not too deep. A bigger portion of the blade will sit on the ice allowing it to be able to move freely on the ice but still giving enough control. For skating on hard ice, a smaller radius of hollow or deeper hollow is preferred, whereupon the blade will cut deeper into the icy surface and the user will get more grip in the ice.

[0027] Thus, a deeper hollow means a smaller radius of hollow, whereupon the inner and the outer edges are sharper. A deeper hollow gives skaters more grip and less glide. A sharp edges create less contact between the blade and the ice, and this will result in more pressure on the ice. Because of the higher pressure, the ice melts more. A shallow hollow means a larger radius of the hollow. This is for skaters who prefer less grip but more glide. There is more contact between the skate blade and the ice. More contact generates less pressure, whereupon the ice melts less. In general, heavier skaters should have more ice contact, so a large radius of hollow or shallow hollow is desired. If the skater is lightweight, less ice contact is needed, so a smaller radius of hollow or a deeper hollow is desired.

[0028] To suit the individual requirements of the hockey players, or other skaters, the shaping of the skate blade should be profiled. Figure 4 shows a side of an ice-hockey skate blade. The skate blade 400 is circular when looking from a side, and it can be divided into three sections, front or toe (20%) 401, middle (60%) 402, and rear or heel (20%) 403.

[0029] Profiling is targeted to the middle part 402 of the skate blade by changing the radius of the profile. The measurement of radius of the profile is in cm (feet). In other words, profiling means changing the contact between the ice and the skate blade. The larger the radius of the profile, the more contact the blade has with the ice. More contact with the ice means better stability and higher top speed. A smaller radius of the profile has less contact with the ice, and this makes it easier to maneuver on the ice. With less contact comes more weight in a small area, which will increase the friction. In this case, the acceleration is higher, but the top speed and stability are lower. A large radius of profile is more energy-efficient than a small radius of profile.

[0030] Depending on the skating style and preferences of the skater, such as an ice-hockey player, a different profile is chosen. There are four parameters to consider: acceleration, mobility, speed and stability. The most common profile is a single radius. A single radius uses the same radius all over the middle section 402. A single radius means a single point is in constant contact with the ice. Each radius size comes with different radius or profiles. Figure 5 illustrates an example of a two-radius profile, where the middle section uses two different radii (10' 20') so that the change of the radius is in the middle 500 of the middle section.

[0031] Profiles can go up to a quad radius, which means that four separate points of the blade are in constant contact with the ice. Figure 6 illustrates an example of an ice-hockey skate blade, which has been separated into four different zones 601, 602, 603, 604. Each zone 601, 602, 603, 604 represents one of the parameters: acceleration, mobility, speed and stability respectively. Thus, the ultimate goal of profiling and sharpening is to maximize the performance of each parameter.

[0032] The different radii of the zones can be made to the blade by controlling the vertical movement and the force of the grinding wheel with a respective zone. This means that the grinding tool determines which zone is being sharpened and adjusts the force applied by the grinding wheel accordingly, so that a hollow of a desired radius (i.e. depth) is obtained. By this, the various zones of the hollow can have different radii.

[0033] In the present embodiments, data concerning various profiles of the skate blades and well as details concerning a skater having such skate profile is stored in a memory. Therefore the data is available for the grinding apparatus as well as for other users. This feature of the present embodiments is discussed later with reference to Figure 16.

[0034] A grinding apparatus comprises a grinding tool, e.g. a grinding wheel, to sharpen a skate blade. The loss of grains from the wheel means that the wheel is changing in size. The grinding ratio (i.e., G-ratio) is defined as the volume of material being removed divided by the volume of the wheel lost. The G-ratio gives an idea of the amount of work a wheel can do during its lifetime. The higher the G-ratio, the better the grinding conditions. Grinding wheels lose their geometry during use. "Truing" is a method to restore the original shape. A single-point diamond tool can be used to "true" the wheel. A grinding wheel also needs to be sharpened. The process of sharpening the grinding wheel is called "dressing". After dressing, abrasive grains are exposed to the outer surface of the grinding wheel. The grinding wheel will not cut without exposed abrasive grains. A grinding wheel consists of abrasive particles and bonding material to hold the abrasive particles in place.

[0035] The present embodiments take into account the deterioration of the grinding wheel, so that the grinding apparatus may control sharpening by controlling the vertical movement of the grinding wheel according to a gap between the grinding wheel and the skate blade. Therefore, possible uneven wearings of the grinding wheel do not affect to the final result of the sharpening. This is discussed in more detailed with reference to Figure 9.

[0036] To achieve a good surface finish, the grinding wheel should have a small grain size, high wheel speed, and a dense wheel structure. Grain size or grit size can differ from 10 to 600 with 10 being roughest and 600 finest.

[0037] In grinding, energy is converted into heat and is concentrated within the zone to be grinded. Grinding burn is thermal damage caused by an incorrect grinding process. It causes a decrease in the hardness of the material. Using correct indications of wheel wear and dressing the wheel from time to time will avoid grinding burn. Also, the amount of force applied by the grinding wheel and cutting speeds are important parameters to consider during the grinding process. In the present solution, the risk of grinding burns is decreased by using a rather fast grinding wheel speed and work speed, while using a small depth of cut. Thus, in the present solution, when grinding a skate blade, no cooling lubricant will be used. This will limit the infeed value and the material removal rate.

[0038] As said, Figure 6 shows an example of a quadruple radius profile. In this example, the quad profile has a configuration of four different radii, 183 cm, 274 cm, 366 cm, 457 cm (6, 9, 12, 15 ft) It is appreciated that a profile may have one or more radii. Changing the length of each zone has a massive impact on the feel and performance of the skater, such as ice-hockey player. If, for example, the skater has a deep hollow, whereupon the blade goes deep into the ice, it means that the skaters have to put more effort into every stride. Profiling gives the skater better control, better mobility, better acceleration, which means the skater can reduce its depth of hollow (larger radius of hollow).

[0039] Making a quadruple radius, as shown in Figure 6, by hand is almost impossible. Profiling machines utilize profile templates to be used when sharpening the skate blade. The template acts as a guide and is copied on the new blade. Finding the right profile can be a difficult process because of the limited templates available.

[0040] The present embodiments aim to make sharpening outcome more precise and thus make skaters' performance better. The solution is to sharpen the skate blade into any pre-defined profile, and to give more freedom and better performance on the ice to the skaters. The embodiments can use automated method so it will be easier to use, and at the same time, it will provide more options for profiling the skate blade to the desired shape. The main goal is to give more people a wider and easier access to custom-made profiling to improve the overall performance of the skater.

[0041] The present embodiments are targeted to an apparatus for grinding. The apparatus for grinding comprises at least the grinding tool, such as a grinding wheel and the elements for controlling the grinding tool. The functions of the apparatus may be based on a predefined profile template according to which the sharpening is carried out. The profile template (which defines the desired profile) can be obtained from a storage. According to an embodiment, the apparatus for grinding may comprise a profiling tool acting as a profiling apparatus for determining an actual profile of the skate blade to be sharpened. According to an alternative embodiment, the profiling apparatus may be an external profiling apparatus. Such a profiling apparatus may have a wired or wireless data transfer network with the apparatus for grinding. The profiling apparatus is configured to determine the actual profile of the skate blade being scanned. Based on the determined profile and the desired profile, the profiling apparatus may generate control instructions for controlling the grinding wheel. Instead of the profiling apparatus, the control instructions may be determined by a computer of the system (discussed further in Figure 17). The grinding apparatus is able to perform sharpening of skate blades based on the control instructions. The profile for specific blades is selected by a user (e.g. a sharpener) or automatically determined based on an identification of a skater, or proposed based on a certain parameters being input to the system.

[0042] The operation of the grinding apparatus can be based on any known programming language, for example CNC (Computerized Numerical Control). Sharpening devices of the prior art have not used CNC. In addition, in the grinding apparatus according to present embodiments the quality of sharpening can be ensured by a measuring equipment, for example a laser measurement, which monitors the grinding process during the operation. Thus, the grinding apparatus achieves accuracy of less than 0.1 millimeters. This accuracy has not been achieved by sharpening devices of prior art, since the device parameters needed for sharpening have been manually adjusted. Accuracy makes the sharpening of blades for each user profile similar, while with the prior solutions, the sharpening is manual or mechanically automated.

[0043] In order to meet the required accuracy, the components to create the grinding apparatus should be carefully selected. For example, a linear guide rail block can be a HIWIN ™< block type of linear guideway. Similarly, the guide rail may be selected from HIWIN ™< guiderails. The grinding motor can be a suitable servomotor (e.g. Beckhoff ™< ). In addition the grinding apparatus comprises a stepper motor with incremental encoder, e.g. Beckhoff ™< . The lead screw may be four, two or one start type of lead screws. Single start means a 2mm lead and a 2mm pitch. The double start has 4mm lead and a 2mm pitch. Four strate has a 8mm lead and 2mm pitch. A four-start configuration makes the nut to move 8mm with one full rotation of the stepper motor. The accuracy of the screw can be calculated by dividing the lead with the number of steps. X-, Z-, and Y-motion motors can be a stepper motor, servo motor, or other kind of motor, which achieve the accuracy of less than 0,1 mm. Choice of the lead screw can add torque and improve accuracy.

[0044] The apparatus according to the present embodiments is easy to use, and at the same time, it will provide more options for profiling the skate blade to the desired shape. One of the goals is to give more people a wider and easier access to custom-made profiling to improve the overall performance of the skater. By making the design portable, the grinding machine can be used in harsh conditions and in different environments.

[0045] The apparatuses of prior art use a mechanic copying method to profile a skate blade. Such a method is not flexible when the profile needs to be changed to meet the needs of different skaters. Each skater, e.g. an ice-hockey player, has his / her own profile in order to get the best performance. Instead of using a mechanic copying method, the profiling apparatus according to present embodiments is able to make a digital profile for the skate blade and the grinding apparatus is able to shape the skate blade to the defined shape.

[0046] Figure 8 illustrates an operation of the grinding apparatus machine, according to an embodiment, as a flowchart. The process begins by designing a digital profile or by choosing an existing profile 810. Such a profile is referred to as "desired digital profile" or a "desired profile". The skate blade is measured 820 or scanned to determine the actual profile. In addition the size of the grinding wheel is measured. The measurement is carried out with a laser, by means of which the accuracy can be selected and the number of data points to be observed can be determined. The size of the grinding wheel is defined by a side radius of the grinding wheel, which is defined by a measurement point of the laser and a position information of motor of the Y axis. The measured points are stored, and a data set is created 830 based on them. The blade is then automatically sharpened 840 based on the desired digital profile or recreated measured data set. The data set is recreated if the profile needs to be manually modified or an existing profile is selected for a user. This has been discussed in relation to Figure 14, steps 1407, 1409.

[0047] A laser scanner is used as a profiling apparatus for determining the actual profile. The laser scanner can be mounted onto the grinding apparatus, and can move horizontally. Figure 9 illustrates an example of creation of data points with a laser. The measuring rate of a laser scanner can be up to 190,000 points / second, and example Z-axis resolution start from 0,8µm. The data points can be shown on a linear diagram, e.g. on a two- or three-dimensional view. To get the curvature (i.e. the hollow) of the blade 900, the gap 905 between the grinding wheel 910 and the skate blade 900 is measured in every point. The middle point of the grinding wheel is the reference point 915 because it does not move vertically during the measuring process. The determination of the gap is important since it may vary because of the irregular deterioration of the grinding wheel. When the gap is defined for every position of the grinding wheel, the grinding apparatus is able to adjust the distance between the grinding wheel and the blade so that the sharpening can be made evenly.

[0048] After the measurement of the blade profile, the location and curvature of the blade are known and stored into a data set, which is further stored in a memory of the system. The data set of the measured profile can then be compared with the desired profile in order to create the motion path (i.e. a grinding path) for the grinding wheel. The radius of hollow can be checked by adding a second equivalent system vertically to check the grinding wheel radius and the gap between them.

[0049] There are four parameters to take into account while profiling the blade: acceleration, mobility, speed and stability. Profiling is needed because these four parameters can be changed according to desires of the user. The performance of the ice-hockey player can get better if the machine can adapt the profile to these four parameters. The laser works by sending a laser beam through the sensors onto the skate blade and the grinding wheel.

[0050] The system according to the embodiments may also store a unique skate profile for each user, which works through a digital application. This information can be used to support coaching and skater development.

[0051] For a CNC-type (Computer Numerical Control) grinding machine, the desired profile can be accurately achieved through controlling the trajectory of the grinding wheel by means of control code during grinding process.

[0052] For performing the grinding, the grinding apparatus uses the desired profile for an object. The desired profile may be received from a user input or from a database storing information on profiles of ice skates for certain skaters. After having determined the desired profile for an object, the process continues by defining a trajectory of the grinding tool in terms of multiple grinding paths. The trajectory can be defined by comparing the actual profile of the object to the desired profile. For example, the trajectory can be defined in XY plane, as indicated in Figure 10. In such XY plane, multiple grinding paths are defined so that when performing the grinding form the actual profile to the desired profile, the grinding tools operates on each path, and after having finished a path, the grinding tool proceeds to the next path in Y direction with a certain feeding rate until the desired profiled has been reached. Feeding rate defines the rate how the grinding tool, such as a grinding wheel, is fed towards a stationary skate blade.

[0053] In the grinding apparatuses of the prior art, the grinding wheel has always been touching the skate blade because of a pre-defined counterweight. The present solution does not use a counterweight but it uses exact stepper motors and leadscrews to guarantee the position of the grinding wheel. To make sure that the grinding wheel is touching the skate blade at all times, a spring can be placed underneath the grinding motor holder. The spring force should be greater than the weight its holding added by the grinding force or contact force. During the grinding process, the material is removed from the skate blade, and the pre-loaded spring pushes the grinding motor up when more space is created. Thus the spring enables passive force control of the grinding force.

[0054] An example of a grinding procedure, according to embodiments, is illustrated in Figure 10. In Figure 10's example, the grinding is performed under constant feeding rate. Constant feeding rate means that feeding speed and the rotation speed of the grinding wheel is kept constant even if more material is removed.

[0055] Figure 10 shows a grinding tool 1001, which is in the form of grinding wheel. The grinding tool 1001 touches the (actual) profile 1003 of an object to be grinded in order to remove material from the object to meet the desired profile 1002. A cutting contour 1004 is the line on which the grinding tool operates. Thus, the amount of the material to be removed (i.e. space between the actual profile 1003 and the cutting contour 1004) varies from C to D. It is to be noticed that the path that the grinding tool 1001 follows, varies according to the material to be removed. In Figure 10, the paths A, Aa have been indicated for the grinding tool 201. B indicates constant feeding rate of the grinding tool.

[0056] The initial profiles of objects are irregular, which may cause load to the grinding tool as well as to the driving axes under a constant feeding, since the amount of materials to be removed varies. If the initial profile is far from the desired one, the loading force to the driving axes of the motions should be limited, whereupon the feeding rate of the grinding wheel is small and grinding efficiency is low.

[0057] In the present embodiments, it is no longer necessary to constrain the feeding to a small rate in each grinding path, regardless of the different material being grinded and the initial profile deviation. A passive contacting (i.e. grinding) force is adopted between the grinded materials and the grinding tool to keep the load on the driving axes of motions inside a safe range. The profiling principle according to another embodiment is shown in Figure 11.

[0058] Figure 11 shows a grinding tool 1101 that operates on an object having an actual profile 1103. The grinding tool 1101 is controlled to grind the actual profile 1103 of the object towards the desired profile 1102. The cutting contour is referred to as reference number 1104. The grinding paths A, Aa are defined for the grinding tool according to the actual profile and the desired profile, according to which the grinding tool 1101 operates. The feeding rate is indicated with B.

[0059] The maximum feeding rate of the grinding apparatus can be set large enough to cover the maximum deviation between the actual profile and the desired profile, e.g., the feeding rate B between the first tool path Aa and the second tool path A as in Figure 11. A special force control may be applied to allow the grinding tool to follow the first tool path Aa of the actual material's profile which avoids the "hard" contact between the actual profile and the grinding tool following the second tool path A. Since the grinding tool is under the force towards Y direction, it will eventually generate the cutting contour according the second tool path A.

[0060] Figure 12 illustrates the principle of the grinding apparatus according to an embodiment. The platform provides for the grinding tool 1201 at least two degrees of freedom (2-DOF) in directions X and Y, i.e. two-dimensional movement. Any trajectory for the grinding tool 1201 in such XY plane can thus be implemented to grind the profile 1203 of the object. The distance between the up and down position limiters 1206 determines the maximum feeding rate in each tool path. The trajectory in Y direction is enabled by a sliding joint (or a prismatic joint) 1207. The trajectory in Y direction is limited by the position of the up position limiter. A spring 1205 may be used between the Y motion actuator, i.e., sliding / prismatic joint 1207, and the grinding tool 1201, whereupon the grinding tool 1201 eventually reaches the desired Y position under the spring force that is adjustable by changing the spring preload. The trajectory in X direction is enabled with a sliding joint (or a prismatic joint) 1208.

[0061] An example of the design of the grinding apparatus 1300 having a grinding tool is illustrated as a side view in Figure 13. Any 2D profiles can be produced by the trajectory of the grinding tool 1301, which is realized by at least two independent motions in X and Y directories, and controlled programmatically. The position in Y direction can be limited by position limiters 1306. The accurate control of motions in X and Y directions can be realized through close-loop servo control or through stepper motor control.

[0062] The example of Figure 13 is one of the realizations of the apparatus according to an embodiment as shown in Figure 12. Thus, the present solution should not be unnecessarily limited to the design shown in Figure 13.

[0063] The skate blade to be sharpened is fixed to the grinding apparatus with a mechanical fastener. The mechanical fastener can be implemented by two metallic sheets, between which the blade can be fixed. The sheets are mechanically pressed (e.g. manually or automatically, for example by a electromechanical cylinder) against each other, whereupon the blade is steadily secured to the fastener. which is automatically placed to the center of the grinding wheel. The same fastener can be utilized in the grinding apparatus, when the blade is measured.

[0064] Figure 14 illustrates a method according to an embodiment. It is to be noticed that the flowchart of Figure 14 illustrates a detailed example, where some of the steps may be removed or replaced or modified. The method of Figure 14 comprises the following: blade is set to the apparatus 1401; the profile of the blade is measured 1403; the measurements of the profile are displayed 1405; optionally a desired profile is either selected manually 1409; a desired profile is selected automatically 1407 or fast sharpening is performed using existing shape 1406; If the desired profile is selected manually, one or more radii are defined for the desired profile in the longitudinal direction of the blade 1408; a cross section of blade shape is defined 1410 (e.g. as shown in Figure 2); A roughness of the blade is selected 1411; The grinding is started 1413; The sharpening is performed 1415 according to the instructions; The blade shape is monitored by a machine vision 1417; The measured blade profile (Figure 2, Figure 6) is printed on the screen 1419 with a detailed information. The detailed information comprises information on the center of the blade (Figure 4), but also the area where the sharpening is started and where the sharpening is finished, and the changing radii between the starting point and the finishing point. This information also provides data concerning the height / length of the blade being measured with a laser; The measured blade profile is stored to the data storage being associated with a specific skater 1421. The stored blade profile can be used by a sharpener in the subsequent sharpening(s), or the information of the blade profile can be utilized when determined the shaping of the following blades, for example by modifying one or more parameters that are needed when defining a profile; The process is finished 1423.

[0065] An apparatus for sharpening metallic objects according to an embodiment comprises means for holding an object having an actual profile; a grinding tool for grinding the profile of the object; means for providing movement of a grinding tool in at least two dimensions; means for receiving control instructions for moving the grinding tool at least two-dimensionally and for applying grinding force to the grinding tool towards the object, which control instructions have been generated according to a desired profile for the object, wherein the control instructions define grinding paths for the grinding tool to grind the object from the actual profile to the desired profile; and means for controlling the grinding tool according to the control instructions

[0066] Figure 17 illustrates an example of a system according to an embodiment as a simplified block chart. The system comprises a grinding apparatus 1710 and a profiling apparatus 1720. In addition, the system comprises memory means 1730, such as a cloud, for storing data. Instead of the cloud storage, a memory storage of any other format is applicable as well. The system may also comprise a computer 1740 for providing at least a user interface to the data stored in the memory 1730. The user interface may be a web site by means of which data in the memory 1730 can be reached, or the user interface may be a user interface of a computer program by means of which various tasks (data processing, control instruction creation, data retrieval, etc.) for the present solution can be executed. The computer 1740 also comprises a processor, for processing data and generating instructions to the grinding apparatus 1710. According to an embodiment, the profiling apparatus 1720 and the grinding apparatus 1710 are located in a same physical device. According to an embodiment, the profiling apparatus 1620 and the grinding apparatus 1710 and the computer 1740 are located in a same physical device. According to yet another embodiment, the computer 1740 and the grinding apparatus 1710 are located in a same physical device. It is to be appreciated that these various embodiments are examples, and therefore, any other configuration of the various elements shown in Figure 17 is possible.

[0067] The memory stores user profiles. Here, "a user" refers to a skater, for example an ice-hockey player. Such a user profile contains information relating to the user, for example age, weight, skills, player position, etc. In addition the profile contains information on the desired skate blade profile. Such an information can be entered to the memory manually by defining certain parameters for the skate blade. However, by utilizing the teachings of the present solution, the profile may be automatically determined by using the profiling apparatus 1620. Such a profiling apparatus 1620 is configured to scan the skate blade, and to store the scanned information to the memory 1630.

[0068] When sharpening a skate blade for a certain skater, the blade profile is obtained from the memory 1730 by the grinding apparatus 1710 or by a computer 1740 (in the case where the computer controls the grinding apparatus). The profile is presented as data points according to which the grinding apparatus 1710 is configured to control the grinding wheel to perform the sharpening. In order to perform the controlling of the grinding wheel, grinding paths should be determined based on the data points. The grinding paths may be determined by a processor of the grinding apparatus 1710 or by of the computer 1740. In the latter example, the control instructions defining the grinding paths are transmitted to the grinding apparatus.

[0069] Every time a skate blade is being scanned and a blade profile is stored to the memory 1730, the data concerning different skaters and their desired blades is increasing. Therefore, after enough data has been gathered and stored for skaters of different types, the system may provide blade template information to a new users based on the data they use for a query. Therefore, the user interface means of the computer 1740 is configured to receive information relating to a user, for example his / her height, weight, playing position, etc., and as a response to the received information the processor may determine suitable blade profile(s) and to output a proposal relating to the suitable blade profile on the user interface for a selection.

[0070] The system is a learning solution, which means that after a certain decision relating to the proposal, the system can be trained based on whether the decision (i.e. the proposed skate blade) was suitable. If the skater indicates that the proposed blade was not satisfying, and defines the drawbacks, the system may adjust its operation based on that. This is made possible with solutions, such as machine learning, deep learning, neural networks, which is continuously trained with the data being entered to the memory, and after receiving certain parameters (relating to the skater) as an input, the solution is enabled to make an intelligent decision on the desired skate profile.

[0071] It thus is appreciated that the present embodiments are also targeted to a digital application which is a commercial solution for data collection. With the help of information collected by the present solution, for example, the maintenance organization of the hockey team's coaching team is able to sharpen each player's skates to suit their personal preferences automatically with little effort. The service has a user-specific profile in which each blade sharpening is stored, as well as the exact dimensions of the blade.

[0072] The method according to an embodiment is shown in Figure 16. The method generally comprises detecting 1610 that an object is placed to a grinding apparatus; determining 1620 a profile of the object; determining 1630 a desired profile for the object; generating 1640 control instructions based on the desired profile, wherein the control instructions comprises grinding paths for a grinding tool to grind the object from the profile to the desired profile and grinding force to the grinding tool be applied to the object; and controlling 1650 the movements of the grinding tool according to the control instructions in at least two dimensions. Each of the steps can be implemented by a respective module of a computer system.

[0073] An apparatus according to an embodiment comprises means for detecting that an object is placed to a grinding apparatus; means for determining a profile of the object; means for determining a desired profile for the object; means for generating control instructions based on the desired profile, wherein the control instructions comprises grinding paths for a grinding tool to grind the object from the profile to the desired profile and grinding force to the grinding tool to be applied to the object; and means for controlling the movements of the grinding tool according to the control instructions in at least two dimensions. The means comprises at least one processor, and a memory including a computer program code, wherein the processor may further comprise processor circuitry. The memory and the computer program code are configured to, with the at least one processor, cause the apparatus to perform the method of Figure 16 according to various embodiments.

[0074] The various embodiments may provide advantages. The manual work of a portable skate blade machine can be replaced using a CNC type grinding device approach according to present embodiments. The device is a combination of a CNC grinding system and a laser profile scanner. A laser scanner makes it possible to measure the gap between the skate blade and the grinding wheel to get highly accurate data sets of the skate blade profile. The device according to the present embodiment is compact and lightweight. This is possible, since the moving grinding wheel allows gaining space. The present embodiments are based on CNC-technology, which the prior system lack.

[0075] The various embodiments can be implemented with the help of computer program code that resides in a memory and causes the relevant apparatuses to carry out the method. For example, a device may comprise circuitry and electronics for handling, receiving and transmitting data, computer program code in a memory, and a processor that, when running the computer program code, causes the device to carry out the features of an embodiment.

[0076] If desired, the different functions discussed herein may be performed in a different order and / or concurrently with other. Furthermore, if desired, one or more of the above-described functions and embodiments may be optional or may be combined.

[0077] It is also noted herein that while the above describes example embodiments, these descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications, which may be made without departing from the scope of the present disclosure as, defined in the appended claims.

Claims

1. An apparatus for sharpening metallic blade-like objects, the apparatus comprising: - means for holding an object having an actual profile; - a grinding tool for grinding the profile of the object; characterized in that the apparatus further comprises - means for providing a movement of a grinding tool in at least two dimensions; - means for receiving control instructions for moving the grinding tool at least two-dimensionally and for applying grinding force to the grinding tool towards the object, which control instructions are in use generated according to a desired profile for the object, wherein the control instructions define grinding paths for the grinding tool to grind the object from the actual profile to the desired profile; - means for controlling the grinding tool according to the control instructions, charaterised in that the grinding tool is controlled by a controller configured to grind the profile of the object under constant feeding rate, wherein constant feeding rate means that feeding speed and the rotation speed of the grinding wheel is kept constant even if more material is removed.

2. The apparatus according to claim 1, wherein the control instructions of the controller are in use generated by taking into account data concerning a size of the grinding tool.

3. The apparatus according to claim 1 or 2, wherein the control instructions of the controller are in use generated by taking into account data concerning a deterioration of the grinding tool.

4. The apparatus according to claim 1 or 2 or 3, wherein in use the desired profile of the control instructions of the controller indicates more than one zones on the object that are to be grinded differently.

5. The apparatus according to claim 4, comprising means for determining which zone is to be sharpened and for adjusting grinding force of the grinding tool and for controlling vertical movement of the grinding tool accordingly6. The apparatus according to any of the claims 1 to 5, further comprising means for controlling the grinding force.

7. The apparatus according to any of the claims 1 to 6, further comprising means for determining the profile of the object.

8. The apparatus according to claim 7, further comprising means for comparing the determined profile to the desired profile, and means for generating the control instructions based on the result of the comparison.

9. The apparatus according to any of the claims 1 to 8, further comprising means for determining the desired profile from a memory.

10. The apparatus according to any of the claims 1 to 9, further comprising means for data transfer.

11. A method for sharpening metallic blade-like objects, the method comprising - detecting that an object is placed to a grinding apparatus; - determining a profile of the object; - determining a desired profile for the object; - generating control instructions based on the desired profile, wherein the control instructions comprise grinding paths for a grinding tool to grind the object from the profile to the desired profile and grinding force to the grinding tool to be applied to the object; - controlling the movements of the grinding tool according to the control instructions in at least two dimensions, characterised by - controlling the griding tool to grind the profile of the object under constant feeding rate, wherein constant feeding rate means that feeding speed and the rotation speed of the grinding wheel is kept constant even if more material is removed.

12. The method according to claim 11, further comprising determining a size of the grinding tool, and generating the control instructions by taking into account the determined size.

13. The method according to claim 11 or 12, further comprising determining a deterioration of the grinding tool and generating the control instructions by taking into account the determined deterioration.

14. The method according to claim 11 or 12 or 13, wherein the desired profile indicates more than one zone on the object that are to be grinded differently, whereupon the method comprises determining which zone is to be grinded and adjusting the grinding force of the grinding tool and for controlling the vertical movement of the grinding tool accordingly.

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