Field of technology

The invention concerns a tool with ground spike, mainly cannula or lancet for puncturing or pricking the skin without the jump transitions of the ground edge, whereby the ground edge ensures smoother course of the puncture force. The invention discloses a method of production of the cannula or lance with the continuous cut, without rims in the transition zones of the edge, as well as device for productive realization of that method.

Prior state of the art

Cannulas or lancets which are used for puncturing the body or pricking the skin for human or veterinary purposes but also in the industry for pricking of various seals are usually parts of one-off syringes or injection needles and similar tools or pikes, testing tools which analyze the blood sample, and so on. They are usually metal and have a spike ground by grinding in contact with the surface of the grinding device. There are contradictory demands in production of cannulas and/or lancets, whereby it is necessary to maintain high productivity as well as safety and medical functionality. The edge must me mechanically stable as well as sharp.

Cannulas and lancets with front cut are known, cannulas and lancets with rear cut are known, V-bevel type cannulas are known, and so on. Standard grounded cannula and/or lancet has a main cut led under the angle a1 which is ground as first on the semi-product of the tube or cylindrical rod. The slope of the cannula or lancet is then subsequently changed to angle a2, which is usually larger than angle a1 ; the cannula or lancet is rotated within the axis of the tube or rod, respectively, by rotation angle e1 and a first facet is ground. At the same slope of angle a2 the cannula or lancet is rotated in opposite direction by rotation angle e2 and second facet is ground. If the angle e1 equals angle e2, the first and second facet are symmetrical. Since the grinding in individual steps runs in planar surface of the grinding device - for example, belt or disc grinder - all produced grinding surfaces are planar and there are transition rims between them which connect these planar surfaces.

Publication DE 10207770 discloses a grinding of the cannula with a main cut and facets, whereby aside from the main cut in angle a2 the subsequent surface is also ground under angle a3. This improves the course of puncture force but transition rims cause a local increase of puncture force irrespective of the bevel. Document WO 2018045386 discloses various angular relations between the main cut and the facets in order to optimize the features of the cannula including the decrease in the puncture force. This solution makes use of a small angular difference between the cuts, which decreases the influence of a transition rim, which, however, nonetheless remains in the geometry of the spike.

Publication W02005072610 discloses a grinding of the lancet from various opposite sides which results in a very sharp tip. Such method leads to decrease of the puncture force but it is protracted and the produced spike can be mechanically unstable which can cause health risks.

Solution according to W02006014686 uses a double lancet where the edges are oriented mutually against each other, which however increases production costs and which has limited usage.

Publications FR1225009, AU5191096, US3788320, US5607401, US5254106 disclose variously led cuts with a planar surface, whereby a decrease in the puncture force is to be achieved, but these solutions offer only partial advantages and lead to complicated production, which in one-off cannulas or lancets manifests itself by significant increase in price. The edges of the tools pursuant to publications W02006106880, WO2012073947, DE102005027147, JPH1094601, SK501032012, EP2774643, JP2003290354,

DE202004005618, EP2022399, EP1964516 consist of surfaces which are ground under multiple angles, whereby there is a transition rim between the surfaces. Publication EP0739639 discloses side cuts in places of both transition rims, which diminishes the length of the transition rim but which still leads to production complications and the decrease in the peak of the puncture force is only small. Bending of the tip according to US2009192486 should improve the course of puncturing, but it mainly causes complications in production.

Such production of geometry of the spike of the tool is desired, in which the edge will have preferable and proven features of hitherto known solutions with main cut and two facets, whereby the course of the puncture force decreases. It would be also very preferable if the new solution had high efficacy of the production without increase in the temporal and financial demands, since this is crucial in case of one-off products.

Essence of the invention

Abovementioned deficiencies are significantly remedied by a tool with ground edge, mainly as cannula or lancet, which includes a metal body, mainly in form of a tube (or pipe) or rod with a spike on one end, whereby the spike is ground into edge, whereby the edge includes aslant led main cut with angle a1 against the axis of the tube or rod, as well as first and second facet which are led aslant with angle a2 against the axis of the tube or rod, where the angle a2 is in the same semi-plane from the axis of the tube or the rod as angle a1, and where the first and second facet are at the same time in the transversal cross-section of the tube or the rod led by rotation angles e1 on one side and e2 on the opposite side from the plane of the main cut, and where the plane of one facet is adjacent to the surface of the second facet by means of a transition trim on the tip of the edge, according to this invention, which essence lies in the fact that between the main cut and the first facet and between the main cut and the second facet there is a curved transition zone without the transition rim.

Important feature of the proposed invention is production of the continuous transition between the cuts and facets. A single transition rim is left between the first and second facet, whereby the groundplan of this transition rim on the tip of the edge is oriented in the direction of the body, that is, in the axis of the tube or rod. This single transition rim helps during the initial puncturing or incision by the cannula or lancet into the tissue, mainly skin, epidermis and subsequent layers. All other transition rims are absent in the proposed technical solution and they are substituted by the transition zone with mainly cylindrical and/or ellipsoid or other continuous curved course. The continuous curve in this file denotes a curve which lacks spike as a point without the determinable derivation, that is, a significant discontinuity is absent in it, and one-sided derivation limits exist, but their tangents from right to left differ.

First and second facet can be mutually axially symmetrical or axially asymmetrical or reflectively symmetrical or reflectively dissymmetrical according to the longitudinal plane which runs through the axis of the tool.

The production of continuous, rounded transition zone between the cuts, that is, between continuous adjoining planes ensures significant decrease of the peaks of the puncture force alongside the route of penetration of the cannula or lancet into the biological tissue. Thanks to this the puncturing and insertion of the cannula or lancet is less painful and is subjectively better perceived by the patients.

In case the tool should include - aside from main cut and two facets - other cuts, too, that is, other independent surfaces, such surfaces will be likewise connected with the neighboring surfaces by means of continuously curved transitions.

The term “tube” in this file generally means cylindrical body with an opening or a cavity, usually long and thin, with very oblong and curved shape. The transversal cross- section of the tube is closed at least in the place where the grounded edge follows the body of the tube, and it is thus O-shaped, not open and C-shaped.

The term “rod” in this files generally means cylindrical body, usually thin and long, or it denotes a very oblong and curved object, respectively, whereby the transversal cross-section of the rod is closed at least in a place where the ground edge follows upon the body of the rod, that is, it is thus O-shaped, not open and C-shaped. The term “rod” in this file can be considered synonymous with “wire” or “wire cutting”.

The transition rims between individually ground surfaces on the spike of the cannula or lancet according to the prior art are results of multiple compromises which are imposed on the tool. In order to achieve low initial puncture force and, at the same time, mechanical solidity of the spike, the edge requires at least two cuts with two angles different against the axis of the body. In order to diminish the surface of the spike’s cross-section which in the initial stage enters the biological material the cannula or lancet has side facets which tighten the width of the cannula or lancet in the vicinity of the tip. The side facets are ground after the rotation of the tube or rod to one and then to the other side against the plane of the main cut. The transition rims between these and other cuts on the spike are then consequences of variously led steps of grinding. The larger the angular change, the sharper the transition rim. It is at the same time important that the spikes of the cannulas or lancet are ground by a highly productive methods when there are multiple tubes and/or rods placed in the holder together at the same time and the holder leans against and approaches the grinding device, for example grinding wheel or other type of grinding device. The existence of the transition rims between variously angularly led ground surfaces on the spike of the cannula or lancet according to the prior state of the art is a necessary consequence of the gradually led grinding in multiple steps when the end of the tube or rod is ground in stages which are separated by moving the end of the tube or the rod from the engagement with the ground surface, and subsequently the end of the tube and the rod is brought closer into the engagement in the changed angle of contact.

The original transition rim between the facet and the main cut is a result of contact of two surfaces which are intersections of the tube or cylindrical body, whereby these surfaces have different angles in both directions. The curvature of the original transition rim is thus produced in such a way that the normal line of the resulting surface is subsequently rotated in the plane of the transversal cross-section of the tube or rod by an angle e and in the longitudinal plane of the body the normal line changes the angular direction by the difference a2 - a1. The length on which the change of the course of the normal line occurs can be chosen differently and an arrangement is also possible where the angular position of the normal line is changed continuously already from the tip of the edge, that is, from the transition rim between the first and second facet. In such case the transition between the facet and the main cut is produced continuously from the beginning of the facet and the angles a2 and e1 and/or e2, respectively, are measured in one point, that is, from the tangent towards the circular curvature. In another arrangement the curvature zone can have a length that is at least 25% of the length of the facet and/or at least 25% of the length of the main cut. The proposed invention leaves out the transition rims between the facets and the main cut, or eventually between the further cuts themselves, whereby such solution can be reached by a new method. The deficiencies in the prior state of the art are significantly remedied by a new method of production of the tool with the ground edge, mainly cannula or lancet, where the metal body in form of a tube or a rod is placed in a holder in such a way that the end of the tube or the rod protrudes from the holder and the end of the tube or the rod is entered into contact with the moving grinding device, whereby on the end of the tube or the rod there are at least two surfaces ground under different angles a1, a2 against the axis of the tube or the rod, where the angle a2 is in the same semi-plane from the longitudinal axis of the tube or the rod as the angle a1 , according to this invention, which essence lies in the fact that the change of the angular position of the end of the tube or the rod between the angles a1, a2 is realized continuously and during the ongoing contact of the end of the tube or the rod with the moving grinding device.

A significant feature of the new method of grinding is the fact that the stage where the end of the tube or the rod is moved away from the relatively moving grinding surface, so that a new angle of the slope can be set and subsequently a neighboring surface is ground under different angle or slope, is left out. Usually the moving away and bringing closer is realized in such a way that the rotating grinding wheel is fixedly placed and the approaching movements and the setting of the angles is realized by the holder of the tubes. An opposite method can be chosen in principle, where the holder of the tubes is fixedly placed and it is the rotating grinding wheel which is moved in such a way that the necessary angular position and distance from the ends of the tubes are achieved. A combined method is possible, two, where both systems are movably placed, that is, both the rotating grinding wheel and the holder move and each system realizes specific movement.

In the method according to this invention the surfaces of the spike are ground continually; that means that the angle of slope of the end of the end of the tube or rod while being ground (for example, from a1, a2) is changed during the grinding without interruption of the contact of the end of the tube or the rod with the grinding device. This produced a cylindrical or ellipsoidal or continuously curved transition in a transition between the cuts with various angles of slopes against the longitudinal axis of the tube or the rod, whereby the transition is without transition rims. During grinding of the facet, it is necessary to rotate the tube alongside its longitudinal axis, for example, during the grinding of the first facet the rotation should be in angle e1. This is a rotation angle by which the cut of the first facet deviates from the plane of the main cut projected onto the transversal cross-section. During continuous grinding which forms the main feature of this invention the transition between the facet and the main cut is ground in such a way that not only the angle changes from a2 to a1, but the tube or the rod rotates along its longitudinal axis from angle e1, e2 to angle 0, too, that is, the tube or the rod rotates into the plane of the main cut. The curvature zone r in which the angle continuously changes from a2 to a1 and from e1, e2 to angle 0 can have length that is at least 25% of the facet’s length and at least 25% of the length of the main cut. The term “continuously” qualifying the angular changes in this file means that the angular change runs without significant jump changes, whereby the change needs not to be even. The angular change can be continuous and, at the same time, the gradient of change can increase. The setting of the angular changes will be preferably realized by the programming of the system which controls the mutual movement of the holder against the grinding device and which usually controls the rotation of the tubes or the rods in the holder in order to achieve their rotation by angle e1 and e2, too. Usually the control of the angular changes will use typical constant derivation of the angle at least on the part of the operating route of the grinding.

Abovementioned deficiencies in the prior state of the art are significantly remedied by the device for the production of the tool with ground edge itself, too, whereby the tool with ground edge is mainly cannula or lancet, where the device includes a holder of at least one body in form of a tube or a rod, which is a semi-product for production of cannula or lancet, as well as the grinding device with the moving grinding surface, preferably in form of a grinding wheel, whereby the device has a mechanical support mean (or mechanical support instrument) for the bringing of the holder closer to the grinding device and for maintaining the holder in the desired angular position for the grinding of the surfaces of the edge of the tool with at least two different angles of slope a1, a2 against the axis of the tube or the rod, and where the holder is designed for the controlled rotation of the tube or the rod alongside its longitudinal axis in angles at least e1, e2, according to this invention, which essence lies in the fact that the mechanical support mean is designed for the continuous change of the slope of the holder between the angles a1, a2 whereby the edge is simultaneously ground, whereby the mechanical support mean is coupled with the rotation of the tube or the rod in the holder in order to achieve simultaneous change of the angles e1, e2 alongside the change of the angles a1, a2.

Mechanical support mean can have a form of a positioning head with a computer- controlled movement. In a preferable arrangement the coupling between the mechanical support mean and the rotation in the holder is realized by means of a computer control of independent engines for the angular movement of the holder and the engine for the rotation of the tubes or rods. During the computer control one can achieve variously long curvature zone between the facet and the main cut and one can also easily achieve jump-less and, at the same time, non-linear angular change.

An important feature of the device according to this invention is that the mechanical support mean is designed for continuous, temporally regulated change of the slope with ongoing grinding without the need to interrupt the grinding by a step in which the end of the tube or the rod, or end of the partially ground cannula or lancet, respectively, are distanced from the grinding device. The mechanical support mean is capable of altering the slope of the angle of the holder against the tangent against the grinding device in the place of the operating contact while the grinding of the edge is simultaneously ongoing. These capabilities involve an ability to overcome respective resistant forces and moments, and also the ability to change the respective angles in a controlled way.

The advantage of the proposed invention is an improvement of the course of the puncture force, decrease of the puncture work (integral of the curve of the puncture force) and thereby achievement of the better acceptability of the cannula, lancet or needle, respectively, by the patients. A fact is also a significant advantage that the new method of the grinding does not prolong the production time, which is crucial factor in case of one-off tools where it is important to maintain low price of the tool. On the contrary - the new method of grinding is capable of shortening the production time by leaving out a stage in which the grinding is interrupted in order to set a new position or new angle of the holder, respectively. With continuous grinding according to this invention the changing of the position of the holder and the rotation of the tubes or the rods is realized simultaneously with the grinding. The computer control of the mutual movements and angular changes allows for a possibility of variously shaped transition zones.

Description of drawings

The invention is further disclosed by means of drawings 1 to 20. The depicted ratio of individual elements such as, for example, width of the wall of the cannula or the ratio of the length of a lancet against its diameter, are examples only and cannot be interpreted as a feature limiting the scope of protection.

Figures 1 to 5 depict a standard cannula and a lancet with the ground edge according to state of the art. Figure 1 is a groundplan view of the edge of the tool, on the left there is an edge of the cannula and on the right there is an edge of the lancet with section plane marked by A-A, whereby the plane is subsequently depicted in detail on figure 2, with cannula again on the left and lancet on the right.

Figure 3 is a side view of the cannula from figure 1 , and figure 4 is a view of the lancet from the figure 1. The same cannula and lancet are depicted on the figure 5 after their rotation alongside the axis of the tool by rotation angle e1 , which is suggested by an arrow in the upper part of the drawing; the cannula is on the left and lancet on the right.

Figure 6 depicts cannula on the left and lancet on the right pursuant to proposed invention, where in the groundplan view we see that the transition rims are lacking. Figure 6 depicts a cut plane A-A, too. Figure 7 is a detail of the transversal cross-section of the spike of cannula and lancet in a place through the first and second facet according to plane A-A.

Figure 8 is a side view of the continuous profile of the ground edge of the tool, where cannula is on the left and lancet on the right. Figure 9 is then a view of the cannula and lancet rotated alongside their axes by rotation angle e1, which is suggested by an arrow in the upper part of the drawing.

Figure 10 is detailed view of the edge of the cannula and lancet where the marked lines x are led as a middle of the stretch of cuts. Subsequently, Figure 11 depicts a side-plan projection of the line x for three different curvatures between the facets and the main cut. The curvature zone is marked by dashed lines and the letter “r”. A length of the curvature zone increases on the graphs (charts) from top to bottom. In figure 10, the stages of the course of grinding are marked by Roman numerals I to V in circles.

Figures 12 and 13 shows a graph of puncture force F in dependence on the line of entry of the cannula to the measured tissue, whereby the measured tissue imitates the biological material. Graph on figure 12 corresponds to the state-of-the-art cannula and graph on the figure 13 corresponds to cannula according to this invention. Figure 16 then shows the differences of the puncture force between the state of the art and the proposed invention.

Figures 14 and 15 shows a graph of puncture force F in dependence on the line of entry of the lancet to the measured tissue, whereby the measured tissue imitates the biological material. Graph on figure 14 corresponds to the state-of-the-art lancet and graph on the figure 15 corresponds to lancet according to this invention. Figure 17 then shows the differences of the puncture force between the state of the art and the proposed invention.

Hatched surface on figures 16 and 17 depicts a difference in an energy needed for the insertion or puncturing of the tool; the less energy is needed the less pain patient feels during puncturing.

Figure 18 depicts a cannula with a continuous transition of the cut where the main cut runs into the secondary cut from the angle a1 to a3, whereby there is a curvature between the main cut and the secondary cut. Figure 19 depicts a lancet with a continuous transition of the cut where the main cut runs into the secondary cut from the angle a1 to a3, whereby there is a curvature between the main cut and the secondary cut.

Figure 20 is a schematic depiction of the mechanical support mean cooperating with the grinding device and the movable holder of the tubes. An arrow b marks the angular rotation of the holder with the tubes and/or rods; an arrow c marks the rotation of the tubes in the holder in order to rotate the rotation angles of the facets; and an arrow a marks a slidable movement of the holder against the grinding device. Examples of realization

Example 1

In this example the cannula 2 with ground edge 3 according to figures 6 to 13 and 16 is produced out of a tube 1_ from a stainless steel harmless to health (e.g. 1.4301, AISI 304). Tubes are ground together in groups on an adapted single-purpose grinder. In this example the grinder has a grinding device 9 in form of a grinding wheel. A mechanical support mean 12 is movably placed on the frame of the grinder, whereby the mechanical support mean 12 controls the angle a and the position of the holder 10. A group of the tubes 1 is attached in the holder 0, whereby the holder 10 ensures the rotation of each tube 1 alongside its longitudinal axis.

Tubes in the holder are rotated by a rotational angle e1 and the whole holder 10 is at the same time tilted by an angle a2 against the contact surface of the grinding device 9. The holder 10 approaches the grinding device 9 in this position and a first facet 5 is ground. After the grinding of the first facet 5 all tubes 1 in the holder 10 are gradually rotated from the rotation angle e1 to angle 0, that is, to the plane of the main cut 4 in the transversal cross- section and at the same time during the change of the rotation angle e1 the holder 10 with the tubes is tilted from the angle a2 to the angle a1. A distance of the holder 10 from the grinding device 9 is changed appropriately compared to these angular changes in such a way that the end of a tube is in the operating contact with the grinding device 9. The main cut 4 with the angle a1 continues to be ground continuously and without interruption.

When the main cut 4 with angle a1 is ground, the distance of the holder 10 from the grinding device 9 starts to change in the opposite direction without the interruption of the process. During this change of the distance the angle of the holder 10 changes from the angle a1 to angle a2 and the rotation angle also in certain time starts to change from angle 0 to angle e2. Such is the second facet 6 ground. All movements during the grinding are realized simultaneously and without interruption. Cannula 2 is from the beginning of the grinding of the first facet 5 to the end of the grinding of the second facet 6 always in contact with the grinding device 9. Such method of grinding is marked on the figure 10 as transition from point I to point II and then continuously to the point III, then continuously to the point IV, then continuously to the point V, where the grinding of the edge 3 ends. In this example the first facet 5 and the second facet 6 are mutually reflectively symmetrical, that is, there are axially symmetrical pursuant to the longitudinal axial plane of the cannula 2 through which the axis of the tube runs. In another example of realization an asymmetry can be chosen, or dissymmetry pursuant to demands of the design.

All movements during grinding are controlled by a computer program which can set the course of a curve x, that is, mainly the length of curvature r within the line of grinding. Computer control allows to change the derivation of the angular changes e1 , e2 and a2, a1 in such a way that it is continuous and capable of producing variously long curvatures r according to figure 11.

Result of this method is a cannula 2 which has a rim 8 between the first facet 5 and the second facet 6, but lacks a transition rim 7 between the facets 5, 6 and the main cut 4.

Further processing of the cannula 2 follows methods in the prior state of the art, where burrs and remnants of chip processing are removed from the cannula 2. The cannula 2 produced according to this invention is used for the production of needles for intramuscular, subcutaneous, hypodermic, intravenous or intraarterial application for human or veterinary use.

Overall, the cannula 2 has smaller surface below the curve according to graphs 12 and 13, compared with cannulas from the prior state of the art with the transition rim 7. This difference in puncture energy corresponds to the sensation of less pain during the insertion into the tissue of a patient or an animal.

The length of grinding of the edge 3 in this example is less than during hitherto known state-of-the-art grinding, since the stage of distancing of the holder 10 from the grinding device 9, during which the angle a2 is jump changed into angle a1, and during which the angle e1, e2 becomes equal 0, is left out.

Example 2

In this example a lancet 22 with ground edge 3 according to figures 6 to 11, 14, 15 and 17 is produced from the rod H in the similar way as cannula 2 in example 1. The body is formed by a rod H, as opposed to the tube 1 in example 1 in case of cannula 2.

Example 3

Cannula 2 or lancet 22 with a ground edge 3 is in this example produced from the tube 1 or the rod H, respectively, from a suitable plastic harmless to health or from the suitable, desirably solid ceramics harmless to health.

Method of grinding in this example is similar to example 1 or example 4.

Example 4

In this example the end of the tube 1 is ground in a way which pursuant to figure 10 proceeds from point I to point II, then continuously to point III, then it is ground to point V and continuously to point IV, then continuously to point III, where grinding of the edge 3 ends.

The tubes 1_ are in inserted to the holder 10 as rotated by rotational angle e1. Whole holder 0 is tilted by angle a2 against the contact surface of the grinding device 9. The holder 10 in this position approaches the grinding device 9 and the first facet 5 is ground. After the grinding of the first facet 5 all tubes in the holder 10 are subsequently rotated from the rotational angle e1 to angle 0, that is, to the plane of the main cut 4 in the transversal cross- section, and at the same time during the change of the rotational angle e1 the holder 10 with the tubes 1_ is tilted from the angle a2 into angle a1. The distance of the holder 10 from the grinding device 9 is changed appropriately relative to these angular changes in such a way that the end of the tube 1_ is in the operating contact with the grinding device 9. The main cut 4 with angle a1 is then ground continuously and without interruption.

The second facet 6 and its transition to the main cut 4 is ground in the similar way in the next independent step, which is realized continuously during a single approach of the end of the tube to the grinding device 9. The tube 1 in the holder is rotated by a rotational angle e2 and at the same time the holder 10 is tilted by the angle a2 against the contact surface of the grinding device 9. the holder in this position approaches the grinding device 9 and a second facet 6 is ground. After the grinding of the second facet 6 all tubes 1 in the holder 10 are gradually rotated from the rotational angle e2 to angle 0, that is, to the plane of the main cut 4 in the transversal cross-section and at the same time during the change of the rotational angle e2 the holder 10 with the tubes tilts from angle a2 to angle a1. The distance of the holder 10 from the grinding device 9 is changed appropriately relative to these angular changes in such a way that the end of the tube 1 is in the operating contact with the grinding device 9. The main cut 4 with angle a1 is then ground continuously and without interruption.

Example 5

The end of the rod V\_ is ground similarly as in example 4. Pursuant to figure 10 it proceeds from point I to point II, then continuously to point III, then it is ground to point V and continuously to point IV, then continuously to point III, where grinding of the edge 3 ends. The result is a lanced 22 with continuous, gradual edge 3.

Example 6

The cannula 2 with ground edge as depicted on the figure 18 has, aside from the main cut 4, a secondary cut 41_ led under the angle a3, too. The prolongation of the length of the edge 3 diminishes the size of the puncture force but prolongs the length of the puncture route alongside the edge 3. In order to diminish the overall expended energy of the puncture, the transition between the main cut 4 and the secondary cut 41_ is curved and rounded. The course of curvature between the main cut 4 and the secondary cut 41_ is such that after the grinding of the main cut 4 the holder 0 with the tubes gradually tilts from the angle a1 to angle a3, and the distance of the holder 10 from the grinding device 9 is changed appropriately relative to these angular changes in such a way that the end of the tube 1 is in the operating contact with the grinding device 9. Example 7

The lancet 22 with ground edge as depicted on the figure 19 has, aside from the main cut 4, a secondary cut 41_ led under the angle a3, too. The course of curvature between the main cut 4 and the secondary cut 41_ is such that after the grinding of the main cut 4 the holder 10 with the rods V\_ gradually tilts from the angle a1 to angle a3, and the distance of the holder 10 from the grinding device 9 is changed appropriately relative to these angular changes in such a way that the end of the rod V\_ is in the operating contact with the grinding device 9.

Example 8

In this example the device for realization of the method according to this invention is construed in such a way that the holder 10 of the tubes 1 or rods V\_ is placed on the device’s frame, whereby the holder 10 ensures the changes of the rotational angle e1, e2. Rotational placement of the grinding device 9 (in this example in form of a disc grinder) is placed on a bi axial line and it can be moved and lifted in axes x, y against the holder 10, whereby it alters not only the distance of the grinding device 9 from the ends of the tubes 1 or rods 11, but the angular position of the tangent of the grinding device 9 against the axis of the tubes or the rods changes, too. The mutual relative movement of the end of the body of the tube 1 or the rod H against the grinding device 9 is similar as in previous examples.

Industrial applicability

Industrial applicability is obvious. According to this invention it is possible to industrially and repeatedly produce and use tools, mainly cannula or lancet, with ground edge, which as a transition rim between facets and main cut removed, which improves the course of the puncture force. The cannula or lancet is subsequently used mainly in production of syringes, needles and various tools and devices for human or veterinary use.

List of symbols

1 - tube

11 - rod

2 - cannula

22 - lancet

3 - edge

4 - main cut

41 - secondary cut 5 - first facet

6 - second facet

7 - transition rim

8 - rim between facets

9 - grinding device

10 - holder

12 - mechanical support mean a1 - angle against the body of the tube or the rod a2 - angle against the body of the tube or the rod a3 - angle against the body of the tube or the rod e1 - rotational angle against the plane of main cut in the transversal cross-section of the tube or the rod e2 - rotational angle against the plane of main cut in the transversal cross-section of the tube or the rod

A-A - plane of the depicted cross-section x - line of the center of the stretch of the ground edge r - curvature zone F - size of the puncture force s - puncture route a - slidable movement of the mechanical support mean b - angular rotation of the holder c - rotation in the axis of the tube or the rod I, II, III, IV, V - stages of grinding