Gripper for tufting machine

Abstract

The invention relates to a gripper (1) for a tufting machine, comprising a base body (2) and an insert body (3). The gripper (1) has a holding section (4) and a guide section (5) extending longitudinally. The guide section (5) terminates longitudinally away from the holding section (4) in a hook (14) which has an inner surface (15) in which a joining gap (18) is arranged between the base body (2) and the insert body (3). According to the invention, the gripper (1) is characterized in that a stop (6) is arranged in the guide section (5) of the gripper (1) on the base body (2), against which the insert body (3) is abutted longitudinally relative to the holding section (4) in order to limit the size of the joining gap (18) on the inner surface of the hook (14).

Description

[0001] Grippers for tufting machines are available in many different designs. Their function is to take the yarn from a needle, which transports the yarn through a backing material, in order to form a loop. This loop is often cut immediately after being created. For this, the gripper works in conjunction with a knife that rests against the gripper and slides along it. To protect the gripper from excessive wear caused by the knife, an insert made of a wear-resistant material is frequently attached to the gripper's base and is usually soldered in place.

[0002] Such grippers are shown, for example, in US 2009 / 107371, EP 2 412 859 A1, EP 1 953 290 A1, EP 0 200 810A1 and DE 23 41 567 A1.

[0003] EP 2 412 860 A9 also shows such a gripper. To secure the insert body in its intended position during the gripper's manufacture (especially during the soldering process), one embodiment features a spring element located in the holding section of the base body. The spring element is very delicate and therefore limited in its effectiveness.

[0004] All the grippers mentioned above share the common feature of potentially having a considerable gap between the base body and the insert body. At the point where the yarn comes into contact with this gap, the yarn will eventually wash out the relatively soft solder and then be damaged by the edges of the base body and the insert body. This results in the carpet surface appearing uneven and rough due to the broken filaments. This problem occurs more frequently on the inside of a hook because the yarn is inevitably in frequent contact with the gap there, as this area is designed to receive the yarn from the needle, thus creating a necessary relative movement between the yarn and the gripper. In some cases, the yarn can even become jammed and then break.

[0005] Based on this prior art, the object of the present invention is to provide a gripper in which the above-mentioned problems are avoided or reduced and a uniform appearance of the product is obtained.

[0006] This problem is solved by a gripper comprising a base body and an insert body, the gripper having a holding section and a guide section in its longitudinal direction. The guide section terminates in a hook on the longitudinal side opposite the holding section. The hook has an inner surface in which a gap is arranged between the base body and the insert body. According to the invention, a stop element is arranged on the base body in the guide section of the gripper, against which the insert body is abutted in the longitudinal direction relative to the holding section. This design of the base body limits the size of the gap on the inner surface of the hook. Accordingly, a contact element is arranged on the insert body in the guide section of the gripper, which is abutted against the stop element of the base body in the longitudinal direction relative to the holding section.During the manufacture of the gripper, the base body and the insert body must be joined and connected. Soldering is a preferred method for creating this connection. However, during the soldering process, specifically as the solder cools and hardens, the insert body's position relative to the base body can shift. The gap between the base body and the insert body can then grow uncontrollably and unevenly at different points. A similar shift can occur during the curing of an adhesive bond when the base body and insert body are glued together. Regardless of the specific type of connection, the lifting element on the base body and the contact element on the insert body determine a relative longitudinal position of the bodies, in which the joining gap on the inside of the hook, in particular, has a limited size.The limited size of the joining gap on the inside of the hook reduces the risk of damage to the yarn at the edges of the base body and the insert body, which define the joining gap on the inside of the hook. According to the invention, the insert body is attached to the base body at three points in the longitudinal direction, with a joining gap between each of the attached bodies. At both ends of the insert body in the longitudinal direction, the base body encompasses the insert body. These two attachments act in the longitudinal direction but are oriented differently. The third attachment, according to the invention, acts in the same longitudinal orientation as the attachment in the holding area. Due to its arrangement in the guide area, this third attachment limits the size of the joining gap on the inside of the hook.

[0007] The gripper's longitudinal direction is defined by the cutting edge, which is formed in a known manner in the guide section on the gripper body. Perpendicular to the longitudinal direction, the lateral direction indicates the distance between the two larger flat sides of the narrow gripper. Perpendicular to both of the aforementioned directions is the vertical direction, which points towards the substrate material when the gripper is installed in the machine. The gripper's retaining section serves to attach the gripper to the tufting machine and forms an end section of the gripper in the longitudinal direction. Often, several grippers are combined in a module, and the retaining section is then defined within a so-called module block.

[0008] The hook prevents the gripped loops from sliding back off the gripper. For this purpose, the hook extends vertically from the cutting edge or an extension thereof, thus increasing the gripper's vertical reach. In other words, the entire guide area forms an elongated, hook-shaped body at the end furthest from the holding section. The hook features an inner surface whose perpendicular plane is oriented approximately longitudinally to the holding section. The base body and the insert body extend into the hook, forming a gap along the inner surface. It can be advantageous for this gap to be positioned far towards the outer edge of the hook's inner surface. A loop under tension will then not come into contact with this gap as frequently.Preferably, at least 50% of the inside surface of the hook is formed by the insert body. However, it is also conceivable that the inside surface is formed by the insert body to 65% or 80%.

[0009] It is advantageous if the lifting element is arranged longitudinally on the base body in the guide section at its end, in the direction away from the holding section. This results in a small longitudinal distance between the lifting element and the end of the gripper furthest from the holding section compared to its overall longitudinal extent. Variations in the dimensions of the base body, which in conventional manufacturing methods for such base bodies are fractions of the total extent, are then correspondingly smaller in this end region. In a preferred embodiment, the insert body is longitudinally encompassed by the base body at both ends, so that a maximum degree of inaccuracy in longitudinal positioning cannot be exceeded.However, the base body and the insert body are relatively long in the longitudinal direction, so that variations in the lengths of both parts are not negligible due to the manufacturing process. By arranging the lifting and positioning elements in the end region furthest from the holding section, the deviations in this end region are correspondingly reduced. Since the lifting and positioning elements work together for precise positioning, the two positioning elements must be arranged to coincide on the base body and the insert body. In the holding section, the exact longitudinal positioning of both parts is not critical in the embodiments according to the invention.

[0010] Preferably, the longitudinal distance of the lifting device from the end of the guide section towards the holding section can be at least twice as large as the longitudinal distance of the lifting device from the end of the guide section of the gripper furthest from the holding section. However, the difference in distances can also be at least a factor of 3 or at least a factor of 4 or more.

[0011] Preferably, the lifting device is fixedly attached to the base body and the support device is fixedly attached to the insert body. "Fixedly attached" in the context of this invention means that it is neither displaceable nor deformable relative to the respective body. In particular, spring elements known from the prior art are not fixedly attached in this sense.

[0012] In an advantageous embodiment, the lifting device has a lifting surface element with a perpendicular surface that points longitudinally towards the end of the gripper's guide section furthest from the holding section. It is further preferred that the lifting device has a contact surface element arranged on the insert body, with a perpendicular surface that points longitudinally towards the holding section. It is also advantageous if the two surface elements are arranged adjacent to one another. The surface elements with the corresponding orientation can be relatively small or, on curved surfaces, can be present only at a few points. If no appropriately oriented surface elements are present, the bodies may not be positioned exactly relative to each other. According to the invention, surface elements that are only approximately aligned accordingly can also be present. The term "adjacent" can have various meanings in this document.Firstly, the surface elements can be in direct contact with each other to ensure precise positioning. Secondly, the invention also provides for an adhesive (such as solder, glue, or similar) to be arranged between the surface elements, i.e., between the base body and the insert body. This intermediate layer can be taken into account and factored into the design of the relative position of the lifting device and the mounting device. Likewise, an adhesive can be present between the lifting device and the mounting device when referring to the insert body being attached to the base body.

[0013] The lifting element can be formed by a projection on the base body. The contact element can then be formed, complementary to the lifting element, as a recess on the insert body. In a preferred embodiment, the lifting element is a projection on the base body and the contact element is a corresponding recess on the insert body. Surface elements of the recess then rest against surface elements of the projection, with or without an intermediate layer of an adhesive, thus precisely adjusting the relative position of the bodies to each other. The projection can be formed integrally with the base body or insert body and thus, in particular, be made of the same material. The projection can be formed by an additional component that is fixed to one of the bodies.

[0014] In an advantageous embodiment, the base body and the insert body do not overlap in any lateral direction. In particular, both bodies then have the same width. However, this does not preclude one or both bodies from having a reduced width in certain areas. For example, at the end of the gripper furthest from the holding section, the width of the base body and / or the insert body may be reduced, for example, to create clearance for the tufting needle or to taper the gripper to facilitate loop pickup. Other gripper shapes are known that adjust the width of the bodies, all of which are expressly compatible with the present invention. It is also possible for the gripper to have rounded edges in various directions at its end furthest from the holding section.Therefore, the flat sides of the gripper are not necessarily flat across their entire surface. However, embodiments of the invention are included in which the insert body is, for example, received in a pocket of the base body and thus has a narrower width, at least in some sections, than the base body at its widest point.

[0015] A bonding agent, in particular a solder, is preferably arranged between the base body and the insert body. However, any other bonding agent, such as adhesives, can be used in the present invention. It is further preferred that the bonding agent be present at every point where the base body and the insert body adjoin each other. However, it is also possible that no bonding agent is present in various adjacent areas, such as in the area of ​​the lifting and mounting elements, and that the bodies are in direct contact.

[0016] The insert body can be made of carbide or entirely of carbide or another particularly wear-resistant material. The base body preferably has or is made entirely of tool steel. All materials suitable for the specific application are conceivable for both the base body and the insert body. This fundamental concept imposes no restrictions on material selection, provided that lifting slings and / or attachment points can be formed onto the bodies and joined using an adhesive. Fig. 1 Figure 1 Fig. 2 shows a gripper according to the invention in a view of a flat side, wherein the gripper is held in a gripper block. Figure 2 Fig. 3 shows another gripper according to the invention, again in a view of a flat side. Figure 3 shows an enlarged view of the end area of ​​the gripper Figure 1 Fig. 4a Figure 4a shows the basic body from the Figure 3Fig. 4b Figure 4b shows the deployment unit from the Figure 3 Fig. 5 Figure 5 Fig. 6 shows another gripper according to the invention. Figure 6 shows another gripper according to the invention

[0017] Figure 1 Figure 1 shows a gripper 1 according to the invention in a view of a flat side 16, wherein the gripper 1 is held in a gripper block 17. For the sake of simplicity, details have been largely omitted from the drawings in all figures. For example, an extensive joining gap is never shown between the base body 2 and the insert body 3, but only a simple line is drawn at the joining point. The longitudinal and vertical directions are also indicated. The orientation is the same for all subsequent drawings. The gripper block 17 of the Figure 1 Additional grippers 1 may be defined that are hidden by the gripper 1 shown. In this respect, it serves Figure 1 This is just a rough overview.

[0018] Figure 2Figure 1 shows another gripper 1 according to the invention, again in a view of a flat side 16. For clarity, the holding section 4 and the guide section 5 are indicated by curved brackets. Both the base body 2 and the insert body 3 extend into the holding section 4 and the guide section 5 and into the hook 14. The hook forms, among other things, an inner surface 15 that faces the holding section 4. In this embodiment, the insert body 3 forms a contact element 7 that projects from the insert body 3 and interacts with a stop element 6 that is recessed into the base body 2. The stop element 6 on the base body 2 has a perpendicular surface 9, which is shown as an arrow extending from the stop element 6. Likewise, the perpendicular surface 11 of the contact element 7 of the insert body 3 is shown as an arrow extending from the contact element 7.On the inside 15 of the hook 14, the base body 2 and the insert body 3 form a joining gap 18, which, however, is only shown as a simple line.

[0019] Figure 3 shows an enlarged view of the end area of ​​gripper 1. Figure 1 The end of the gripper 1 has a pointed end, as illustrated by the chamfered edge 19 on the base body 2. The insert body 3 forms most of the inner surface 15 of the hook 14. A lifting element 6 is formed on the base body 2, projecting beyond it. Correspondingly, a contact element 7 is formed on the insert body 3, adjacent to the lifting element 6 on the base body 2. Again, the joining gap 18 between the base body 2 and the insert body 3 is shown only as a simple line, although a clearly visible gap may exist between the parts.

[0020] Figure 4a shows the basic body 2 from Figure 3 . Figure 4bshows the insert body 3 from Figure 3 The two bodies are precisely aligned longitudinally; however, for clarity, the insert body is shifted downwards in the opposite vertical direction H. The base body has a projection 12, which forms a contact surface area 8 with a perpendicular surface 9, represented by an arrow. The insert body 3 has a recess 13. A contact surface element 10 with a perpendicular surface 11, represented by an arrow, rests in the recess 13.

[0021] Figure 5 Figure 1 shows another gripper according to the invention. In contrast to the previous embodiments, the insert body 3 has a projection 12 which is arranged in the longitudinal direction L at the very end of the insert body 3.

[0022] Figure 6Figure 1 shows another gripper 1 according to the invention. In this embodiment, the support means 7 is again provided on the insert body 3 in the longitudinal direction L at the end of the insert body 3, but in this example at the lower region of the insert body 3 in the vertical direction H. A corresponding lifting means 6 is formed on the base body 2. Reference symbol list 1 Grabber 2 basic body 3 Deployable body 4 Stop section 5 Guided section 6 Lifting equipment 7 Investment funds 8 Stop surface element 9 Perpendicular to the surface of the stop surface element 10 Plant surface element 11 Perpendicular to the surface of the mounting surface element 12 projection 13 in-depth 14 Hook 15 Inside of the hook 16 Flat side 17 Gripper block 18 Joining gap 19 chamfered edge B Latitude H Altitude L Longitudinal direction

Claims

1. Gripper (1) for a tufting machine, comprising a gripper body (2) and an insert (3), wherein the gripper (1) has, in the longitudinal direction (L), a holding section (4) and a guiding section (5), wherein, at the end further away from the holding section (4), in the longitudinal direction (L), the guiding section (5) terminates in a hook (14) and the holding section (4) in its entirety forms a elongated body, wherein both the gripper body (2) and the insert (3) extend in the holding section (4) and in the guiding section (5) and as far as in the hook (14), wherein said hook has an inner side (15), in which a joint gap (18) is arranged between the gripper body (2) and the insert (3), characterised in that a stop means (6), against which the insert (3) abuts in the longitudinal direction (L) towards the holding section (4), is arranged on the gripper body (2) in the guiding section (5) of the gripper (1) in order to limit the size of the joint gap (18) in the inner side (15) of the hook (14).

2. Gripper (1) according to claim 1, characterised in that a contact means (7), which abuts against the gripper body's stop means (6) in the longitudinal direction (L) towards the holding section (4), is arranged on the insert (3) in the guiding section (5) of the gripper.

3. Gripper (1) according to claim 2, characterised in that at least 50% of an inner side (15), facing towards the holding section (4), of the hook (14) is formed by the insert (3).

4. Gripper (1) according to any one of the preceding claims, characterised in that the stop means (6) on the gripper body (2) is arranged longitudinally in the guiding section (5), in the end area thereof which is further away from the holding section (4).

5. Gripper (1) according to any one of the preceding claims, characterised in that the distance, in the longitudinal direction (L), between the stop means (6) and the end of the guiding section (5) nearer to the holding section (4) is at least twice as great as the distance, in the longitudinal direction, between the stop means (6) and the end of the guiding section (5) of the gripper (1) which is further away from the holding section (4).

6. Gripper (1) according to any one of the preceding claims 2 to 5, characterised in that the stop means (6) is arranged securely on the gripper body (2) and the contact means (7) securely on the insert (3).

7. Gripper (1) according to any one of the preceding claims 2 to 6, characterised in that the stop means (6) has a stop-surface element (8) with a surface normal (9) pointing, in the longitudinal direction (L), towards the end of the guiding section (5) of the gripper (1) which is further away from the holding section, and the contact means (7) has, arranged on the insert (6), a contact-surface element (10) with a surface normal (11) pointing, in the longitudinal direction (L), towards the holding section (2), and that the two surface elements (8, 10) are arranged such as to be mutually contiguous.

8. Gripper (1) according to any one of the preceding claims 2 to 8, characterised in that the stop means (6) is formed by a projection (12) on the gripper body (2) and the contact means (7) is formed by a depression (13) in the insert (3).

9. Gripper (1) according to claim 8, characterised in that the projection (12) is formed integrally with the gripper body (2).

10. Gripper (1) according to claim 8, characterised in that the projection (12) is formed by an additional part.

11. Gripper according to any one of the preceding claims, characterised in that the gripper body (2) and the insert (3) do not overlap in a lateral direction (B).

12. Gripper (1) according to any one of the preceding claims, characterised in that a bonding agent, in particular a solder, is disposed between the gripper body (2) and the insert (3).

13. Gripper (1) according to any one of the preceding claims, characterised in that the insert (3) comprises hard metal.

14. Gripper (1) according to any one of the preceding claims, characterised in that the gripper body (2) comprises a tool steel.

Images