Suction cup with lip having reduced hardness polymeric material at rim portion

Abstract

To provide a suction cup having a lip made of a polymeric material different from the rest of the suction cup while reducing or avoiding the formation of cracks.SOLUTION: A suction cup for an automated gripping operation, such as for lifting an object, is disclosed, wherein a rim portion (30) of a lip (20) of the suction cup is made of a first polymeric material having a first hardness that is low compared to a second hardness of a second polymeric material of an inner central portion (40) of the lip (20). The first and second polymeric materials of the lip (20) of the disclosed suction cup are bonded to one another with an overlap (50). The coupling can be achieved by injection molding of the suction cup.SELECTED DRAWING: Figure 2A

Description

[Technical Field]

[0001] The present invention relates generally to suction cups for automated gripping operations, such as for lifting objects, and more particularly to suction cups in which a rim portion of the lip of the suction cup is made of a first polymeric material having a lower hardness compared to a second polymeric material from which a central portion of the lip is made. The first and second polymeric materials of the lip of the suction cup are bonded to one another with an overlap. The bonding can be achieved by injection molding. [Background technology]

[0002] Suction cups are well known in the art of automated gripping operations and are intended to be fluidly connected to a vacuum source.

[0003] EP 2411314 for example discloses a suction cup with a replaceable sealing surface so that the lip of the suction cup can be replaced. The lip can be suitably snap-fit ​​onto the body of the suction cup, for example a bellows.

[0004] In some applications, it may be desirable to have the lip made from a different polymeric material than the polymeric material of the rest of the suction cup, for example when different properties of the polymeric material of the lip, for example with respect to flexibility, are desired compared to the properties of the polymeric material of the rest of the suction cup.

[0005] Two-component bellows suction cups made from silicone are available from Schmalz (DE) under the trade name "Bellows Suction Cups PSPF," and the high-strength 2C connection between the bellows and the sealing lip is said to combine sophisticated material properties in one suction cup.

[0006] The inventors have found that a problem that can arise when two polymeric materials are used and combined, as in the prior art, is that the lip tends to form cracks, thereby shortening the expected lifespan of the suction cup compared to the lifespan of a suction cup made from the same polymeric material as the rest of the suction cup to which it is connected, e.g., a bellows. When this happens, the entire suction cup must be replaced. If not replaced, the cracks will eventually penetrate the polymeric material, risking the release of part of the lip and the risk of the object being gripped in an incorrect manner, which may result in damage to the incorrectly gripped object.

[0007] It would be desirable to provide a suction cup having a lip made from a different polymeric material than the rest of the suction cup while reducing or avoiding the formation of cracks.

[0008] According to the present invention, the above object is achieved by a suction cup according to independent claim 1, comprising a lip, the outer rim portion of which is made from a polymeric material having reduced hardness compared to the hardness of the polymeric material of the central portion of the lip, extending in a radially inward direction so as to partially overlap the inner central portion of the lip, the outer rim portion and the central portion being bonded to each other in the area of ​​overlap, the bonding of the two materials being advantageously achieved by injection molding. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] European Patent No. 2411314 Summary of the Invention [Means for solving the problem]

[0010] Thus, in a first aspect, the present invention relates to a suction cup (10) for use in automated gripping operations, configured to be fluidly connected to a vacuum source (not shown), comprising a lip (20) having an outer rim portion (40) made of a first polymeric material of a first hardness and a second polymeric material of a second hardness lower than the first polymeric material, wherein the lip (20) presents an inner central portion (30) made of the first polymeric material, the outer rim portion (40) of the lip (20) extending radially inwardly thereby forming an area of ​​overlap (50) with the inner central portion (30) of the lip (20) on an upper side (35) or a lower side (37) of the inner central portion (30) of the lip (20), and wherein in the area of ​​overlap (50) the first and second polymeric materials are bonded to each other.

[0011] The overlap of the present invention provides an increased bond area compared to the prior art, where there is no overlap 50 and the bond is only achieved at the boundary layer along the rim of the area where two different polymeric materials meet and abut one another.

[0012] Additionally, the present invention's overlap 50 allows for flexing of the lower hardness outer rim portion 40 within the same polymeric material without involving tension forces acting at the interface between two different first and second polymeric materials, thereby avoiding undesirable flexing at the bond interface between the two different polymeric materials.

[0013] The overlap 50 of the present invention allows for the use of softer polymeric materials with polymeric materials having lower hardness than would be possible in the prior art where there is only an edge bond along the cross section of the lip / bellows. The enhanced bonding surface 50 can also compensate for the reduced bonding capacity of softer polymeric materials due, for example, to the presence of plasticizers in such softer materials.

[0014] Also, in the overlap 50 region of the present invention, the harder polymeric material underlying or overlying 30 can also act as a stabilizer for the entire lip 20 such that flexing in the inner central portion 30 of the lip 20 is reduced.

[0015] The overlap 50 of the present invention allows the outer rim portion 40 of the lip 20 to be thinner.

[0016] The overlap 50 of the present invention allows the lip 20 to have a natural / intended bending area that is located within the very same more flexible polymeric material.

[0017] The present invention's use of two different polymeric materials for the lip 20, including the overlap 50, facilitates providing the lip 20 with differentiated properties, primarily with respect to flexibility, along the radial direction of the lip from the harder central inner portion 30 to the softer outer rim portion 40. The flexibility of the lip 20 and the sealing ability of the lip 20 may also increase as one progresses radially from the harder central inner portion 30 to the softer outer rim portion 40.

[0018] The overlap of the present invention allows for improved lip life.

[0019] The suction cup 10 of the present invention is suitably manufactured using injection molding, for example two-component injection molding.

[0020] It is generally preferred that the area of ​​overlap 50 of lip 20 with central portion 30 be formed on the upper side 35 of central portion 30 of lip 20 .

[0021] Thus, in a second aspect, the present invention relates to a method for manufacturing a suction cup (10) having a lip (20), the lip (20) being formed from two different polymeric materials using two-component injection molding, wherein a second polymeric material having a second hardness is injected into a cavity comprising an inner central portion (30) of the lip (20) made of a first polymeric material having a first hardness onto an upper side (35) of the central portion (30) of the lip (20) to form a region of overlap (50) of the two polymeric materials, the second hardness being lower than the first hardness, thereby bonding the two polymeric materials together in the region of overlap (50).

[0022] In an alternative embodiment, the area of ​​overlap 50 with the central portion 30 of the lip 20 is formed on the underside 37 of the central portion 30 of the lip 20 .

[0023] Thus, in a third aspect, the present invention relates to a method of manufacturing a suction cup (10) having a lip (20), the lip (20) being formed from two different polymeric materials using two-component injection molding, wherein a second polymeric material having a second hardness is injected into a cavity comprising an inner central portion (30) of the lip (20) made of a first material having a first hardness, onto an underside (37) of the central portion (30) of the lip (20) to form a region of overlap (50) of the two polymeric materials, the second hardness being lower than the first hardness, thereby bonding the two polymeric materials together in the region of overlap (50).

[0024] With the overlap 50 of the present invention, during lip flexure, instead of the tensile forces acting on the boundary layer of the prior art two-component lip, there are shear forces acting on the boundary layer, as shown in Figures 2B, 3A, and 4A.

[0025] Further embodiments and advantages of the present invention will become apparent from the following detailed description and appended claims. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 shows a cross section of a prior art suction cup 10 in which the outer rim portion of the lip 20 is joined to the inner central lip portion. [Figure 1A] 2 is a fragmentary view of Detail A of FIG. 1 showing the tensile forces acting on the interface in a prior art two-component lip by arrows. [Figure 2] 1 shows a cross-sectional view of an embodiment of the suction cup 10 of the present invention, exhibiting the lip 20, where the inner central underside 60 of the outer rim portion 40 extends essentially parallel to the upper side 35 of the inner central portion 30 of the lip 20. In the illustrated embodiment, the overlap region 50 of the present invention is formed on the upper side 35 of the inner central portion 30 of the lip 20. [Figure 2A] 3 is an enlarged view of detail A of FIG. 2, showing lip 20 of FIG. 2. [Figure 2B] 2B is an enlarged view of detail B of FIG. 2A, showing by arrows the shear forces acting on the bonding surfaces of the two-component lip 20 of the present invention shown in FIG. 2 at the area of ​​overlap 50. FIG. [Figure 3] 1 shows a cross section of another embodiment of the suction cup 10 of the present invention, illustrating the lip 20 having an inner central underside surface 60 of the outer rim portion 40 that is essentially flush with the outer underside surface 70 of the inner central portion 30 of the lip 20. In the illustrated embodiment, the overlap region 50 of the present invention is formed on the upper side 35 of the inner central portion 30 of the lip 20. [Figure 3A] 4 is an enlarged view of detail A of FIG. 3 showing by arrows the shear forces acting on the bonding surface of the two-component lip 20 of the present invention of FIG. 3. [Figure 4] 1 shows a cross-sectional view of yet another embodiment of the suction cup 10 of the present invention, in which the overlap region 50 of the present invention is formed on the underside 37 of the inner central portion 30 of the lip 20. [Figure 4A] 5 is an enlarged view of detail A of FIG. 4 showing by arrows the shear forces acting on the bonding surface of the two-component lip 20 of the present invention of FIG. 4. [Figure 5]1 shows a bottom view of one embodiment of a suction cup 10 of the present invention having a cleat 80 disposed on the underside of the lip 20 of the suction cup. In the illustrated embodiment, the overlap region 50 of the present invention is formed on the upper side 35 of the inner central portion 30 of the lip 20. DETAILED DESCRIPTION OF THE INVENTION

[0027] Although the top of the suction cup shown in Figures 1, 2 and 3 has been cut off, it will be apparent to one skilled in the art that the cut off portion of the suction cup may be similar to the top of the suction cup shown in Figure 4, for example.

[0028] For a suction cup to be suitable for use with high fluid flows through it, particularly if it also includes a bellows, the lip and bellows of the suction cup should be made of a polymeric material with a sufficient degree of hardness so that the bellows and lip are stable, reducing undesirable rocking of the suction cup under load and preventing the bellows and lip from collapsing inward or causing their inner surfaces to approach each other, thereby potentially preventing them from sticking together. At the same time, the lip should be soft and flexible to achieve the desired sealing action even with flexible materials, such as pouches or plastic bags. The present invention makes it possible to easily achieve such a combination.

[0029] In a typical embodiment of the suction cup of the present invention, the inner central portion 30 of the lip 20 is integrally formed with the bellows 25 from the same first polymeric material, while the outer rim portion 40 of the lip 20 is formed from a similar second polymeric material that is simply less hard than the first polymeric material.

[0030] The second polymeric material from which outer rim portion 40 is formed preferably does not extend beyond lip 20. Thus, the area of ​​overlap 50 of the first and second polymeric materials is preferably essentially limited to lip 20, as shown, for example, in Figures 2-4.

[0031] The first and second polymeric materials of the lip of the present invention can be selected from elastomeric polymeric materials, preferably thermoplastic elastomers (TPEs). Generally, thermoplastic elastomers can be subdivided into different categories: thermoplastic styrenic block copolymers (TPE-S), thermoplastic elastomeric polyolefins (TPE-O), thermoplastic vulcanizates (TPE-V), thermoplastic polyurethane elastomers (TPE-U), thermoplastic copolyester elastomers (TPE-E), and thermoplastic polyamide elastomers (TPE-A). Currently preferred categories are TPE-S, TPE-V, and TPE-U, especially TPE-S. While the first and second polymeric materials can be selected from different categories listed above, the compositions of the first and second polymeric materials should preferably be selected so that they share a common category. As an example, the first polymeric material can be composed of a blend of TPE-S and TPE-U, while the second polymeric material can be composed of TPE-S. More preferably, the first and second polymeric materials are selected from one and the same category.

[0032] The bonding of the first and second polymeric materials to each other in the overlap region can be achieved by an injection molding process, preferably in which a softer material is injected and bonded to a harder material. Any additional means for bonding the first and second polymeric materials to each other in the overlap region, such as mechanical or chemical means such as adhesives, are not required and are preferably not used. The bonding in the overlap region is preferably the result of injection molding, more specifically, a two-component injection molding process. Bonding or other adhesion of the first and second polymeric materials to each other is not required outside the overlap region. Thus, in a preferred embodiment, there is no other bonding or other adhesion of the first and second polymeric materials to each other outside the overlap region. The bonding of the first and second polymeric materials to each other in the overlap region is intended to be permanent. Therefore, the first and second polymeric materials should be permanently bonded to each other in the overlap region as a result of the molding process and should not be removable from each other.

[0033] The nature of the bond between the two polymeric materials is preferably a melt bond, which is conveniently achieved by using two-component injection molding in two cavities, with the inner central portion 30 of the lip 20 formed in a first cavity and then the outer rim portion 40 of the lip 20 formed in a second cavity, partially overlapping the inner central portion 30 of the lip 20, i.e., with an overlap 50 on either the upper side 35 or the lower side 37.

[0034] To improve bond strength, the surface area of ​​the first polymeric material in the region of overlap 50 can be enhanced by a pattern, such as a zigzag pattern, formed in the region of the overlap of the first material. Alternatively, the surface of the first polymeric material in the region of overlap 50 can exhibit blind holes (not shown) into which the second polymeric material enters during its injection. This allows anchors (not shown) of the second polymeric material to be formed in the first polymeric material, enhancing adhesion between the polymeric materials.

[0035] The two different polymeric materials can be made or selected to exhibit different colors, with a particular color indicating, for example, a particular hardness and / or a particular category of TPE.

[0036] Cleats 80 may be advantageously provided on the inner central portion 30 of lip 20 and / or the outer rim portion 40 of lip 20, particularly on the inner central underside 60 of outer rim portion 40 of lip 20, as shown, for example, in Figure 5. Cleats 80, when present, function to ensure a constant distance of the central portions of the undersides 60, 70 of lip 20 to the object to be gripped (not shown), thereby allowing for improved suction of outer rim portion 40.

[0037] If a bellows is included, the harder material of the central portion 30 of the lip 20, and typically the bellows, is typically selected to exhibit a Shore A hardness of up to 100, e.g., in the range of 40 to 90, e.g., about 60, and the softer material of the outer rim portion 40 of the lip 20 is typically selected to exhibit a Shore A hardness of 10 to 60, e.g., about 30. Typically, the two materials are selected so that the difference in hardness between the hard and soft material is in the range of 15 to 45 Shore A. [Explanation of symbols]

[0038] 10 suction cups 20 Lip 25 Bellows 30 Inner center of lip 20 35 Upper side of the inner center part of lip 20 37 Underside of the inner center part of lip 20 40 Lip 20 outer rim part 50 Area of ​​overlap 60 Lower surface of the inner center of the outer rim part of lip 20 70 The outer underside of the inner central part of the lip 20 80 Cleats

Claims

1. 1. A suction cup for use in automated gripping operations, configured to be fluidly connected to a vacuum source, the suction cup comprising a lip having an outer rim portion made of a first polymeric material having a first hardness and a second polymeric material having a second hardness lower than the first polymeric material, the lip presents an inner central portion made of the first polymeric material, the outer rim portion of the lip extends radially inwardly thereby forming an area of ​​overlap with the central portion of the lip above or below the central portion of the lip, and in the area of ​​overlap, the first and second polymeric materials are bonded to one another; Features a suction cup.

2. 2. The suction cup of claim 1, wherein the outer rim portion of the lip extends radially inwardly, thereby forming the area of ​​overlap with the central portion of the lip above the central portion of the lip.

3. 2. The suction cup of claim 1, wherein the outer rim portion of the lip extends radially inwardly, thereby forming the area of ​​overlap with the central portion of the lip on the underside of the central portion of the lip.

4. 3. The suction cup of claim 2, wherein an inner central lower surface of said outer rim portion is essentially flush with an outer lower surface of said inner central portion of said lip.

5. 3. The suction cup of claim 2, wherein an inner central underside of the outer rim portion extends essentially parallel to the upper side of the central portion of the lip.

6. 6. A suction cup according to claim 4 or 5, wherein the inner central underside of the outer rim portion of the lip presents a cleat.

7. 7. A suction cup according to any one of claims 2 to 6, wherein the underside of the inner central portion of the lip presents cleats.

8. A suction cup according to any one of claims 1 to 7, wherein the first and second polymeric materials are thermoplastic elastomers.

9. 1. A method of manufacturing a suction cup having a lip formed from two different polymeric materials using two-component injection molding, comprising: injecting a second polymeric material having a second hardness into a cavity containing an inner central portion of the lip made of a first polymeric material having a first hardness and above the central portion of the lip to form an area of ​​overlap of the two polymeric materials, the second hardness being less than the first hardness, thereby bonding the two polymeric materials together in the area of ​​overlap; A method for manufacturing a suction cup, comprising:

10. 1. A method of manufacturing a suction cup having a lip formed from two different polymeric materials using two-component injection molding, comprising: and injecting a second polymeric material into a cavity containing an inner central portion of the lip made of a first polymeric material having a first hardness and underneath the central portion of the lip to form an area of ​​overlap of the two polymeric materials, the second hardness being less than the first hardness, thereby bonding the two polymeric materials together in the area of ​​overlap. A method for manufacturing a suction cup, comprising:

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