Operating pliers for operating a hollow body and method for manufacturing the same

Abstract

The invention relates to an arm (10) of an operating clamp (1) for handling hollow bodies in a manufacturing unit for plastic containers, the operating clamp comprising two arms (10) for being held by a holding member and for gripping the hollow body, the arm (10) comprising a base (2) and a jaw (3) extending from the base (2), the base (2) having a front edge (30) for contacting the hollow body, the arm (10) being formed by: a metal core (4) extending in the jaw (3) after being retracted behind the front edge (30); and a plastic complement (5) at least partially covering the metal core (4), the plastic complement (5) constituting at least the front edge (30) and being fixed to the metal core (4).

Description

Technical Field

[0001] The field of the invention is that of maintenance of production units for producing containers from plastic preforms.

[0002] More specifically, the invention relates to operating tongs for handling hollow bodies, which grip the hollow bodies to be transported within a manufacturing cell. Background Art

[0003] To manufacture plastic containers, such as PET (polyethylene terephthalate) containers, preforms are first heated in a heating unit before being sent to a forming unit where they are inserted into a mold and a pressurized fluid is injected into the preform to stretch the plastic material against the mold walls, forming the container.

[0004] In the remainder of the description, hollow body will be used to denote preforms and finished containers which have been subjected to at least one blow moulding operation or stretch blow moulding operation.

[0005] In the container manufacturing cell, operating grippers transport preforms, blanks and containers from one station to another.

[0006] These clamps include two separate arms, and the two arms are generally symmetrical to each other.

[0007] The arm includes a base connected to the holding member and a jaw extending from the base. The jaw has a leading edge for contacting the hollow body when the hollow body is inserted into, withdrawn from, or clamped by the clamp.

[0008] These clamps are metal parts obtained through precision machining. In this way, the clamps can have precise characteristics to withstand the manufacturing conditions of the container (temperature, speed, forces, etc.).

[0009] The shape accuracy of these clamps is also particularly important to avoid that the front edge of the hollow body is left with marks by the clamps during the conveying of the hollow body. In fact, the marks of the clamps on the hollow body are a defect of the goods that can cause the cancellation of the purchase contract for the sale of the container to be manufactured and therefore having the same marks.

[0010] In practice, unfortunately, these clamps are fragile. In fact, in particular when preforms or containers are inserted into the clamps or when the hollow bodies held by the operating clamps are grasped by the operating member and pulled out from the clamps, these clamps are relatively frequently damaged.

[0011] In particular, during this extraction process, a sheathing force is generated, which corresponds to the force with which the hollow body is pulled out of the clamp. This sheathing can lead to bending of the clamp and subsequent damage.

[0012] These clamps are precision machined parts.

[0013] A container manufacturer may have a manufacturing cell that requires more than thirty different shapes of operating clamps. Therefore, no stock of replacement parts is built up. As a result, damage to the operating clamp results in a period of time during which the clamp cannot be replaced, or during which the manufacturing cell must be stopped. This leads to a loss of production.

[0014] Replacement of these clamps can also be expensive, especially if the orders are piecemeal and require very quick delivery.

[0015] Therefore, a situation in which one or more clamps are damaged is problematic since this results in a loss of production, or even downtime, as well as high costs for being able to quickly replace the clamps.

[0016] The object of the present invention is to remedy this situation. Summary of the invention

[0017] More specifically, the object of the present invention is to propose a solution aimed at at least temporarily remedying the drawbacks associated with damage to the handling grippers for handling hollow bodies in a manufacturing unit for plastic containers.

[0018] The invention also aims to provide a solution which makes it possible to quickly restart the production of containers at the same speed as before the damage.

[0019] Another object of the invention is to provide such a solution which does not incur unjustified additional costs to implement.

[0020] These objects and others that will appear later are achieved by the present invention, which relates to an arm of an operating clamp for handling hollow bodies in a manufacturing unit for plastic containers, the operating clamp comprising two arms for being held by a holding member and for gripping the hollow body, the arms comprising:

[0021] - a base having cooperating means for cooperating with the retaining member to establish the coupling of the arm to the retaining member;

[0022] - a jaw extending from the base and having a leading edge for contacting the hollow body;

[0023] Characterized in that the arm is formed by:

[0024] - a metal core, which at least partially constitutes the base and the cooperating means, which extends in the jaws retracted behind the front edge;

[0025] - a plastic complement at least partially covering the metal core, the plastic complement constituting at least the leading edge and being fixedly connected to the metal core.

[0026] Thanks to the arm of the clamp according to the invention, the clamp can be repaired partially or completely, quickly and without having the same high costs as a rush order of the clamp obtained by precision machining.

[0027] More precisely, the arms of the clamp according to the invention have a shape identical to that of the arms of the clamp to be repaired.

[0028] According to the principles of the invention, the arms of the clamp have a composite design of a metal core and a covered plastic complement. This composite design allows the incorporation of:

[0029] - a first part formed of standardized metal reinforcements, which are readily available and cheap and can therefore be manufactured in large quantities to constitute stocks;

[0030] A second part formed from a plastic material which can be produced easily and quickly, in particular directly at the location of the manufacturing unit, while having low manufacturing costs.

[0031] This composite design allows the clamp to be changed to support the manufacturing conditions of the container, especially the high temperatures of the oven of the manufacturing unit.

[0032] Although the composite clamp does not have a very long service life, it provides the operator of the manufacturing cell with sufficient time to provide an operating clamp of metal obtained by precision machining at a reasonable cost.

[0033] Since the replacement jaws according to the invention can be produced quickly on site, a shortage of replacement operating jaws in stock does not lead to particularly long production interruptions.

[0034] Finally, the leading edge made of plastic material has the ability to leave no mark on the hollow body in the manufacturing unit, as long as it is identical to the leading edge of the precision-machined clamp and the plastic used therein has a lower hardness than steel.

[0035] The plastic complement in fact allows the arms of the operating pliers according to the invention to be operated without damaging the hollow body.

[0036] This plastic material may be relatively brittle, but this brittleness is compensated by the presence of the metal core.

[0037] The arm of the pliers according to the invention also has the advantage that it can be easily and inexpensively adapted to be exchanged for operating pliers of different specifications.

[0038] In fact, the metal core can have a standardized design that allows for the production of operating jaws with different spacings (gaps). As for the plastic complement, it is designed in different ways to adapt to the desired final shape of the operating jaw to be replaced.

[0039] According to a first embodiment, the metal core comprises:

[0040] - a metal block which at least partially constitutes the base and the mating means;

[0041] - A metal rod which is connected to the metal block and extends from the metal block into the jaws.

[0042] The metal block, which essentially forms the base of the arm, is a strong, low-stress element in contrast to the jaws of the arms of the clamp. Therefore, the metal block can be produced by precision machining and can be reused.

[0043] The metal rod itself forms an element which is inexpensive to produce and can easily be replaced together with the reusable metal block during the manufacture of a new clamp arm.

[0044] Advantageously, the metal block has two cavities, each cavity being adapted to receive a metal rod for coupling the metal rod to the metal block, the cavities being arranged on either side of a central axis of the metal block.

[0045] Due to this design, the metal block can be used indiscriminately to produce the right or left arm of the clamp.

[0046] According to a second embodiment, the metal core is a flat metal plate.

[0047] The use of flat metal sheets proved to be particularly suitable, since this material has the ability to produce the structural resistance required of the metal core.

[0048] Such a metal plate also has low manufacturing costs.

[0049] The metal core can be obtained by machining, laser cutting or stamping the metal flat sheet.

[0050] It is worth noting that such a metal core does not necessarily have to be obtained by precision machining. Very advantageously, in contact with the hollow body is a plastic complement covering at least a portion of the metal core.

[0051] According to a preferred design, the metal core has at least one through hole arranged in the thickness thereof, and the plastic complement has two surfaces located on both sides of the through hole and is fixedly connected through the through hole.

[0052] In this way, the plastic complement is fastened to the metal core in a particularly strong manner.

[0053] As a result, the plastic complement is reinforced by the metal core and the metal core is optimally able to absorb the forces exerted on the plastic complement.

[0054] Preferably, the metal core is embedded in the plastic complement. In this case, the fixation of the plastic complement on the metal core is optimized and the ability of the metal core to absorb forces is enhanced.

[0055] This design also minimizes the amount of material used to form the metal core.Thus, the plastic complement forms the main part of the arm of the operating pliers according to the invention and ultimately constitutes the shape of the arm of the operating pliers.

[0056] Preferably, the plastic complement is a one-piece piece.

[0057] In this way, the strength of the plastic complement is optimized.

[0058] According to another possible embodiment, the plastic complement is made of at least two parts assembled to each other.

[0059] According to a preferred embodiment, the plastic complement is obtained by plastic additive manufacturing. Due to this embodiment, the plastic complement can be produced quickly and at low cost as required.

[0060] It should be noted that in this case, the plastic complement can be produced directly at the location of the plastic container manufacturing unit. This capability is particularly important for operators of manufacturing units who need to be able to respond quickly to damage to the hollow body handling clamps.

[0061] This additive manufacturing of plastics for producing the plastic complement also enables a very rapid adaptation to the shape of the plastic complement that one seeks to achieve.

[0062] The invention also relates to a method for manufacturing an arm of an operating pliers for operating a hollow body as described above.

[0063] The manufacturing method is characterized in that it comprises:

[0064] - preliminary steps for obtaining a metal core;

[0065] - a fixing step of fixing a plastic complement to the metal core, the plastic complement being implemented so as to at least partially cover the metal core.

[0066] In a preliminary step of obtaining the metal core, the metal core is manufactured or directly purchased.

[0067] The method enables rapid production of a handling clamp for handling hollow bodies of a manufacturing unit for plastic containers, the handling clamp having a feature capable of temporarily withstanding the constraints of the manufacturing unit without damaging the hollow body to be temporarily inserted, conveyed and extracted by the handling clamp.

[0068] This manufacturing method is therefore particularly suitable for being able to carry out temporary replacement of operating jaws obtained by precision machining, which may be damaged and whose rapid replacement would be very expensive or whose non-replacement would lead to a loss of production or to undesirable interruptions in production.

[0069] Advantageously, the manufacturing method comprises a step of additive manufacturing of the plastic complement.

[0070] Thus, the manufacturing method provides the ability to quickly adapt the shape of a plastic complement and to obtain such a plastic complement quickly and at low cost.

[0071] For example, an operating pliers for operating a hollow body according to the invention can be produced in less than one hour.

[0072] According to a preferred embodiment, the additive manufacturing step comprises:

[0073] - a first printing sub-step of printing an intermediate shape of the plastic complement having a cavity of the metal core, the cavity opening being on one face of the intermediate shape;

[0074] - a second printing sub-step of printing the final shape of the plastic complement from the intermediate shape;

[0075] The manufacturing method comprises an insertion step of inserting a metal core into a mold cavity presented by an intermediate shape, the insertion step being between a first printing sub-step and a second printing sub-step.

[0076] Then, during an additive manufacturing step, the metal core is at least partially embedded directly into the plastic complement.

[0077] This makes it possible to maximize the structural strength of the arm of the operating pliers according to the invention thus obtained.

[0078] More specifically, this additive manufacturing step promotes the adhesion of the plastic material of the plastic complement on the metal core.

[0079] Preferably, the metal core is heated prior to the inserting step.

[0080] The plastic material thus has better adhesion on the metal core.

[0081] According to an advantageous solution, before the insertion step, the metal core is at least partially covered with a printing lacquer.

[0082] In this case, it has been found that the adhesion of the plastic material to the metal core is further improved and the arms of the operating pliers obtained have a higher quality finish than arms of the operating pliers obtained by a method without printing lacquer. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Other characteristics and advantages of the invention will become more apparent from a reading of the following description of two preferred embodiments of the invention given by way of illustrative and non-limiting examples, and of the accompanying drawings, in which:

[0084] Figure 1 is a top perspective view of an operating pliers having an operating hollow body with two arms according to the present invention;

[0085] Figure 2is a top perspective view of an arm according to a first embodiment comprising a metal core and a plastic complement covering the metal core, the plastic complement being shown in a partial cross-section;

[0086] Figure 3 is a top perspective view of a metal core according to a first embodiment;

[0087] Figure 4 is a perspective view from below of an operating clamp for operating a hollow body, the operating clamp comprising two arms according to a second embodiment of the invention, one of which has its plastic complement removed and the other of which has its metal reinforcement shown in perspective through its plastic complement;

[0088] Figure 5 is a top perspective view of a metal block of a metal reinforcement of an arm according to a second embodiment;

[0089] Figure 6 is a top perspective view of a plastic complement of an arm according to a second embodiment. DETAILED DESCRIPTION

[0090] The term "hollow body" is used hereinafter to denote preforms and finished containers which have been subjected to at least one blow moulding operation or stretch blow moulding operation.

[0091] refer to Figure 1 , shows a handling tongs 1 for handling hollow bodies. Such a handling tongs 1 is used in a production unit for plastic containers, which comprises the following machines: blow molding machine, filling machine, labeling machine, etc.

[0092] The operating pliers 1 comprise two arms 10 .

[0093] The two arms 10 are designed to be held by a holding member (not shown) of a manufacturing unit. To this end, each arm 10 comprises cooperating means 20 for cooperating with the holding member to establish the coupling of the arm 10 with the holding member.

[0094] The arms 10 are used to grasp the hollow body by its neck. The two arms 10 together define a receiving space 100 for receiving the hollow body when the hollow body is grasped.

[0095] The hollow body is essentially nested in this receiving space 100 .

[0096] More specifically, each arm 10 is held in place by a retaining member, and these arms 10 have only relative mobility with respect to one another for allowing insertion, delivery and extraction of the hollow body.

[0097] refer to Figure 1 , Figure 2 and Figure 4 , each arm 10 comprises:

[0098] - base 2;

[0099] - Jaws 3 extending from the base 2 .

[0100] The base 2 has cooperating means 20 for cooperating with the retaining member to establish the coupling of the arm 10 to the retaining member. These cooperating means take the shape of through holes passing through the base 2.

[0101] The base 2 has a substantially rectangular parallelepiped shape.

[0102] The jaws 3 themselves have a front edge 30 for contacting the hollow body.

[0103] More specifically, refer to Figure 1 , Figure 2 and Figure 4 , jaw 3 comprises:

[0104] - a body 310 which extends directly from the base 2;

[0105] A head 311 situated at the end of the body 310 opposite the base 2 with respect to the body 310 and having a front edge 30 .

[0106] like Figure 1 , Figure 4 and Figure 6 As shown, the front edge 30 comprises a recess 300 . The neck of the hollow body gripped by the operating pliers 1 rests on the recess 300 provided by each arm 10 of the operating pliers 1 .

[0107] Therefore, the shape of the arms 10 of the operating pliers 1 according to the invention is identical to the shape of the arms of the original metal operating pliers.

[0108] These original metal operating pliers are produced by precision machining. When the arm of the original operating pliers is damaged, the arm 10 according to the present invention is used to temporarily replace the damaged arm.

[0109] According to the principles of the present invention and with reference to Figures 1 to 6 , the arm 10 is formed by a metal core 4 and a plastic complement 5 .

[0110] The metal core 4 at least partially constitutes the base 2 and the mating means 20 .

[0111] refer to Figure 2 and Figure 4 , the metal core 4 extends in the jaws 3 retracted behind the front edge 30. The metal core 4 extending in the jaws 3 has the function of reinforcing the jaws.

[0112] Thus, in the jaw 3 , more specifically in the head 311 of the jaw 3 , the end of the metal core 4 has a portion that is set back behind the leading edge 30 and is located along the leading edge.

[0113] According to the principles of the present invention and with reference to Figures 1 to 6 , Plastic complement 5:

[0114] - at least partially covers the metal core 4;

[0115] - forms at least the front edge 30 of the jaw 3.

[0116] By the expression “the plastic complement constitutes at least the leading edge” it is understood that only the plastic complement forms the leading edge 30. The metal core 4 does not form or constitute at least a part of this leading edge 30. Thus, only the plastic complement 5 of the arm 10 of the operating pliers 1 according to the invention can come into contact with the hollow body.

[0117] The plastic complement 5 is fixedly connected to the metal core 4 .

[0118] according to Figures 1 to 3 In the embodiment shown, the plastic complement 5 covers the entirety of the metal core 4 except for the first through hole 41 located in the base 2 .

[0119] refer to Figure 1 and Figure 2 , the metal core 4 is partially buried in the plastic complement 5.

[0120] The plastic complement 5 is in particular a monolithic part and is in particular obtained by additive manufacturing of plastic.

[0121] In other words, the plastic complement 5 is produced by three-dimensional printing (3D printing) around the metal core 4 .

[0122] The plastic complement 5 has a moulding cavity allowing it to accommodate the metal core 4 of the metal core.

[0123] The mold cavity corresponds in particular to the outer shape of the metal core 4 with a gap of 0.1 mm added.

[0124] refer to Figure 2 , the metal core 4 is flat and more specifically is produced in a metal flat plate.

[0125] More specifically, the metal core is obtained by laser cutting a flat metal plate.

[0126] The metal core 4 comprises:

[0127] - a first through hole 41 which is used to participate in the formation of the mating means 20;

[0128] - a second through hole 42;

[0129] - a third through hole 43 .

[0130] The second through hole 42 and the third through hole 43 participate in fixing the plastic complement 5 to the metal core 4 .

[0131] In fact, the plastic complement 5 has two faces situated on either side of the second through hole 42 and the third through hole 43 , and the plastic complement is fixed by means of these through holes 42 , 43 .

[0132] More specifically, the metal core 4 extends longitudinally and has:

[0133] - a first section 401 comprising a first through hole 41;

[0134] A second section 402 comprising a second through hole 42 and a third through hole 43;

[0135] - Third section 403.

[0136] according to Figure 2 and Figure 3 , by cooperating with plastic complement 5:

[0137] a first section 401 of the metal core 4 participates in forming the base 2 of the arm 10 ;

[0138] - the second section 402 of the metal core 4 participates in forming the body 310 of the jaws 3;

[0139] The third section 403 of the metal core 4 participates in forming the head 311 of the jaw 3 .

[0140] The third section 403 of the metal core 4 has, in particular, a curved shape which is matched to the shape of the front edge 30 formed by the plastic complement 5 .

[0141] according to Figures 4 to 6 In the second embodiment shown, the plastic complement 5 covers a portion of the metal core 4 .

[0142] Furthermore, according to the second embodiment, the metal core 4 comprises:

[0143] - a metal block 45;

[0144] A metal rod 46 which is coupled to the metal block 45 .

[0145] The metal block 45 at least partially constitutes the base and the mating means.

[0146] A metal rod 46 extends from the metal block 45 into the jaws 3 .

[0147] The metal block 45 has a first through hole 41 , which is used to participate in the formation of the fitting device 20 .

[0148] In order to allow the attachment of the metal rod 46 , the metal block 45 has two chambers 450 , each chamber being suitable for receiving a metal rod 46 .

[0149] refer to Figure 5 These chambers 450 are arranged on both sides of the symmetry center plane P of the metal block 45.

[0150] like Figure 4 As shown, the metal block 45 is designed to manufacture the right arm 10 a or the left arm 10 b of the operating pliers 1 for operating the hollow body.

[0151] If the plastic complement 5 is damaged, the metal block 45 can be reused.

[0152] The metal block 45 can be produced by precision machining.

[0153] To manufacture the right arm 10 a or the left arm 10 b , the metal rod 46 must be inserted into the appropriate cavity 450 .

[0154] The plastic complement 5 then completely covers the metal rod 46 and partially covers the metal block 45 .

[0155] The metal block 45 has special protrusions on its surface for being covered by the plastic complement 5. This special protrusion is used to improve the fixing of the plastic complement 5 to the metal block 45.

[0156] More specifically, if Figure 4 and Figure 5 As shown, the metal block 45 comprises an end 47 with a T-shaped profile and a notch 471 perpendicular to the T-shaped profile, from which the plastic complement 5 extends.

[0157] In other words, the metal block 45 has two protrusions 470 at the end 47 thereof, one of which is located on the upper surface of the end 47 and the other is located on the lower surface of the end 47. The notch 471 extends perpendicularly to the protrusions 470 through the centers of the two protrusions.

[0158] refer to Figure 6 , plastic complement 5 has:

[0159] - two grooves 51 complementary in shape to the tab 470;

[0160] A flange 52 of complementary shape to the recess 471 .

[0161] Of course, the plastic complement 5 also has a hole 53 that is complementary in shape to the metal rod 46 .

[0162] The arm 10 of the operating pliers 1 is obtained by the manufacturing method according to the invention.

[0163] The manufacturing method comprises:

[0164] - Preparatory steps for obtaining the metal core 4;

[0165] A fixing step of fixing the plastic complement 5 to the metal core 4 , the plastic complement 5 being implemented so as to cover at least a portion of the metal core 4 .

[0166] The preparatory step for obtaining the metal core 4 is to carry out a method of manufacturing the metal core 4 or obtaining the metal core.

[0167] For example, in the case where the metal core 4 includes a metal block 45 produced by precision machining, the metal block 45 may be purchased.

[0168] The manufacturing method advantageously comprises an additive manufacturing step of additively manufacturing the plastic complement 5 .

[0169] The consolidation step can then take place simultaneously with the additive manufacturing step, for example if the plastic complement 5 is in one piece and is at least partially embedded in the metal core 4 .

[0170] In this case, the additive manufacturing steps include, in sequence:

[0171] - A first printing sub-step, printing the intermediate shape of the plastic complement 5;

[0172] - a second printing sub-step of printing the final shape of the plastic complement from the intermediate shape;

[0173] The additive manufacturing step is advantageously parameterized by a three-dimensional drawing of the original operating jaws produced by precision machining. This three-dimensional drawing is re-machined by subtracting the volume of the metal core to be at least partially embedded, with a clearance of 0.1 mm.

[0174] The intermediate shape of the plastic complement 5 has a cavity for the metal core 4 which opens on one of the faces of the intermediate shape.

[0175] The manufacturing method thus comprises an insertion step of the metal core 4 into the mould cavity presented by the intermediate shape of the plastic complement 5 .

[0176] This insertion step is interposed between the first printing sub-step and the second printing sub-step to allow the metal core 4 to be at least partially buried in the plastic complement 5 , thereby assembling the metal core 4 and the plastic complement 5 .

[0177] In order to improve the adhesion of the plastic complement 5 on the metal core 4 , the metal core 4 is heated before the insertion step.

[0178] For example, if the material used for printing the plastic complement 5 is provided with a heated printing plate, the metal core 4 is placed on this printing plate before the first printing sub-step.

[0179] Furthermore, before the insertion step, the metal core 4 is at least partially covered with a printing lacquer.

[0180] Printing lacquer corresponds to a product sprayed on a surface intended to come into contact with a 3D printing material. This printing lacquer makes it possible to improve the adhesion (or in other words "adhesion") of the material printed on the surface sprayed with the lacquer.

[0181] The production unit of the plastic container can be combined with a three-dimensional printer implementing the production method according to the invention.

[0182] Advantageously, the printer comprises a selection interface for selecting the clamps to be produced and connection means to a remote server providing protocols for operating the clamps.

[0183] Thus, the production of the operating tongs is initiated by means of a selection interface which causes a connection to a remote server and the downloading of a recipe corresponding to the desired operating tongs.

[0184] The remote server may be located at and managed by the designer of the manufacturing unit for the container, so that the designer can quickly make changes to various operating clamp solutions, such as correcting identified manufacturing defects, all of which is transparent to the end user who only needs to start manufacturing the operating clamp.

Claims

1. An arm (10) of an operating clamp (1), the operating clamp being used for operating a hollow body in a manufacturing unit for plastic containers, the operating clamp comprising two arms (10) for being held by a holding member and for gripping the hollow body, the arms (10) comprising: - a base (2) having cooperating means (20) for cooperating with the retaining member to establish the coupling of the arm (10) to the retaining member; - a jaw (3) extending from the base (2) and having a leading edge (30) for contacting the hollow body; Characterized in that the arm (10) is formed by: a metal core (4) which at least partially forms the fitting means (20), the metal core (4) extending in the jaws (3) retracted behind the front edge (30); - a plastic complement (5) at least partially covering the metal core (4), the plastic complement (5) constituting at least the leading edge (30) and being fixedly connected to the metal core (4); The metal core (4) comprises: - a metal block (45) which at least partially constitutes the fitting device (20); - a metal rod (46) connected to the metal block (45) and extending from the metal block (45) into the jaws (3); The metal block (45) has two chambers (450), each chamber is suitable for accommodating a metal rod (46) to connect the metal rod to the metal block (45), and the two chambers (450) are symmetrical to each other relative to a symmetry center plane (P) of the metal block (45).

2. An arm (10) of an operating clamp (1) according to claim 1, characterized in that The metal core (4) has at least one through hole arranged in its thickness, and the plastic complement (5) has two surfaces located on both sides of the through hole and is fixedly connected through the through hole.

3. The arm (10) of the operating pliers (1) according to claim 1, characterized in that The metal core (4) is embedded in the plastic complement (5).

4. The arm (10) of the operating pliers (1) according to claim 1, characterized in that The plastic complement (5) is a one-piece piece.

5. The arm (10) of the operating pliers (1) according to claim 1, characterized in that The plastic complement (5) is obtained by plastic additive manufacturing.

6. Method for manufacturing an arm (10) of an operating clamp (1) according to any one of claims 1 to 5, the operating clamp being used for operating a hollow body, characterized in that The manufacturing method includes: - a preliminary step of obtaining a metal core (4); - a step of fastening the plastic complement (5) to the metal core (4), the plastic complement (5) being implemented so as to at least partially cover the metal core (4); The manufacturing method also includes an additive manufacturing step of the plastic complement (5); Additive manufacturing steps include: - a first printing sub-step, printing an intermediate shape of the plastic complement (5), the intermediate shape having a cavity of the metal core (4), the cavity opening being on one face of the intermediate shape; - a second printing sub-step, printing the final shape of the plastic complement (5) from the intermediate shape; The manufacturing method comprises an inserting step of inserting a metal core (4) into a mold cavity represented by an intermediate shape, the inserting step being between a first printing sub-step and a second printing sub-step.

7. The manufacturing method according to claim 6, characterized in that: The metal core (4) is heated prior to the insertion step.

8. The manufacturing method according to any one of claims 6 and 7, characterized in that: Prior to the insertion step, the metal core (4) is at least partially covered with a printing lacquer.

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